// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;
pragma experimental ABIEncoderV2;

import "@balancer-labs/v2-interfaces/contracts/pool-linear/IStaticAToken.sol";

import "../LinearPool.sol";

contract AaveLinearPool is LinearPool {
    ILendingPool private immutable _lendingPool;

    struct ConstructorArgs {
        IVault vault;
        string name;
        string symbol;
        IERC20 mainToken;
        IERC20 wrappedToken;
        address assetManager;
        uint256 upperTarget;
        uint256 swapFeePercentage;
        uint256 pauseWindowDuration;
        uint256 bufferPeriodDuration;
        address owner;
    }

    constructor(ConstructorArgs memory args)
        LinearPool(
            args.vault,
            args.name,
            args.symbol,
            args.mainToken,
            args.wrappedToken,
            args.upperTarget,
            _toAssetManagerArray(args),
            args.swapFeePercentage,
            args.pauseWindowDuration,
            args.bufferPeriodDuration,
            args.owner
        )
    {
        _lendingPool = IStaticAToken(address(args.wrappedToken)).LENDING_POOL();
        _require(address(args.mainToken) == IStaticAToken(address(args.wrappedToken)).ASSET(), Errors.TOKENS_MISMATCH);
    }

    function _toAssetManagerArray(ConstructorArgs memory args) private pure returns (address[] memory) {
        // We assign the same asset manager to both the main and wrapped tokens.
        address[] memory assetManagers = new address[](2);
        assetManagers[0] = args.assetManager;
        assetManagers[1] = args.assetManager;

        return assetManagers;
    }

    function _getWrappedTokenRate() internal view override returns (uint256) {
        // This pulls in the implementation of `rate` used in the StaticAToken contract
        // except avoiding storing relevant variables in storage for gas reasons.
        // solhint-disable-next-line max-line-length
        // see: https://github.com/aave/protocol-v2/blob/ac58fea62bb8afee23f66197e8bce6d79ecda292/contracts/protocol/tokenization/StaticATokenLM.sol#L255-L257
        uint256 rate = _lendingPool.getReserveNormalizedIncome(address(getMainToken()));

        // This function returns a 18 decimal fixed point number, but `rate` has 27 decimals (i.e. a 'ray' value)
        // so we need to convert it.
        return rate / 10**9;
    }
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;

import "@balancer-labs/v2-interfaces/contracts/solidity-utils/helpers/BalancerErrors.sol";
import "@balancer-labs/v2-interfaces/contracts/solidity-utils/helpers/IAuthentication.sol";

/**
 * @dev Building block for performing access control on external functions.
 *
 * This contract is used via the `authenticate` modifier (or the `_authenticateCaller` function), which can be applied
 * to external functions to only make them callable by authorized accounts.
 *
 * Derived contracts must implement the `_canPerform` function, which holds the actual access control logic.
 */
abstract contract Authentication is IAuthentication {
    bytes32 private immutable _actionIdDisambiguator;

    /**
     * @dev The main purpose of the `actionIdDisambiguator` is to prevent accidental function selector collisions in
     * multi contract systems.
     *
     * There are two main uses for it:
     *  - if the contract is a singleton, any unique identifier can be used to make the associated action identifiers
     *    unique. The contract's own address is a good option.
     *  - if the contract belongs to a family that shares action identifiers for the same functions, an identifier
     *    shared by the entire family (and no other contract) should be used instead.
     */
    constructor(bytes32 actionIdDisambiguator) {
        _actionIdDisambiguator = actionIdDisambiguator;
    }

    /**
     * @dev Reverts unless the caller is allowed to call this function. Should only be applied to external functions.
     */
    modifier authenticate() {
        _authenticateCaller();
        _;
    }

    /**
     * @dev Reverts unless the caller is allowed to call the entry point function.
     */
    function _authenticateCaller() internal view {
        bytes32 actionId = getActionId(msg.sig);
        _require(_canPerform(actionId, msg.sender), Errors.SENDER_NOT_ALLOWED);
    }

    function getActionId(bytes4 selector) public view override returns (bytes32) {
        // Each external function is dynamically assigned an action identifier as the hash of the disambiguator and the
        // function selector. Disambiguation is necessary to avoid potential collisions in the function selectors of
        // multiple contracts.
        return keccak256(abi.encodePacked(_actionIdDisambiguator, selector));
    }

    function _canPerform(bytes32 actionId, address user) internal view virtual returns (bool);
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;

// solhint-disable

/**
 * @dev Reverts if `condition` is false, with a revert reason containing `errorCode`. Only codes up to 999 are
 * supported.
 * Uses the default 'BAL' prefix for the error code
 */
function _require(bool condition, uint256 errorCode) pure {
    if (!condition) _revert(errorCode);
}

/**
 * @dev Reverts if `condition` is false, with a revert reason containing `errorCode`. Only codes up to 999 are
 * supported.
 */
function _require(bool condition, uint256 errorCode, bytes3 prefix) pure {
    if (!condition) _revert(errorCode, prefix);
}

/**
 * @dev Reverts with a revert reason containing `errorCode`. Only codes up to 999 are supported.
 * Uses the default 'BAL' prefix for the error code
 */
function _revert(uint256 errorCode) pure {
    _revert(errorCode, 0x42414c); // This is the raw byte representation of "BAL"
}

/**
 * @dev Reverts with a revert reason containing `errorCode`. Only codes up to 999 are supported.
 */
function _revert(uint256 errorCode, bytes3 prefix) pure {
    uint256 prefixUint = uint256(uint24(prefix));
    // We're going to dynamically create a revert string based on the error code, with the following format:
    // 'BAL#{errorCode}'
    // where the code is left-padded with zeroes to three digits (so they range from 000 to 999).
    //
    // We don't have revert strings embedded in the contract to save bytecode size: it takes much less space to store a
    // number (8 to 16 bits) than the individual string characters.
    //
    // The dynamic string creation algorithm that follows could be implemented in Solidity, but assembly allows for a
    // much denser implementation, again saving bytecode size. Given this function unconditionally reverts, this is a
    // safe place to rely on it without worrying about how its usage might affect e.g. memory contents.
    assembly {
        // First, we need to compute the ASCII representation of the error code. We assume that it is in the 0-999
        // range, so we only need to convert three digits. To convert the digits to ASCII, we add 0x30, the value for
        // the '0' character.

        let units := add(mod(errorCode, 10), 0x30)

        errorCode := div(errorCode, 10)
        let tenths := add(mod(errorCode, 10), 0x30)

        errorCode := div(errorCode, 10)
        let hundreds := add(mod(errorCode, 10), 0x30)

        // With the individual characters, we can now construct the full string.
        // We first append the '#' character (0x23) to the prefix. In the case of 'BAL', it results in 0x42414c23 ('BAL#')
        // Then, we shift this by 24 (to provide space for the 3 bytes of the error code), and add the
        // characters to it, each shifted by a multiple of 8.
        // The revert reason is then shifted left by 200 bits (256 minus the length of the string, 7 characters * 8 bits
        // per character = 56) to locate it in the most significant part of the 256 slot (the beginning of a byte
        // array).
        let formattedPrefix := shl(24, add(0x23, shl(8, prefixUint)))

        let revertReason := shl(200, add(formattedPrefix, add(add(units, shl(8, tenths)), shl(16, hundreds))))

        // We can now encode the reason in memory, which can be safely overwritten as we're about to revert. The encoded
        // message will have the following layout:
        // [ revert reason identifier ] [ string location offset ] [ string length ] [ string contents ]

        // The Solidity revert reason identifier is 0x08c739a0, the function selector of the Error(string) function. We
        // also write zeroes to the next 28 bytes of memory, but those are about to be overwritten.
        mstore(0x0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
        // Next is the offset to the location of the string, which will be placed immediately after (20 bytes away).
        mstore(0x04, 0x0000000000000000000000000000000000000000000000000000000000000020)
        // The string length is fixed: 7 characters.
        mstore(0x24, 7)
        // Finally, the string itself is stored.
        mstore(0x44, revertReason)

        // Even if the string is only 7 bytes long, we need to return a full 32 byte slot containing it. The length of
        // the encoded message is therefore 4 + 32 + 32 + 32 = 100.
        revert(0, 100)
    }
}

library Errors {
    // Math
    uint256 internal constant ADD_OVERFLOW = 0;
    uint256 internal constant SUB_OVERFLOW = 1;
    uint256 internal constant SUB_UNDERFLOW = 2;
    uint256 internal constant MUL_OVERFLOW = 3;
    uint256 internal constant ZERO_DIVISION = 4;
    uint256 internal constant DIV_INTERNAL = 5;
    uint256 internal constant X_OUT_OF_BOUNDS = 6;
    uint256 internal constant Y_OUT_OF_BOUNDS = 7;
    uint256 internal constant PRODUCT_OUT_OF_BOUNDS = 8;
    uint256 internal constant INVALID_EXPONENT = 9;

    // Input
    uint256 internal constant OUT_OF_BOUNDS = 100;
    uint256 internal constant UNSORTED_ARRAY = 101;
    uint256 internal constant UNSORTED_TOKENS = 102;
    uint256 internal constant INPUT_LENGTH_MISMATCH = 103;
    uint256 internal constant ZERO_TOKEN = 104;

    // Shared pools
    uint256 internal constant MIN_TOKENS = 200;
    uint256 internal constant MAX_TOKENS = 201;
    uint256 internal constant MAX_SWAP_FEE_PERCENTAGE = 202;
    uint256 internal constant MIN_SWAP_FEE_PERCENTAGE = 203;
    uint256 internal constant MINIMUM_BPT = 204;
    uint256 internal constant CALLER_NOT_VAULT = 205;
    uint256 internal constant UNINITIALIZED = 206;
    uint256 internal constant BPT_IN_MAX_AMOUNT = 207;
    uint256 internal constant BPT_OUT_MIN_AMOUNT = 208;
    uint256 internal constant EXPIRED_PERMIT = 209;
    uint256 internal constant NOT_TWO_TOKENS = 210;
    uint256 internal constant DISABLED = 211;

    // Pools
    uint256 internal constant MIN_AMP = 300;
    uint256 internal constant MAX_AMP = 301;
    uint256 internal constant MIN_WEIGHT = 302;
    uint256 internal constant MAX_STABLE_TOKENS = 303;
    uint256 internal constant MAX_IN_RATIO = 304;
    uint256 internal constant MAX_OUT_RATIO = 305;
    uint256 internal constant MIN_BPT_IN_FOR_TOKEN_OUT = 306;
    uint256 internal constant MAX_OUT_BPT_FOR_TOKEN_IN = 307;
    uint256 internal constant NORMALIZED_WEIGHT_INVARIANT = 308;
    uint256 internal constant INVALID_TOKEN = 309;
    uint256 internal constant UNHANDLED_JOIN_KIND = 310;
    uint256 internal constant ZERO_INVARIANT = 311;
    uint256 internal constant ORACLE_INVALID_SECONDS_QUERY = 312;
    uint256 internal constant ORACLE_NOT_INITIALIZED = 313;
    uint256 internal constant ORACLE_QUERY_TOO_OLD = 314;
    uint256 internal constant ORACLE_INVALID_INDEX = 315;
    uint256 internal constant ORACLE_BAD_SECS = 316;
    uint256 internal constant AMP_END_TIME_TOO_CLOSE = 317;
    uint256 internal constant AMP_ONGOING_UPDATE = 318;
    uint256 internal constant AMP_RATE_TOO_HIGH = 319;
    uint256 internal constant AMP_NO_ONGOING_UPDATE = 320;
    uint256 internal constant STABLE_INVARIANT_DIDNT_CONVERGE = 321;
    uint256 internal constant STABLE_GET_BALANCE_DIDNT_CONVERGE = 322;
    uint256 internal constant RELAYER_NOT_CONTRACT = 323;
    uint256 internal constant BASE_POOL_RELAYER_NOT_CALLED = 324;
    uint256 internal constant REBALANCING_RELAYER_REENTERED = 325;
    uint256 internal constant GRADUAL_UPDATE_TIME_TRAVEL = 326;
    uint256 internal constant SWAPS_DISABLED = 327;
    uint256 internal constant CALLER_IS_NOT_LBP_OWNER = 328;
    uint256 internal constant PRICE_RATE_OVERFLOW = 329;
    uint256 internal constant INVALID_JOIN_EXIT_KIND_WHILE_SWAPS_DISABLED = 330;
    uint256 internal constant WEIGHT_CHANGE_TOO_FAST = 331;
    uint256 internal constant LOWER_GREATER_THAN_UPPER_TARGET = 332;
    uint256 internal constant UPPER_TARGET_TOO_HIGH = 333;
    uint256 internal constant UNHANDLED_BY_LINEAR_POOL = 334;
    uint256 internal constant OUT_OF_TARGET_RANGE = 335;
    uint256 internal constant UNHANDLED_EXIT_KIND = 336;
    uint256 internal constant UNAUTHORIZED_EXIT = 337;
    uint256 internal constant MAX_MANAGEMENT_SWAP_FEE_PERCENTAGE = 338;
    uint256 internal constant UNHANDLED_BY_MANAGED_POOL = 339;
    uint256 internal constant UNHANDLED_BY_PHANTOM_POOL = 340;
    uint256 internal constant TOKEN_DOES_NOT_HAVE_RATE_PROVIDER = 341;
    uint256 internal constant INVALID_INITIALIZATION = 342;
    uint256 internal constant OUT_OF_NEW_TARGET_RANGE = 343;
    uint256 internal constant FEATURE_DISABLED = 344;
    uint256 internal constant UNINITIALIZED_POOL_CONTROLLER = 345;
    uint256 internal constant SET_SWAP_FEE_DURING_FEE_CHANGE = 346;
    uint256 internal constant SET_SWAP_FEE_PENDING_FEE_CHANGE = 347;
    uint256 internal constant CHANGE_TOKENS_DURING_WEIGHT_CHANGE = 348;
    uint256 internal constant CHANGE_TOKENS_PENDING_WEIGHT_CHANGE = 349;
    uint256 internal constant MAX_WEIGHT = 350;
    uint256 internal constant UNAUTHORIZED_JOIN = 351;
    uint256 internal constant MAX_MANAGEMENT_AUM_FEE_PERCENTAGE = 352;
    uint256 internal constant FRACTIONAL_TARGET = 353;

    // Lib
    uint256 internal constant REENTRANCY = 400;
    uint256 internal constant SENDER_NOT_ALLOWED = 401;
    uint256 internal constant PAUSED = 402;
    uint256 internal constant PAUSE_WINDOW_EXPIRED = 403;
    uint256 internal constant MAX_PAUSE_WINDOW_DURATION = 404;
    uint256 internal constant MAX_BUFFER_PERIOD_DURATION = 405;
    uint256 internal constant INSUFFICIENT_BALANCE = 406;
    uint256 internal constant INSUFFICIENT_ALLOWANCE = 407;
    uint256 internal constant ERC20_TRANSFER_FROM_ZERO_ADDRESS = 408;
    uint256 internal constant ERC20_TRANSFER_TO_ZERO_ADDRESS = 409;
    uint256 internal constant ERC20_MINT_TO_ZERO_ADDRESS = 410;
    uint256 internal constant ERC20_BURN_FROM_ZERO_ADDRESS = 411;
    uint256 internal constant ERC20_APPROVE_FROM_ZERO_ADDRESS = 412;
    uint256 internal constant ERC20_APPROVE_TO_ZERO_ADDRESS = 413;
    uint256 internal constant ERC20_TRANSFER_EXCEEDS_ALLOWANCE = 414;
    uint256 internal constant ERC20_DECREASED_ALLOWANCE_BELOW_ZERO = 415;
    uint256 internal constant ERC20_TRANSFER_EXCEEDS_BALANCE = 416;
    uint256 internal constant ERC20_BURN_EXCEEDS_ALLOWANCE = 417;
    uint256 internal constant SAFE_ERC20_CALL_FAILED = 418;
    uint256 internal constant ADDRESS_INSUFFICIENT_BALANCE = 419;
    uint256 internal constant ADDRESS_CANNOT_SEND_VALUE = 420;
    uint256 internal constant SAFE_CAST_VALUE_CANT_FIT_INT256 = 421;
    uint256 internal constant GRANT_SENDER_NOT_ADMIN = 422;
    uint256 internal constant REVOKE_SENDER_NOT_ADMIN = 423;
    uint256 internal constant RENOUNCE_SENDER_NOT_ALLOWED = 424;
    uint256 internal constant BUFFER_PERIOD_EXPIRED = 425;
    uint256 internal constant CALLER_IS_NOT_OWNER = 426;
    uint256 internal constant NEW_OWNER_IS_ZERO = 427;
    uint256 internal constant CODE_DEPLOYMENT_FAILED = 428;
    uint256 internal constant CALL_TO_NON_CONTRACT = 429;
    uint256 internal constant LOW_LEVEL_CALL_FAILED = 430;
    uint256 internal constant NOT_PAUSED = 431;
    uint256 internal constant ADDRESS_ALREADY_ALLOWLISTED = 432;
    uint256 internal constant ADDRESS_NOT_ALLOWLISTED = 433;
    uint256 internal constant ERC20_BURN_EXCEEDS_BALANCE = 434;
    uint256 internal constant INVALID_OPERATION = 435;
    uint256 internal constant CODEC_OVERFLOW = 436;
    uint256 internal constant IN_RECOVERY_MODE = 437;
    uint256 internal constant NOT_IN_RECOVERY_MODE = 438;
    uint256 internal constant INDUCED_FAILURE = 439;
    uint256 internal constant EXPIRED_SIGNATURE = 440;
    uint256 internal constant MALFORMED_SIGNATURE = 441;
    uint256 internal constant SAFE_CAST_VALUE_CANT_FIT_UINT64 = 442;
    uint256 internal constant UNHANDLED_FEE_TYPE = 443;

    // Vault
    uint256 internal constant INVALID_POOL_ID = 500;
    uint256 internal constant CALLER_NOT_POOL = 501;
    uint256 internal constant SENDER_NOT_ASSET_MANAGER = 502;
    uint256 internal constant USER_DOESNT_ALLOW_RELAYER = 503;
    uint256 internal constant INVALID_SIGNATURE = 504;
    uint256 internal constant EXIT_BELOW_MIN = 505;
    uint256 internal constant JOIN_ABOVE_MAX = 506;
    uint256 internal constant SWAP_LIMIT = 507;
    uint256 internal constant SWAP_DEADLINE = 508;
    uint256 internal constant CANNOT_SWAP_SAME_TOKEN = 509;
    uint256 internal constant UNKNOWN_AMOUNT_IN_FIRST_SWAP = 510;
    uint256 internal constant MALCONSTRUCTED_MULTIHOP_SWAP = 511;
    uint256 internal constant INTERNAL_BALANCE_OVERFLOW = 512;
    uint256 internal constant INSUFFICIENT_INTERNAL_BALANCE = 513;
    uint256 internal constant INVALID_ETH_INTERNAL_BALANCE = 514;
    uint256 internal constant INVALID_POST_LOAN_BALANCE = 515;
    uint256 internal constant INSUFFICIENT_ETH = 516;
    uint256 internal constant UNALLOCATED_ETH = 517;
    uint256 internal constant ETH_TRANSFER = 518;
    uint256 internal constant CANNOT_USE_ETH_SENTINEL = 519;
    uint256 internal constant TOKENS_MISMATCH = 520;
    uint256 internal constant TOKEN_NOT_REGISTERED = 521;
    uint256 internal constant TOKEN_ALREADY_REGISTERED = 522;
    uint256 internal constant TOKENS_ALREADY_SET = 523;
    uint256 internal constant TOKENS_LENGTH_MUST_BE_2 = 524;
    uint256 internal constant NONZERO_TOKEN_BALANCE = 525;
    uint256 internal constant BALANCE_TOTAL_OVERFLOW = 526;
    uint256 internal constant POOL_NO_TOKENS = 527;
    uint256 internal constant INSUFFICIENT_FLASH_LOAN_BALANCE = 528;

    // Fees
    uint256 internal constant SWAP_FEE_PERCENTAGE_TOO_HIGH = 600;
    uint256 internal constant FLASH_LOAN_FEE_PERCENTAGE_TOO_HIGH = 601;
    uint256 internal constant INSUFFICIENT_FLASH_LOAN_FEE_AMOUNT = 602;
    uint256 internal constant AUM_FEE_PERCENTAGE_TOO_HIGH = 603;

    // Misc
    uint256 internal constant UNIMPLEMENTED = 998;
    uint256 internal constant SHOULD_NOT_HAPPEN = 999;
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;

import "@balancer-labs/v2-interfaces/contracts/vault/IVault.sol";

import "@balancer-labs/v2-solidity-utils/contracts/openzeppelin/ERC20Permit.sol";

/**
 * @title Highly opinionated token implementation
 * @author Balancer Labs
 * @dev
 * - Includes functions to increase and decrease allowance as a workaround
 *   for the well-known issue with `approve`:
 *   https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
 * - Allows for 'infinite allowance', where an allowance of 0xff..ff is not
 *   decreased by calls to transferFrom
 * - Lets a token holder use `transferFrom` to send their own tokens,
 *   without first setting allowance
 * - Emits 'Approval' events whenever allowance is changed by `transferFrom`
 * - Assigns infinite allowance for all token holders to the Vault
 */
contract BalancerPoolToken is ERC20Permit {
    IVault private immutable _vault;

    constructor(
        string memory tokenName,
        string memory tokenSymbol,
        IVault vault
    ) ERC20(tokenName, tokenSymbol) ERC20Permit(tokenName) {
        _vault = vault;
    }

    function getVault() public view returns (IVault) {
        return _vault;
    }

    // Overrides

    /**
     * @dev Override to grant the Vault infinite allowance, causing for Pool Tokens to not require approval.
     *
     * This is sound as the Vault already provides authorization mechanisms when initiation token transfers, which this
     * contract inherits.
     */
    function allowance(address owner, address spender) public view override returns (uint256) {
        if (spender == address(getVault())) {
            return uint256(-1);
        } else {
            return super.allowance(owner, spender);
        }
    }

    /**
     * @dev Override to allow for 'infinite allowance' and let the token owner use `transferFrom` with no self-allowance
     */
    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) public override returns (bool) {
        uint256 currentAllowance = allowance(sender, msg.sender);
        _require(msg.sender == sender || currentAllowance >= amount, Errors.ERC20_TRANSFER_EXCEEDS_ALLOWANCE);

        _transfer(sender, recipient, amount);

        if (msg.sender != sender && currentAllowance != uint256(-1)) {
            // Because of the previous require, we know that if msg.sender != sender then currentAllowance >= amount
            _approve(sender, msg.sender, currentAllowance - amount);
        }

        return true;
    }

    /**
     * @dev Override to allow decreasing allowance by more than the current amount (setting it to zero)
     */
    function decreaseAllowance(address spender, uint256 amount) public override returns (bool) {
        uint256 currentAllowance = allowance(msg.sender, spender);

        if (amount >= currentAllowance) {
            _approve(msg.sender, spender, 0);
        } else {
            // No risk of underflow due to if condition
            _approve(msg.sender, spender, currentAllowance - amount);
        }

        return true;
    }

    // Internal functions

    function _mintPoolTokens(address recipient, uint256 amount) internal {
        _mint(recipient, amount);
    }

    function _burnPoolTokens(address sender, uint256 amount) internal {
        _burn(sender, amount);
    }
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;
pragma experimental ABIEncoderV2;

import "@balancer-labs/v2-interfaces/contracts/pool-utils/IAssetManager.sol";
import "@balancer-labs/v2-interfaces/contracts/vault/IVault.sol";
import "@balancer-labs/v2-interfaces/contracts/vault/IBasePool.sol";

import "@balancer-labs/v2-solidity-utils/contracts/helpers/InputHelpers.sol";
import "@balancer-labs/v2-solidity-utils/contracts/helpers/WordCodec.sol";
import "@balancer-labs/v2-solidity-utils/contracts/helpers/TemporarilyPausable.sol";
import "@balancer-labs/v2-solidity-utils/contracts/openzeppelin/ERC20.sol";
import "@balancer-labs/v2-solidity-utils/contracts/math/FixedPoint.sol";
import "@balancer-labs/v2-solidity-utils/contracts/math/Math.sol";

import "./BalancerPoolToken.sol";
import "./BasePoolAuthorization.sol";
import "./RecoveryMode.sol";

// solhint-disable max-states-count

/**
 * @notice Reference implementation for the base layer of a Pool contract.
 * @dev Reference implementation for the base layer of a Pool contract that manages a single Pool with optional
 * Asset Managers, an admin-controlled swap fee percentage, and an emergency pause mechanism.
 *
 * This Pool pays protocol fees by minting BPT directly to the ProtocolFeeCollector instead of using the
 * `dueProtocolFees` return value. This results in the underlying tokens continuing to provide liquidity
 * for traders, while still keeping gas usage to a minimum since only a single token (the BPT) is transferred.
 *
 * Note that neither swap fees nor the pause mechanism are used by this contract. They are passed through so that
 * derived contracts can use them via the `_addSwapFeeAmount` and `_subtractSwapFeeAmount` functions, and the
 * `whenNotPaused` modifier.
 *
 * No admin permissions are checked here: instead, this contract delegates that to the Vault's own Authorizer.
 *
 * Because this contract doesn't implement the swap hooks, derived contracts should generally inherit from
 * BaseGeneralPool or BaseMinimalSwapInfoPool. Otherwise, subclasses must inherit from the corresponding interfaces
 * and implement the swap callbacks themselves.
 */
abstract contract BasePool is IBasePool, BasePoolAuthorization, BalancerPoolToken, TemporarilyPausable, RecoveryMode {
    using WordCodec for bytes32;
    using FixedPoint for uint256;
    using BasePoolUserData for bytes;

    uint256 private constant _MIN_TOKENS = 2;

    uint256 private constant _DEFAULT_MINIMUM_BPT = 1e6;

    // 1e18 corresponds to 1.0, or a 100% fee
    uint256 private constant _MIN_SWAP_FEE_PERCENTAGE = 1e12; // 0.0001%
    uint256 private constant _MAX_SWAP_FEE_PERCENTAGE = 1e17; // 10% - this fits in 64 bits

    // `_miscData` is a storage slot that can be used to store unrelated pieces of information. All pools store the
    // recovery mode flag and swap fee percentage, but `miscData` can be extended to store more pieces of information.
    // The most signficant bit is reserved for the recovery mode flag, and the swap fee percentage is stored in
    // the next most significant 63 bits, leaving the remaining 192 bits free to store any other information derived
    // pools might need.
    //
    // This slot is preferred for gas-sensitive operations as it is read in all joins, swaps and exits,
    // and therefore warm.

    // [ recovery | swap  fee | available ]
    // [   1 bit  |  63 bits  |  192 bits ]
    // [ MSB                          LSB ]
    bytes32 private _miscData;

    uint256 private constant _SWAP_FEE_PERCENTAGE_OFFSET = 192;
    uint256 private constant _RECOVERY_MODE_BIT_OFFSET = 255;

    // A fee can never be larger than FixedPoint.ONE, which fits in 60 bits, so 63 is more than enough.
    uint256 private constant _SWAP_FEE_PERCENTAGE_BIT_LENGTH = 63;

    bytes32 private immutable _poolId;

    // Note that this value is immutable in the Vault, so we can make it immutable here and save gas
    IProtocolFeesCollector private immutable _protocolFeesCollector;

    event SwapFeePercentageChanged(uint256 swapFeePercentage);

    constructor(
        IVault vault,
        IVault.PoolSpecialization specialization,
        string memory name,
        string memory symbol,
        IERC20[] memory tokens,
        address[] memory assetManagers,
        uint256 swapFeePercentage,
        uint256 pauseWindowDuration,
        uint256 bufferPeriodDuration,
        address owner
    )
        // Base Pools are expected to be deployed using factories. By using the factory address as the action
        // disambiguator, we make all Pools deployed by the same factory share action identifiers. This allows for
        // simpler management of permissions (such as being able to manage granting the 'set fee percentage' action in
        // any Pool created by the same factory), while still making action identifiers unique among different factories
        // if the selectors match, preventing accidental errors.
        Authentication(bytes32(uint256(msg.sender)))
        BalancerPoolToken(name, symbol, vault)
        BasePoolAuthorization(owner)
        TemporarilyPausable(pauseWindowDuration, bufferPeriodDuration)
    {
        _require(tokens.length >= _MIN_TOKENS, Errors.MIN_TOKENS);
        _require(tokens.length <= _getMaxTokens(), Errors.MAX_TOKENS);

        // The Vault only requires the token list to be ordered for the Two Token Pools specialization. However,
        // to make the developer experience consistent, we are requiring this condition for all the native pools.
        // Also, since these Pools will register tokens only once, we can ensure the Pool tokens will follow the same
        // order. We rely on this property to make Pools simpler to write, as it lets us assume that the
        // order of token-specific parameters (such as token weights) will not change.
        InputHelpers.ensureArrayIsSorted(tokens);

        _setSwapFeePercentage(swapFeePercentage);

        bytes32 poolId = vault.registerPool(specialization);

        vault.registerTokens(poolId, tokens, assetManagers);

        // Set immutable state variables - these cannot be read from during construction
        _poolId = poolId;
        _protocolFeesCollector = vault.getProtocolFeesCollector();
    }

    // Getters / Setters

    /**
     * @notice Return the pool id.
     */
    function getPoolId() public view override returns (bytes32) {
        return _poolId;
    }

    function _getTotalTokens() internal view virtual returns (uint256);

    function _getMaxTokens() internal pure virtual returns (uint256);

    /**
     * @dev Returns the minimum BPT supply. This amount is minted to the zero address during initialization, effectively
     * locking it.
     *
     * This is useful to make sure Pool initialization happens only once, but derived Pools can change this value (even
     * to zero) by overriding this function.
     */
    function _getMinimumBpt() internal pure virtual returns (uint256) {
        return _DEFAULT_MINIMUM_BPT;
    }

    /**
     * @notice Return the current value of the swap fee percentage.
     * @dev This is stored in `_miscData`.
     */
    function getSwapFeePercentage() public view virtual override returns (uint256) {
        return _miscData.decodeUint(_SWAP_FEE_PERCENTAGE_OFFSET, _SWAP_FEE_PERCENTAGE_BIT_LENGTH);
    }

    /**
     * @notice Return the ProtocolFeesCollector contract.
     * @dev This is immutable, and retrieved from the Vault on construction. (It is also immutable in the Vault.)
     */
    function getProtocolFeesCollector() public view returns (IProtocolFeesCollector) {
        return _protocolFeesCollector;
    }

    /**
     * @notice Set the swap fee percentage.
     * @dev This is a permissioned function, and disabled if the pool is paused. The swap fee must be within the
     * bounds set by MIN_SWAP_FEE_PERCENTAGE/MAX_SWAP_FEE_PERCENTAGE. Emits the SwapFeePercentageChanged event.
     */
    function setSwapFeePercentage(uint256 swapFeePercentage) public virtual authenticate whenNotPaused {
        _setSwapFeePercentage(swapFeePercentage);
    }

    function _setSwapFeePercentage(uint256 swapFeePercentage) internal virtual {
        _require(swapFeePercentage >= _getMinSwapFeePercentage(), Errors.MIN_SWAP_FEE_PERCENTAGE);
        _require(swapFeePercentage <= _getMaxSwapFeePercentage(), Errors.MAX_SWAP_FEE_PERCENTAGE);

        _miscData = _miscData.insertUint(
            swapFeePercentage,
            _SWAP_FEE_PERCENTAGE_OFFSET,
            _SWAP_FEE_PERCENTAGE_BIT_LENGTH
        );

        emit SwapFeePercentageChanged(swapFeePercentage);
    }

    function _getMinSwapFeePercentage() internal pure virtual returns (uint256) {
        return _MIN_SWAP_FEE_PERCENTAGE;
    }

    function _getMaxSwapFeePercentage() internal pure virtual returns (uint256) {
        return _MAX_SWAP_FEE_PERCENTAGE;
    }

    /**
     * @notice Returns whether the pool is in Recovery Mode.
     */
    function inRecoveryMode() public view override returns (bool) {
        return _miscData.decodeBool(_RECOVERY_MODE_BIT_OFFSET);
    }

    /**
     * @dev Sets the recoveryMode state, and emits the corresponding event.
     */
    function _setRecoveryMode(bool enabled) internal virtual override {
        _miscData = _miscData.insertBool(enabled, _RECOVERY_MODE_BIT_OFFSET);

        emit RecoveryModeStateChanged(enabled);
    }

    /**
     * @notice Set the asset manager parameters for the given token.
     * @dev This is a permissioned function, unavailable when the pool is paused.
     * The details of the configuration data are set by each Asset Manager. (For an example, see
     * `RewardsAssetManager`.)
     */
    function setAssetManagerPoolConfig(IERC20 token, bytes memory poolConfig)
        public
        virtual
        authenticate
        whenNotPaused
    {
        _setAssetManagerPoolConfig(token, poolConfig);
    }

    function _setAssetManagerPoolConfig(IERC20 token, bytes memory poolConfig) private {
        bytes32 poolId = getPoolId();
        (, , , address assetManager) = getVault().getPoolTokenInfo(poolId, token);

        IAssetManager(assetManager).setConfig(poolId, poolConfig);
    }

    /**
     * @notice Pause the pool: an emergency action which disables all pool functions.
     * @dev This is a permissioned function that will only work during the Pause Window set during pool factory
     * deployment (see `TemporarilyPausable`).
     */
    function pause() external authenticate {
        _setPaused(true);
    }

    /**
     * @notice Reverse a `pause` operation, and restore a pool to normal functionality.
     * @dev This is a permissioned function that will only work on a paused pool within the Buffer Period set during
     * pool factory deployment (see `TemporarilyPausable`). Note that any paused pools will automatically unpause
     * after the Buffer Period expires.
     */
    function unpause() external authenticate {
        _setPaused(false);
    }

    function _isOwnerOnlyAction(bytes32 actionId) internal view virtual override returns (bool) {
        return
            (actionId == getActionId(this.setSwapFeePercentage.selector)) ||
            (actionId == getActionId(this.setAssetManagerPoolConfig.selector));
    }

    function _getMiscData() internal view returns (bytes32) {
        return _miscData;
    }

    /**
     * @dev Inserts data into the least-significant 192 bits of the misc data storage slot.
     * Note that the remaining 64 bits are used for the swap fee percentage and cannot be overloaded.
     */
    function _setMiscData(bytes32 newData) internal {
        _miscData = _miscData.insertBits192(newData, 0);
    }

    // Join / Exit Hooks

    modifier onlyVault(bytes32 poolId) {
        _require(msg.sender == address(getVault()), Errors.CALLER_NOT_VAULT);
        _require(poolId == getPoolId(), Errors.INVALID_POOL_ID);
        _;
    }

    /**
     * @notice Vault hook for adding liquidity to a pool (including the first time, "initializing" the pool).
     * @dev This function can only be called from the Vault, from `joinPool`.
     */
    function onJoinPool(
        bytes32 poolId,
        address sender,
        address recipient,
        uint256[] memory balances,
        uint256 lastChangeBlock,
        uint256 protocolSwapFeePercentage,
        bytes memory userData
    ) external override onlyVault(poolId) returns (uint256[] memory, uint256[] memory) {
        _beforeSwapJoinExit();

        uint256[] memory scalingFactors = _scalingFactors();

        if (totalSupply() == 0) {
            (uint256 bptAmountOut, uint256[] memory amountsIn) = _onInitializePool(
                poolId,
                sender,
                recipient,
                scalingFactors,
                userData
            );

            // On initialization, we lock _getMinimumBpt() by minting it for the zero address. This BPT acts as a
            // minimum as it will never be burned, which reduces potential issues with rounding, and also prevents the
            // Pool from ever being fully drained.
            _require(bptAmountOut >= _getMinimumBpt(), Errors.MINIMUM_BPT);
            _mintPoolTokens(address(0), _getMinimumBpt());
            _mintPoolTokens(recipient, bptAmountOut - _getMinimumBpt());

            // amountsIn are amounts entering the Pool, so we round up.
            _downscaleUpArray(amountsIn, scalingFactors);

            return (amountsIn, new uint256[](balances.length));
        } else {
            _upscaleArray(balances, scalingFactors);
            (uint256 bptAmountOut, uint256[] memory amountsIn) = _onJoinPool(
                poolId,
                sender,
                recipient,
                balances,
                lastChangeBlock,
                inRecoveryMode() ? 0 : protocolSwapFeePercentage, // Protocol fees are disabled while in recovery mode
                scalingFactors,
                userData
            );

            // Note we no longer use `balances` after calling `_onJoinPool`, which may mutate it.

            _mintPoolTokens(recipient, bptAmountOut);

            // amountsIn are amounts entering the Pool, so we round up.
            _downscaleUpArray(amountsIn, scalingFactors);

            // This Pool ignores the `dueProtocolFees` return value, so we simply return a zeroed-out array.
            return (amountsIn, new uint256[](balances.length));
        }
    }

    /**
     * @notice Vault hook for removing liquidity from a pool.
     * @dev This function can only be called from the Vault, from `exitPool`.
     */
    function onExitPool(
        bytes32 poolId,
        address sender,
        address recipient,
        uint256[] memory balances,
        uint256 lastChangeBlock,
        uint256 protocolSwapFeePercentage,
        bytes memory userData
    ) external override onlyVault(poolId) returns (uint256[] memory, uint256[] memory) {
        uint256[] memory amountsOut;
        uint256 bptAmountIn;

        // When a user calls `exitPool`, this is the first point of entry from the Vault.
        // We first check whether this is a Recovery Mode exit - if so, we proceed using this special lightweight exit
        // mechanism which avoids computing any complex values, interacting with external contracts, etc., and generally
        // should always work, even if the Pool's mathematics or a dependency break down.
        if (userData.isRecoveryModeExitKind()) {
            // This exit kind is only available in Recovery Mode.
            _ensureInRecoveryMode();

            // Note that we don't upscale balances nor downscale amountsOut - we don't care about scaling factors during
            // a recovery mode exit.
            (bptAmountIn, amountsOut) = _doRecoveryModeExit(balances, totalSupply(), userData);
        } else {
            // Note that we only call this if we're not in a recovery mode exit.
            _beforeSwapJoinExit();

            uint256[] memory scalingFactors = _scalingFactors();
            _upscaleArray(balances, scalingFactors);

            (bptAmountIn, amountsOut) = _onExitPool(
                poolId,
                sender,
                recipient,
                balances,
                lastChangeBlock,
                inRecoveryMode() ? 0 : protocolSwapFeePercentage, // Protocol fees are disabled while in recovery mode
                scalingFactors,
                userData
            );

            // amountsOut are amounts exiting the Pool, so we round down.
            _downscaleDownArray(amountsOut, scalingFactors);
        }

        // Note we no longer use `balances` after calling `_onExitPool`, which may mutate it.

        _burnPoolTokens(sender, bptAmountIn);

        // This Pool ignores the `dueProtocolFees` return value, so we simply return a zeroed-out array.
        return (amountsOut, new uint256[](balances.length));
    }

    // Query functions

    /**
     * @notice "Dry run" `onJoinPool`.
     * @dev Returns the amount of BPT that would be granted to `recipient` if the `onJoinPool` hook were called by the
     * Vault with the same arguments, along with the number of tokens `sender` would have to supply.
     *
     * This function is not meant to be called directly, but rather from a helper contract that fetches current Vault
     * data, such as the protocol swap fee percentage and Pool balances.
     *
     * Like `IVault.queryBatchSwap`, this function is not view due to internal implementation details: the caller must
     * explicitly use eth_call instead of eth_sendTransaction.
     */
    function queryJoin(
        bytes32 poolId,
        address sender,
        address recipient,
        uint256[] memory balances,
        uint256 lastChangeBlock,
        uint256 protocolSwapFeePercentage,
        bytes memory userData
    ) external override returns (uint256 bptOut, uint256[] memory amountsIn) {
        InputHelpers.ensureInputLengthMatch(balances.length, _getTotalTokens());

        _queryAction(
            poolId,
            sender,
            recipient,
            balances,
            lastChangeBlock,
            protocolSwapFeePercentage,
            userData,
            _onJoinPool,
            _downscaleUpArray
        );

        // The `return` opcode is executed directly inside `_queryAction`, so execution never reaches this statement,
        // and we don't need to return anything here - it just silences compiler warnings.
        return (bptOut, amountsIn);
    }

    /**
     * @notice "Dry run" `onExitPool`.
     * @dev Returns the amount of BPT that would be burned from `sender` if the `onExitPool` hook were called by the
     * Vault with the same arguments, along with the number of tokens `recipient` would receive.
     *
     * This function is not meant to be called directly, but rather from a helper contract that fetches current Vault
     * data, such as the protocol swap fee percentage and Pool balances.
     *
     * Like `IVault.queryBatchSwap`, this function is not view due to internal implementation details: the caller must
     * explicitly use eth_call instead of eth_sendTransaction.
     */
    function queryExit(
        bytes32 poolId,
        address sender,
        address recipient,
        uint256[] memory balances,
        uint256 lastChangeBlock,
        uint256 protocolSwapFeePercentage,
        bytes memory userData
    ) external override returns (uint256 bptIn, uint256[] memory amountsOut) {
        InputHelpers.ensureInputLengthMatch(balances.length, _getTotalTokens());

        _queryAction(
            poolId,
            sender,
            recipient,
            balances,
            lastChangeBlock,
            protocolSwapFeePercentage,
            userData,
            _onExitPool,
            _downscaleDownArray
        );

        // The `return` opcode is executed directly inside `_queryAction`, so execution never reaches this statement,
        // and we don't need to return anything here - it just silences compiler warnings.
        return (bptIn, amountsOut);
    }

    // Internal hooks to be overridden by derived contracts - all token amounts (except BPT) in these interfaces are
    // upscaled.

    /**
     * @dev Called when the Pool is joined for the first time; that is, when the BPT total supply is zero.
     *
     * Returns the amount of BPT to mint, and the token amounts the Pool will receive in return.
     *
     * Minted BPT will be sent to `recipient`, except for _getMinimumBpt(), which will be deducted from this amount and
     * sent to the zero address instead. This will cause that BPT to remain forever locked there, preventing total BTP
     * from ever dropping below that value, and ensuring `_onInitializePool` can only be called once in the entire
     * Pool's lifetime.
     *
     * The tokens granted to the Pool will be transferred from `sender`. These amounts are considered upscaled and will
     * be downscaled (rounding up) before being returned to the Vault.
     */
    function _onInitializePool(
        bytes32 poolId,
        address sender,
        address recipient,
        uint256[] memory scalingFactors,
        bytes memory userData
    ) internal virtual returns (uint256 bptAmountOut, uint256[] memory amountsIn);

    /**
     * @dev Called whenever the Pool is joined after the first initialization join (see `_onInitializePool`).
     *
     * Returns the amount of BPT to mint, the token amounts that the Pool will receive in return, and the number of
     * tokens to pay in protocol swap fees.
     *
     * Implementations of this function might choose to mutate the `balances` array to save gas (e.g. when
     * performing intermediate calculations, such as subtraction of due protocol fees). This can be done safely.
     *
     * Minted BPT will be sent to `recipient`.
     *
     * The tokens granted to the Pool will be transferred from `sender`. These amounts are considered upscaled and will
     * be downscaled (rounding up) before being returned to the Vault.
     *
     * Due protocol swap fees will be taken from the Pool's balance in the Vault (see `IBasePool.onJoinPool`). These
     * amounts are considered upscaled and will be downscaled (rounding down) before being returned to the Vault.
     */
    function _onJoinPool(
        bytes32 poolId,
        address sender,
        address recipient,
        uint256[] memory balances,
        uint256 lastChangeBlock,
        uint256 protocolSwapFeePercentage,
        uint256[] memory scalingFactors,
        bytes memory userData
    ) internal virtual returns (uint256 bptAmountOut, uint256[] memory amountsIn);

    /**
     * @dev Called whenever the Pool is exited.
     *
     * Returns the amount of BPT to burn, the token amounts for each Pool token that the Pool will grant in return, and
     * the number of tokens to pay in protocol swap fees.
     *
     * Implementations of this function might choose to mutate the `balances` array to save gas (e.g. when
     * performing intermediate calculations, such as subtraction of due protocol fees). This can be done safely.
     *
     * BPT will be burnt from `sender`.
     *
     * The Pool will grant tokens to `recipient`. These amounts are considered upscaled and will be downscaled
     * (rounding down) before being returned to the Vault.
     *
     * Due protocol swap fees will be taken from the Pool's balance in the Vault (see `IBasePool.onExitPool`). These
     * amounts are considered upscaled and will be downscaled (rounding down) before being returned to the Vault.
     */
    function _onExitPool(
        bytes32 poolId,
        address sender,
        address recipient,
        uint256[] memory balances,
        uint256 lastChangeBlock,
        uint256 protocolSwapFeePercentage,
        uint256[] memory scalingFactors,
        bytes memory userData
    ) internal virtual returns (uint256 bptAmountIn, uint256[] memory amountsOut);

    /**
     * @dev Called at the very beginning of swaps, joins and exits, even before the scaling factors are read. Derived
     * contracts can extend this implementation to perform any state-changing operations they might need (including e.g.
     * updating the scaling factors),
     *
     * The only scenario in which this function is not called is during a recovery mode exit. This makes it safe to
     * perform non-trivial computations or interact with external dependencies here, as recovery mode will not be
     * affected.
     *
     * Since this contract does not implement swaps, derived contracts must also make sure this function is called on
     * swap handlers.
     */
    function _beforeSwapJoinExit() internal virtual {
        // All joins, exits and swaps are disabled (except recovery mode exits).
        _ensureNotPaused();
    }

    // Internal functions

    /**
     * @dev Pays protocol fees by minting `bptAmount` to the Protocol Fee Collector.
     */
    function _payProtocolFees(uint256 bptAmount) internal {
        _mintPoolTokens(address(getProtocolFeesCollector()), bptAmount);
    }

    /**
     * @dev Adds swap fee amount to `amount`, returning a higher value.
     */
    function _addSwapFeeAmount(uint256 amount) internal view returns (uint256) {
        // This returns amount + fee amount, so we round up (favoring a higher fee amount).
        return amount.divUp(getSwapFeePercentage().complement());
    }

    /**
     * @dev Subtracts swap fee amount from `amount`, returning a lower value.
     */
    function _subtractSwapFeeAmount(uint256 amount) internal view returns (uint256) {
        // This returns amount - fee amount, so we round up (favoring a higher fee amount).
        uint256 feeAmount = amount.mulUp(getSwapFeePercentage());
        return amount.sub(feeAmount);
    }

    // Scaling

    /**
     * @dev Returns a scaling factor that, when multiplied to a token amount for `token`, normalizes its balance as if
     * it had 18 decimals.
     */
    function _computeScalingFactor(IERC20 token) internal view returns (uint256) {
        if (address(token) == address(this)) {
            return FixedPoint.ONE;
        }

        // Tokens that don't implement the `decimals` method are not supported.
        uint256 tokenDecimals = ERC20(address(token)).decimals();

        // Tokens with more than 18 decimals are not supported.
        uint256 decimalsDifference = Math.sub(18, tokenDecimals);
        return FixedPoint.ONE * 10**decimalsDifference;
    }

    /**
     * @dev Returns the scaling factor for one of the Pool's tokens. Reverts if `token` is not a token registered by the
     * Pool.
     *
     * All scaling factors are fixed-point values with 18 decimals, to allow for this function to be overridden by
     * derived contracts that need to apply further scaling, making these factors potentially non-integer.
     *
     * The largest 'base' scaling factor (i.e. in tokens with less than 18 decimals) is 10**18, which in fixed-point is
     * 10**36. This value can be multiplied with a 112 bit Vault balance with no overflow by a factor of ~1e7, making
     * even relatively 'large' factors safe to use.
     *
     * The 1e7 figure is the result of 2**256 / (1e18 * 1e18 * 2**112).
     */
    function _scalingFactor(IERC20 token) internal view virtual returns (uint256);

    /**
     * @dev Same as `_scalingFactor()`, except for all registered tokens (in the same order as registered). The Vault
     * will always pass balances in this order when calling any of the Pool hooks.
     */
    function _scalingFactors() internal view virtual returns (uint256[] memory);

    function getScalingFactors() external view override returns (uint256[] memory) {
        return _scalingFactors();
    }

    /**
     * @dev Applies `scalingFactor` to `amount`, resulting in a larger or equal value depending on whether it needed
     * scaling or not.
     */
    function _upscale(uint256 amount, uint256 scalingFactor) internal pure returns (uint256) {
        // Upscale rounding wouldn't necessarily always go in the same direction: in a swap for example the balance of
        // token in should be rounded up, and that of token out rounded down. This is the only place where we round in
        // the same direction for all amounts, as the impact of this rounding is expected to be minimal (and there's no
        // rounding error unless `_scalingFactor()` is overriden).
        return FixedPoint.mulDown(amount, scalingFactor);
    }

    /**
     * @dev Same as `_upscale`, but for an entire array. This function does not return anything, but instead *mutates*
     * the `amounts` array.
     */
    function _upscaleArray(uint256[] memory amounts, uint256[] memory scalingFactors) internal pure {
        uint256 length = amounts.length;
        InputHelpers.ensureInputLengthMatch(length, scalingFactors.length);

        for (uint256 i = 0; i < length; ++i) {
            amounts[i] = FixedPoint.mulDown(amounts[i], scalingFactors[i]);
        }
    }

    /**
     * @dev Reverses the `scalingFactor` applied to `amount`, resulting in a smaller or equal value depending on
     * whether it needed scaling or not. The result is rounded down.
     */
    function _downscaleDown(uint256 amount, uint256 scalingFactor) internal pure returns (uint256) {
        return FixedPoint.divDown(amount, scalingFactor);
    }

    /**
     * @dev Same as `_downscaleDown`, but for an entire array. This function does not return anything, but instead
     * *mutates* the `amounts` array.
     */
    function _downscaleDownArray(uint256[] memory amounts, uint256[] memory scalingFactors) internal pure {
        uint256 length = amounts.length;
        InputHelpers.ensureInputLengthMatch(length, scalingFactors.length);

        for (uint256 i = 0; i < length; ++i) {
            amounts[i] = FixedPoint.divDown(amounts[i], scalingFactors[i]);
        }
    }

    /**
     * @dev Reverses the `scalingFactor` applied to `amount`, resulting in a smaller or equal value depending on
     * whether it needed scaling or not. The result is rounded up.
     */
    function _downscaleUp(uint256 amount, uint256 scalingFactor) internal pure returns (uint256) {
        return FixedPoint.divUp(amount, scalingFactor);
    }

    /**
     * @dev Same as `_downscaleUp`, but for an entire array. This function does not return anything, but instead
     * *mutates* the `amounts` array.
     */
    function _downscaleUpArray(uint256[] memory amounts, uint256[] memory scalingFactors) internal pure {
        uint256 length = amounts.length;
        InputHelpers.ensureInputLengthMatch(length, scalingFactors.length);

        for (uint256 i = 0; i < length; ++i) {
            amounts[i] = FixedPoint.divUp(amounts[i], scalingFactors[i]);
        }
    }

    function _getAuthorizer() internal view override returns (IAuthorizer) {
        // Access control management is delegated to the Vault's Authorizer. This lets Balancer Governance manage which
        // accounts can call permissioned functions: for example, to perform emergency pauses.
        // If the owner is delegated, then *all* permissioned functions, including `setSwapFeePercentage`, will be under
        // Governance control.
        return getVault().getAuthorizer();
    }

    function _queryAction(
        bytes32 poolId,
        address sender,
        address recipient,
        uint256[] memory balances,
        uint256 lastChangeBlock,
        uint256 protocolSwapFeePercentage,
        bytes memory userData,
        function(bytes32, address, address, uint256[] memory, uint256, uint256, uint256[] memory, bytes memory)
            internal
            returns (uint256, uint256[] memory) _action,
        function(uint256[] memory, uint256[] memory) internal view _downscaleArray
    ) private {
        // This uses the same technique used by the Vault in queryBatchSwap. Refer to that function for a detailed
        // explanation.

        if (msg.sender != address(this)) {
            // We perform an external call to ourselves, forwarding the same calldata. In this call, the else clause of
            // the preceding if statement will be executed instead.

            // solhint-disable-next-line avoid-low-level-calls
            (bool success, ) = address(this).call(msg.data);

            // solhint-disable-next-line no-inline-assembly
            assembly {
                // This call should always revert to decode the bpt and token amounts from the revert reason
                switch success
                    case 0 {
                        // Note we are manually writing the memory slot 0. We can safely overwrite whatever is
                        // stored there as we take full control of the execution and then immediately return.

                        // We copy the first 4 bytes to check if it matches with the expected signature, otherwise
                        // there was another revert reason and we should forward it.
                        returndatacopy(0, 0, 0x04)
                        let error := and(mload(0), 0xffffffff00000000000000000000000000000000000000000000000000000000)

                        // If the first 4 bytes don't match with the expected signature, we forward the revert reason.
                        if eq(eq(error, 0x43adbafb00000000000000000000000000000000000000000000000000000000), 0) {
                            returndatacopy(0, 0, returndatasize())
                            revert(0, returndatasize())
                        }

                        // The returndata contains the signature, followed by the raw memory representation of the
                        // `bptAmount` and `tokenAmounts` (array: length + data). We need to return an ABI-encoded
                        // representation of these.
                        // An ABI-encoded response will include one additional field to indicate the starting offset of
                        // the `tokenAmounts` array. The `bptAmount` will be laid out in the first word of the
                        // returndata.
                        //
                        // In returndata:
                        // [ signature ][ bptAmount ][ tokenAmounts length ][ tokenAmounts values ]
                        // [  4 bytes  ][  32 bytes ][       32 bytes      ][ (32 * length) bytes ]
                        //
                        // We now need to return (ABI-encoded values):
                        // [ bptAmount ][ tokeAmounts offset ][ tokenAmounts length ][ tokenAmounts values ]
                        // [  32 bytes ][       32 bytes     ][       32 bytes      ][ (32 * length) bytes ]

                        // We copy 32 bytes for the `bptAmount` from returndata into memory.
                        // Note that we skip the first 4 bytes for the error signature
                        returndatacopy(0, 0x04, 32)

                        // The offsets are 32-bytes long, so the array of `tokenAmounts` will start after
                        // the initial 64 bytes.
                        mstore(0x20, 64)

                        // We now copy the raw memory array for the `tokenAmounts` from returndata into memory.
                        // Since bpt amount and offset take up 64 bytes, we start copying at address 0x40. We also
                        // skip the first 36 bytes from returndata, which correspond to the signature plus bpt amount.
                        returndatacopy(0x40, 0x24, sub(returndatasize(), 36))

                        // We finally return the ABI-encoded uint256 and the array, which has a total length equal to
                        // the size of returndata, plus the 32 bytes of the offset but without the 4 bytes of the
                        // error signature.
                        return(0, add(returndatasize(), 28))
                    }
                    default {
                        // This call should always revert, but we fail nonetheless if that didn't happen
                        invalid()
                    }
            }
        } else {
            // This imitates the relevant parts of the bodies of onJoin and onExit. Since they're not virtual, we know
            // that their implementations will match this regardless of what derived contracts might do.

            _beforeSwapJoinExit();

            uint256[] memory scalingFactors = _scalingFactors();
            _upscaleArray(balances, scalingFactors);

            (uint256 bptAmount, uint256[] memory tokenAmounts) = _action(
                poolId,
                sender,
                recipient,
                balances,
                lastChangeBlock,
                protocolSwapFeePercentage,
                scalingFactors,
                userData
            );

            _downscaleArray(tokenAmounts, scalingFactors);

            // solhint-disable-next-line no-inline-assembly
            assembly {
                // We will return a raw representation of `bptAmount` and `tokenAmounts` in memory, which is composed of
                // a 32-byte uint256, followed by a 32-byte for the array length, and finally the 32-byte uint256 values
                // Because revert expects a size in bytes, we multiply the array length (stored at `tokenAmounts`) by 32
                let size := mul(mload(tokenAmounts), 32)

                // We store the `bptAmount` in the previous slot to the `tokenAmounts` array. We can make sure there
                // will be at least one available slot due to how the memory scratch space works.
                // We can safely overwrite whatever is stored in this slot as we will revert immediately after that.
                let start := sub(tokenAmounts, 0x20)
                mstore(start, bptAmount)

                // We send one extra value for the error signature "QueryError(uint256,uint256[])" which is 0x43adbafb
                // We use the previous slot to `bptAmount`.
                mstore(sub(start, 0x20), 0x0000000000000000000000000000000000000000000000000000000043adbafb)
                start := sub(start, 0x04)

                // When copying from `tokenAmounts` into returndata, we copy the additional 68 bytes to also return
                // the `bptAmount`, the array 's length, and the error signature.
                revert(start, add(size, 68))
            }
        }
    }
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;

import "@balancer-labs/v2-interfaces/contracts/vault/IAuthorizer.sol";

import "@balancer-labs/v2-solidity-utils/contracts/helpers/Authentication.sol";

/**
 * @dev Base authorization layer implementation for Pools.
 *
 * The owner account can call some of the permissioned functions - access control of the rest is delegated to the
 * Authorizer. Note that this owner is immutable: more sophisticated permission schemes, such as multiple ownership,
 * granular roles, etc., could be built on top of this by making the owner a smart contract.
 *
 * Access control of all other permissioned functions is delegated to an Authorizer. It is also possible to delegate
 * control of *all* permissioned functions to the Authorizer by setting the owner address to `_DELEGATE_OWNER`.
 */
abstract contract BasePoolAuthorization is Authentication {
    address private immutable _owner;

    address private constant _DELEGATE_OWNER = 0xBA1BA1ba1BA1bA1bA1Ba1BA1ba1BA1bA1ba1ba1B;

    constructor(address owner) {
        _owner = owner;
    }

    function getOwner() public view returns (address) {
        return _owner;
    }

    function getAuthorizer() external view returns (IAuthorizer) {
        return _getAuthorizer();
    }

    function _canPerform(bytes32 actionId, address account) internal view override returns (bool) {
        if ((getOwner() != _DELEGATE_OWNER) && _isOwnerOnlyAction(actionId)) {
            // Only the owner can perform "owner only" actions, unless the owner is delegated.
            return msg.sender == getOwner();
        } else {
            // Non-owner actions are always processed via the Authorizer, as "owner only" ones are when delegated.
            return _getAuthorizer().canPerform(actionId, account, address(this));
        }
    }

    function _isOwnerOnlyAction(bytes32 actionId) internal view virtual returns (bool);

    function _getAuthorizer() internal view virtual returns (IAuthorizer);
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;

library BasePoolUserData {
    // Special ExitKind for all pools, used in Recovery Mode. Use the max 8-bit value to prevent conflicts
    // with future additions to the ExitKind enums (or any front-end code that maps to existing values)
    uint8 public constant RECOVERY_MODE_EXIT_KIND = 255;

    // Return true if this is the special exit kind.
    function isRecoveryModeExitKind(bytes memory self) internal pure returns (bool) {
        // Check for the "no data" case, or abi.decode would revert
        return self.length > 0 && abi.decode(self, (uint8)) == RECOVERY_MODE_EXIT_KIND;
    }

    // Parse the bptAmountIn out of the userData
    function recoveryModeExit(bytes memory self) internal pure returns (uint256 bptAmountIn) {
        (, bptAmountIn) = abi.decode(self, (uint8, uint256));
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.7.0;

/**
 * @dev https://eips.ethereum.org/EIPS/eip-712[EIP 712] is a standard for hashing and signing of typed structured data.
 *
 * The encoding specified in the EIP is very generic, and such a generic implementation in Solidity is not feasible,
 * thus this contract does not implement the encoding itself. Protocols need to implement the type-specific encoding
 * they need in their contracts using a combination of `abi.encode` and `keccak256`.
 *
 * This contract implements the EIP 712 domain separator ({_domainSeparatorV4}) that is used as part of the encoding
 * scheme, and the final step of the encoding to obtain the message digest that is then signed via ECDSA
 * ({_hashTypedDataV4}).
 *
 * The implementation of the domain separator was designed to be as efficient as possible while still properly updating
 * the chain id to protect against replay attacks on an eventual fork of the chain.
 *
 * NOTE: This contract implements the version of the encoding known as "v4", as implemented by the JSON RPC method
 * https://docs.metamask.io/guide/signing-data.html[`eth_signTypedDataV4` in MetaMask].
 *
 * _Available since v3.4._
 */
abstract contract EIP712 {
    /* solhint-disable var-name-mixedcase */
    bytes32 private immutable _HASHED_NAME;
    bytes32 private immutable _HASHED_VERSION;
    bytes32 private immutable _TYPE_HASH;

    /* solhint-enable var-name-mixedcase */

    /**
     * @dev Initializes the domain separator and parameter caches.
     *
     * The meaning of `name` and `version` is specified in
     * https://eips.ethereum.org/EIPS/eip-712#definition-of-domainseparator[EIP 712]:
     *
     * - `name`: the user readable name of the signing domain, i.e. the name of the DApp or the protocol.
     * - `version`: the current major version of the signing domain.
     *
     * NOTE: These parameters cannot be changed except through a xref:learn::upgrading-smart-contracts.adoc[smart
     * contract upgrade].
     */
    constructor(string memory name, string memory version) {
        _HASHED_NAME = keccak256(bytes(name));
        _HASHED_VERSION = keccak256(bytes(version));
        _TYPE_HASH = keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)");
    }

    /**
     * @dev Returns the domain separator for the current chain.
     */
    function _domainSeparatorV4() internal view virtual returns (bytes32) {
        return keccak256(abi.encode(_TYPE_HASH, _HASHED_NAME, _HASHED_VERSION, _getChainId(), address(this)));
    }

    /**
     * @dev Given an already https://eips.ethereum.org/EIPS/eip-712#definition-of-hashstruct[hashed struct], this
     * function returns the hash of the fully encoded EIP712 message for this domain.
     *
     * This hash can be used together with {ECDSA-recover} to obtain the signer of a message. For example:
     *
     * ```solidity
     * bytes32 digest = _hashTypedDataV4(keccak256(abi.encode(
     *     keccak256("Mail(address to,string contents)"),
     *     mailTo,
     *     keccak256(bytes(mailContents))
     * )));
     * address signer = ECDSA.recover(digest, signature);
     * ```
     */
    function _hashTypedDataV4(bytes32 structHash) internal view virtual returns (bytes32) {
        return keccak256(abi.encodePacked("\x19\x01", _domainSeparatorV4(), structHash));
    }

    function _getChainId() private view returns (uint256 chainId) {
        // Silence state mutability warning without generating bytecode.
        // See https://github.com/ethereum/solidity/issues/10090#issuecomment-741789128 and
        // https://github.com/ethereum/solidity/issues/2691
        this;

        // solhint-disable-next-line no-inline-assembly
        assembly {
            chainId := chainid()
        }
    }
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;

import "@balancer-labs/v2-interfaces/contracts/solidity-utils/helpers/BalancerErrors.sol";
import "@balancer-labs/v2-interfaces/contracts/solidity-utils/helpers/ISignaturesValidator.sol";

import "../openzeppelin/EIP712.sol";

/**
 * @dev Utility for signing Solidity function calls.
 */
abstract contract EOASignaturesValidator is ISignaturesValidator, EIP712 {
    // Replay attack prevention for each account.
    mapping(address => uint256) internal _nextNonce;

    function getDomainSeparator() public view override returns (bytes32) {
        return _domainSeparatorV4();
    }

    function getNextNonce(address account) public view override returns (uint256) {
        return _nextNonce[account];
    }

    function _ensureValidSignature(
        address account,
        bytes32 structHash,
        bytes memory signature,
        uint256 errorCode
    ) internal {
        return _ensureValidSignature(account, structHash, signature, type(uint256).max, errorCode);
    }

    function _ensureValidSignature(
        address account,
        bytes32 structHash,
        bytes memory signature,
        uint256 deadline,
        uint256 errorCode
    ) internal {
        bytes32 digest = _hashTypedDataV4(structHash);
        _require(_isValidSignature(account, digest, signature), errorCode);

        // We could check for the deadline before validating the signature, but this leads to saner error processing (as
        // we only care about expired deadlines if the signature is correct) and only affects the gas cost of the revert
        // scenario, which will only occur infrequently, if ever.
        // The deadline is timestamp-based: it should not be relied upon for sub-minute accuracy.
        // solhint-disable-next-line not-rely-on-time
        _require(deadline >= block.timestamp, Errors.EXPIRED_SIGNATURE);

        // We only advance the nonce after validating the signature. This is irrelevant for this module, but it can be
        // important in derived contracts that override _isValidSignature (e.g. SignaturesValidator), as we want for
        // the observable state to still have the current nonce as the next valid one.
        _nextNonce[account] += 1;
    }

    function _isValidSignature(
        address account,
        bytes32 digest,
        bytes memory signature
    ) internal view virtual returns (bool) {
        _require(signature.length == 65, Errors.MALFORMED_SIGNATURE);

        bytes32 r;
        bytes32 s;
        uint8 v;

        // ecrecover takes the r, s and v signature parameters, and the only way to get them is to use assembly.
        // solhint-disable-next-line no-inline-assembly
        assembly {
            r := mload(add(signature, 0x20))
            s := mload(add(signature, 0x40))
            v := byte(0, mload(add(signature, 0x60)))
        }

        address recoveredAddress = ecrecover(digest, v, r, s);

        // ecrecover returns the zero address on recover failure, so we need to handle that explicitly.
        return (recoveredAddress != address(0) && recoveredAddress == account);
    }

    function _toArraySignature(
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal pure returns (bytes memory) {
        bytes memory signature = new bytes(65);
        // solhint-disable-next-line no-inline-assembly
        assembly {
            mstore(add(signature, 32), r)
            mstore(add(signature, 64), s)
            mstore8(add(signature, 96), v)
        }

        return signature;
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.7.0;

import "@balancer-labs/v2-interfaces/contracts/solidity-utils/helpers/BalancerErrors.sol";
import "@balancer-labs/v2-interfaces/contracts/solidity-utils/openzeppelin/IERC20.sol";

import "./SafeMath.sol";

/**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20PresetMinterPauser}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * We have followed general OpenZeppelin guidelines: functions revert instead
 * of returning `false` on failure. This behavior is nonetheless conventional
 * and does not conflict with the expectations of ERC20 applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */
contract ERC20 is IERC20 {
    using SafeMath for uint256;

    mapping(address => uint256) private _balances;

    mapping(address => mapping(address => uint256)) private _allowances;

    uint256 private _totalSupply;

    string private _name;
    string private _symbol;
    uint8 private _decimals;

    /**
     * @dev Sets the values for {name} and {symbol}, initializes {decimals} with
     * a default value of 18.
     *
     * To select a different value for {decimals}, use {_setupDecimals}.
     *
     * All three of these values are immutable: they can only be set once during
     * construction.
     */
    constructor(string memory name_, string memory symbol_) {
        _name = name_;
        _symbol = symbol_;
        _decimals = 18;
    }

    /**
     * @dev Returns the name of the token.
     */
    function name() public view returns (string memory) {
        return _name;
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view returns (string memory) {
        return _symbol;
    }

    /**
     * @dev Returns the number of decimals used to get its user representation.
     * For example, if `decimals` equals `2`, a balance of `505` tokens should
     * be displayed to a user as `5,05` (`505 / 10 ** 2`).
     *
     * Tokens usually opt for a value of 18, imitating the relationship between
     * Ether and Wei. This is the value {ERC20} uses, unless {_setupDecimals} is
     * called.
     *
     * NOTE: This information is only used for _display_ purposes: it in
     * no way affects any of the arithmetic of the contract, including
     * {IERC20-balanceOf} and {IERC20-transfer}.
     */
    function decimals() public view returns (uint8) {
        return _decimals;
    }

    /**
     * @dev See {IERC20-totalSupply}. The total supply should only be read using this function
     *
     * Can be overridden by derived contracts to store the total supply in a different way (e.g. packed with other
     * storage values).
     */
    function totalSupply() public view virtual override returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev Sets a new value for the total supply. It should only be set using this function.
     *
     * * Can be overridden by derived contracts to store the total supply in a different way (e.g. packed with other
     * storage values).
     */
    function _setTotalSupply(uint256 value) internal virtual {
        _totalSupply = value;
    }

    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view override returns (uint256) {
        return _balances[account];
    }

    /**
     * @dev See {IERC20-transfer}.
     *
     * Requirements:
     *
     * - `recipient` cannot be the zero address.
     * - the caller must have a balance of at least `amount`.
     */
    function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(msg.sender, recipient, amount);
        return true;
    }

    /**
     * @dev See {IERC20-allowance}.
     */
    function allowance(address owner, address spender) public view virtual override returns (uint256) {
        return _allowances[owner][spender];
    }

    /**
     * @dev See {IERC20-approve}.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        _approve(msg.sender, spender, amount);
        return true;
    }

    /**
     * @dev See {IERC20-transferFrom}.
     *
     * Emits an {Approval} event indicating the updated allowance. This is not
     * required by the EIP. See the note at the beginning of {ERC20}.
     *
     * Requirements:
     *
     * - `sender` and `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     * - the caller must have allowance for ``sender``'s tokens of at least
     * `amount`.
     */
    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) public virtual override returns (bool) {
        _transfer(sender, recipient, amount);
        _approve(
            sender,
            msg.sender,
            _allowances[sender][msg.sender].sub(amount, Errors.ERC20_TRANSFER_EXCEEDS_ALLOWANCE)
        );
        return true;
    }

    /**
     * @dev Atomically increases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        _approve(msg.sender, spender, _allowances[msg.sender][spender].add(addedValue));
        return true;
    }

    /**
     * @dev Atomically decreases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `spender` must have allowance for the caller of at least
     * `subtractedValue`.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        _approve(
            msg.sender,
            spender,
            _allowances[msg.sender][spender].sub(subtractedValue, Errors.ERC20_DECREASED_ALLOWANCE_BELOW_ZERO)
        );
        return true;
    }

    /**
     * @dev Moves tokens `amount` from `sender` to `recipient`.
     *
     * This is internal function is equivalent to {transfer}, and can be used to
     * e.g. implement automatic token fees, slashing mechanisms, etc.
     *
     * Emits a {Transfer} event.
     *
     * Requirements:
     *
     * - `sender` cannot be the zero address.
     * - `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     */
    function _transfer(
        address sender,
        address recipient,
        uint256 amount
    ) internal virtual {
        _require(sender != address(0), Errors.ERC20_TRANSFER_FROM_ZERO_ADDRESS);
        _require(recipient != address(0), Errors.ERC20_TRANSFER_TO_ZERO_ADDRESS);

        _beforeTokenTransfer(sender, recipient, amount);

        _balances[sender] = _balances[sender].sub(amount, Errors.ERC20_TRANSFER_EXCEEDS_BALANCE);
        _balances[recipient] = _balances[recipient].add(amount);
        emit Transfer(sender, recipient, amount);
    }

    /** @dev Creates `amount` tokens and assigns them to `account`, increasing
     * the total supply.
     *
     * Emits a {Transfer} event with `from` set to the zero address.
     *
     * Requirements:
     *
     * - `to` cannot be the zero address.
     */
    function _mint(address account, uint256 amount) internal virtual {
        _beforeTokenTransfer(address(0), account, amount);

        _setTotalSupply(totalSupply().add(amount));
        _balances[account] = _balances[account].add(amount);
        emit Transfer(address(0), account, amount);
    }

    /**
     * @dev Destroys `amount` tokens from `account`, reducing the
     * total supply.
     *
     * Emits a {Transfer} event with `to` set to the zero address.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     * - `account` must have at least `amount` tokens.
     */
    function _burn(address account, uint256 amount) internal virtual {
        _require(account != address(0), Errors.ERC20_BURN_FROM_ZERO_ADDRESS);

        _beforeTokenTransfer(account, address(0), amount);

        _balances[account] = _balances[account].sub(amount, Errors.ERC20_BURN_EXCEEDS_BALANCE);
        _setTotalSupply(totalSupply().sub(amount));
        emit Transfer(account, address(0), amount);
    }

    /**
     * @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
     *
     * This internal function is equivalent to `approve`, and can be used to
     * e.g. set automatic allowances for certain subsystems, etc.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `owner` cannot be the zero address.
     * - `spender` cannot be the zero address.
     */
    function _approve(
        address owner,
        address spender,
        uint256 amount
    ) internal virtual {
        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    /**
     * @dev Sets {decimals} to a value other than the default one of 18.
     *
     * WARNING: This function should only be called from the constructor. Most
     * applications that interact with token contracts will not expect
     * {decimals} to ever change, and may work incorrectly if it does.
     */
    function _setupDecimals(uint8 decimals_) internal {
        _decimals = decimals_;
    }

    /**
     * @dev Hook that is called before any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * will be to transferred to `to`.
     * - when `from` is zero, `amount` tokens will be minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens will be burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {
        // solhint-disable-previous-line no-empty-blocks
    }
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;

import "@balancer-labs/v2-interfaces/contracts/solidity-utils/openzeppelin/IERC20.sol";
import "@balancer-labs/v2-interfaces/contracts/vault/IAsset.sol";

// solhint-disable

function _asIAsset(IERC20[] memory tokens) pure returns (IAsset[] memory assets) {
    // solhint-disable-next-line no-inline-assembly
    assembly {
        assets := tokens
    }
}

function _sortTokens(
    IERC20 tokenA,
    IERC20 tokenB,
    IERC20 tokenC
) pure returns (IERC20[] memory tokens) {
    (uint256 indexTokenA, uint256 indexTokenB, uint256 indexTokenC) = _getSortedTokenIndexes(tokenA, tokenB, tokenC);
    tokens = new IERC20[](3);
    tokens[indexTokenA] = tokenA;
    tokens[indexTokenB] = tokenB;
    tokens[indexTokenC] = tokenC;
}

function _insertSorted(IERC20[] memory tokens, IERC20 token) pure returns (IERC20[] memory sorted) {
    sorted = new IERC20[](tokens.length + 1);

    if (tokens.length == 0) {
        sorted[0] = token;
        return sorted;
    }

    uint256 i;
    for (i = tokens.length; i > 0 && tokens[i - 1] > token; i--) sorted[i] = tokens[i - 1];
    for (uint256 j = 0; j < i; j++) sorted[j] = tokens[j];
    sorted[i] = token;
}

function _appendToken(IERC20[] memory tokens, IERC20 newToken) pure returns (IERC20[] memory newTokens) {
    uint256 numTokens = tokens.length;
    newTokens = new IERC20[](numTokens + 1);

    for (uint256 i = 0; i < numTokens; ++i) newTokens[i] = tokens[i];
    newTokens[numTokens] = newToken;
}

function _getSortedTokenIndexes(
    IERC20 tokenA,
    IERC20 tokenB,
    IERC20 tokenC
)
    pure
    returns (
        uint256 indexTokenA,
        uint256 indexTokenB,
        uint256 indexTokenC
    )
{
    if (tokenA < tokenB) {
        if (tokenB < tokenC) {
            // (tokenA, tokenB, tokenC)
            return (0, 1, 2);
        } else if (tokenA < tokenC) {
            // (tokenA, tokenC, tokenB)
            return (0, 2, 1);
        } else {
            // (tokenC, tokenA, tokenB)
            return (1, 2, 0);
        }
    } else {
        // tokenB < tokenA
        if (tokenC < tokenB) {
            // (tokenC, tokenB, tokenA)
            return (2, 1, 0);
        } else if (tokenC < tokenA) {
            // (tokenB, tokenC, tokenA)
            return (2, 0, 1);
        } else {
            // (tokenB, tokenA, tokenC)
            return (1, 0, 2);
        }
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.7.0;

import "@balancer-labs/v2-interfaces/contracts/solidity-utils/openzeppelin/IERC20Permit.sol";

import "./ERC20.sol";
import "../helpers/EOASignaturesValidator.sol";

/**
 * @dev Implementation of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
 * https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
 *
 * Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
 * presenting a message signed by the account. By not relying on `{IERC20-approve}`, the token holder account doesn't
 * need to send a transaction, and thus is not required to hold Ether at all.
 *
 * _Available since v3.4._
 */
abstract contract ERC20Permit is ERC20, IERC20Permit, EOASignaturesValidator {
    // solhint-disable-next-line var-name-mixedcase
    bytes32 private constant _PERMIT_TYPEHASH = keccak256(
        "Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)"
    );

    /**
     * @dev Initializes the {EIP712} domain separator using the `name` parameter, and setting `version` to `"1"`.
     *
     * It's a good idea to use the same `name` that is defined as the ERC20 token name.
     */
    constructor(string memory name) EIP712(name, "1") {
        // solhint-disable-previous-line no-empty-blocks
    }

    /**
     * @dev See {IERC20Permit-permit}.
     */
    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) public virtual override {
        bytes32 structHash = keccak256(
            abi.encode(_PERMIT_TYPEHASH, owner, spender, value, getNextNonce(owner), deadline)
        );

        _ensureValidSignature(owner, structHash, _toArraySignature(v, r, s), deadline, Errors.INVALID_SIGNATURE);

        _approve(owner, spender, value);
    }

    /**
     * @dev See {IERC20Permit-nonces}.
     */
    function nonces(address owner) public view override returns (uint256) {
        return getNextNonce(owner);
    }

    /**
     * @dev See {IERC20Permit-DOMAIN_SEPARATOR}.
     */
    // solhint-disable-next-line func-name-mixedcase
    function DOMAIN_SEPARATOR() external view override returns (bytes32) {
        return getDomainSeparator();
    }
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;

import "@balancer-labs/v2-interfaces/contracts/solidity-utils/helpers/BalancerErrors.sol";

import "./LogExpMath.sol";

/* solhint-disable private-vars-leading-underscore */

library FixedPoint {
    uint256 internal constant ONE = 1e18; // 18 decimal places
    uint256 internal constant TWO = 2 * ONE;
    uint256 internal constant FOUR = 4 * ONE;
    uint256 internal constant MAX_POW_RELATIVE_ERROR = 10000; // 10^(-14)

    // Minimum base for the power function when the exponent is 'free' (larger than ONE).
    uint256 internal constant MIN_POW_BASE_FREE_EXPONENT = 0.7e18;

    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        // Fixed Point addition is the same as regular checked addition

        uint256 c = a + b;
        _require(c >= a, Errors.ADD_OVERFLOW);
        return c;
    }

    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        // Fixed Point addition is the same as regular checked addition

        _require(b <= a, Errors.SUB_OVERFLOW);
        uint256 c = a - b;
        return c;
    }

    function mulDown(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 product = a * b;
        _require(a == 0 || product / a == b, Errors.MUL_OVERFLOW);

        return product / ONE;
    }

    function mulUp(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 product = a * b;
        _require(a == 0 || product / a == b, Errors.MUL_OVERFLOW);

        if (product == 0) {
            return 0;
        } else {
            // The traditional divUp formula is:
            // divUp(x, y) := (x + y - 1) / y
            // To avoid intermediate overflow in the addition, we distribute the division and get:
            // divUp(x, y) := (x - 1) / y + 1
            // Note that this requires x != 0, which we already tested for.

            return ((product - 1) / ONE) + 1;
        }
    }

    function divDown(uint256 a, uint256 b) internal pure returns (uint256) {
        _require(b != 0, Errors.ZERO_DIVISION);

        if (a == 0) {
            return 0;
        } else {
            uint256 aInflated = a * ONE;
            _require(aInflated / a == ONE, Errors.DIV_INTERNAL); // mul overflow

            return aInflated / b;
        }
    }

    function divUp(uint256 a, uint256 b) internal pure returns (uint256) {
        _require(b != 0, Errors.ZERO_DIVISION);

        if (a == 0) {
            return 0;
        } else {
            uint256 aInflated = a * ONE;
            _require(aInflated / a == ONE, Errors.DIV_INTERNAL); // mul overflow

            // The traditional divUp formula is:
            // divUp(x, y) := (x + y - 1) / y
            // To avoid intermediate overflow in the addition, we distribute the division and get:
            // divUp(x, y) := (x - 1) / y + 1
            // Note that this requires x != 0, which we already tested for.

            return ((aInflated - 1) / b) + 1;
        }
    }

    /**
     * @dev Returns x^y, assuming both are fixed point numbers, rounding down. The result is guaranteed to not be above
     * the true value (that is, the error function expected - actual is always positive).
     */
    function powDown(uint256 x, uint256 y) internal pure returns (uint256) {
        // Optimize for when y equals 1.0, 2.0 or 4.0, as those are very simple to implement and occur often in 50/50
        // and 80/20 Weighted Pools
        if (y == ONE) {
            return x;
        } else if (y == TWO) {
            return mulDown(x, x);
        } else if (y == FOUR) {
            uint256 square = mulDown(x, x);
            return mulDown(square, square);
        } else {
            uint256 raw = LogExpMath.pow(x, y);
            uint256 maxError = add(mulUp(raw, MAX_POW_RELATIVE_ERROR), 1);

            if (raw < maxError) {
                return 0;
            } else {
                return sub(raw, maxError);
            }
        }
    }

    /**
     * @dev Returns x^y, assuming both are fixed point numbers, rounding up. The result is guaranteed to not be below
     * the true value (that is, the error function expected - actual is always negative).
     */
    function powUp(uint256 x, uint256 y) internal pure returns (uint256) {
        // Optimize for when y equals 1.0, 2.0 or 4.0, as those are very simple to implement and occur often in 50/50
        // and 80/20 Weighted Pools
        if (y == ONE) {
            return x;
        } else if (y == TWO) {
            return mulUp(x, x);
        } else if (y == FOUR) {
            uint256 square = mulUp(x, x);
            return mulUp(square, square);
        } else {
            uint256 raw = LogExpMath.pow(x, y);
            uint256 maxError = add(mulUp(raw, MAX_POW_RELATIVE_ERROR), 1);

            return add(raw, maxError);
        }
    }

    /**
     * @dev Returns the complement of a value (1 - x), capped to 0 if x is larger than 1.
     *
     * Useful when computing the complement for values with some level of relative error, as it strips this error and
     * prevents intermediate negative values.
     */
    function complement(uint256 x) internal pure returns (uint256) {
        return (x < ONE) ? (ONE - x) : 0;
    }
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;

/**
 * @dev This is an empty interface used to represent either ERC20-conforming token contracts or ETH (using the zero
 * address sentinel value). We're just relying on the fact that `interface` can be used to declare new address-like
 * types.
 *
 * This concept is unrelated to a Pool's Asset Managers.
 */
interface IAsset {
    // solhint-disable-previous-line no-empty-blocks
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;
pragma experimental ABIEncoderV2;

import "../solidity-utils/openzeppelin/IERC20.sol";

interface IAssetManager {
    /**
     * @notice Emitted when asset manager is rebalanced
     */
    event Rebalance(bytes32 poolId);

    /**
     * @notice Sets the config
     */
    function setConfig(bytes32 poolId, bytes calldata config) external;

    /**
     * Note: No function to read the asset manager config is included in IAssetManager
     * as the signature is expected to vary between asset manager implementations
     */

    /**
     * @notice Returns the asset manager's token
     */
    function getToken() external view returns (IERC20);

    /**
     * @return the current assets under management of this asset manager
     */
    function getAUM(bytes32 poolId) external view returns (uint256);

    /**
     * @return poolCash - The up-to-date cash balance of the pool
     * @return poolManaged - The up-to-date managed balance of the pool
     */
    function getPoolBalances(bytes32 poolId) external view returns (uint256 poolCash, uint256 poolManaged);

    /**
     * @return The difference in tokens between the target investment
     * and the currently invested amount (i.e. the amount that can be invested)
     */
    function maxInvestableBalance(bytes32 poolId) external view returns (int256);

    /**
     * @notice Updates the Vault on the value of the pool's investment returns
     */
    function updateBalanceOfPool(bytes32 poolId) external;

    /**
     * @notice Determines whether the pool should rebalance given the provided balances
     */
    function shouldRebalance(uint256 cash, uint256 managed) external view returns (bool);

    /**
     * @notice Rebalances funds between the pool and the asset manager to maintain target investment percentage.
     * @param poolId - the poolId of the pool to be rebalanced
     * @param force - a boolean representing whether a rebalance should be forced even when the pool is near balance
     */
    function rebalance(bytes32 poolId, bool force) external;

    /**
     * @notice allows an authorized rebalancer to remove capital to facilitate large withdrawals
     * @param poolId - the poolId of the pool to withdraw funds back to
     * @param amount - the amount of tokens to withdraw back to the pool
     */
    function capitalOut(bytes32 poolId, uint256 amount) external;
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;

interface IAuthentication {
    /**
     * @dev Returns the action identifier associated with the external function described by `selector`.
     */
    function getActionId(bytes4 selector) external view returns (bytes32);
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;

interface IAuthorizer {
    /**
     * @dev Returns true if `account` can perform the action described by `actionId` in the contract `where`.
     */
    function canPerform(
        bytes32 actionId,
        address account,
        address where
    ) external view returns (bool);
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;
pragma experimental ABIEncoderV2;

import "./IVault.sol";
import "./IPoolSwapStructs.sol";

/**
 * @dev Interface for adding and removing liquidity that all Pool contracts should implement. Note that this is not
 * the complete Pool contract interface, as it is missing the swap hooks. Pool contracts should also inherit from
 * either IGeneralPool or IMinimalSwapInfoPool
 */
interface IBasePool is IPoolSwapStructs {
    /**
     * @dev Called by the Vault when a user calls `IVault.joinPool` to add liquidity to this Pool. Returns how many of
     * each registered token the user should provide, as well as the amount of protocol fees the Pool owes to the Vault.
     * The Vault will then take tokens from `sender` and add them to the Pool's balances, as well as collect
     * the reported amount in protocol fees, which the pool should calculate based on `protocolSwapFeePercentage`.
     *
     * Protocol fees are reported and charged on join events so that the Pool is free of debt whenever new users join.
     *
     * `sender` is the account performing the join (from which tokens will be withdrawn), and `recipient` is the account
     * designated to receive any benefits (typically pool shares). `balances` contains the total balances
     * for each token the Pool registered in the Vault, in the same order that `IVault.getPoolTokens` would return.
     *
     * `lastChangeBlock` is the last block in which *any* of the Pool's registered tokens last changed its total
     * balance.
     *
     * `userData` contains any pool-specific instructions needed to perform the calculations, such as the type of
     * join (e.g., proportional given an amount of pool shares, single-asset, multi-asset, etc.)
     *
     * Contracts implementing this function should check that the caller is indeed the Vault before performing any
     * state-changing operations, such as minting pool shares.
     */
    function onJoinPool(
        bytes32 poolId,
        address sender,
        address recipient,
        uint256[] memory balances,
        uint256 lastChangeBlock,
        uint256 protocolSwapFeePercentage,
        bytes memory userData
    ) external returns (uint256[] memory amountsIn, uint256[] memory dueProtocolFeeAmounts);

    /**
     * @dev Called by the Vault when a user calls `IVault.exitPool` to remove liquidity from this Pool. Returns how many
     * tokens the Vault should deduct from the Pool's balances, as well as the amount of protocol fees the Pool owes
     * to the Vault. The Vault will then take tokens from the Pool's balances and send them to `recipient`,
     * as well as collect the reported amount in protocol fees, which the Pool should calculate based on
     * `protocolSwapFeePercentage`.
     *
     * Protocol fees are charged on exit events to guarantee that users exiting the Pool have paid their share.
     *
     * `sender` is the account performing the exit (typically the pool shareholder), and `recipient` is the account
     * to which the Vault will send the proceeds. `balances` contains the total token balances for each token
     * the Pool registered in the Vault, in the same order that `IVault.getPoolTokens` would return.
     *
     * `lastChangeBlock` is the last block in which *any* of the Pool's registered tokens last changed its total
     * balance.
     *
     * `userData` contains any pool-specific instructions needed to perform the calculations, such as the type of
     * exit (e.g., proportional given an amount of pool shares, single-asset, multi-asset, etc.)
     *
     * Contracts implementing this function should check that the caller is indeed the Vault before performing any
     * state-changing operations, such as burning pool shares.
     */
    function onExitPool(
        bytes32 poolId,
        address sender,
        address recipient,
        uint256[] memory balances,
        uint256 lastChangeBlock,
        uint256 protocolSwapFeePercentage,
        bytes memory userData
    ) external returns (uint256[] memory amountsOut, uint256[] memory dueProtocolFeeAmounts);

    /**
     * @dev Returns this Pool's ID, used when interacting with the Vault (to e.g. join the Pool or swap with it).
     */
    function getPoolId() external view returns (bytes32);

    /**
     * @dev Returns the current swap fee percentage as a 18 decimal fixed point number, so e.g. 1e17 corresponds to a
     * 10% swap fee.
     */
    function getSwapFeePercentage() external view returns (uint256);

    /**
     * @dev Returns the scaling factors of each of the Pool's tokens. This is an implementation detail that is typically
     * not relevant for outside parties, but which might be useful for some types of Pools.
     */
    function getScalingFactors() external view returns (uint256[] memory);

    function queryJoin(
        bytes32 poolId,
        address sender,
        address recipient,
        uint256[] memory balances,
        uint256 lastChangeBlock,
        uint256 protocolSwapFeePercentage,
        bytes memory userData
    ) external returns (uint256 bptOut, uint256[] memory amountsIn);

    function queryExit(
        bytes32 poolId,
        address sender,
        address recipient,
        uint256[] memory balances,
        uint256 lastChangeBlock,
        uint256 protocolSwapFeePercentage,
        bytes memory userData
    ) external returns (uint256 bptIn, uint256[] memory amountsOut);
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.7.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.7.0;

/**
 * @dev Interface of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
 * https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
 *
 * Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
 * presenting a message signed by the account. By not relying on `{IERC20-approve}`, the token holder account doesn't
 * need to send a transaction, and thus is not required to hold Ether at all.
 */
interface IERC20Permit {
    /**
     * @dev Sets `value` as the allowance of `spender` over `owner`'s tokens,
     * given `owner`'s signed approval.
     *
     * IMPORTANT: The same issues {IERC20-approve} has related to transaction
     * ordering also apply here.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `deadline` must be a timestamp in the future.
     * - `v`, `r` and `s` must be a valid `secp256k1` signature from `owner`
     * over the EIP712-formatted function arguments.
     * - the signature must use ``owner``'s current nonce (see {nonces}).
     *
     * For more information on the signature format, see the
     * https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP
     * section].
     */
    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;

    /**
     * @dev Returns the current nonce for `owner`. This value must be
     * included whenever a signature is generated for {permit}.
     *
     * Every successful call to {permit} increases ``owner``'s nonce by one. This
     * prevents a signature from being used multiple times.
     */
    function nonces(address owner) external view returns (uint256);

    /**
     * @dev Returns the domain separator used in the encoding of the signature for `permit`, as defined by {EIP712}.
     */
    // solhint-disable-next-line func-name-mixedcase
    function DOMAIN_SEPARATOR() external view returns (bytes32);
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;

// Inspired by Aave Protocol's IFlashLoanReceiver.

import "../solidity-utils/openzeppelin/IERC20.sol";

interface IFlashLoanRecipient {
    /**
     * @dev When `flashLoan` is called on the Vault, it invokes the `receiveFlashLoan` hook on the recipient.
     *
     * At the time of the call, the Vault will have transferred `amounts` for `tokens` to the recipient. Before this
     * call returns, the recipient must have transferred `amounts` plus `feeAmounts` for each token back to the
     * Vault, or else the entire flash loan will revert.
     *
     * `userData` is the same value passed in the `IVault.flashLoan` call.
     */
    function receiveFlashLoan(
        IERC20[] memory tokens,
        uint256[] memory amounts,
        uint256[] memory feeAmounts,
        bytes memory userData
    ) external;
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;
pragma experimental ABIEncoderV2;

import "./IBasePool.sol";

/**
 * @dev IPools with the General specialization setting should implement this interface.
 *
 * This is called by the Vault when a user calls `IVault.swap` or `IVault.batchSwap` to swap with this Pool.
 * Returns the number of tokens the Pool will grant to the user in a 'given in' swap, or that the user will
 * grant to the pool in a 'given out' swap.
 *
 * This can often be implemented by a `view` function, since many pricing algorithms don't need to track state
 * changes in swaps. However, contracts implementing this in non-view functions should check that the caller is
 * indeed the Vault.
 */
interface IGeneralPool is IBasePool {
    function onSwap(
        SwapRequest memory swapRequest,
        uint256[] memory balances,
        uint256 indexIn,
        uint256 indexOut
    ) external returns (uint256 amount);
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;

interface ILendingPool {
    /**
     * @dev returns a 27 decimal fixed point 'ray' value so a rate of 1 is represented as 1e27
     */
    function getReserveNormalizedIncome(address asset) external view returns (uint256);
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;
pragma experimental ABIEncoderV2;

import "../solidity-utils/openzeppelin/IERC20.sol";
import "../vault/IBasePool.sol";

interface ILinearPool is IBasePool {
    /**
     * @dev Returns the Pool's main token.
     */
    function getMainToken() external view returns (IERC20);

    /**
     * @dev Returns the Pool's wrapped token.
     */
    function getWrappedToken() external view returns (IERC20);

    /**
     * @dev Returns the index of the Pool's BPT in the Pool tokens array (as returned by IVault.getPoolTokens).
     */
    function getBptIndex() external view returns (uint256);

    /**
     * @dev Returns the index of the Pool's main token in the Pool tokens array (as returned by IVault.getPoolTokens).
     */
    function getMainIndex() external view returns (uint256);

    /**
     * @dev Returns the index of the Pool's wrapped token in the Pool tokens array (as returned by
     * IVault.getPoolTokens).
     */
    function getWrappedIndex() external view returns (uint256);

    /**
     * @dev Returns the Pool's targets for the main token balance. These values have had the main token's scaling
     * factor applied to them.
     */
    function getTargets() external view returns (uint256 lowerTarget, uint256 upperTarget);
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;
pragma experimental ABIEncoderV2;

import "../solidity-utils/openzeppelin/IERC20.sol";

import "./IVault.sol";

interface IPoolSwapStructs {
    // This is not really an interface - it just defines common structs used by other interfaces: IGeneralPool and
    // IMinimalSwapInfoPool.
    //
    // This data structure represents a request for a token swap, where `kind` indicates the swap type ('given in' or
    // 'given out') which indicates whether or not the amount sent by the pool is known.
    //
    // The pool receives `tokenIn` and sends `tokenOut`. `amount` is the number of `tokenIn` tokens the pool will take
    // in, or the number of `tokenOut` tokens the Pool will send out, depending on the given swap `kind`.
    //
    // All other fields are not strictly necessary for most swaps, but are provided to support advanced scenarios in
    // some Pools.
    //
    // `poolId` is the ID of the Pool involved in the swap - this is useful for Pool contracts that implement more than
    // one Pool.
    //
    // The meaning of `lastChangeBlock` depends on the Pool specialization:
    //  - Two Token or Minimal Swap Info: the last block in which either `tokenIn` or `tokenOut` changed its total
    //    balance.
    //  - General: the last block in which *any* of the Pool's registered tokens changed its total balance.
    //
    // `from` is the origin address for the funds the Pool receives, and `to` is the destination address
    // where the Pool sends the outgoing tokens.
    //
    // `userData` is extra data provided by the caller - typically a signature from a trusted party.
    struct SwapRequest {
        IVault.SwapKind kind;
        IERC20 tokenIn;
        IERC20 tokenOut;
        uint256 amount;
        // Misc data
        bytes32 poolId;
        uint256 lastChangeBlock;
        address from;
        address to;
        bytes userData;
    }
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;
pragma experimental ABIEncoderV2;

import "../solidity-utils/openzeppelin/IERC20.sol";

import "./IVault.sol";
import "./IAuthorizer.sol";

interface IProtocolFeesCollector {
    event SwapFeePercentageChanged(uint256 newSwapFeePercentage);
    event FlashLoanFeePercentageChanged(uint256 newFlashLoanFeePercentage);

    function withdrawCollectedFees(
        IERC20[] calldata tokens,
        uint256[] calldata amounts,
        address recipient
    ) external;

    function setSwapFeePercentage(uint256 newSwapFeePercentage) external;

    function setFlashLoanFeePercentage(uint256 newFlashLoanFeePercentage) external;

    function getSwapFeePercentage() external view returns (uint256);

    function getFlashLoanFeePercentage() external view returns (uint256);

    function getCollectedFeeAmounts(IERC20[] memory tokens) external view returns (uint256[] memory feeAmounts);

    function getAuthorizer() external view returns (IAuthorizer);

    function vault() external view returns (IVault);
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;

interface IRateProvider {
    /**
     * @dev Returns an 18 decimal fixed point number that is the exchange rate of the token to some other underlying
     * token. The meaning of this rate depends on the context.
     */
    function getRate() external view returns (uint256);
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;

/**
 * @dev Interface for the RecoveryMode module.
 */
interface IRecoveryMode {
    /**
     * @dev Emitted when the Recovery Mode status changes.
     */
    event RecoveryModeStateChanged(bool enabled);

    /**
     * @notice Enables Recovery Mode in the Pool, disabling protocol fee collection and allowing for safe proportional
     * exits with low computational complexity and no dependencies.
     */
    function enableRecoveryMode() external;

    /**
     * @notice Disables Recovery Mode in the Pool, restoring protocol fee collection and disallowing proportional exits.
     */
    function disableRecoveryMode() external;

    /**
     * @notice Returns true if the Pool is in Recovery Mode.
     */
    function inRecoveryMode() external view returns (bool);
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;

/**
 * @dev Interface for the SignatureValidator helper, used to support meta-transactions.
 */
interface ISignaturesValidator {
    /**
     * @dev Returns the EIP712 domain separator.
     */
    function getDomainSeparator() external view returns (bytes32);

    /**
     * @dev Returns the next nonce used by an address to sign messages.
     */
    function getNextNonce(address user) external view returns (uint256);
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;

import "./ILendingPool.sol";

interface IStaticAToken {
    /**
     * @dev returns the address of the staticAToken's underlying asset
     */
    // solhint-disable-next-line func-name-mixedcase
    function ASSET() external view returns (address);

    /**
     * @dev returns the address of the staticAToken's lending pool
     */
    // solhint-disable-next-line func-name-mixedcase
    function LENDING_POOL() external view returns (ILendingPool);

    /**
     * @dev returns a 27 decimal fixed point 'ray' value so a rate of 1 is represented as 1e27
     */
    function rate() external view returns (uint256);

    function deposit(
        address,
        uint256,
        uint16,
        bool
    ) external returns (uint256);

    function withdraw(
        address,
        uint256,
        bool
    ) external returns (uint256, uint256);

    function staticToDynamicAmount(uint256 amount) external view returns (uint256);
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;

/**
 * @dev Interface for the TemporarilyPausable helper.
 */
interface ITemporarilyPausable {
    /**
     * @dev Emitted every time the pause state changes by `_setPaused`.
     */
    event PausedStateChanged(bool paused);

    /**
     * @dev Returns the current paused state.
     */
    function getPausedState()
        external
        view
        returns (
            bool paused,
            uint256 pauseWindowEndTime,
            uint256 bufferPeriodEndTime
        );
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma experimental ABIEncoderV2;

import "../solidity-utils/openzeppelin/IERC20.sol";
import "../solidity-utils/helpers/IAuthentication.sol";
import "../solidity-utils/helpers/ISignaturesValidator.sol";
import "../solidity-utils/helpers/ITemporarilyPausable.sol";
import "../solidity-utils/misc/IWETH.sol";

import "./IAsset.sol";
import "./IAuthorizer.sol";
import "./IFlashLoanRecipient.sol";
import "./IProtocolFeesCollector.sol";

pragma solidity ^0.7.0;

/**
 * @dev Full external interface for the Vault core contract - no external or public methods exist in the contract that
 * don't override one of these declarations.
 */
interface IVault is ISignaturesValidator, ITemporarilyPausable, IAuthentication {
    // Generalities about the Vault:
    //
    // - Whenever documentation refers to 'tokens', it strictly refers to ERC20-compliant token contracts. Tokens are
    // transferred out of the Vault by calling the `IERC20.transfer` function, and transferred in by calling
    // `IERC20.transferFrom`. In these cases, the sender must have previously allowed the Vault to use their tokens by
    // calling `IERC20.approve`. The only deviation from the ERC20 standard that is supported is functions not returning
    // a boolean value: in these scenarios, a non-reverting call is assumed to be successful.
    //
    // - All non-view functions in the Vault are non-reentrant: calling them while another one is mid-execution (e.g.
    // while execution control is transferred to a token contract during a swap) will result in a revert. View
    // functions can be called in a re-reentrant way, but doing so might cause them to return inconsistent results.
    // Contracts calling view functions in the Vault must make sure the Vault has not already been entered.
    //
    // - View functions revert if referring to either unregistered Pools, or unregistered tokens for registered Pools.

    // Authorizer
    //
    // Some system actions are permissioned, like setting and collecting protocol fees. This permissioning system exists
    // outside of the Vault in the Authorizer contract: the Vault simply calls the Authorizer to check if the caller
    // can perform a given action.

    /**
     * @dev Returns the Vault's Authorizer.
     */
    function getAuthorizer() external view returns (IAuthorizer);

    /**
     * @dev Sets a new Authorizer for the Vault. The caller must be allowed by the current Authorizer to do this.
     *
     * Emits an `AuthorizerChanged` event.
     */
    function setAuthorizer(IAuthorizer newAuthorizer) external;

    /**
     * @dev Emitted when a new authorizer is set by `setAuthorizer`.
     */
    event AuthorizerChanged(IAuthorizer indexed newAuthorizer);

    // Relayers
    //
    // Additionally, it is possible for an account to perform certain actions on behalf of another one, using their
    // Vault ERC20 allowance and Internal Balance. These accounts are said to be 'relayers' for these Vault functions,
    // and are expected to be smart contracts with sound authentication mechanisms. For an account to be able to wield
    // this power, two things must occur:
    //  - The Authorizer must grant the account the permission to be a relayer for the relevant Vault function. This
    //    means that Balancer governance must approve each individual contract to act as a relayer for the intended
    //    functions.
    //  - Each user must approve the relayer to act on their behalf.
    // This double protection means users cannot be tricked into approving malicious relayers (because they will not
    // have been allowed by the Authorizer via governance), nor can malicious relayers approved by a compromised
    // Authorizer or governance drain user funds, since they would also need to be approved by each individual user.

    /**
     * @dev Returns true if `user` has approved `relayer` to act as a relayer for them.
     */
    function hasApprovedRelayer(address user, address relayer) external view returns (bool);

    /**
     * @dev Allows `relayer` to act as a relayer for `sender` if `approved` is true, and disallows it otherwise.
     *
     * Emits a `RelayerApprovalChanged` event.
     */
    function setRelayerApproval(
        address sender,
        address relayer,
        bool approved
    ) external;

    /**
     * @dev Emitted every time a relayer is approved or disapproved by `setRelayerApproval`.
     */
    event RelayerApprovalChanged(address indexed relayer, address indexed sender, bool approved);

    // Internal Balance
    //
    // Users can deposit tokens into the Vault, where they are allocated to their Internal Balance, and later
    // transferred or withdrawn. It can also be used as a source of tokens when joining Pools, as a destination
    // when exiting them, and as either when performing swaps. This usage of Internal Balance results in greatly reduced
    // gas costs when compared to relying on plain ERC20 transfers, leading to large savings for frequent users.
    //
    // Internal Balance management features batching, which means a single contract call can be used to perform multiple
    // operations of different kinds, with different senders and recipients, at once.

    /**
     * @dev Returns `user`'s Internal Balance for a set of tokens.
     */
    function getInternalBalance(address user, IERC20[] memory tokens) external view returns (uint256[] memory);

    /**
     * @dev Performs a set of user balance operations, which involve Internal Balance (deposit, withdraw or transfer)
     * and plain ERC20 transfers using the Vault's allowance. This last feature is particularly useful for relayers, as
     * it lets integrators reuse a user's Vault allowance.
     *
     * For each operation, if the caller is not `sender`, it must be an authorized relayer for them.
     */
    function manageUserBalance(UserBalanceOp[] memory ops) external payable;

    /**
     * @dev Data for `manageUserBalance` operations, which include the possibility for ETH to be sent and received
     without manual WETH wrapping or unwrapping.
     */
    struct UserBalanceOp {
        UserBalanceOpKind kind;
        IAsset asset;
        uint256 amount;
        address sender;
        address payable recipient;
    }

    // There are four possible operations in `manageUserBalance`:
    //
    // - DEPOSIT_INTERNAL
    // Increases the Internal Balance of the `recipient` account by transferring tokens from the corresponding
    // `sender`. The sender must have allowed the Vault to use their tokens via `IERC20.approve()`.
    //
    // ETH can be used by passing the ETH sentinel value as the asset and forwarding ETH in the call: it will be wrapped
    // and deposited as WETH. Any ETH amount remaining will be sent back to the caller (not the sender, which is
    // relevant for relayers).
    //
    // Emits an `InternalBalanceChanged` event.
    //
    //
    // - WITHDRAW_INTERNAL
    // Decreases the Internal Balance of the `sender` account by transferring tokens to the `recipient`.
    //
    // ETH can be used by passing the ETH sentinel value as the asset. This will deduct WETH instead, unwrap it and send
    // it to the recipient as ETH.
    //
    // Emits an `InternalBalanceChanged` event.
    //
    //
    // - TRANSFER_INTERNAL
    // Transfers tokens from the Internal Balance of the `sender` account to the Internal Balance of `recipient`.
    //
    // Reverts if the ETH sentinel value is passed.
    //
    // Emits an `InternalBalanceChanged` event.
    //
    //
    // - TRANSFER_EXTERNAL
    // Transfers tokens from `sender` to `recipient`, using the Vault's ERC20 allowance. This is typically used by
    // relayers, as it lets them reuse a user's Vault allowance.
    //
    // Reverts if the ETH sentinel value is passed.
    //
    // Emits an `ExternalBalanceTransfer` event.

    enum UserBalanceOpKind { DEPOSIT_INTERNAL, WITHDRAW_INTERNAL, TRANSFER_INTERNAL, TRANSFER_EXTERNAL }

    /**
     * @dev Emitted when a user's Internal Balance changes, either from calls to `manageUserBalance`, or through
     * interacting with Pools using Internal Balance.
     *
     * Because Internal Balance works exclusively with ERC20 tokens, ETH deposits and withdrawals will use the WETH
     * address.
     */
    event InternalBalanceChanged(address indexed user, IERC20 indexed token, int256 delta);

    /**
     * @dev Emitted when a user's Vault ERC20 allowance is used by the Vault to transfer tokens to an external account.
     */
    event ExternalBalanceTransfer(IERC20 indexed token, address indexed sender, address recipient, uint256 amount);

    // Pools
    //
    // There are three specialization settings for Pools, which allow for cheaper swaps at the cost of reduced
    // functionality:
    //
    //  - General: no specialization, suited for all Pools. IGeneralPool is used for swap request callbacks, passing the
    // balance of all tokens in the Pool. These Pools have the largest swap costs (because of the extra storage reads),
    // which increase with the number of registered tokens.
    //
    //  - Minimal Swap Info: IMinimalSwapInfoPool is used instead of IGeneralPool, which saves gas by only passing the
    // balance of the two tokens involved in the swap. This is suitable for some pricing algorithms, like the weighted
    // constant product one popularized by Balancer V1. Swap costs are smaller compared to general Pools, and are
    // independent of the number of registered tokens.
    //
    //  - Two Token: only allows two tokens to be registered. This achieves the lowest possible swap gas cost. Like
    // minimal swap info Pools, these are called via IMinimalSwapInfoPool.

    enum PoolSpecialization { GENERAL, MINIMAL_SWAP_INFO, TWO_TOKEN }

    /**
     * @dev Registers the caller account as a Pool with a given specialization setting. Returns the Pool's ID, which
     * is used in all Pool-related functions. Pools cannot be deregistered, nor can the Pool's specialization be
     * changed.
     *
     * The caller is expected to be a smart contract that implements either `IGeneralPool` or `IMinimalSwapInfoPool`,
     * depending on the chosen specialization setting. This contract is known as the Pool's contract.
     *
     * Note that the same contract may register itself as multiple Pools with unique Pool IDs, or in other words,
     * multiple Pools may share the same contract.
     *
     * Emits a `PoolRegistered` event.
     */
    function registerPool(PoolSpecialization specialization) external returns (bytes32);

    /**
     * @dev Emitted when a Pool is registered by calling `registerPool`.
     */
    event PoolRegistered(bytes32 indexed poolId, address indexed poolAddress, PoolSpecialization specialization);

    /**
     * @dev Returns a Pool's contract address and specialization setting.
     */
    function getPool(bytes32 poolId) external view returns (address, PoolSpecialization);

    /**
     * @dev Registers `tokens` for the `poolId` Pool. Must be called by the Pool's contract.
     *
     * Pools can only interact with tokens they have registered. Users join a Pool by transferring registered tokens,
     * exit by receiving registered tokens, and can only swap registered tokens.
     *
     * Each token can only be registered once. For Pools with the Two Token specialization, `tokens` must have a length
     * of two, that is, both tokens must be registered in the same `registerTokens` call, and they must be sorted in
     * ascending order.
     *
     * The `tokens` and `assetManagers` arrays must have the same length, and each entry in these indicates the Asset
     * Manager for the corresponding token. Asset Managers can manage a Pool's tokens via `managePoolBalance`,
     * depositing and withdrawing them directly, and can even set their balance to arbitrary amounts. They are therefore
     * expected to be highly secured smart contracts with sound design principles, and the decision to register an
     * Asset Manager should not be made lightly.
     *
     * Pools can choose not to assign an Asset Manager to a given token by passing in the zero address. Once an Asset
     * Manager is set, it cannot be changed except by deregistering the associated token and registering again with a
     * different Asset Manager.
     *
     * Emits a `TokensRegistered` event.
     */
    function registerTokens(
        bytes32 poolId,
        IERC20[] memory tokens,
        address[] memory assetManagers
    ) external;

    /**
     * @dev Emitted when a Pool registers tokens by calling `registerTokens`.
     */
    event TokensRegistered(bytes32 indexed poolId, IERC20[] tokens, address[] assetManagers);

    /**
     * @dev Deregisters `tokens` for the `poolId` Pool. Must be called by the Pool's contract.
     *
     * Only registered tokens (via `registerTokens`) can be deregistered. Additionally, they must have zero total
     * balance. For Pools with the Two Token specialization, `tokens` must have a length of two, that is, both tokens
     * must be deregistered in the same `deregisterTokens` call.
     *
     * A deregistered token can be re-registered later on, possibly with a different Asset Manager.
     *
     * Emits a `TokensDeregistered` event.
     */
    function deregisterTokens(bytes32 poolId, IERC20[] memory tokens) external;

    /**
     * @dev Emitted when a Pool deregisters tokens by calling `deregisterTokens`.
     */
    event TokensDeregistered(bytes32 indexed poolId, IERC20[] tokens);

    /**
     * @dev Returns detailed information for a Pool's registered token.
     *
     * `cash` is the number of tokens the Vault currently holds for the Pool. `managed` is the number of tokens
     * withdrawn and held outside the Vault by the Pool's token Asset Manager. The Pool's total balance for `token`
     * equals the sum of `cash` and `managed`.
     *
     * Internally, `cash` and `managed` are stored using 112 bits. No action can ever cause a Pool's token `cash`,
     * `managed` or `total` balance to be greater than 2^112 - 1.
     *
     * `lastChangeBlock` is the number of the block in which `token`'s total balance was last modified (via either a
     * join, exit, swap, or Asset Manager update). This value is useful to avoid so-called 'sandwich attacks', for
     * example when developing price oracles. A change of zero (e.g. caused by a swap with amount zero) is considered a
     * change for this purpose, and will update `lastChangeBlock`.
     *
     * `assetManager` is the Pool's token Asset Manager.
     */
    function getPoolTokenInfo(bytes32 poolId, IERC20 token)
        external
        view
        returns (
            uint256 cash,
            uint256 managed,
            uint256 lastChangeBlock,
            address assetManager
        );

    /**
     * @dev Returns a Pool's registered tokens, the total balance for each, and the latest block when *any* of
     * the tokens' `balances` changed.
     *
     * The order of the `tokens` array is the same order that will be used in `joinPool`, `exitPool`, as well as in all
     * Pool hooks (where applicable). Calls to `registerTokens` and `deregisterTokens` may change this order.
     *
     * If a Pool only registers tokens once, and these are sorted in ascending order, they will be stored in the same
     * order as passed to `registerTokens`.
     *
     * Total balances include both tokens held by the Vault and those withdrawn by the Pool's Asset Managers. These are
     * the amounts used by joins, exits and swaps. For a detailed breakdown of token balances, use `getPoolTokenInfo`
     * instead.
     */
    function getPoolTokens(bytes32 poolId)
        external
        view
        returns (
            IERC20[] memory tokens,
            uint256[] memory balances,
            uint256 lastChangeBlock
        );

    /**
     * @dev Called by users to join a Pool, which transfers tokens from `sender` into the Pool's balance. This will
     * trigger custom Pool behavior, which will typically grant something in return to `recipient` - often tokenized
     * Pool shares.
     *
     * If the caller is not `sender`, it must be an authorized relayer for them.
     *
     * The `assets` and `maxAmountsIn` arrays must have the same length, and each entry indicates the maximum amount
     * to send for each asset. The amounts to send are decided by the Pool and not the Vault: it just enforces
     * these maximums.
     *
     * If joining a Pool that holds WETH, it is possible to send ETH directly: the Vault will do the wrapping. To enable
     * this mechanism, the IAsset sentinel value (the zero address) must be passed in the `assets` array instead of the
     * WETH address. Note that it is not possible to combine ETH and WETH in the same join. Any excess ETH will be sent
     * back to the caller (not the sender, which is important for relayers).
     *
     * `assets` must have the same length and order as the array returned by `getPoolTokens`. This prevents issues when
     * interacting with Pools that register and deregister tokens frequently. If sending ETH however, the array must be
     * sorted *before* replacing the WETH address with the ETH sentinel value (the zero address), which means the final
     * `assets` array might not be sorted. Pools with no registered tokens cannot be joined.
     *
     * If `fromInternalBalance` is true, the caller's Internal Balance will be preferred: ERC20 transfers will only
     * be made for the difference between the requested amount and Internal Balance (if any). Note that ETH cannot be
     * withdrawn from Internal Balance: attempting to do so will trigger a revert.
     *
     * This causes the Vault to call the `IBasePool.onJoinPool` hook on the Pool's contract, where Pools implement
     * their own custom logic. This typically requires additional information from the user (such as the expected number
     * of Pool shares). This can be encoded in the `userData` argument, which is ignored by the Vault and passed
     * directly to the Pool's contract, as is `recipient`.
     *
     * Emits a `PoolBalanceChanged` event.
     */
    function joinPool(
        bytes32 poolId,
        address sender,
        address recipient,
        JoinPoolRequest memory request
    ) external payable;

    struct JoinPoolRequest {
        IAsset[] assets;
        uint256[] maxAmountsIn;
        bytes userData;
        bool fromInternalBalance;
    }

    /**
     * @dev Called by users to exit a Pool, which transfers tokens from the Pool's balance to `recipient`. This will
     * trigger custom Pool behavior, which will typically ask for something in return from `sender` - often tokenized
     * Pool shares. The amount of tokens that can be withdrawn is limited by the Pool's `cash` balance (see
     * `getPoolTokenInfo`).
     *
     * If the caller is not `sender`, it must be an authorized relayer for them.
     *
     * The `tokens` and `minAmountsOut` arrays must have the same length, and each entry in these indicates the minimum
     * token amount to receive for each token contract. The amounts to send are decided by the Pool and not the Vault:
     * it just enforces these minimums.
     *
     * If exiting a Pool that holds WETH, it is possible to receive ETH directly: the Vault will do the unwrapping. To
     * enable this mechanism, the IAsset sentinel value (the zero address) must be passed in the `assets` array instead
     * of the WETH address. Note that it is not possible to combine ETH and WETH in the same exit.
     *
     * `assets` must have the same length and order as the array returned by `getPoolTokens`. This prevents issues when
     * interacting with Pools that register and deregister tokens frequently. If receiving ETH however, the array must
     * be sorted *before* replacing the WETH address with the ETH sentinel value (the zero address), which means the
     * final `assets` array might not be sorted. Pools with no registered tokens cannot be exited.
     *
     * If `toInternalBalance` is true, the tokens will be deposited to `recipient`'s Internal Balance. Otherwise,
     * an ERC20 transfer will be performed. Note that ETH cannot be deposited to Internal Balance: attempting to
     * do so will trigger a revert.
     *
     * `minAmountsOut` is the minimum amount of tokens the user expects to get out of the Pool, for each token in the
     * `tokens` array. This array must match the Pool's registered tokens.
     *
     * This causes the Vault to call the `IBasePool.onExitPool` hook on the Pool's contract, where Pools implement
     * their own custom logic. This typically requires additional information from the user (such as the expected number
     * of Pool shares to return). This can be encoded in the `userData` argument, which is ignored by the Vault and
     * passed directly to the Pool's contract.
     *
     * Emits a `PoolBalanceChanged` event.
     */
    function exitPool(
        bytes32 poolId,
        address sender,
        address payable recipient,
        ExitPoolRequest memory request
    ) external;

    struct ExitPoolRequest {
        IAsset[] assets;
        uint256[] minAmountsOut;
        bytes userData;
        bool toInternalBalance;
    }

    /**
     * @dev Emitted when a user joins or exits a Pool by calling `joinPool` or `exitPool`, respectively.
     */
    event PoolBalanceChanged(
        bytes32 indexed poolId,
        address indexed liquidityProvider,
        IERC20[] tokens,
        int256[] deltas,
        uint256[] protocolFeeAmounts
    );

    enum PoolBalanceChangeKind { JOIN, EXIT }

    // Swaps
    //
    // Users can swap tokens with Pools by calling the `swap` and `batchSwap` functions. To do this,
    // they need not trust Pool contracts in any way: all security checks are made by the Vault. They must however be
    // aware of the Pools' pricing algorithms in order to estimate the prices Pools will quote.
    //
    // The `swap` function executes a single swap, while `batchSwap` can perform multiple swaps in sequence.
    // In each individual swap, tokens of one kind are sent from the sender to the Pool (this is the 'token in'),
    // and tokens of another kind are sent from the Pool to the recipient in exchange (this is the 'token out').
    // More complex swaps, such as one token in to multiple tokens out can be achieved by batching together
    // individual swaps.
    //
    // There are two swap kinds:
    //  - 'given in' swaps, where the amount of tokens in (sent to the Pool) is known, and the Pool determines (via the
    // `onSwap` hook) the amount of tokens out (to send to the recipient).
    //  - 'given out' swaps, where the amount of tokens out (received from the Pool) is known, and the Pool determines
    // (via the `onSwap` hook) the amount of tokens in (to receive from the sender).
    //
    // Additionally, it is possible to chain swaps using a placeholder input amount, which the Vault replaces with
    // the calculated output of the previous swap. If the previous swap was 'given in', this will be the calculated
    // tokenOut amount. If the previous swap was 'given out', it will use the calculated tokenIn amount. These extended
    // swaps are known as 'multihop' swaps, since they 'hop' through a number of intermediate tokens before arriving at
    // the final intended token.
    //
    // In all cases, tokens are only transferred in and out of the Vault (or withdrawn from and deposited into Internal
    // Balance) after all individual swaps have been completed, and the net token balance change computed. This makes
    // certain swap patterns, such as multihops, or swaps that interact with the same token pair in multiple Pools, cost
    // much less gas than they would otherwise.
    //
    // It also means that under certain conditions it is possible to perform arbitrage by swapping with multiple
    // Pools in a way that results in net token movement out of the Vault (profit), with no tokens being sent in (only
    // updating the Pool's internal accounting).
    //
    // To protect users from front-running or the market changing rapidly, they supply a list of 'limits' for each token
    // involved in the swap, where either the maximum number of tokens to send (by passing a positive value) or the
    // minimum amount of tokens to receive (by passing a negative value) is specified.
    //
    // Additionally, a 'deadline' timestamp can also be provided, forcing the swap to fail if it occurs after
    // this point in time (e.g. if the transaction failed to be included in a block promptly).
    //
    // If interacting with Pools that hold WETH, it is possible to both send and receive ETH directly: the Vault will do
    // the wrapping and unwrapping. To enable this mechanism, the IAsset sentinel value (the zero address) must be
    // passed in the `assets` array instead of the WETH address. Note that it is possible to combine ETH and WETH in the
    // same swap. Any excess ETH will be sent back to the caller (not the sender, which is relevant for relayers).
    //
    // Finally, Internal Balance can be used when either sending or receiving tokens.

    enum SwapKind { GIVEN_IN, GIVEN_OUT }

    /**
     * @dev Performs a swap with a single Pool.
     *
     * If the swap is 'given in' (the number of tokens to send to the Pool is known), it returns the amount of tokens
     * taken from the Pool, which must be greater than or equal to `limit`.
     *
     * If the swap is 'given out' (the number of tokens to take from the Pool is known), it returns the amount of tokens
     * sent to the Pool, which must be less than or equal to `limit`.
     *
     * Internal Balance usage and the recipient are determined by the `funds` struct.
     *
     * Emits a `Swap` event.
     */
    function swap(
        SingleSwap memory singleSwap,
        FundManagement memory funds,
        uint256 limit,
        uint256 deadline
    ) external payable returns (uint256);

    /**
     * @dev Data for a single swap executed by `swap`. `amount` is either `amountIn` or `amountOut` depending on
     * the `kind` value.
     *
     * `assetIn` and `assetOut` are either token addresses, or the IAsset sentinel value for ETH (the zero address).
     * Note that Pools never interact with ETH directly: it will be wrapped to or unwrapped from WETH by the Vault.
     *
     * The `userData` field is ignored by the Vault, but forwarded to the Pool in the `onSwap` hook, and may be
     * used to extend swap behavior.
     */
    struct SingleSwap {
        bytes32 poolId;
        SwapKind kind;
        IAsset assetIn;
        IAsset assetOut;
        uint256 amount;
        bytes userData;
    }

    /**
     * @dev Performs a series of swaps with one or multiple Pools. In each individual swap, the caller determines either
     * the amount of tokens sent to or received from the Pool, depending on the `kind` value.
     *
     * Returns an array with the net Vault asset balance deltas. Positive amounts represent tokens (or ETH) sent to the
     * Vault, and negative amounts represent tokens (or ETH) sent by the Vault. Each delta corresponds to the asset at
     * the same index in the `assets` array.
     *
     * Swaps are executed sequentially, in the order specified by the `swaps` array. Each array element describes a
     * Pool, the token to be sent to this Pool, the token to receive from it, and an amount that is either `amountIn` or
     * `amountOut` depending on the swap kind.
     *
     * Multihop swaps can be executed by passing an `amount` value of zero for a swap. This will cause the amount in/out
     * of the previous swap to be used as the amount in for the current one. In a 'given in' swap, 'tokenIn' must equal
     * the previous swap's `tokenOut`. For a 'given out' swap, `tokenOut` must equal the previous swap's `tokenIn`.
     *
     * The `assets` array contains the addresses of all assets involved in the swaps. These are either token addresses,
     * or the IAsset sentinel value for ETH (the zero address). Each entry in the `swaps` array specifies tokens in and
     * out by referencing an index in `assets`. Note that Pools never interact with ETH directly: it will be wrapped to
     * or unwrapped from WETH by the Vault.
     *
     * Internal Balance usage, sender, and recipient are determined by the `funds` struct. The `limits` array specifies
     * the minimum or maximum amount of each token the vault is allowed to transfer.
     *
     * `batchSwap` can be used to make a single swap, like `swap` does, but doing so requires more gas than the
     * equivalent `swap` call.
     *
     * Emits `Swap` events.
     */
    function batchSwap(
        SwapKind kind,
        BatchSwapStep[] memory swaps,
        IAsset[] memory assets,
        FundManagement memory funds,
        int256[] memory limits,
        uint256 deadline
    ) external payable returns (int256[] memory);

    /**
     * @dev Data for each individual swap executed by `batchSwap`. The asset in and out fields are indexes into the
     * `assets` array passed to that function, and ETH assets are converted to WETH.
     *
     * If `amount` is zero, the multihop mechanism is used to determine the actual amount based on the amount in/out
     * from the previous swap, depending on the swap kind.
     *
     * The `userData` field is ignored by the Vault, but forwarded to the Pool in the `onSwap` hook, and may be
     * used to extend swap behavior.
     */
    struct BatchSwapStep {
        bytes32 poolId;
        uint256 assetInIndex;
        uint256 assetOutIndex;
        uint256 amount;
        bytes userData;
    }

    /**
     * @dev Emitted for each individual swap performed by `swap` or `batchSwap`.
     */
    event Swap(
        bytes32 indexed poolId,
        IERC20 indexed tokenIn,
        IERC20 indexed tokenOut,
        uint256 amountIn,
        uint256 amountOut
    );

    /**
     * @dev All tokens in a swap are either sent from the `sender` account to the Vault, or from the Vault to the
     * `recipient` account.
     *
     * If the caller is not `sender`, it must be an authorized relayer for them.
     *
     * If `fromInternalBalance` is true, the `sender`'s Internal Balance will be preferred, performing an ERC20
     * transfer for the difference between the requested amount and the User's Internal Balance (if any). The `sender`
     * must have allowed the Vault to use their tokens via `IERC20.approve()`. This matches the behavior of
     * `joinPool`.
     *
     * If `toInternalBalance` is true, tokens will be deposited to `recipient`'s internal balance instead of
     * transferred. This matches the behavior of `exitPool`.
     *
     * Note that ETH cannot be deposited to or withdrawn from Internal Balance: attempting to do so will trigger a
     * revert.
     */
    struct FundManagement {
        address sender;
        bool fromInternalBalance;
        address payable recipient;
        bool toInternalBalance;
    }

    /**
     * @dev Simulates a call to `batchSwap`, returning an array of Vault asset deltas. Calls to `swap` cannot be
     * simulated directly, but an equivalent `batchSwap` call can and will yield the exact same result.
     *
     * Each element in the array corresponds to the asset at the same index, and indicates the number of tokens (or ETH)
     * the Vault would take from the sender (if positive) or send to the recipient (if negative). The arguments it
     * receives are the same that an equivalent `batchSwap` call would receive.
     *
     * Unlike `batchSwap`, this function performs no checks on the sender or recipient field in the `funds` struct.
     * This makes it suitable to be called by off-chain applications via eth_call without needing to hold tokens,
     * approve them for the Vault, or even know a user's address.
     *
     * Note that this function is not 'view' (due to implementation details): the client code must explicitly execute
     * eth_call instead of eth_sendTransaction.
     */
    function queryBatchSwap(
        SwapKind kind,
        BatchSwapStep[] memory swaps,
        IAsset[] memory assets,
        FundManagement memory funds
    ) external returns (int256[] memory assetDeltas);

    // Flash Loans

    /**
     * @dev Performs a 'flash loan', sending tokens to `recipient`, executing the `receiveFlashLoan` hook on it,
     * and then reverting unless the tokens plus a proportional protocol fee have been returned.
     *
     * The `tokens` and `amounts` arrays must have the same length, and each entry in these indicates the loan amount
     * for each token contract. `tokens` must be sorted in ascending order.
     *
     * The 'userData' field is ignored by the Vault, and forwarded as-is to `recipient` as part of the
     * `receiveFlashLoan` call.
     *
     * Emits `FlashLoan` events.
     */
    function flashLoan(
        IFlashLoanRecipient recipient,
        IERC20[] memory tokens,
        uint256[] memory amounts,
        bytes memory userData
    ) external;

    /**
     * @dev Emitted for each individual flash loan performed by `flashLoan`.
     */
    event FlashLoan(IFlashLoanRecipient indexed recipient, IERC20 indexed token, uint256 amount, uint256 feeAmount);

    // Asset Management
    //
    // Each token registered for a Pool can be assigned an Asset Manager, which is able to freely withdraw the Pool's
    // tokens from the Vault, deposit them, or assign arbitrary values to its `managed` balance (see
    // `getPoolTokenInfo`). This makes them extremely powerful and dangerous. Even if an Asset Manager only directly
    // controls one of the tokens in a Pool, a malicious manager could set that token's balance to manipulate the
    // prices of the other tokens, and then drain the Pool with swaps. The risk of using Asset Managers is therefore
    // not constrained to the tokens they are managing, but extends to the entire Pool's holdings.
    //
    // However, a properly designed Asset Manager smart contract can be safely used for the Pool's benefit,
    // for example by lending unused tokens out for interest, or using them to participate in voting protocols.
    //
    // This concept is unrelated to the IAsset interface.

    /**
     * @dev Performs a set of Pool balance operations, which may be either withdrawals, deposits or updates.
     *
     * Pool Balance management features batching, which means a single contract call can be used to perform multiple
     * operations of different kinds, with different Pools and tokens, at once.
     *
     * For each operation, the caller must be registered as the Asset Manager for `token` in `poolId`.
     */
    function managePoolBalance(PoolBalanceOp[] memory ops) external;

    struct PoolBalanceOp {
        PoolBalanceOpKind kind;
        bytes32 poolId;
        IERC20 token;
        uint256 amount;
    }

    /**
     * Withdrawals decrease the Pool's cash, but increase its managed balance, leaving the total balance unchanged.
     *
     * Deposits increase the Pool's cash, but decrease its managed balance, leaving the total balance unchanged.
     *
     * Updates don't affect the Pool's cash balance, but because the managed balance changes, it does alter the total.
     * The external amount can be either increased or decreased by this call (i.e., reporting a gain or a loss).
     */
    enum PoolBalanceOpKind { WITHDRAW, DEPOSIT, UPDATE }

    /**
     * @dev Emitted when a Pool's token Asset Manager alters its balance via `managePoolBalance`.
     */
    event PoolBalanceManaged(
        bytes32 indexed poolId,
        address indexed assetManager,
        IERC20 indexed token,
        int256 cashDelta,
        int256 managedDelta
    );

    // Protocol Fees
    //
    // Some operations cause the Vault to collect tokens in the form of protocol fees, which can then be withdrawn by
    // permissioned accounts.
    //
    // There are two kinds of protocol fees:
    //
    //  - flash loan fees: charged on all flash loans, as a percentage of the amounts lent.
    //
    //  - swap fees: a percentage of the fees charged by Pools when performing swaps. For a number of reasons, including
    // swap gas costs and interface simplicity, protocol swap fees are not charged on each individual swap. Rather,
    // Pools are expected to keep track of how much they have charged in swap fees, and pay any outstanding debts to the
    // Vault when they are joined or exited. This prevents users from joining a Pool with unpaid debt, as well as
    // exiting a Pool in debt without first paying their share.

    /**
     * @dev Returns the current protocol fee module.
     */
    function getProtocolFeesCollector() external view returns (IProtocolFeesCollector);

    /**
     * @dev Safety mechanism to pause most Vault operations in the event of an emergency - typically detection of an
     * error in some part of the system.
     *
     * The Vault can only be paused during an initial time period, after which pausing is forever disabled.
     *
     * While the contract is paused, the following features are disabled:
     * - depositing and transferring internal balance
     * - transferring external balance (using the Vault's allowance)
     * - swaps
     * - joining Pools
     * - Asset Manager interactions
     *
     * Internal Balance can still be withdrawn, and Pools exited.
     */
    function setPaused(bool paused) external;

    /**
     * @dev Returns the Vault's WETH instance.
     */
    function WETH() external view returns (IWETH);
    // solhint-disable-previous-line func-name-mixedcase
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;

import "../openzeppelin/IERC20.sol";

/**
 * @dev Interface for WETH9.
 * See https://github.com/gnosis/canonical-weth/blob/0dd1ea3e295eef916d0c6223ec63141137d22d67/contracts/WETH9.sol
 */
interface IWETH is IERC20 {
    function deposit() external payable;

    function withdraw(uint256 amount) external;
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;

import "@balancer-labs/v2-interfaces/contracts/solidity-utils/openzeppelin/IERC20.sol";
import "@balancer-labs/v2-interfaces/contracts/solidity-utils/helpers/BalancerErrors.sol";

library InputHelpers {
    function ensureInputLengthMatch(uint256 a, uint256 b) internal pure {
        _require(a == b, Errors.INPUT_LENGTH_MISMATCH);
    }

    function ensureInputLengthMatch(
        uint256 a,
        uint256 b,
        uint256 c
    ) internal pure {
        _require(a == b && b == c, Errors.INPUT_LENGTH_MISMATCH);
    }

    function ensureArrayIsSorted(IERC20[] memory array) internal pure {
        address[] memory addressArray;
        // solhint-disable-next-line no-inline-assembly
        assembly {
            addressArray := array
        }
        ensureArrayIsSorted(addressArray);
    }

    function ensureArrayIsSorted(address[] memory array) internal pure {
        if (array.length < 2) {
            return;
        }

        address previous = array[0];
        for (uint256 i = 1; i < array.length; ++i) {
            address current = array[i];
            _require(previous < current, Errors.UNSORTED_ARRAY);
            previous = current;
        }
    }
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;

import "@balancer-labs/v2-solidity-utils/contracts/math/FixedPoint.sol";
import "@balancer-labs/v2-solidity-utils/contracts/math/Math.sol";

// These functions start with an underscore, as if they were part of a contract and not a library. At some point this
// should be fixed.
// solhint-disable private-vars-leading-underscore

library LinearMath {
    using FixedPoint for uint256;

    // A thorough derivation of the formulas and derivations found here exceeds the scope of this file, so only
    // introductory notions will be presented.

    // A Linear Pool holds three tokens: the main token, the wrapped token, and the Pool share token (BPT). It is
    // possible to exchange any of these tokens for any of the other two (so we have three trading pairs) in both
    // directions (the first token of each pair can be bought or sold for the second) and by specifying either the input
    // or output amount (typically referred to as 'given in' or 'given out'). A full description thus requires
    // 3*2*2 = 12 functions.
    // Wrapped tokens have a known, trusted exchange rate to main tokens. All functions here assume such a rate has
    // already been applied, meaning main and wrapped balances can be compared as they are both expressed in the same
    // units (those of main token).
    // Additionally, Linear Pools feature a lower and upper target that represent the desired range of values for the
    // main token balance. Any action that moves the main balance away from this range is charged a proportional fee,
    // and any action that moves it towards this range is incentivized by paying the actor using these collected fees.
    // The collected fees are not stored in a separate data structure: they are a function of the current main balance,
    // targets and fee percentage. The main balance sans fees is known as the 'nominal balance', which is always smaller
    // than the real balance except when the real balance is within the targets.
    // The rule under which Linear Pools conduct trades between main and wrapped tokens is by keeping the sum of nominal
    // main balance and wrapped balance constant: this value is known as the 'invariant'. BPT is backed by nominal
    // reserves, meaning its supply is proportional to the invariant. As the wrapped token appreciates in value and its
    // exchange rate to the main token increases, so does the invariant and thus the value of BPT (in main token units).

    struct Params {
        uint256 fee;
        uint256 lowerTarget;
        uint256 upperTarget;
    }

    function _calcBptOutPerMainIn(
        uint256 mainIn,
        uint256 mainBalance,
        uint256 wrappedBalance,
        uint256 bptSupply,
        Params memory params
    ) internal pure returns (uint256) {
        // Amount out, so we round down overall.

        if (bptSupply == 0) {
            // BPT typically grows in the same ratio the invariant does. The first time liquidity is added however, the
            // BPT supply is initialized to equal the invariant (which in this case is just the nominal main balance as
            // there is no wrapped balance).
            return _toNominal(mainIn, params);
        }

        uint256 previousNominalMain = _toNominal(mainBalance, params);
        uint256 afterNominalMain = _toNominal(mainBalance.add(mainIn), params);
        uint256 deltaNominalMain = afterNominalMain.sub(previousNominalMain);
        uint256 invariant = _calcInvariant(previousNominalMain, wrappedBalance);
        return Math.divDown(Math.mul(bptSupply, deltaNominalMain), invariant);
    }

    function _calcBptInPerMainOut(
        uint256 mainOut,
        uint256 mainBalance,
        uint256 wrappedBalance,
        uint256 bptSupply,
        Params memory params
    ) internal pure returns (uint256) {
        // Amount in, so we round up overall.

        uint256 previousNominalMain = _toNominal(mainBalance, params);
        uint256 afterNominalMain = _toNominal(mainBalance.sub(mainOut), params);
        uint256 deltaNominalMain = previousNominalMain.sub(afterNominalMain);
        uint256 invariant = _calcInvariant(previousNominalMain, wrappedBalance);
        return Math.divUp(Math.mul(bptSupply, deltaNominalMain), invariant);
    }

    function _calcWrappedOutPerMainIn(
        uint256 mainIn,
        uint256 mainBalance,
        Params memory params
    ) internal pure returns (uint256) {
        // Amount out, so we round down overall.

        uint256 previousNominalMain = _toNominal(mainBalance, params);
        uint256 afterNominalMain = _toNominal(mainBalance.add(mainIn), params);
        return afterNominalMain.sub(previousNominalMain);
    }

    function _calcWrappedInPerMainOut(
        uint256 mainOut,
        uint256 mainBalance,
        Params memory params
    ) internal pure returns (uint256) {
        // Amount in, so we round up overall.

        uint256 previousNominalMain = _toNominal(mainBalance, params);
        uint256 afterNominalMain = _toNominal(mainBalance.sub(mainOut), params);
        return previousNominalMain.sub(afterNominalMain);
    }

    function _calcMainInPerBptOut(
        uint256 bptOut,
        uint256 mainBalance,
        uint256 wrappedBalance,
        uint256 bptSupply,
        Params memory params
    ) internal pure returns (uint256) {
        // Amount in, so we round up overall.

        if (bptSupply == 0) {
            // BPT typically grows in the same ratio the invariant does. The first time liquidity is added however, the
            // BPT supply is initialized to equal the invariant (which in this case is just the nominal main balance as
            // there is no wrapped balance).
            return _fromNominal(bptOut, params);
        }

        uint256 previousNominalMain = _toNominal(mainBalance, params);
        uint256 invariant = _calcInvariant(previousNominalMain, wrappedBalance);
        uint256 deltaNominalMain = Math.divUp(Math.mul(invariant, bptOut), bptSupply);
        uint256 afterNominalMain = previousNominalMain.add(deltaNominalMain);
        uint256 newMainBalance = _fromNominal(afterNominalMain, params);
        return newMainBalance.sub(mainBalance);
    }

    function _calcMainOutPerBptIn(
        uint256 bptIn,
        uint256 mainBalance,
        uint256 wrappedBalance,
        uint256 bptSupply,
        Params memory params
    ) internal pure returns (uint256) {
        // Amount out, so we round down overall.

        uint256 previousNominalMain = _toNominal(mainBalance, params);
        uint256 invariant = _calcInvariant(previousNominalMain, wrappedBalance);
        uint256 deltaNominalMain = Math.divDown(Math.mul(invariant, bptIn), bptSupply);
        uint256 afterNominalMain = previousNominalMain.sub(deltaNominalMain);
        uint256 newMainBalance = _fromNominal(afterNominalMain, params);
        return mainBalance.sub(newMainBalance);
    }

    function _calcMainOutPerWrappedIn(
        uint256 wrappedIn,
        uint256 mainBalance,
        Params memory params
    ) internal pure returns (uint256) {
        // Amount out, so we round down overall.

        uint256 previousNominalMain = _toNominal(mainBalance, params);
        uint256 afterNominalMain = previousNominalMain.sub(wrappedIn);
        uint256 newMainBalance = _fromNominal(afterNominalMain, params);
        return mainBalance.sub(newMainBalance);
    }

    function _calcMainInPerWrappedOut(
        uint256 wrappedOut,
        uint256 mainBalance,
        Params memory params
    ) internal pure returns (uint256) {
        // Amount in, so we round up overall.

        uint256 previousNominalMain = _toNominal(mainBalance, params);
        uint256 afterNominalMain = previousNominalMain.add(wrappedOut);
        uint256 newMainBalance = _fromNominal(afterNominalMain, params);
        return newMainBalance.sub(mainBalance);
    }

    function _calcBptOutPerWrappedIn(
        uint256 wrappedIn,
        uint256 mainBalance,
        uint256 wrappedBalance,
        uint256 bptSupply,
        Params memory params
    ) internal pure returns (uint256) {
        // Amount out, so we round down overall.

        if (bptSupply == 0) {
            // BPT typically grows in the same ratio the invariant does. The first time liquidity is added however, the
            // BPT supply is initialized to equal the invariant (which in this case is just the wrapped balance as
            // there is no main balance).
            return wrappedIn;
        }

        uint256 nominalMain = _toNominal(mainBalance, params);
        uint256 previousInvariant = _calcInvariant(nominalMain, wrappedBalance);

        uint256 newWrappedBalance = wrappedBalance.add(wrappedIn);
        uint256 newInvariant = _calcInvariant(nominalMain, newWrappedBalance);

        uint256 newBptBalance = Math.divDown(Math.mul(bptSupply, newInvariant), previousInvariant);

        return newBptBalance.sub(bptSupply);
    }

    function _calcBptInPerWrappedOut(
        uint256 wrappedOut,
        uint256 mainBalance,
        uint256 wrappedBalance,
        uint256 bptSupply,
        Params memory params
    ) internal pure returns (uint256) {
        // Amount in, so we round up overall.

        uint256 nominalMain = _toNominal(mainBalance, params);
        uint256 previousInvariant = _calcInvariant(nominalMain, wrappedBalance);

        uint256 newWrappedBalance = wrappedBalance.sub(wrappedOut);
        uint256 newInvariant = _calcInvariant(nominalMain, newWrappedBalance);

        uint256 newBptBalance = Math.divDown(Math.mul(bptSupply, newInvariant), previousInvariant);

        return bptSupply.sub(newBptBalance);
    }

    function _calcWrappedInPerBptOut(
        uint256 bptOut,
        uint256 mainBalance,
        uint256 wrappedBalance,
        uint256 bptSupply,
        Params memory params
    ) internal pure returns (uint256) {
        // Amount in, so we round up overall.

        if (bptSupply == 0) {
            // BPT typically grows in the same ratio the invariant does. The first time liquidity is added however, the
            // BPT supply is initialized to equal the invariant (which in this case is just the wrapped balance as
            // there is no main balance).
            return bptOut;
        }

        uint256 nominalMain = _toNominal(mainBalance, params);
        uint256 previousInvariant = _calcInvariant(nominalMain, wrappedBalance);

        uint256 newBptBalance = bptSupply.add(bptOut);
        uint256 newWrappedBalance = Math.divUp(Math.mul(newBptBalance, previousInvariant), bptSupply).sub(nominalMain);

        return newWrappedBalance.sub(wrappedBalance);
    }

    function _calcWrappedOutPerBptIn(
        uint256 bptIn,
        uint256 mainBalance,
        uint256 wrappedBalance,
        uint256 bptSupply,
        Params memory params
    ) internal pure returns (uint256) {
        // Amount out, so we round down overall.

        uint256 nominalMain = _toNominal(mainBalance, params);
        uint256 previousInvariant = _calcInvariant(nominalMain, wrappedBalance);

        uint256 newBptBalance = bptSupply.sub(bptIn);
        uint256 newWrappedBalance = Math.divUp(Math.mul(newBptBalance, previousInvariant), bptSupply).sub(nominalMain);

        return wrappedBalance.sub(newWrappedBalance);
    }

    function _calcInvariant(uint256 nominalMainBalance, uint256 wrappedBalance) internal pure returns (uint256) {
        return nominalMainBalance.add(wrappedBalance);
    }

    function _toNominal(uint256 real, Params memory params) internal pure returns (uint256) {
        // Fees are always rounded down: either direction would work but we need to be consistent, and rounding down
        // uses less gas.

        if (real < params.lowerTarget) {
            uint256 fees = (params.lowerTarget - real).mulDown(params.fee);
            return real.sub(fees);
        } else if (real <= params.upperTarget) {
            return real;
        } else {
            uint256 fees = (real - params.upperTarget).mulDown(params.fee);
            return real.sub(fees);
        }
    }

    function _fromNominal(uint256 nominal, Params memory params) internal pure returns (uint256) {
        // Since real = nominal + fees, rounding down fees is equivalent to rounding down real.

        if (nominal < params.lowerTarget) {
            return (nominal.add(params.fee.mulDown(params.lowerTarget))).divDown(FixedPoint.ONE.add(params.fee));
        } else if (nominal <= params.upperTarget) {
            return nominal;
        } else {
            return (nominal.sub(params.fee.mulDown(params.upperTarget)).divDown(FixedPoint.ONE.sub(params.fee)));
        }
    }

    function _calcTokensOutGivenExactBptIn(
        uint256[] memory balances,
        uint256 bptAmountIn,
        uint256 bptTotalSupply,
        uint256 bptIndex
    ) internal pure returns (uint256[] memory) {
        /**********************************************************************************************
        // exactBPTInForTokensOut                                                                    //
        // (per token)                                                                               //
        // aO = tokenAmountOut             /        bptIn         \                                  //
        // b = tokenBalance      a0 = b * | ---------------------  |                                 //
        // bptIn = bptAmountIn             \     bptTotalSupply    /                                 //
        // bpt = bptTotalSupply                                                                      //
        **********************************************************************************************/

        // Since we're computing an amount out, we round down overall. This means rounding down on both the
        // multiplication and division.

        uint256 bptRatio = bptAmountIn.divDown(bptTotalSupply);

        uint256[] memory amountsOut = new uint256[](balances.length);
        for (uint256 i = 0; i < balances.length; i++) {
            // BPT is skipped as those tokens are not the LPs, but rather the preminted and undistributed amount.
            if (i != bptIndex) {
                amountsOut[i] = balances[i].mulDown(bptRatio);
            }
        }

        return amountsOut;
    }
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;
pragma experimental ABIEncoderV2;

import "@balancer-labs/v2-interfaces/contracts/solidity-utils/helpers/BalancerErrors.sol";
import "@balancer-labs/v2-interfaces/contracts/pool-utils/BasePoolUserData.sol";
import "@balancer-labs/v2-interfaces/contracts/pool-utils/IRateProvider.sol";
import "@balancer-labs/v2-interfaces/contracts/pool-linear/ILinearPool.sol";
import "@balancer-labs/v2-interfaces/contracts/vault/IGeneralPool.sol";

import "@balancer-labs/v2-pool-utils/contracts/BasePool.sol";
import "@balancer-labs/v2-pool-utils/contracts/rates/PriceRateCache.sol";

import "@balancer-labs/v2-solidity-utils/contracts/helpers/ERC20Helpers.sol";
import "@balancer-labs/v2-solidity-utils/contracts/math/FixedPoint.sol";

import "./LinearMath.sol";

/**
 * @dev Linear Pools are designed to hold two assets: "main" and "wrapped" tokens that have an equal value underlying
 * token (e.g., DAI and waDAI). There must be an external feed available to provide an exact, non-manipulable exchange
 * rate between the tokens. In particular, any reversible manipulation (e.g. causing the rate to increase and then
 * decrease) can lead to severe issues and loss of funds.
 *
 * The Pool will register three tokens in the Vault however: the two assets and the BPT itself,
 * so that BPT can be exchanged (effectively joining and exiting) via swaps.
 *
 * Despite inheriting from BasePool, much of the basic behavior changes. This Pool does not support regular joins and
 * exits, as the initial BPT supply is 'preminted' during initialization. No further BPT can be minted, and BPT can
 * only be burned if governance enables Recovery Mode and LPs use it to exit proportionally.
 *
 * Unlike most other Pools, this one does not attempt to create revenue by charging fees: value is derived by holding
 * the wrapped, yield-bearing asset. However, the 'swap fee percentage' value is still used, albeit with a different
 * meaning. This Pool attempts to hold a certain amount of "main" tokens, between a lower and upper target value.
 * The pool charges fees on trades that move the balance outside that range, which are then paid back as incentives to
 * traders whose swaps return the balance to the desired region.
 *
 * The net revenue via fees is expected to be zero: all collected fees are used to pay for this 'rebalancing'.
 * Accordingly, this Pool does not pay any protocol fees.
 */
abstract contract LinearPool is ILinearPool, IGeneralPool, IRateProvider, BasePool {
    using WordCodec for bytes32;
    using FixedPoint for uint256;
    using PriceRateCache for bytes32;
    using BasePoolUserData for bytes;

    uint256 private constant _TOTAL_TOKENS = 3; // Main token, wrapped token, BPT

    // This is the maximum token amount the Vault can hold. In regular operation, the total BPT supply remains constant
    // and equal to _INITIAL_BPT_SUPPLY, but most of it remains in the Pool, waiting to be exchanged for tokens. The
    // actual amount of BPT in circulation is the total supply minus the amount held by the Pool, and is known as the
    // 'virtual supply'.
    // The total supply can only change if recovery mode is enabled and recovery mode exits are processed, resulting in
    // BPT being burned. This BPT can never be minted again, so it is technically possible for the preminted supply to
    // run out, but a) this process is controlled by Governance via enabling and disabling recovery mode, and b) the
    // initial supply is so large that it would take a huge number of interactions to acquire sufficient tokens to join
    // the Pool, and then burn the acquired BPT, resulting in prohibitively large gas costs.
    uint256 private constant _INITIAL_BPT_SUPPLY = 2**(112) - 1;

    IERC20 private immutable _mainToken;
    IERC20 private immutable _wrappedToken;

    // The indices of each token when registered, which can then be used to access the balances array.
    uint256 private immutable _bptIndex;
    uint256 private immutable _mainIndex;
    uint256 private immutable _wrappedIndex;

    // Both BPT and the main token have a regular, constant scaling factor (equal to FixedPoint.ONE for BPT, and
    // dependent on the number of decimals for the main token). However, the wrapped token's scaling factor has two
    // components: the usual token decimal scaling factor, and an externally provided rate used to convert wrapped
    // tokens to an equivalent main token amount. This external rate is expected to be ever increasing, reflecting the
    // fact that the wrapped token appreciates in value over time (e.g. because it is accruing interest).
    uint256 private immutable _scalingFactorMainToken;
    uint256 private immutable _scalingFactorWrappedToken;

    // The lower and upper targets are in BasePool's misc data field, which has 192 bits available (as it shares the
    // same storage slot as the swap fee percentage and recovery mode flag, which together take up 64 bits).
    // We use 64 of these 192 for the targets (32 for each).
    //
    // The targets are already scaled by the main token's scaling factor (which makes the token behave as if it had 18
    // decimals), but we only store the integer part: the targets must be multiplied by 1e18 before being used.
    // This means the targets' resolution does not include decimal places in the main token (so e.g. a target of 500.1
    // DAI is impossible). Since targets are expected to be relatively large, this is a non-issue. With 32 bits per
    // target, we can represent values as high as ~4 billion (2^32).
    // [        64 bits       |    32 bits   |    32 bits    | 128 bits ]
    // [       reserved       | upper target |  lower target | reserved ]
    // [  base pool swap fee  |                  misc data              ]
    // [ MSB                                                        LSB ]

    uint256 private constant _TARGET_SCALING = 1e18;

    uint256 private constant _TARGET_BITS = 32;

    uint256 private constant _LOWER_TARGET_OFFSET = 32;
    uint256 private constant _UPPER_TARGET_OFFSET = 64;

    uint256 private constant _MAX_UPPER_TARGET = (2**(32) - 1) * _TARGET_SCALING;

    event TargetsSet(IERC20 indexed token, uint256 lowerTarget, uint256 upperTarget);

    constructor(
        IVault vault,
        string memory name,
        string memory symbol,
        IERC20 mainToken,
        IERC20 wrappedToken,
        uint256 upperTarget,
        address[] memory assetManagers,
        uint256 swapFeePercentage,
        uint256 pauseWindowDuration,
        uint256 bufferPeriodDuration,
        address owner
    )
        BasePool(
            vault,
            IVault.PoolSpecialization.GENERAL,
            name,
            symbol,
            _sortTokens(mainToken, wrappedToken, this),
            _insertNullBptAssetManager(mainToken, wrappedToken, assetManagers),
            swapFeePercentage,
            pauseWindowDuration,
            bufferPeriodDuration,
            owner
        )
    {
        // Set tokens
        _mainToken = mainToken;
        _wrappedToken = wrappedToken;

        // Set token indexes
        (uint256 mainIndex, uint256 wrappedIndex, uint256 bptIndex) = _getSortedTokenIndexes(
            mainToken,
            wrappedToken,
            this
        );
        _bptIndex = bptIndex;
        _mainIndex = mainIndex;
        _wrappedIndex = wrappedIndex;

        // Set scaling factors
        _scalingFactorMainToken = _computeScalingFactor(mainToken);
        _scalingFactorWrappedToken = _computeScalingFactor(wrappedToken);

        // Set initial targets. The lower target must be set to zero because initially there are no accumulated fees.
        // Otherwise the pool would owe fees from the start, which would make the rate manipulable.
        uint256 lowerTarget = 0;
        _setTargets(mainToken, lowerTarget, upperTarget);
    }

    /**
     * @dev Inserts a zero-valued entry in the `assetManagers` array at the BPT token index, ensuring that BPT is not
     * managed even if the main or wrapped tokens are.
     */
    function _insertNullBptAssetManager(
        IERC20 mainToken,
        IERC20 wrappedToken,
        address[] memory assetManagers
    ) private view returns (address[] memory) {
        (, , uint256 bptIndex) = _getSortedTokenIndexes(mainToken, wrappedToken, this);

        address[] memory extendedAssetManagers = new address[](assetManagers.length + 1);
        for (uint256 i = 0; i < extendedAssetManagers.length; ++i) {
            if (i < bptIndex) {
                extendedAssetManagers[i] = assetManagers[i];
            } else if (i > bptIndex) {
                extendedAssetManagers[i] = assetManagers[i - 1];
            } else {
                extendedAssetManagers[i] = address(0);
            }
        }

        return extendedAssetManagers;
    }

    /**
     * @notice Return the main token address as an IERC20.
     */
    function getMainToken() public view override returns (IERC20) {
        return _mainToken;
    }

    /**
     * @notice Return the wrapped token address as an IERC20.
     */
    function getWrappedToken() public view override returns (IERC20) {
        return _wrappedToken;
    }

    /**
     * @notice Return the index of the BPT token.
     * @dev Note that this is an index into the registered token list (with 3 tokens).
     */
    function getBptIndex() public view override returns (uint256) {
        return _bptIndex;
    }

    /**
     * @notice Return the index of the main token.
     * @dev Note that this is an index into the registered token list, which includes the BPT token.
     */
    function getMainIndex() external view override returns (uint256) {
        return _mainIndex;
    }

    /**
     * @notice Return the index of the wrapped token.
     * @dev Note that this is an index into the registered token list, which includes the BPT token.
     */
    function getWrappedIndex() external view override returns (uint256) {
        return _wrappedIndex;
    }

    /**
     * @dev Finishes initialization of the Linear Pool: it is unusable before calling this function as no BPT will have
     * been minted.
     *
     * Since Linear Pools have preminted BPT stored in the Vault, they require an initial join to deposit said BPT as
     * their balance. Unfortunately, this cannot be performed during construction, as a join involves calling the
     * `onJoinPool` function on the Pool, and the Pool will not have any code until construction finishes. Therefore,
     * this must happen in a separate call.
     *
     * It is highly recommended to create Linear pools using the LinearPoolFactory, which calls `initialize`
     * automatically.
     */
    function initialize() external {
        bytes32 poolId = getPoolId();
        (IERC20[] memory tokens, , ) = getVault().getPoolTokens(poolId);

        // Joins typically involve the Pool receiving tokens in exchange for newly-minted BPT. In this case however, the
        // Pool will mint the entire BPT supply to itself, and join itself with it.
        uint256[] memory maxAmountsIn = new uint256[](_TOTAL_TOKENS);
        maxAmountsIn[_bptIndex] = _INITIAL_BPT_SUPPLY;

        // The first time this executes, it will call `_onInitializePool` (as the BPT supply will be zero). Future calls
        // will be routed to `_onJoinPool`, which always reverts, meaning `initialize` will only execute once.
        IVault.JoinPoolRequest memory request = IVault.JoinPoolRequest({
            assets: _asIAsset(tokens),
            maxAmountsIn: maxAmountsIn,
            userData: "",
            fromInternalBalance: false
        });

        getVault().joinPool(poolId, address(this), address(this), request);
    }

    /**
     * @dev Implementation of onSwap, from IGeneralPool.
     */
    function onSwap(
        SwapRequest memory request,
        uint256[] memory balances,
        uint256 indexIn,
        uint256 indexOut
    ) external override onlyVault(request.poolId) returns (uint256) {
        _beforeSwapJoinExit();

        // In most Pools, swaps involve exchanging one token held by the Pool for another. In this case however, since
        // one of the three tokens is the BPT itself, a swap might also be a join (main/wrapped for BPT) or an exit
        // (BPT for main/wrapped).
        // All three swap types (swaps, joins and exits) are fully disabled if the emergency pause is enabled. Under
        // these circumstances, the Pool should be exited using the regular Vault.exitPool function.

        // Sanity check: this is not entirely necessary as the Vault's interface enforces the indices to be valid, but
        // the check is cheap to perform.
        _require(indexIn < _TOTAL_TOKENS && indexOut < _TOTAL_TOKENS, Errors.OUT_OF_BOUNDS);

        // Note that we already know the indices of the main token, wrapped token and BPT, so there is no need to pass
        // these indices to the inner functions.

        // Upscale balances by the scaling factors (taking into account the wrapped token rate)
        uint256[] memory scalingFactors = _scalingFactors();
        _upscaleArray(balances, scalingFactors);

        (uint256 lowerTarget, uint256 upperTarget) = getTargets();
        LinearMath.Params memory params = LinearMath.Params({
            fee: getSwapFeePercentage(),
            lowerTarget: lowerTarget,
            upperTarget: upperTarget
        });

        if (request.kind == IVault.SwapKind.GIVEN_IN) {
            // The amount given is for token in, the amount calculated is for token out
            request.amount = _upscale(request.amount, scalingFactors[indexIn]);
            uint256 amountOut = _onSwapGivenIn(request, balances, params);

            // amountOut tokens are exiting the Pool, so we round down.
            return _downscaleDown(amountOut, scalingFactors[indexOut]);
        } else {
            // The amount given is for token out, the amount calculated is for token in
            request.amount = _upscale(request.amount, scalingFactors[indexOut]);
            uint256 amountIn = _onSwapGivenOut(request, balances, params);

            // amountIn tokens are entering the Pool, so we round up.
            return _downscaleUp(amountIn, scalingFactors[indexIn]);
        }
    }

    function _onSwapGivenIn(
        SwapRequest memory request,
        uint256[] memory balances,
        LinearMath.Params memory params
    ) internal view returns (uint256) {
        if (request.tokenIn == this) {
            return _swapGivenBptIn(request, balances, params);
        } else if (request.tokenIn == _mainToken) {
            return _swapGivenMainIn(request, balances, params);
        } else if (request.tokenIn == _wrappedToken) {
            return _swapGivenWrappedIn(request, balances, params);
        } else {
            _revert(Errors.INVALID_TOKEN);
        }
    }

    function _swapGivenBptIn(
        SwapRequest memory request,
        uint256[] memory balances,
        LinearMath.Params memory params
    ) internal view returns (uint256) {
        _require(request.tokenOut == _mainToken || request.tokenOut == _wrappedToken, Errors.INVALID_TOKEN);
        return
            (request.tokenOut == _mainToken ? LinearMath._calcMainOutPerBptIn : LinearMath._calcWrappedOutPerBptIn)(
                request.amount,
                balances[_mainIndex],
                balances[_wrappedIndex],
                _getVirtualSupply(balances[_bptIndex]),
                params
            );
    }

    function _swapGivenMainIn(
        SwapRequest memory request,
        uint256[] memory balances,
        LinearMath.Params memory params
    ) internal view returns (uint256) {
        _require(request.tokenOut == _wrappedToken || request.tokenOut == this, Errors.INVALID_TOKEN);
        return
            request.tokenOut == this
                ? LinearMath._calcBptOutPerMainIn(
                    request.amount,
                    balances[_mainIndex],
                    balances[_wrappedIndex],
                    _getVirtualSupply(balances[_bptIndex]),
                    params
                )
                : LinearMath._calcWrappedOutPerMainIn(request.amount, balances[_mainIndex], params);
    }

    function _swapGivenWrappedIn(
        SwapRequest memory request,
        uint256[] memory balances,
        LinearMath.Params memory params
    ) internal view returns (uint256) {
        _require(request.tokenOut == _mainToken || request.tokenOut == this, Errors.INVALID_TOKEN);
        return
            request.tokenOut == this
                ? LinearMath._calcBptOutPerWrappedIn(
                    request.amount,
                    balances[_mainIndex],
                    balances[_wrappedIndex],
                    _getVirtualSupply(balances[_bptIndex]),
                    params
                )
                : LinearMath._calcMainOutPerWrappedIn(request.amount, balances[_mainIndex], params);
    }

    function _onSwapGivenOut(
        SwapRequest memory request,
        uint256[] memory balances,
        LinearMath.Params memory params
    ) internal view returns (uint256) {
        if (request.tokenOut == this) {
            return _swapGivenBptOut(request, balances, params);
        } else if (request.tokenOut == _mainToken) {
            return _swapGivenMainOut(request, balances, params);
        } else if (request.tokenOut == _wrappedToken) {
            return _swapGivenWrappedOut(request, balances, params);
        } else {
            _revert(Errors.INVALID_TOKEN);
        }
    }

    function _swapGivenBptOut(
        SwapRequest memory request,
        uint256[] memory balances,
        LinearMath.Params memory params
    ) internal view returns (uint256) {
        _require(request.tokenIn == _mainToken || request.tokenIn == _wrappedToken, Errors.INVALID_TOKEN);
        return
            (request.tokenIn == _mainToken ? LinearMath._calcMainInPerBptOut : LinearMath._calcWrappedInPerBptOut)(
                request.amount,
                balances[_mainIndex],
                balances[_wrappedIndex],
                _getVirtualSupply(balances[_bptIndex]),
                params
            );
    }

    function _swapGivenMainOut(
        SwapRequest memory request,
        uint256[] memory balances,
        LinearMath.Params memory params
    ) internal view returns (uint256) {
        _require(request.tokenIn == _wrappedToken || request.tokenIn == this, Errors.INVALID_TOKEN);
        return
            request.tokenIn == this
                ? LinearMath._calcBptInPerMainOut(
                    request.amount,
                    balances[_mainIndex],
                    balances[_wrappedIndex],
                    _getVirtualSupply(balances[_bptIndex]),
                    params
                )
                : LinearMath._calcWrappedInPerMainOut(request.amount, balances[_mainIndex], params);
    }

    function _swapGivenWrappedOut(
        SwapRequest memory request,
        uint256[] memory balances,
        LinearMath.Params memory params
    ) internal view returns (uint256) {
        _require(request.tokenIn == _mainToken || request.tokenIn == this, Errors.INVALID_TOKEN);
        return
            request.tokenIn == this
                ? LinearMath._calcBptInPerWrappedOut(
                    request.amount,
                    balances[_mainIndex],
                    balances[_wrappedIndex],
                    _getVirtualSupply(balances[_bptIndex]),
                    params
                )
                : LinearMath._calcMainInPerWrappedOut(request.amount, balances[_mainIndex], params);
    }

    function _onInitializePool(
        bytes32,
        address sender,
        address recipient,
        uint256[] memory,
        bytes memory
    ) internal view override returns (uint256, uint256[] memory) {
        // Linear Pools can only be initialized by the Pool performing the initial join via the `initialize` function.
        _require(sender == address(this), Errors.INVALID_INITIALIZATION);
        _require(recipient == address(this), Errors.INVALID_INITIALIZATION);

        // The full BPT supply will be minted and deposited in the Pool. Note that there is no need to approve the Vault
        // as it already has infinite BPT allowance.
        uint256 bptAmountOut = _INITIAL_BPT_SUPPLY;

        uint256[] memory amountsIn = new uint256[](_TOTAL_TOKENS);
        amountsIn[_bptIndex] = _INITIAL_BPT_SUPPLY;

        return (bptAmountOut, amountsIn);
    }

    function _onJoinPool(
        bytes32,
        address,
        address,
        uint256[] memory,
        uint256,
        uint256,
        uint256[] memory,
        bytes memory
    ) internal pure override returns (uint256, uint256[] memory) {
        _revert(Errors.UNHANDLED_BY_LINEAR_POOL);
    }

    function _onExitPool(
        bytes32,
        address,
        address,
        uint256[] memory,
        uint256,
        uint256,
        uint256[] memory,
        bytes memory
    ) internal pure override returns (uint256, uint256[] memory) {
        _revert(Errors.UNHANDLED_BY_LINEAR_POOL);
    }

    /**
     * @dev We cannot use the default RecoveryMode implementation here, since we need to account for the BPT token.
     */
    function _doRecoveryModeExit(
        uint256[] memory registeredBalances,
        uint256,
        bytes memory userData
    ) internal virtual override returns (uint256, uint256[] memory) {
        (uint256 bptAmountIn, uint256[] memory amountsOut) = super._doRecoveryModeExit(
            registeredBalances,
            _getVirtualSupply(registeredBalances[getBptIndex()]),
            userData
        );

        // By default the pool will pay out an amount of BPT equivalent to that which the user burns.
        // We zero this amount out, as otherwise a single user could drain the pool.
        amountsOut[getBptIndex()] = 0;

        return (bptAmountIn, amountsOut);
    }

    function _getMaxTokens() internal pure override returns (uint256) {
        return _TOTAL_TOKENS;
    }

    function _getMinimumBpt() internal pure override returns (uint256) {
        // Linear Pools don't lock any BPT, as the total supply will already be forever non-zero due to the preminting
        // mechanism, ensuring initialization only occurs once.
        return 0;
    }

    function _getTotalTokens() internal view virtual override returns (uint256) {
        return _TOTAL_TOKENS;
    }

    function _scalingFactor(IERC20 token) internal view virtual override returns (uint256) {
        if (token == _mainToken) {
            return _scalingFactorMainToken;
        } else if (token == _wrappedToken) {
            // The wrapped token's scaling factor is not constant, but increases over time as the wrapped token
            // increases in value.
            return _scalingFactorWrappedToken.mulDown(_getWrappedTokenRate());
        } else if (token == this) {
            return FixedPoint.ONE;
        } else {
            _revert(Errors.INVALID_TOKEN);
        }
    }

    function _scalingFactors() internal view virtual override returns (uint256[] memory) {
        uint256[] memory scalingFactors = new uint256[](_TOTAL_TOKENS);

        // The wrapped token's scaling factor is not constant, but increases over time as the wrapped token increases in
        // value.
        scalingFactors[_mainIndex] = _scalingFactorMainToken;
        scalingFactors[_wrappedIndex] = _scalingFactorWrappedToken.mulDown(_getWrappedTokenRate());
        scalingFactors[_bptIndex] = FixedPoint.ONE;

        return scalingFactors;
    }

    // Price rates

    /**
     * @dev For a Linear Pool, the rate represents the appreciation of BPT with respect to the underlying tokens. This
     * rate increases slowly as the wrapped token appreciates in value.
     */
    function getRate() external view override returns (uint256) {
        bytes32 poolId = getPoolId();
        (, uint256[] memory balances, ) = getVault().getPoolTokens(poolId);
        _upscaleArray(balances, _scalingFactors());

        (uint256 lowerTarget, uint256 upperTarget) = getTargets();
        LinearMath.Params memory params = LinearMath.Params({
            fee: getSwapFeePercentage(),
            lowerTarget: lowerTarget,
            upperTarget: upperTarget
        });

        uint256 totalBalance = LinearMath._calcInvariant(
            LinearMath._toNominal(balances[_mainIndex], params),
            balances[_wrappedIndex]
        );

        // Note that we're dividing by the virtual supply, which may be zero (causing this call to revert). However, the
        // only way for that to happen would be for all LPs to exit the Pool, and nothing prevents new LPs from
        // joining it later on.
        return totalBalance.divUp(_getVirtualSupply(balances[_bptIndex]));
    }

    /**
     * @notice Return the conversion rate between the wrapped and main tokens.
     * @dev This is an 18-decimal fixed point value.
     */
    function getWrappedTokenRate() external view returns (uint256) {
        return _getWrappedTokenRate();
    }

    /**
     * @dev Should be an 18-decimal fixed point value that represents the value of the wrapped token in terms of the
     * main token. The final wrapped token scaling factor is this value multiplied by the wrapped token's decimal
     * scaling factor.
     */
    function _getWrappedTokenRate() internal view virtual returns (uint256);

    /**
     * @notice Return the lower and upper bounds of the zero-fee trading range for the main token balance.
     */
    function getTargets() public view override returns (uint256 lowerTarget, uint256 upperTarget) {
        bytes32 miscData = _getMiscData();

        // Since targets are stored downscaled by _TARGET_SCALING, we undo that when reading them.
        lowerTarget = miscData.decodeUint(_LOWER_TARGET_OFFSET, _TARGET_BITS) * _TARGET_SCALING;
        upperTarget = miscData.decodeUint(_UPPER_TARGET_OFFSET, _TARGET_BITS) * _TARGET_SCALING;
    }

    function _setTargets(
        IERC20 mainToken,
        uint256 lowerTarget,
        uint256 upperTarget
    ) private {
        _require(lowerTarget <= upperTarget, Errors.LOWER_GREATER_THAN_UPPER_TARGET);
        _require(upperTarget <= _MAX_UPPER_TARGET, Errors.UPPER_TARGET_TOO_HIGH);

        // Targets are stored downscaled by _TARGET_SCALING to make them fit in _TARGET_BITS at the cost of some
        // resolution. We check that said resolution is not being used before downscaling.

        _require(upperTarget % _TARGET_SCALING == 0, Errors.FRACTIONAL_TARGET);
        _require(lowerTarget % _TARGET_SCALING == 0, Errors.FRACTIONAL_TARGET);

        _setMiscData(
            WordCodec.encodeUint(lowerTarget / _TARGET_SCALING, _LOWER_TARGET_OFFSET, _TARGET_BITS) |
                WordCodec.encodeUint(upperTarget / _TARGET_SCALING, _UPPER_TARGET_OFFSET, _TARGET_BITS)
        );

        emit TargetsSet(mainToken, lowerTarget, upperTarget);
    }

    /**
     * @notice Set the lower and upper bounds of the zero-fee trading range for the main token balance.
     * @dev For a new target range to be valid:
     *      - the current balance must be between the current targets (meaning no fees are currently pending)
     *      - the current balance must be between the new targets (meaning setting them does not create pending fees)
     *
     * The first requirement could be relaxed, as the LPs actually benefit from the pending fees not being paid out,
     * but being stricter makes analysis easier at little expense.
     */
    function setTargets(uint256 newLowerTarget, uint256 newUpperTarget) external authenticate {
        (uint256 currentLowerTarget, uint256 currentUpperTarget) = getTargets();
        _require(_isMainBalanceWithinTargets(currentLowerTarget, currentUpperTarget), Errors.OUT_OF_TARGET_RANGE);
        _require(_isMainBalanceWithinTargets(newLowerTarget, newUpperTarget), Errors.OUT_OF_NEW_TARGET_RANGE);

        _setTargets(_mainToken, newLowerTarget, newUpperTarget);
    }

    /**
     * @notice Set the swap fee percentage.
     * @dev This is a permissioned function, and disabled if the pool is paused.
     * Note that we override the public version of setSwapFeePercentage instead of the internal one
     * (_setSwapFeePercentage) as the internal one is called during construction, and therefore cannot access immutable
     * state variables, which we use below.
     */
    function setSwapFeePercentage(uint256 swapFeePercentage) public override {
        // For the swap fee percentage to be changeable:
        //  - the pool must currently be between the current targets (meaning no fees are currently pending)
        //
        // As the amount of accrued fees is not explicitly stored but rather derived from the main token balance and the
        // current swap fee percentage, requiring for no fees to be pending prevents the fee setter from changing the
        // amount of pending fees, which they could use to e.g. drain Pool funds in the form of inflated fees.

        (uint256 lowerTarget, uint256 upperTarget) = getTargets();
        _require(_isMainBalanceWithinTargets(lowerTarget, upperTarget), Errors.OUT_OF_TARGET_RANGE);

        super.setSwapFeePercentage(swapFeePercentage);
    }

    function _isMainBalanceWithinTargets(uint256 lowerTarget, uint256 upperTarget) private view returns (bool) {
        (uint256 cash, uint256 managed, , ) = getVault().getPoolTokenInfo(getPoolId(), _mainToken);

        uint256 mainTokenBalance = _upscale(cash + managed, _scalingFactor(_mainToken));

        return mainTokenBalance >= lowerTarget && mainTokenBalance <= upperTarget;
    }

    function _isOwnerOnlyAction(bytes32 actionId) internal view virtual override returns (bool) {
        return actionId == getActionId(this.setTargets.selector) || super._isOwnerOnlyAction(actionId);
    }

    /**
     * @notice Returns the number of tokens in circulation.
     *
     * @dev In other pools, this would be the same as `totalSupply`, but since this pool pre-mints BPT and holds it in
     * the Vault as a token, we need to subtract the Vault's balance to get the total "circulating supply". Both the
     * totalSupply and Vault balance can change. If users join or exit using swaps, some of the preminted BPT are
     * exchanged, so the Vault's balance increases after joins and decreases after exits. If users call the recovery
     * mode exit function, the totalSupply can change as BPT are burned.
     */
    function getVirtualSupply() external view returns (uint256) {
        // For a 3 token General Pool, it is cheaper to query the balance for a single token than to read all balances,
        // as getPoolTokenInfo will check for token existence, token balance and Asset Manager (3 reads), while
        // getPoolTokens will read the number of tokens, their addresses and balances (7 reads).
        (uint256 cash, uint256 managed, , ) = getVault().getPoolTokenInfo(getPoolId(), IERC20(this));

        // Note that unlike all other balances, the Vault's BPT balance does not need scaling as its scaling factor is
        // ONE. This addition cannot overflow due to the Vault's balance limits.
        return _getVirtualSupply(cash + managed);
    }

    // The initial amount of BPT pre-minted is _PREMINTED_TOKEN_BALANCE, and it goes entirely to the pool balance in the
    // vault. So the virtualSupply (the actual supply in circulation) is defined as:
    // virtualSupply = totalSupply() - _balances[_bptIndex]
    function _getVirtualSupply(uint256 bptBalance) internal view returns (uint256) {
        return totalSupply().sub(bptBalance);
    }
}