// 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/vault/IGeneralPool.sol";

import "./BasePool.sol";

/**
 * @dev Extension of `BasePool`, adding a handler for `IGeneralPool.onSwap`.
 *
 * Derived contracts must call `BasePool`'s constructor, and implement `_onSwapGivenIn` and `_onSwapGivenOut` along with
 * `BasePool`'s virtual functions. Inheriting from this contract lets derived contracts choose the General
 * specialization setting.
 */
abstract contract BaseGeneralPool is IGeneralPool, BasePool {
    // Swap Hooks

    function onSwap(
        SwapRequest memory swapRequest,
        uint256[] memory balances,
        uint256 indexIn,
        uint256 indexOut
    ) external override onlyVault(swapRequest.poolId) returns (uint256) {
        _beforeSwapJoinExit();

        _validateIndexes(indexIn, indexOut, _getTotalTokens());
        uint256[] memory scalingFactors = _scalingFactors();

        return
            swapRequest.kind == IVault.SwapKind.GIVEN_IN
                ? _swapGivenIn(swapRequest, balances, indexIn, indexOut, scalingFactors)
                : _swapGivenOut(swapRequest, balances, indexIn, indexOut, scalingFactors);
    }

    function _swapGivenIn(
        SwapRequest memory swapRequest,
        uint256[] memory balances,
        uint256 indexIn,
        uint256 indexOut,
        uint256[] memory scalingFactors
    ) internal virtual returns (uint256) {
        // Fees are subtracted before scaling, to reduce the complexity of the rounding direction analysis.
        swapRequest.amount = _subtractSwapFeeAmount(swapRequest.amount);

        _upscaleArray(balances, scalingFactors);
        swapRequest.amount = _upscale(swapRequest.amount, scalingFactors[indexIn]);

        uint256 amountOut = _onSwapGivenIn(swapRequest, balances, indexIn, indexOut);

        // amountOut tokens are exiting the Pool, so we round down.
        return _downscaleDown(amountOut, scalingFactors[indexOut]);
    }

    function _swapGivenOut(
        SwapRequest memory swapRequest,
        uint256[] memory balances,
        uint256 indexIn,
        uint256 indexOut,
        uint256[] memory scalingFactors
    ) internal virtual returns (uint256) {
        _upscaleArray(balances, scalingFactors);
        swapRequest.amount = _upscale(swapRequest.amount, scalingFactors[indexOut]);

        uint256 amountIn = _onSwapGivenOut(swapRequest, balances, indexIn, indexOut);

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

        // Fees are added after scaling happens, to reduce the complexity of the rounding direction analysis.
        return _addSwapFeeAmount(amountIn);
    }

    /*
     * @dev Called when a swap with the Pool occurs, where the amount of tokens entering the Pool is known.
     *
     * Returns the amount of tokens that will be taken from the Pool in return.
     *
     * All amounts inside `swapRequest` and `balances` are upscaled. The swap fee has already been deducted from
     * `swapRequest.amount`.
     *
     * The return value is also considered upscaled, and will be downscaled (rounding down) before returning it to the
     * Vault.
     */
    function _onSwapGivenIn(
        SwapRequest memory swapRequest,
        uint256[] memory balances,
        uint256 indexIn,
        uint256 indexOut
    ) internal virtual returns (uint256);

    /*
     * @dev Called when a swap with the Pool occurs, where the amount of tokens exiting the Pool is known.
     *
     * Returns the amount of tokens that will be granted to the Pool in return.
     *
     * All amounts inside `swapRequest` and `balances` are upscaled.
     *
     * The return value is also considered upscaled, and will be downscaled (rounding up) before applying the swap fee
     * and returning it to the Vault.
     */
    function _onSwapGivenOut(
        SwapRequest memory swapRequest,
        uint256[] memory balances,
        uint256 indexIn,
        uint256 indexOut
    ) internal virtual returns (uint256);

    function _validateIndexes(
        uint256 indexIn,
        uint256 indexOut,
        uint256 limit
    ) private pure {
        _require(indexIn < limit && indexOut < limit, Errors.OUT_OF_BOUNDS);
    }
}

// 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/pool-utils/IControlledPool.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,
    IControlledPool,
    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 override 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);

        // Some pools need to update their state when leaving recovery mode to ensure proper functioning of the Pool.
        // We do not allow an `_onEnableRecoveryMode()` hook as this may jeopardize the ability to enable Recovery mode.
        if (!enabled) _onDisableRecoveryMode();
    }

    /**
     * @dev Performs any necessary actions on the disabling of Recovery Mode.
     * This is usually to reset any fee collection mechanisms to ensure that they operate correctly going forward.
     */
    function _onDisableRecoveryMode() internal virtual {}

    /**
     * @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
        override
        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)) ||
            super._isOwnerOnlyAction(actionId);
    }

    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) internal view virtual returns (bool) {
        return false;
    }

    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: 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-stable/StablePoolUserData.sol";
import "@balancer-labs/v2-interfaces/contracts/solidity-utils/helpers/BalancerErrors.sol";
import "@balancer-labs/v2-interfaces/contracts/standalone-utils/IProtocolFeePercentagesProvider.sol";
import "@balancer-labs/v2-interfaces/contracts/pool-utils/IRateProvider.sol";
import "@balancer-labs/v2-interfaces/contracts/pool-utils/IVersion.sol";

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

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

import "./ComposableStablePoolStorage.sol";
import "./ComposableStablePoolRates.sol";
import "./ComposableStablePoolStorage.sol";
import "./ComposableStablePoolRates.sol";
import "./ComposableStablePoolProtocolFees.sol";
import "./StablePoolAmplification.sol";
import "./StableMath.sol";

/**
 * @dev StablePool with preminted BPT and rate providers for each token, allowing for e.g. wrapped tokens with a known
 * price ratio, such as Compound's cTokens.
 *
 * BPT is preminted on Pool initialization and registered as one of the Pool's tokens, allowing for swaps to behave as
 * single-token joins or exits (by swapping a token for BPT). We also support regular joins and exits, which can mint
 * and burn BPT.
 *
 * Preminted BPT is deposited in the Vault as the initial balance of the Pool, and doesn't belong to any entity until
 * transferred out of the Pool. The Pool's arithmetic behaves as if it didn't exist, and the BPT total supply is not
 * a useful value: we rely on the 'virtual supply' (how much BPT is actually owned outside the Vault) instead.
 */
contract ComposableStablePool is
    IRateProvider,
    IVersion,
    BaseGeneralPool,
    StablePoolAmplification,
    ComposableStablePoolRates,
    ComposableStablePoolProtocolFees
{
    using FixedPoint for uint256;
    using PriceRateCache for bytes32;
    using StablePoolUserData for bytes;
    using BasePoolUserData for bytes;

    // The maximum imposed by the Vault, which stores balances in a packed format, is 2**(112) - 1.
    // We are preminting half of that value (rounded up).
    uint256 private constant _PREMINTED_TOKEN_BALANCE = 2**(111);

    string private _version;

    // The constructor arguments are received in a struct to work around stack-too-deep issues
    struct NewPoolParams {
        IVault vault;
        IProtocolFeePercentagesProvider protocolFeeProvider;
        string name;
        string symbol;
        IERC20[] tokens;
        IRateProvider[] rateProviders;
        uint256[] tokenRateCacheDurations;
        bool exemptFromYieldProtocolFeeFlag;
        uint256 amplificationParameter;
        uint256 swapFeePercentage;
        uint256 pauseWindowDuration;
        uint256 bufferPeriodDuration;
        address owner;
        string version;
    }

    constructor(NewPoolParams memory params)
        BasePool(
            params.vault,
            IVault.PoolSpecialization.GENERAL,
            params.name,
            params.symbol,
            _insertSorted(params.tokens, IERC20(this)),
            new address[](params.tokens.length + 1),
            params.swapFeePercentage,
            params.pauseWindowDuration,
            params.bufferPeriodDuration,
            params.owner
        )
        StablePoolAmplification(params.amplificationParameter)
        ComposableStablePoolStorage(_extractStorageParams(params))
        ComposableStablePoolRates(_extractRatesParams(params))
        ProtocolFeeCache(params.protocolFeeProvider, ProtocolFeeCache.DELEGATE_PROTOCOL_SWAP_FEES_SENTINEL)
    {
        _version = params.version;
    }

    // Translate parameters to avoid stack-too-deep issues in the constructor
    function _extractRatesParams(NewPoolParams memory params)
        private
        pure
        returns (ComposableStablePoolRates.RatesParams memory)
    {
        return
            ComposableStablePoolRates.RatesParams({
                tokens: params.tokens,
                rateProviders: params.rateProviders,
                tokenRateCacheDurations: params.tokenRateCacheDurations
            });
    }

    // Translate parameters to avoid stack-too-deep issues in the constructor
    function _extractStorageParams(NewPoolParams memory params)
        private
        view
        returns (ComposableStablePoolStorage.StorageParams memory)
    {
        return
            ComposableStablePoolStorage.StorageParams({
                registeredTokens: _insertSorted(params.tokens, IERC20(this)),
                tokenRateProviders: params.rateProviders,
                exemptFromYieldProtocolFeeFlag: params.exemptFromYieldProtocolFeeFlag
            });
    }

    function version() external view override returns (string memory) {
        return _version;
    }

    /**
     * @notice Return the minimum BPT balance, required to avoid minimum token balances.
     * @dev This amount is minted and immediately burned on pool initialization, so that the total supply
     * (and therefore post-exit token balances), can never be zero. This keeps the math well-behaved when
     * liquidity is low. (It also provides an easy way to check whether a pool has been initialized, to
     * ensure this is only done once.)
     */
    function getMinimumBpt() external pure returns (uint256) {
        return _getMinimumBpt();
    }

    // BasePool hook

    /**
     * @dev Override base pool hook invoked before any swap, join, or exit to ensure rates are updated before
     * the operation.
     */
    function _beforeSwapJoinExit() internal override {
        super._beforeSwapJoinExit();

        // Before the scaling factors are read, we must update the cached rates, as those will be used to compute the
        // scaling factors.
        // Note that this is not done in a recovery mode exit (since _beforeSwapjoinExit() is not called under those
        // conditions), but this is fine as recovery mode exits are unaffected by scaling factors anyway.
        _cacheTokenRatesIfNecessary();
    }

    // Swap Hooks

    /**
     * @dev Override this hook called by the base class `onSwap`, to check whether we are doing a regular swap,
     * or a swap involving BPT, which is equivalent to a single token join or exit. Since one of the Pool's
     * tokens is the preminted BPT, we need to handle swaps where BPT is involved separately.
     *
     * At this point, the balances are unscaled. The indices are coming from the Vault, so they are indices into
     * the array of registered tokens (including BPT).
     *
     * If this is a swap involving BPT, call `_swapWithBpt`, which computes the amountOut using the swapFeePercentage
     * and charges protocol fees, in the same manner as single token join/exits. Otherwise, perform the default
     * processing for a regular swap.
     */
    function _swapGivenIn(
        SwapRequest memory swapRequest,
        uint256[] memory registeredBalances,
        uint256 registeredIndexIn,
        uint256 registeredIndexOut,
        uint256[] memory scalingFactors
    ) internal virtual override returns (uint256) {
        return
            (swapRequest.tokenIn == IERC20(this) || swapRequest.tokenOut == IERC20(this))
                ? _swapWithBpt(swapRequest, registeredBalances, registeredIndexIn, registeredIndexOut, scalingFactors)
                : super._swapGivenIn(
                    swapRequest,
                    registeredBalances,
                    registeredIndexIn,
                    registeredIndexOut,
                    scalingFactors
                );
    }

    /**
     * @dev Override this hook called by the base class `onSwap`, to check whether we are doing a regular swap,
     * or a swap involving BPT, which is equivalent to a single token join or exit. Since one of the Pool's
     * tokens is the preminted BPT, we need to handle swaps where BPT is involved separately.
     *
     * At this point, the balances are unscaled. The indices and balances are coming from the Vault, so they
     * refer to the full set of registered tokens (including BPT).
     *
     * If this is a swap involving BPT, call `_swapWithBpt`, which computes the amountOut using the swapFeePercentage
     * and charges protocol fees, in the same manner as single token join/exits. Otherwise, perform the default
     * processing for a regular swap.
     */
    function _swapGivenOut(
        SwapRequest memory swapRequest,
        uint256[] memory registeredBalances,
        uint256 registeredIndexIn,
        uint256 registeredIndexOut,
        uint256[] memory scalingFactors
    ) internal virtual override returns (uint256) {
        return
            (swapRequest.tokenIn == IERC20(this) || swapRequest.tokenOut == IERC20(this))
                ? _swapWithBpt(swapRequest, registeredBalances, registeredIndexIn, registeredIndexOut, scalingFactors)
                : super._swapGivenOut(
                    swapRequest,
                    registeredBalances,
                    registeredIndexIn,
                    registeredIndexOut,
                    scalingFactors
                );
    }

    /**
     * @dev This is called from the base class `_swapGivenIn`, so at this point the amount has been adjusted
     * for swap fees, and balances have had scaling applied. This will only be called for regular (non-BPT) swaps,
     * so forward to `onRegularSwap`.
     */
    function _onSwapGivenIn(
        SwapRequest memory request,
        uint256[] memory registeredBalances,
        uint256 registeredIndexIn,
        uint256 registeredIndexOut
    ) internal virtual override returns (uint256) {
        return
            _onRegularSwap(
                true, // given in
                request.amount,
                registeredBalances,
                registeredIndexIn,
                registeredIndexOut
            );
    }

    /**
     * @dev This is called from the base class `_swapGivenOut`, so at this point the amount has been adjusted
     * for swap fees, and balances have had scaling applied. This will only be called for regular (non-BPT) swaps,
     * so forward to `onRegularSwap`.
     */
    function _onSwapGivenOut(
        SwapRequest memory request,
        uint256[] memory registeredBalances,
        uint256 registeredIndexIn,
        uint256 registeredIndexOut
    ) internal virtual override returns (uint256) {
        return
            _onRegularSwap(
                false, // given out
                request.amount,
                registeredBalances,
                registeredIndexIn,
                registeredIndexOut
            );
    }

    /**
     * @dev Perform a swap between non-BPT tokens. Scaling and fee adjustments have been performed upstream, so
     * all we need to do here is calculate the price quote, depending on the direction of the swap.
     */
    function _onRegularSwap(
        bool isGivenIn,
        uint256 amountGiven,
        uint256[] memory registeredBalances,
        uint256 registeredIndexIn,
        uint256 registeredIndexOut
    ) private view returns (uint256) {
        // Adjust indices and balances for BPT token
        uint256[] memory balances = _dropBptItem(registeredBalances);
        uint256 indexIn = _skipBptIndex(registeredIndexIn);
        uint256 indexOut = _skipBptIndex(registeredIndexOut);

        (uint256 currentAmp, ) = _getAmplificationParameter();
        uint256 invariant = StableMath._calculateInvariant(currentAmp, balances);

        if (isGivenIn) {
            return StableMath._calcOutGivenIn(currentAmp, balances, indexIn, indexOut, amountGiven, invariant);
        } else {
            return StableMath._calcInGivenOut(currentAmp, balances, indexIn, indexOut, amountGiven, invariant);
        }
    }

    /**
     * @dev Perform a swap involving the BPT token, equivalent to a single-token join or exit. As with the standard
     * joins and swaps, we first pay any protocol fees pending from swaps that occurred since the previous join or
     * exit, then perform the operation (joinSwap or exitSwap), and finally store the "post operation" invariant and
     * amp, which establishes the new basis for protocol fees.
     *
     * At this point, the scaling factors (including rates) have been computed by the base class, but not yet applied
     * to the balances.
     */
    function _swapWithBpt(
        SwapRequest memory swapRequest,
        uint256[] memory registeredBalances,
        uint256 registeredIndexIn,
        uint256 registeredIndexOut,
        uint256[] memory scalingFactors
    ) private returns (uint256) {
        bool isGivenIn = swapRequest.kind == IVault.SwapKind.GIVEN_IN;

        _upscaleArray(registeredBalances, scalingFactors);
        swapRequest.amount = _upscale(
            swapRequest.amount,
            scalingFactors[isGivenIn ? registeredIndexIn : registeredIndexOut]
        );

        (
            uint256 preJoinExitSupply,
            uint256[] memory balances,
            uint256 currentAmp,
            uint256 preJoinExitInvariant
        ) = _beforeJoinExit(registeredBalances);

        // These calls mutate `balances` so that it holds the post join-exit balances.
        (uint256 amountCalculated, uint256 postJoinExitSupply) = registeredIndexOut == getBptIndex()
            ? _doJoinSwap(
                isGivenIn,
                swapRequest.amount,
                balances,
                _skipBptIndex(registeredIndexIn),
                currentAmp,
                preJoinExitSupply,
                preJoinExitInvariant
            )
            : _doExitSwap(
                isGivenIn,
                swapRequest.amount,
                balances,
                _skipBptIndex(registeredIndexOut),
                currentAmp,
                preJoinExitSupply,
                preJoinExitInvariant
            );

        _updateInvariantAfterJoinExit(
            currentAmp,
            balances,
            preJoinExitInvariant,
            preJoinExitSupply,
            postJoinExitSupply
        );

        return
            isGivenIn
                ? _downscaleDown(amountCalculated, scalingFactors[registeredIndexOut]) // Amount out, round down
                : _downscaleUp(amountCalculated, scalingFactors[registeredIndexIn]); // Amount in, round up
    }

    /**
     * @dev This mutates `balances` so that they become the post-joinswap balances. The StableMath interfaces
     * are different depending on the swap direction, so we forward to the appropriate low-level join function.
     */
    function _doJoinSwap(
        bool isGivenIn,
        uint256 amount,
        uint256[] memory balances,
        uint256 indexIn,
        uint256 currentAmp,
        uint256 actualSupply,
        uint256 preJoinExitInvariant
    ) internal view returns (uint256, uint256) {
        return
            isGivenIn
                ? _joinSwapExactTokenInForBptOut(
                    amount,
                    balances,
                    indexIn,
                    currentAmp,
                    actualSupply,
                    preJoinExitInvariant
                )
                : _joinSwapExactBptOutForTokenIn(
                    amount,
                    balances,
                    indexIn,
                    currentAmp,
                    actualSupply,
                    preJoinExitInvariant
                );
    }

    /**
     * @dev Since this is a join, we know the tokenOut is BPT. Since it is GivenIn, we know the tokenIn amount,
     * and must calculate the BPT amount out.
     * We are moving preminted BPT out of the Vault, which increases the virtual supply.
     */
    function _joinSwapExactTokenInForBptOut(
        uint256 amountIn,
        uint256[] memory balances,
        uint256 indexIn,
        uint256 currentAmp,
        uint256 actualSupply,
        uint256 preJoinExitInvariant
    ) internal view returns (uint256, uint256) {
        // The StableMath function was created with joins in mind, so it expects a full amounts array. We create an
        // empty one and only set the amount for the token involved.
        uint256[] memory amountsIn = new uint256[](balances.length);
        amountsIn[indexIn] = amountIn;

        uint256 bptOut = StableMath._calcBptOutGivenExactTokensIn(
            currentAmp,
            balances,
            amountsIn,
            actualSupply,
            preJoinExitInvariant,
            getSwapFeePercentage()
        );

        balances[indexIn] = balances[indexIn].add(amountIn);
        uint256 postJoinExitSupply = actualSupply.add(bptOut);

        return (bptOut, postJoinExitSupply);
    }

    /**
     * @dev Since this is a join, we know the tokenOut is BPT. Since it is GivenOut, we know the BPT amount,
     * and must calculate the token amount in.
     * We are moving preminted BPT out of the Vault, which increases the virtual supply.
     */
    function _joinSwapExactBptOutForTokenIn(
        uint256 bptOut,
        uint256[] memory balances,
        uint256 indexIn,
        uint256 currentAmp,
        uint256 actualSupply,
        uint256 preJoinExitInvariant
    ) internal view returns (uint256, uint256) {
        uint256 amountIn = StableMath._calcTokenInGivenExactBptOut(
            currentAmp,
            balances,
            indexIn,
            bptOut,
            actualSupply,
            preJoinExitInvariant,
            getSwapFeePercentage()
        );

        balances[indexIn] = balances[indexIn].add(amountIn);
        uint256 postJoinExitSupply = actualSupply.add(bptOut);

        return (amountIn, postJoinExitSupply);
    }

    /**
     * @dev This mutates balances so that they become the post-exitswap balances. The StableMath interfaces are
     * different depending on the swap direction, so we forward to the appropriate low-level exit function.
     */
    function _doExitSwap(
        bool isGivenIn,
        uint256 amount,
        uint256[] memory balances,
        uint256 indexOut,
        uint256 currentAmp,
        uint256 actualSupply,
        uint256 preJoinExitInvariant
    ) internal view returns (uint256, uint256) {
        return
            isGivenIn
                ? _exitSwapExactBptInForTokenOut(
                    amount,
                    balances,
                    indexOut,
                    currentAmp,
                    actualSupply,
                    preJoinExitInvariant
                )
                : _exitSwapExactTokenOutForBptIn(
                    amount,
                    balances,
                    indexOut,
                    currentAmp,
                    actualSupply,
                    preJoinExitInvariant
                );
    }

    /**
     * @dev Since this is an exit, we know the tokenIn is BPT. Since it is GivenIn, we know the BPT amount,
     * and must calculate the token amount out.
     * We are moving BPT out of circulation and into the Vault, which decreases the virtual supply.
     */
    function _exitSwapExactBptInForTokenOut(
        uint256 bptAmount,
        uint256[] memory balances,
        uint256 indexOut,
        uint256 currentAmp,
        uint256 actualSupply,
        uint256 preJoinExitInvariant
    ) internal view returns (uint256, uint256) {
        uint256 amountOut = StableMath._calcTokenOutGivenExactBptIn(
            currentAmp,
            balances,
            indexOut,
            bptAmount,
            actualSupply,
            preJoinExitInvariant,
            getSwapFeePercentage()
        );

        balances[indexOut] = balances[indexOut].sub(amountOut);
        uint256 postJoinExitSupply = actualSupply.sub(bptAmount);

        return (amountOut, postJoinExitSupply);
    }

    /**
     * @dev Since this is an exit, we know the tokenIn is BPT. Since it is GivenOut, we know the token amount out,
     * and must calculate the BPT amount in.
     * We are moving BPT out of circulation and into the Vault, which decreases the virtual supply.
     */
    function _exitSwapExactTokenOutForBptIn(
        uint256 amountOut,
        uint256[] memory balances,
        uint256 indexOut,
        uint256 currentAmp,
        uint256 actualSupply,
        uint256 preJoinExitInvariant
    ) internal view returns (uint256, uint256) {
        // The StableMath function was created with exits in mind, so it expects a full amounts array. We create an
        // empty one and only set the amount for the token involved.
        uint256[] memory amountsOut = new uint256[](balances.length);
        amountsOut[indexOut] = amountOut;

        uint256 bptAmount = StableMath._calcBptInGivenExactTokensOut(
            currentAmp,
            balances,
            amountsOut,
            actualSupply,
            preJoinExitInvariant,
            getSwapFeePercentage()
        );

        balances[indexOut] = balances[indexOut].sub(amountOut);
        uint256 postJoinExitSupply = actualSupply.sub(bptAmount);

        return (bptAmount, postJoinExitSupply);
    }

    // Join Hooks

    /**
     * Since this Pool has preminted BPT which is stored in the Vault, it cannot simply be minted at construction.
     *
     * We take advantage of the fact that StablePools have an initialization step where BPT is minted to the first
     * account joining them, and perform both actions at once. By minting the entire BPT supply for the initial joiner
     * and then pulling all tokens except those due the joiner, we arrive at the desired state of the Pool holding all
     * BPT except the joiner's.
     */
    function _onInitializePool(
        bytes32,
        address sender,
        address,
        uint256[] memory scalingFactors,
        bytes memory userData
    ) internal override returns (uint256, uint256[] memory) {
        StablePoolUserData.JoinKind kind = userData.joinKind();
        _require(kind == StablePoolUserData.JoinKind.INIT, Errors.UNINITIALIZED);

        // AmountsIn usually does not include the BPT token; initialization is the one time it has to.
        uint256[] memory amountsInIncludingBpt = userData.initialAmountsIn();
        InputHelpers.ensureInputLengthMatch(amountsInIncludingBpt.length, scalingFactors.length);
        _upscaleArray(amountsInIncludingBpt, scalingFactors);

        (uint256 amp, ) = _getAmplificationParameter();
        uint256[] memory amountsIn = _dropBptItem(amountsInIncludingBpt);
        uint256 invariantAfterJoin = StableMath._calculateInvariant(amp, amountsIn);

        // Set the initial BPT to the value of the invariant
        uint256 bptAmountOut = invariantAfterJoin;

        // BasePool will mint bptAmountOut for the sender: we then also mint the remaining BPT to make up the total
        // supply, and have the Vault pull those tokens from the sender as part of the join.
        // We are only minting half of the maximum value - already an amount many orders of magnitude greater than any
        // conceivable real liquidity - to allow for minting new BPT as a result of regular joins.
        //
        // Note that the sender need not approve BPT for the Vault as the Vault already has infinite BPT allowance for
        // all accounts.
        uint256 initialBpt = _PREMINTED_TOKEN_BALANCE.sub(bptAmountOut);

        _mintPoolTokens(sender, initialBpt);
        amountsInIncludingBpt[getBptIndex()] = initialBpt;

        // Initialization is still a join, so we need to do post-join work.
        _updatePostJoinExit(amp, invariantAfterJoin);

        return (bptAmountOut, amountsInIncludingBpt);
    }

    /**
     * @dev Base pool hook called from `onJoinPool`. Forward to `onJoinExitPool` with `isJoin` set to true.
     */
    function _onJoinPool(
        bytes32,
        address,
        address,
        uint256[] memory registeredBalances,
        uint256,
        uint256,
        uint256[] memory scalingFactors,
        bytes memory userData
    ) internal override returns (uint256, uint256[] memory) {
        return _onJoinExitPool(true, registeredBalances, scalingFactors, userData);
    }

    /**
     * @dev Base pool hook called from `onExitPool`. Forward to `onJoinExitPool` with `isJoin` set to false.
     * Note that recovery mode exits do not call `_onExitPool`.
     */
    function _onExitPool(
        bytes32,
        address,
        address,
        uint256[] memory registeredBalances,
        uint256,
        uint256,
        uint256[] memory scalingFactors,
        bytes memory userData
    ) internal override returns (uint256, uint256[] memory) {
        return _onJoinExitPool(false, registeredBalances, scalingFactors, userData);
    }

    /**
     * @dev Pay protocol fees before the operation, and call `_updateInvariantAfterJoinExit` afterward, to establish
     * the new basis for protocol fees.
     */
    function _onJoinExitPool(
        bool isJoin,
        uint256[] memory registeredBalances,
        uint256[] memory scalingFactors,
        bytes memory userData
    ) internal returns (uint256, uint256[] memory) {
        (
            uint256 preJoinExitSupply,
            uint256[] memory balances,
            uint256 currentAmp,
            uint256 preJoinExitInvariant
        ) = _beforeJoinExit(registeredBalances);


            function(uint256[] memory, uint256, uint256, uint256, uint256[] memory, bytes memory)
                internal
                view
                returns (uint256, uint256[] memory) _doJoinOrExit
         = (isJoin ? _doJoin : _doExit);

        (uint256 bptAmount, uint256[] memory amountsDelta) = _doJoinOrExit(
            balances,
            currentAmp,
            preJoinExitSupply,
            preJoinExitInvariant,
            scalingFactors,
            userData
        );

        // Unlike joinswaps, explicit joins do not mutate balances into the post join-exit balances so we must perform
        // this mutation here.
        function(uint256, uint256) internal pure returns (uint256) _addOrSub = isJoin ? FixedPoint.add : FixedPoint.sub;
        _mutateAmounts(balances, amountsDelta, _addOrSub);
        uint256 postJoinExitSupply = _addOrSub(preJoinExitSupply, bptAmount);

        // Pass in the post-join balances to reset the protocol fee basis.
        // We are minting bptAmount, increasing the total (and virtual) supply post-join
        _updateInvariantAfterJoinExit(
            currentAmp,
            balances,
            preJoinExitInvariant,
            preJoinExitSupply,
            postJoinExitSupply
        );

        // For clarity and simplicity, arrays used and computed in lower level functions do not include BPT.
        // But the amountsIn array passed back to the Vault must include BPT, so we add it back in here.
        return (bptAmount, _addBptItem(amountsDelta, 0));
    }

    /**
     * @dev Pay any due protocol fees and calculate values necessary for performing the join/exit.
     */
    function _beforeJoinExit(uint256[] memory registeredBalances)
        internal
        returns (
            uint256,
            uint256[] memory,
            uint256,
            uint256
        )
    {
        (uint256 lastJoinExitAmp, uint256 lastPostJoinExitInvariant) = getLastJoinExitData();
        (
            uint256 preJoinExitSupply,
            uint256[] memory balances,
            uint256 oldAmpPreJoinExitInvariant
        ) = _payProtocolFeesBeforeJoinExit(registeredBalances, lastJoinExitAmp, lastPostJoinExitInvariant);

        // If the amplification factor is the same as it was during the last join/exit then we can reuse the
        // value calculated using the "old" amplification factor. If not, then we have to calculate this now.
        (uint256 currentAmp, ) = _getAmplificationParameter();
        uint256 preJoinExitInvariant = currentAmp == lastJoinExitAmp
            ? oldAmpPreJoinExitInvariant
            : StableMath._calculateInvariant(currentAmp, balances);

        return (preJoinExitSupply, balances, currentAmp, preJoinExitInvariant);
    }

    /**
     * @dev Support single- and multi-token joins, plus explicit proportional joins.
     */
    function _doJoin(
        uint256[] memory balances,
        uint256 currentAmp,
        uint256 preJoinExitSupply,
        uint256 preJoinExitInvariant,
        uint256[] memory scalingFactors,
        bytes memory userData
    ) internal view returns (uint256, uint256[] memory) {
        StablePoolUserData.JoinKind kind = userData.joinKind();
        if (kind == StablePoolUserData.JoinKind.EXACT_TOKENS_IN_FOR_BPT_OUT) {
            return
                _joinExactTokensInForBPTOut(
                    preJoinExitSupply,
                    preJoinExitInvariant,
                    currentAmp,
                    balances,
                    scalingFactors,
                    userData
                );
        } else if (kind == StablePoolUserData.JoinKind.ALL_TOKENS_IN_FOR_EXACT_BPT_OUT) {
            return _joinAllTokensInForExactBptOut(preJoinExitSupply, balances, userData);
        } else if (kind == StablePoolUserData.JoinKind.TOKEN_IN_FOR_EXACT_BPT_OUT) {
            return _joinTokenInForExactBPTOut(preJoinExitSupply, preJoinExitInvariant, currentAmp, balances, userData);
        } else {
            _revert(Errors.UNHANDLED_JOIN_KIND);
        }
    }

    /**
     * @dev Proportional join. Pays no swap fees.
     */
    function _joinAllTokensInForExactBptOut(
        uint256 actualSupply,
        uint256[] memory balances,
        bytes memory userData
    ) private pure returns (uint256, uint256[] memory) {
        uint256 bptAmountOut = userData.allTokensInForExactBptOut();
        uint256[] memory amountsIn = StableMath._computeProportionalAmountsIn(balances, bptAmountOut, actualSupply);

        return (bptAmountOut, amountsIn);
    }

    /**
     * @dev Multi-token join. Joins with proportional amounts will pay no protocol fees.
     */
    function _joinExactTokensInForBPTOut(
        uint256 actualSupply,
        uint256 preJoinExitInvariant,
        uint256 currentAmp,
        uint256[] memory balances,
        uint256[] memory scalingFactors,
        bytes memory userData
    ) private view returns (uint256, uint256[] memory) {
        (uint256[] memory amountsIn, uint256 minBPTAmountOut) = userData.exactTokensInForBptOut();
        InputHelpers.ensureInputLengthMatch(balances.length, amountsIn.length);

        // The user-provided amountsIn is unscaled, so we address that.
        _upscaleArray(amountsIn, _dropBptItem(scalingFactors));

        uint256 bptAmountOut = StableMath._calcBptOutGivenExactTokensIn(
            currentAmp,
            balances,
            amountsIn,
            actualSupply,
            preJoinExitInvariant,
            getSwapFeePercentage()
        );

        _require(bptAmountOut >= minBPTAmountOut, Errors.BPT_OUT_MIN_AMOUNT);

        return (bptAmountOut, amountsIn);
    }

    /**
     * @dev Single-token join, equivalent to swapping a pool token for BPT.
     */
    function _joinTokenInForExactBPTOut(
        uint256 actualSupply,
        uint256 preJoinExitInvariant,
        uint256 currentAmp,
        uint256[] memory balances,
        bytes memory userData
    ) private view returns (uint256, uint256[] memory) {
        // Since this index is sent in from the user, we interpret it as NOT including the BPT token.
        (uint256 bptAmountOut, uint256 tokenIndex) = userData.tokenInForExactBptOut();
        // Note that there is no maximum amountIn parameter: this is handled by `IVault.joinPool`.

        // Balances are passed through from the Vault hook, and include BPT
        _require(tokenIndex < balances.length, Errors.OUT_OF_BOUNDS);

        // We join with a single token, so initialize amountsIn with zeros.
        uint256[] memory amountsIn = new uint256[](balances.length);

        // And then assign the result to the selected token.
        amountsIn[tokenIndex] = StableMath._calcTokenInGivenExactBptOut(
            currentAmp,
            balances,
            tokenIndex,
            bptAmountOut,
            actualSupply,
            preJoinExitInvariant,
            getSwapFeePercentage()
        );

        return (bptAmountOut, amountsIn);
    }

    // Exit Hooks

    /**
     * @dev Support single- and multi-token exits, plus explicit proportional exits (in addition to the
     * recovery mode exit).
     */
    function _doExit(
        uint256[] memory balances,
        uint256 currentAmp,
        uint256 preJoinExitSupply,
        uint256 preJoinExitInvariant,
        uint256[] memory scalingFactors,
        bytes memory userData
    ) internal view returns (uint256, uint256[] memory) {
        StablePoolUserData.ExitKind kind = userData.exitKind();
        if (kind == StablePoolUserData.ExitKind.BPT_IN_FOR_EXACT_TOKENS_OUT) {
            return
                _exitBPTInForExactTokensOut(
                    preJoinExitSupply,
                    preJoinExitInvariant,
                    currentAmp,
                    balances,
                    scalingFactors,
                    userData
                );
        } else if (kind == StablePoolUserData.ExitKind.EXACT_BPT_IN_FOR_ALL_TOKENS_OUT) {
            return _exitExactBPTInForTokensOut(preJoinExitSupply, balances, userData);
        } else if (kind == StablePoolUserData.ExitKind.EXACT_BPT_IN_FOR_ONE_TOKEN_OUT) {
            return _exitExactBPTInForTokenOut(preJoinExitSupply, preJoinExitInvariant, currentAmp, balances, userData);
        } else {
            _revert(Errors.UNHANDLED_EXIT_KIND);
        }
    }

    /**
     * @dev Proportional exit. Pays no swap fees. This is functionally equivalent to the recovery mode exit,
     * except this doesn't skip protocol fee collection, calling rate providers, etc., and doesn't require
     * recovery mode to be enabled.
     */
    function _exitExactBPTInForTokensOut(
        uint256 actualSupply,
        uint256[] memory balances,
        bytes memory userData
    ) private pure returns (uint256, uint256[] memory) {
        uint256 bptAmountIn = userData.exactBptInForTokensOut();
        uint256[] memory amountsOut = _computeProportionalAmountsOut(balances, actualSupply, bptAmountIn);

        return (bptAmountIn, amountsOut);
    }

    /**
     * @dev Multi-token exit. Proportional exits will pay no protocol fees.
     */
    function _exitBPTInForExactTokensOut(
        uint256 actualSupply,
        uint256 preJoinExitInvariant,
        uint256 currentAmp,
        uint256[] memory balances,
        uint256[] memory scalingFactors,
        bytes memory userData
    ) private view returns (uint256, uint256[] memory) {
        (uint256[] memory amountsOut, uint256 maxBPTAmountIn) = userData.bptInForExactTokensOut();
        InputHelpers.ensureInputLengthMatch(amountsOut.length, balances.length);

        // The user-provided amountsIn is unscaled, so we address that.
        _upscaleArray(amountsOut, _dropBptItem(scalingFactors));

        uint256 bptAmountIn = StableMath._calcBptInGivenExactTokensOut(
            currentAmp,
            balances,
            amountsOut,
            actualSupply,
            preJoinExitInvariant,
            getSwapFeePercentage()
        );
        _require(bptAmountIn <= maxBPTAmountIn, Errors.BPT_IN_MAX_AMOUNT);

        return (bptAmountIn, amountsOut);
    }

    /**
     * @dev Single-token exit, equivalent to swapping BPT for a pool token.
     */
    function _exitExactBPTInForTokenOut(
        uint256 actualSupply,
        uint256 preJoinExitInvariant,
        uint256 currentAmp,
        uint256[] memory balances,
        bytes memory userData
    ) private view returns (uint256, uint256[] memory) {
        // Since this index is sent in from the user, we interpret it as NOT including the BPT token
        (uint256 bptAmountIn, uint256 tokenIndex) = userData.exactBptInForTokenOut();
        // Note that there is no minimum amountOut parameter: this is handled by `IVault.exitPool`.

        _require(tokenIndex < balances.length, Errors.OUT_OF_BOUNDS);

        // We exit in a single token, so initialize amountsOut with zeros
        uint256[] memory amountsOut = new uint256[](balances.length);

        // And then assign the result to the selected token.
        amountsOut[tokenIndex] = StableMath._calcTokenOutGivenExactBptIn(
            currentAmp,
            balances,
            tokenIndex,
            bptAmountIn,
            actualSupply,
            preJoinExitInvariant,
            getSwapFeePercentage()
        );

        return (bptAmountIn, amountsOut);
    }

    /**
     * @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) {
        // Since this Pool uses preminted BPT, we need to replace the total supply with the virtual total supply, and
        // adjust the balances array by removing BPT from it.
        // Note that we don't compute the actual supply, which would require a lot of complex calculations and
        // interactions with external components. This is fine because virtual and actual supply are the same while
        // recovery mode is enabled (since all protocol fees are forfeit and the fee percentages zeroed out).
        (uint256 virtualSupply, uint256[] memory balances) = _dropBptItemFromBalances(registeredBalances);

        (uint256 bptAmountIn, uint256[] memory amountsOut) = super._doRecoveryModeExit(
            balances,
            virtualSupply,
            userData
        );

        // The vault requires an array including BPT, so add it back in here.
        return (bptAmountIn, _addBptItem(amountsOut, 0));
    }

    // BPT rate

    /**
     * Many functions require accessing multiple internal values that might at first seem unrelated, but are actually
     * quite intertwined, and computed at the same time for optimal performance (since calculating some of them also
     * yields intermediate results useful for other queries). This helper function returns many of these values,
     * greatly reducing bytecode size.
     *
     * The return values are:
     *  @return balances - The current upscaled token balances (not including BPT)
     *  @return virtualSupply - The Pool's virtual supply
     *  @return protocolFeeAmount - The amount of unpaid protocol fees in BPT
     *  @return lastJoinExitAmp - The Pool's amplification factor at the last join or exit operation
     *  @return currentInvariantWithLastJoinExitAmp - The invariant of the current balances, calculated using the
     *  amplification factor at the last join or exit operation.
     */
    function _getSupplyAndFeesData()
        private
        view
        returns (
            uint256[] memory balances,
            uint256 virtualSupply,
            uint256 protocolFeeAmount,
            uint256 lastJoinExitAmp,
            uint256 currentInvariantWithLastJoinExitAmp
        )
    {
        // First we query the Vault for current registered balances (which includes preminted BPT), to then calculate
        // the current scaled balances and virtual supply.
        (, uint256[] memory registeredBalances, ) = getVault().getPoolTokens(getPoolId());
        _upscaleArray(registeredBalances, _scalingFactors());
        (virtualSupply, balances) = _dropBptItemFromBalances(registeredBalances);

        // Now we need to calculate any BPT due in the form of protocol fees. This requires data from the last join or
        // exit operation. `lastJoinExitAmp` can be useful in the scenario in which the amplification factor has not
        // changed, meaning this old value is equal to the current value.
        uint256 lastPostJoinExitInvariant;
        (lastJoinExitAmp, lastPostJoinExitInvariant) = getLastJoinExitData();

        // Computing the protocol ownership percentage also yields the invariant using the old amplification factor. If
        // it has not changed, then this is also the current invariant.
        uint256 expectedProtocolOwnershipPercentage;
        (
            expectedProtocolOwnershipPercentage,
            currentInvariantWithLastJoinExitAmp
        ) = _getProtocolPoolOwnershipPercentage(balances, lastJoinExitAmp, lastPostJoinExitInvariant);

        protocolFeeAmount = ProtocolFees.bptForPoolOwnershipPercentage(
            virtualSupply,
            expectedProtocolOwnershipPercentage
        );
    }

    /**
     * @dev This function returns the appreciation of BPT relative to the underlying tokens, as an 18 decimal fixed
     * point number. It is simply the ratio of the invariant to the BPT supply.
     *
     * The total supply is initialized to equal the invariant, so this value starts at one. During Pool operation the
     * invariant always grows and shrinks either proportionally to the total supply (in scenarios with no price impact,
     * e.g. proportional joins), or grows faster and shrinks more slowly than it (whenever swap fees are collected or
     * the token rates increase). Therefore, the rate is a monotonically increasing function.
     *
     * WARNING: since this function reads balances directly from the Vault, it is potentially subject to manipulation
     * via reentrancy if called within a Vault context (i.e. in the middle of a join or an exit). It is up to the
     * caller to ensure that the function is safe to call.
     *
     * This may happen e.g. if one of the tokens in the Pool contains some form of callback behavior in the
     * `transferFrom` function (like ERC777 tokens do). These tokens are strictly incompatible with the
     * Vault and Pool design, and are not safe to be used.
     *
     * There are also other situations where calling this function is unsafe. See
     * https://forum.balancer.fi/t/reentrancy-vulnerability-scope-expanded/4345 for reference.
     *
     * To call this function safely, attempt to trigger the reentrancy guard in the Vault by calling a non-reentrant
     * function before calling `getRate`. That will make the transaction revert in an unsafe context.
     * (See `whenNotInVaultContext` in `ComposableStablePoolRates`).
     */
    function getRate() external view virtual override returns (uint256) {
        // We need to compute the current invariant and actual total supply. The latter includes protocol fees that have
        // accrued but are not yet minted: in calculating these we'll actually end up fetching most of the data we need
        // for the invariant.

        (
            uint256[] memory balances,
            uint256 virtualSupply,
            uint256 protocolFeeAmount,
            uint256 lastJoinExitAmp,
            uint256 currentInvariantWithLastJoinExitAmp
        ) = _getSupplyAndFeesData();

        // Due protocol fees will be minted at the next join or exit, so we can simply add them to the current virtual
        // supply to get the actual supply.
        uint256 actualTotalSupply = virtualSupply.add(protocolFeeAmount);

        // All that's missing now is the invariant. We have the balances required to calculate it already, but still
        // need the current amplification factor.
        (uint256 currentAmp, ) = _getAmplificationParameter();

        // It turns out that the process for due protocol fee calculation involves computing the current invariant,
        // except using the amplification factor at the last join or exit. This would typically not be terribly useful,
        // but since the amplification factor only changes rarely there is high probability of its current value being
        // the same as it was in the last join or exit. If that is the case, then we can skip the costly invariant
        // computation altogether.
        uint256 currentInvariant = (currentAmp == lastJoinExitAmp)
            ? currentInvariantWithLastJoinExitAmp
            : StableMath._calculateInvariant(currentAmp, balances);

        // With the current invariant and actual total supply, we can compute the rate as a fixed-point number.
        return currentInvariant.divDown(actualTotalSupply);
    }

    /**
     * @dev Returns the effective BPT supply.
     *
     * In other pools, this would be the same as `totalSupply`, but there are two key differences here:
     *  - this pool pre-mints BPT and holds it in the Vault as a token, and as such we need to subtract the Vault's
     *    balance to get the total "circulating supply". This is called the 'virtualSupply'.
     *  - the Pool owes debt to the Protocol in the form of unminted BPT, which will be minted immediately before the
     *    next join or exit. We need to take these into account since, even if they don't yet exist, they will
     *    effectively be included in any Pool operation that involves BPT.
     *
     * In the vast majority of cases, this function should be used instead of `totalSupply()`.
     *
     * **IMPORTANT NOTE**: calling this function within a Vault context (i.e. in the middle of a join or an exit) is
     * potentially unsafe, since the returned value is manipulable. It is up to the caller to ensure safety.
     *
     * This is because this function calculates the invariant, which requires the state of the pool to be in sync
     * with the state of the Vault. That condition may not be true in the middle of a join or an exit.
     *
     * To call this function safely, attempt to trigger the reentrancy guard in the Vault by calling a non-reentrant
     * function before calling `getActualSupply`. That will make the transaction revert in an unsafe context.
     * (See `whenNotInVaultContext` in `ComposableStablePoolRates`).
     *
     * See https://forum.balancer.fi/t/reentrancy-vulnerability-scope-expanded/4345 for reference.
     */
    function getActualSupply() external view returns (uint256) {
        (, uint256 virtualSupply, uint256 protocolFeeAmount, , ) = _getSupplyAndFeesData();
        return virtualSupply.add(protocolFeeAmount);
    }

    /**
     * @dev This function will revert when called within a Vault context (i.e. in the middle of a join or an exit).
     *
     * This function depends on the invariant value, which may be calculated incorrectly in the middle of a join or
     * an exit, because the state of the pool could be out of sync with the state of the Vault. The modifier
     * `whenNotInVaultContext` prevents calling this function (and in turn, the external
     * `updateProtocolFeePercentageCache`) in such a context.
     *
     * See https://forum.balancer.fi/t/reentrancy-vulnerability-scope-expanded/4345 for reference.
     */
    function _beforeProtocolFeeCacheUpdate() internal override whenNotInVaultContext {
        // The `getRate()` function depends on the actual supply, which in turn depends on the cached protocol fee
        // percentages. Changing these would therefore result in the rate changing, which is not acceptable as this is a
        // sensitive value.
        // Because of this, we pay any due protocol fees *before* updating the cache, making it so that the new
        // percentages only affect future operation of the Pool, and not past fees. As a result, `getRate()` is
        // unaffected by the cached protocol fee percentages changing.

        // Given that this operation is state-changing and relatively complex, we only allow it as long as the Pool is
        // not paused.
        _ensureNotPaused();

        // We need to calculate the amount of unminted BPT that represents protocol fees to then pay those. This yields
        // some auxiliary values that turn out to also be useful for the rest of the tasks we want to perform.
        (
            uint256[] memory balances,
            ,
            uint256 protocolFeeAmount,
            uint256 lastJoinExitAmp,
            uint256 currentInvariantWithLastJoinExitAmp
        ) = _getSupplyAndFeesData();

        if (protocolFeeAmount > 0) {
            _payProtocolFees(protocolFeeAmount);
        }

        // With the fees paid, we now need to calculate the current invariant so we can store it alongside the current
        // amplification factor, marking the Pool as free of protocol debt.
        (uint256 currentAmp, ) = _getAmplificationParameter();

        // It turns out that the process for due protocol fee calculation involves computing the current invariant,
        // except using the amplification factor at the last join or exit. This would typically not be terribly useful,
        // but since the amplification factor only changes rarely there is high probability of its current value being
        // the same as it was in the last join or exit. If that is the case, then we can skip the costly invariant
        // computation altogether.
        uint256 currentInvariant = (currentAmp == lastJoinExitAmp)
            ? currentInvariantWithLastJoinExitAmp
            : StableMath._calculateInvariant(currentAmp, balances);

        _updatePostJoinExit(currentAmp, currentInvariant);
    }

    /**
     * @dev This function will revert when called within a Vault context (i.e. in the middle of a join or an exit).
     *
     * This function depends on the invariant value, which may be calculated incorrectly in the middle of a join or
     * an exit, because the state of the pool could be out of sync with the state of the Vault.
     *
     * The modifier `whenNotInVaultContext` prevents calling this function (and in turn, the external
     * `disableRecoveryMode`) in such a context.
     *
     * See https://forum.balancer.fi/t/reentrancy-vulnerability-scope-expanded/4345 for reference.
     */
    function _onDisableRecoveryMode() internal override whenNotInVaultContext {
        // Enabling recovery mode short-circuits protocol fee computations, forcefully returning a zero percentage,
        // increasing the return value of `getRate()` and effectively forfeiting due protocol fees.

        // Therefore, when exiting recovery mode we store the current invariant and the amplification factor used to
        // compute it, marking the Pool as free of protocol debt. Otherwise it'd be possible for debt to be
        // retroactively accrued, which would be incorrect and could lead to the value of `getRate` decreasing.

        (, uint256[] memory registeredBalances, ) = getVault().getPoolTokens(getPoolId());
        _upscaleArray(registeredBalances, _scalingFactors());
        uint256[] memory balances = _dropBptItem(registeredBalances);

        (uint256 currentAmp, ) = _getAmplificationParameter();
        uint256 currentInvariant = StableMath._calculateInvariant(currentAmp, balances);

        _updatePostJoinExit(currentAmp, currentInvariant);
    }

    // Helpers

    /**
     * @dev Mutates `amounts` by applying `mutation` with each entry in `arguments`.
     *
     * Equivalent to `amounts = amounts.map(mutation)`.
     */
    function _mutateAmounts(
        uint256[] memory toMutate,
        uint256[] memory arguments,
        function(uint256, uint256) pure returns (uint256) mutation
    ) private pure {
        uint256 length = toMutate.length;
        InputHelpers.ensureInputLengthMatch(length, arguments.length);

        for (uint256 i = 0; i < length; ++i) {
            toMutate[i] = mutation(toMutate[i], arguments[i]);
        }
    }

    // Permissioned functions

    /**
     * @dev Inheritance rules still require us to override this in the most derived contract, even though
     * it only calls super.
     */
    function _isOwnerOnlyAction(bytes32 actionId)
        internal
        view
        virtual
        override(
            // Our inheritance pattern creates a small diamond that requires explicitly listing the parents here.
            // Each parent calls the `super` version, so linearization ensures all implementations are called.
            BasePool,
            ComposableStablePoolProtocolFees,
            StablePoolAmplification,
            ComposableStablePoolRates
        )
        returns (bool)
    {
        return super._isOwnerOnlyAction(actionId);
    }
}

// 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-solidity-utils/contracts/math/FixedPoint.sol";
import "@balancer-labs/v2-solidity-utils/contracts/helpers/WordCodec.sol";
import "@balancer-labs/v2-pool-utils/contracts/protocol-fees/ProtocolFeeCache.sol";
import "@balancer-labs/v2-pool-utils/contracts/protocol-fees/InvariantGrowthProtocolSwapFees.sol";

import "./ComposableStablePoolStorage.sol";
import "./ComposableStablePoolRates.sol";
import "./StableMath.sol";

abstract contract ComposableStablePoolProtocolFees is
    ComposableStablePoolStorage,
    ComposableStablePoolRates,
    ProtocolFeeCache
{
    using FixedPoint for uint256;
    using WordCodec for bytes32;

    // To track protocol fees, we measure and store the value of the invariant after every join and exit.
    // All invariant growth that happens between join and exit events is due to swap fees and yield.
    // For selected tokens, we exclude the yield portion from the computation.
    // Because the invariant depends on the amplification parameter, and this value may change over time, we should only
    // compare invariants that were computed using the same value. We therefore store both values together.
    //
    // These values reside in the same storage slot. The amplification factor is bound by _MAX_AMP * _AMP_PRECISION, or
    // 5e6, which fits in 23 bits. We use all remaining bits for the invariant: this is more than enough, as the
    // invariant is proportional to the total supply, which is capped at 112 bits.
    // The data structure is as follows:
    //
    // [ last join-exit amplification  | last post join-exit invariant ]
    // [           23 bits             |            233 bits           ]
    bytes32 private _lastJoinExitData;

    uint256 private constant _LAST_POST_JOIN_EXIT_INVARIANT_OFFSET = 0;
    uint256 private constant _LAST_POST_JOIN_EXIT_INVARIANT_SIZE = 233;
    uint256 private constant _LAST_JOIN_EXIT_AMPLIFICATION_OFFSET = _LAST_POST_JOIN_EXIT_INVARIANT_OFFSET +
        _LAST_POST_JOIN_EXIT_INVARIANT_SIZE;

    uint256 private constant _LAST_JOIN_EXIT_AMPLIFICATION_SIZE = 23;

    /**
     * @dev Calculates due protocol fees originating from accumulated swap fees and yield of non-exempt tokens, pays
     * them by minting BPT, and returns the actual supply and current balances.
     *
     * We also return the current invariant computed using the amplification factor at the last join or exit, which can
     * be useful to skip computations in scenarios where the amplification factor is not changing.
     */
    function _payProtocolFeesBeforeJoinExit(
        uint256[] memory registeredBalances,
        uint256 lastJoinExitAmp,
        uint256 lastPostJoinExitInvariant
    )
        internal
        returns (
            uint256,
            uint256[] memory,
            uint256
        )
    {
        (uint256 virtualSupply, uint256[] memory balances) = _dropBptItemFromBalances(registeredBalances);

        // First, we'll compute what percentage of the Pool the protocol should own due to charging protocol fees on
        // swap fees and yield.
        (
            uint256 expectedProtocolOwnershipPercentage,
            uint256 currentInvariantWithLastJoinExitAmp
        ) = _getProtocolPoolOwnershipPercentage(balances, lastJoinExitAmp, lastPostJoinExitInvariant);

        // Now that we know what percentage of the Pool's current value the protocol should own, we can compute how
        // much BPT we need to mint to get to this state. Since we're going to mint BPT for the protocol, the value
        // of each BPT is going to be reduced as all LPs get diluted.
        uint256 protocolFeeAmount = ProtocolFees.bptForPoolOwnershipPercentage(
            virtualSupply,
            expectedProtocolOwnershipPercentage
        );

        if (protocolFeeAmount > 0) {
            _payProtocolFees(protocolFeeAmount);
        }

        // We pay fees before a join or exit to ensure the pool is debt-free. This increases the virtual supply (making
        // it match the actual supply).
        //
        // For this addition to overflow, `totalSupply` would also have already overflowed.
        return (virtualSupply + protocolFeeAmount, balances, currentInvariantWithLastJoinExitAmp);
    }

    function _getProtocolPoolOwnershipPercentage(
        uint256[] memory balances,
        uint256 lastJoinExitAmp,
        uint256 lastPostJoinExitInvariant
    ) internal view returns (uint256, uint256) {
        // We compute three invariants, adjusting the balances of tokens that have rate providers by undoing the current
        // rate adjustment and then applying the old rate. This is equivalent to multiplying by old rate / current rate.
        //
        // In all cases we compute invariants with the last join-exit amplification factor, so that changes to the
        // amplification are not translated into changes to the invariant. Since amplification factor changes are both
        // infrequent and slow, they should have little effect on the pool balances, making this a very good
        // approximation.
        //
        // With this technique we obtain an invariant that does not include yield at all, meaning any growth will be due
        // exclusively to swap fees. We call this the 'swap fee growth invariant'.
        // A second invariant will exclude the yield of exempt tokens, and therefore include both swap fees and
        // non-exempt yield. This is called the 'non exempt growth invariant'.
        // Finally, a third invariant includes the yield of all tokens by using only the current rates. We call this the
        // 'total growth invariant', since it includes both swap fee growth, non-exempt yield growth and exempt yield
        // growth. If the last join-exit amplification equals the current one, this invariant equals the current
        // invariant.

        (
            uint256 swapFeeGrowthInvariant,
            uint256 totalNonExemptGrowthInvariant,
            uint256 totalGrowthInvariant
        ) = _getGrowthInvariants(balances, lastJoinExitAmp, lastPostJoinExitInvariant);

        // By comparing the invariant increase attributable to each source of growth to the total growth invariant,
        // we can calculate how much of the current Pool value originates from that source, and then apply the
        // corresponding protocol fee percentage to that amount.

        // We have two sources of growth: swap fees, and non-exempt yield. As we illustrate graphically below:
        //
        // growth due to swap fees        = (swap fee growth invariant - last post join-exit invariant)
        // growth due to non-exempt yield = (non-exempt growth invariant - swap fee growth invariant)
        //
        // These can be converted to additive percentages by normalizing against the total growth invariant value:
        // growth due to swap fees / total growth invariant = % pool ownership due from swap fees
        // growth due to non-exempt yield / total growth invariant = % pool ownership due from non-exempt yield
        //
        //   ┌───────────────────────┐ ──┐
        //   │  exempt yield         │   │  total growth invariant
        //   ├───────────────────────┤   │ ──┐
        //   │  non-exempt yield     │   │   │  non-exempt growth invariant
        //   ├───────────────────────┤   │   │ ──┐
        //   │  swap fees            │   │   │   │  swap fee growth invariant
        //   ├───────────────────────┤   │   │   │ ──┐
        //   │   original value      │   │   │   │   │  last post join-exit invariant
        //   └───────────────────────┘ ──┘ ──┘ ──┘ ──┘
        //
        // Each invariant should be larger than its precedessor. In case any rounding error results in them being
        // smaller, we adjust the subtraction to equal 0.

        // Note: in the unexpected scenario where the rates of the tokens shrink over time instead of growing (i.e. if
        // the yield is negative), the non-exempt growth invariant might actually be *smaller* than the swap fee growth
        // invariant, and the total growth invariant might be *smaller* than the non-exempt growth invariant. Depending
        // on the order in which swaps, joins/exits and rate changes happen, as well as their relative magnitudes, it is
        // possible for the Pool to either pay more or less protocol fees than it should.

        // This patched version handles these edge cases gracefully, as it 1) forcibly bounds the swap fee growth
        // invariant between the total growth and last post join-exit invariant; 2) enforces "all or nothing" exempt
        // flags, which constrains the non-exempt growth invariant to be equal to either the total growth or swap
        // fee growth invariant.
        //
        // Furthermore, the protocol ownership percentage is hard-coded to zero (so protocol fees will be zero),
        // if the total growth invariant has gone *down* since the last join or exit, which is possible if rates
        // declined. Together, these measures ensure protocol fee amounts will be bound by the non-manipulable
        // swap fee growth, or zero in any pathological situations.

        // If the total invariant decreased or stayed the same, there is no growth to split between swap and yield fees.
        if (totalGrowthInvariant <= lastPostJoinExitInvariant) {
            return (0, totalGrowthInvariant);
        }

        // By now, the following inequality applies:
        // totalGrowthInvariant >= totalNonExemptGrowthInvariant >= swapFeeGrowthInvariant >= lastPostJoinExitInvariant
        // So these differences are safe to execute; their lower bound is 0 and they will not overflow.
        uint256 swapFeeGrowthInvariantDelta = swapFeeGrowthInvariant - lastPostJoinExitInvariant;
        uint256 nonExemptYieldGrowthInvariantDelta = totalNonExemptGrowthInvariant - swapFeeGrowthInvariant;

        // We can now derive what percentage of the Pool's total value each invariant delta represents by dividing by
        // the total growth invariant. These values, multiplied by the protocol fee percentage for each growth type,
        // represent the percentage of Pool ownership the protocol should have due to each source.

        uint256 protocolSwapFeePercentage = swapFeeGrowthInvariantDelta.divDown(totalGrowthInvariant).mulDown(
            getProtocolFeePercentageCache(ProtocolFeeType.SWAP)
        );

        uint256 protocolYieldPercentage = nonExemptYieldGrowthInvariantDelta.divDown(totalGrowthInvariant).mulDown(
            getProtocolFeePercentageCache(ProtocolFeeType.YIELD)
        );

        // These percentages can then be simply added to compute the total protocol Pool ownership percentage.
        // This is naturally bounded above by FixedPoint.ONE so this addition cannot overflow.
        return (protocolSwapFeePercentage + protocolYieldPercentage, totalGrowthInvariant);
    }

    /**
     * @dev Returns total growth invariant and swap / yield invariant approximations.
     * The calculated invariants are bounded such that:
     *
     * - if totalGrowthInvariant <= lastPostJoinExitInvariant, the total value has decreased, so we can skip all
     * other invariant calculations and just return `totalGrowthInvariant` for all. Protocol fees should be zero
     * in this case, so callers using this to compute fees must also check for this, and return zero for the
     * protocol ownership percentage.
     *
     * - Otherwise, totalGrowthInvariant >= totalNonExemptGrowthInvariant >=
     *     swapFeeGrowthInvariant >= lastPostJoinExitInvariant
     * This was previously an assumption, but is now ensured by the logic in this function.
     */
    function _getGrowthInvariants(
        uint256[] memory balances,
        uint256 lastJoinExitAmp,
        uint256 lastPostJoinExitInvariant
    )
        internal
        view
        returns (
            uint256 swapFeeGrowthInvariant,
            uint256 totalNonExemptGrowthInvariant,
            uint256 totalGrowthInvariant
        )
    {
        // Total growth invariant is always calculated with the current (scaled / unadjusted) balances.
        totalGrowthInvariant = StableMath._calculateInvariant(lastJoinExitAmp, balances);

        // If total invariant decreased, calculating the other approximations is unnecessary.
        if (totalGrowthInvariant <= lastPostJoinExitInvariant) {
            return (totalGrowthInvariant, totalGrowthInvariant, totalGrowthInvariant);
        }

        // Swap fee invariant is calculated with adjusted balances, to discount the yield.
        swapFeeGrowthInvariant = StableMath._calculateInvariant(
            lastJoinExitAmp,
            _getAdjustedBalances(balances) // Adjust all token balances with rate providers.
        );

        // The `swapFeeGrowthInvariant` cannot ever be outside the bounds:
        // totalGrowthInvariant >= swapFeeGrowthInvariant >= lastPostJoinExitInvariant
        swapFeeGrowthInvariant = Math.min(totalGrowthInvariant, swapFeeGrowthInvariant); // Set upper bound.
        swapFeeGrowthInvariant = Math.max(lastPostJoinExitInvariant, swapFeeGrowthInvariant); // Set lower bound.

        // The only two accepted possibilities are either all tokens exempt, or none tokens exempt.
        // totalNonExemptGrowthInvariant will either be totalGrowthInvariant or swapFeeGrowthInvariant.
        // At this point,
        // - totalGrowthInvariant > lastPostJoinExitInvariant
        // - totalGrowthInvariant >= swapFeeGrowthInvariant >= lastPostJoinExitInvariant
        // So the complete inequality will apply by the end of this function:
        // totalGrowthInvariant >= totalNonExemptGrowthInvariant >= swapFeeGrowthInvariant >= lastPostJoinExitInvariant
        if (isExemptFromYieldProtocolFee()) {
            // If no tokens are charged fees on yield, then the non-exempt growth is equal to the swap fee growth - no
            // yield fees will be collected.

            totalNonExemptGrowthInvariant = swapFeeGrowthInvariant;
        } else {
            // If there are no tokens with fee-exempt yield, then the total non-exempt growth will equal the total
            // growth: all yield growth is non-exempt. There's also no point in adjusting balances, since we
            // already know none are exempt.

            totalNonExemptGrowthInvariant = totalGrowthInvariant;
        }
    }

    /**
     * @dev Store the latest invariant based on the adjusted balances after the join or exit, using current rates.
     * Also cache the amp factor, so that the invariant is not affected by amp updates between joins and exits.
     *
     * Pay protocol fees due on any current join or exit swap.
     */
    function _updateInvariantAfterJoinExit(
        uint256 currentAmp,
        uint256[] memory balances,
        uint256 preJoinExitInvariant,
        uint256 preJoinExitSupply,
        uint256 postJoinExitSupply
    ) internal {
        // `_payProtocolFeesBeforeJoinExit` paid protocol fees accumulated between the previous and current
        // join or exit, while this code pays any protocol fees due on the current join or exit.
        // The amp and rates are constant during a single transaction, so it doesn't matter if there
        // is an ongoing amp change, and we can ignore yield.

        // Compute the growth ratio between the pre- and post-join/exit balances.
        // Note that the pre-join/exit invariant is *not* the invariant from the last join,
        // but computed from the balances before this particular join/exit.

        uint256 postJoinExitInvariant = StableMath._calculateInvariant(currentAmp, balances);

        // Compute the portion of the invariant increase due to fees
        uint256 supplyGrowthRatio = postJoinExitSupply.divDown(preJoinExitSupply);
        uint256 feelessInvariant = preJoinExitInvariant.mulDown(supplyGrowthRatio);

        // The postJoinExitInvariant should always be greater than the feelessInvariant (since the invariant and total
        // supply move proportionally outside of fees, which the postJoinInvariant includes and the feelessInvariant
        // does not). However, in the unexpected case in which due to rounding errors this is not true, we simply skip
        // further computation of protocol fees.
        if (postJoinExitInvariant > feelessInvariant) {
            uint256 invariantDeltaFromFees = postJoinExitInvariant - feelessInvariant;

            // To convert to a percentage of pool ownership, multiply by the rate,
            // then normalize against the final invariant
            uint256 protocolOwnershipPercentage = Math.divDown(
                Math.mul(invariantDeltaFromFees, getProtocolFeePercentageCache(ProtocolFeeType.SWAP)),
                postJoinExitInvariant
            );

            if (protocolOwnershipPercentage > 0) {
                uint256 protocolFeeAmount = ProtocolFees.bptForPoolOwnershipPercentage(
                    postJoinExitSupply,
                    protocolOwnershipPercentage
                );

                _payProtocolFees(protocolFeeAmount);
            }
        }

        _updatePostJoinExit(currentAmp, postJoinExitInvariant);
    }

    /**
     * @dev Update the stored values of the amp and final post-join/exit invariant, to reset the basis for protocol
     * swap fees. Also copy the current rates to the old rates, to establish the new protocol yield basis for protocol
     * yield fees.
     */
    function _updatePostJoinExit(uint256 currentAmp, uint256 postJoinExitInvariant) internal {
        _lastJoinExitData =
            WordCodec.encodeUint(currentAmp, _LAST_JOIN_EXIT_AMPLIFICATION_OFFSET, _LAST_JOIN_EXIT_AMPLIFICATION_SIZE) |
            WordCodec.encodeUint(
                postJoinExitInvariant,
                _LAST_POST_JOIN_EXIT_INVARIANT_OFFSET,
                _LAST_POST_JOIN_EXIT_INVARIANT_SIZE
            );

        _updateOldRates();
    }

    /**
     * @notice Return the amplification factor and invariant as of the most recent join or exit (including BPT swaps)
     */
    function getLastJoinExitData()
        public
        view
        returns (uint256 lastJoinExitAmplification, uint256 lastPostJoinExitInvariant)
    {
        bytes32 rawData = _lastJoinExitData;

        lastJoinExitAmplification = rawData.decodeUint(
            _LAST_JOIN_EXIT_AMPLIFICATION_OFFSET,
            _LAST_JOIN_EXIT_AMPLIFICATION_SIZE
        );

        lastPostJoinExitInvariant = rawData.decodeUint(
            _LAST_POST_JOIN_EXIT_INVARIANT_OFFSET,
            _LAST_POST_JOIN_EXIT_INVARIANT_SIZE
        );
    }

    /**
     * @dev Inheritance rules still require us to override this in the most derived contract, even though
     * it only calls super.
     */
    function _isOwnerOnlyAction(bytes32 actionId)
        internal
        view
        virtual
        override(
            // Our inheritance pattern creates a small diamond that requires explicitly listing the parents here.
            // Each parent calls the `super` version, so linearization ensures all implementations are called.
            BasePool,
            BasePoolAuthorization,
            ComposableStablePoolRates
        )
        returns (bool)
    {
        return super._isOwnerOnlyAction(actionId);
    }
}

// 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/pool-utils/IRateProvider.sol";

import "@balancer-labs/v2-solidity-utils/contracts/helpers/ERC20Helpers.sol";
import "@balancer-labs/v2-solidity-utils/contracts/helpers/InputHelpers.sol";
import "@balancer-labs/v2-pool-utils/contracts/rates/PriceRateCache.sol";

import "./ComposableStablePoolStorage.sol";

abstract contract ComposableStablePoolRates is ComposableStablePoolStorage {
    using PriceRateCache for bytes32;
    using FixedPoint for uint256;

    struct RatesParams {
        IERC20[] tokens;
        IRateProvider[] rateProviders;
        uint256[] tokenRateCacheDurations;
    }

    // Token rate caches are used to avoid querying the price rate for a token every time we need to work with it.
    // The "old rate" field is used for precise protocol fee calculation, to ensure that token yield is only
    // "taxed" once. The data structure is as follows:
    //
    // [ expires | duration | old rate | current rate ]
    // [ uint32  |  uint32  |  uint96  |   uint96     ]

    // Since we never need just one cache but all of them at once, instead of making the mapping go from token address
    // to cache, we go from token index (including BPT), i.e. an array. We use a mapping however instead of a native
    // array to skip the extra read associated with the out-of-bounds check, as we have cheaper ways to guarantee the
    // indices are valid.
    mapping(uint256 => bytes32) internal _tokenRateCaches;

    event TokenRateCacheUpdated(uint256 indexed tokenIndex, uint256 rate);
    event TokenRateProviderSet(uint256 indexed tokenIndex, IRateProvider indexed provider, uint256 cacheDuration);

    constructor(RatesParams memory rateParams) {
        InputHelpers.ensureInputLengthMatch(
            rateParams.tokens.length,
            rateParams.rateProviders.length,
            rateParams.tokenRateCacheDurations.length
        );

        IERC20[] memory registeredTokens = _insertSorted(rateParams.tokens, IERC20(this));
        uint256 bptIndex;
        for (
            bptIndex = registeredTokens.length - 1;
            bptIndex > 0 && registeredTokens[bptIndex] > IERC20(this);
            bptIndex--
        ) {
            // solhint-disable-previous-line no-empty-blocks
        }

        uint256 skipBpt = 0;
        for (uint256 i = 0; i < rateParams.tokens.length; i++) {
            if (i == bptIndex) {
                skipBpt = 1;
            }

            uint256 k = i + skipBpt;
            if (rateParams.rateProviders[i] != IRateProvider(0)) {
                _updateTokenRateCache(k, rateParams.rateProviders[i], rateParams.tokenRateCacheDurations[i]);

                emit TokenRateProviderSet(k, rateParams.rateProviders[i], rateParams.tokenRateCacheDurations[i]);

                // Initialize the old rates as well, in case they are referenced before the first join.
                _updateOldRate(k);
            }
        }
    }

    /**
     * @dev Ensure we are not in a Vault context when this function is called, by attempting a no-op internal
     * balance operation. If we are already in a Vault transaction (e.g., a swap, join, or exit), the Vault's
     * reentrancy protection will cause this function to revert.
     *
     * The exact function call doesn't really matter: we're just trying to trigger the Vault reentrancy check
     * (and not hurt anything in case it works). An empty operation array with no specific operation at all works
     * for that purpose, and is also the least expensive in terms of gas and bytecode size.
     *
     * Use this modifier with any function that can cause a state change in a pool and is either public itself,
     * or called by a public function *outside* a Vault operation (e.g., join, exit, or swap).
     * See https://forum.balancer.fi/t/reentrancy-vulnerability-scope-expanded/4345 for reference.
     */
    modifier whenNotInVaultContext() {
        _ensureNotInVaultContext();
        _;
    }

    /**
     * @dev Reverts if called in the middle of a Vault operation; has no effect otherwise.
     */
    function _ensureNotInVaultContext() private {
        IVault.UserBalanceOp[] memory noop = new IVault.UserBalanceOp[](0);
        getVault().manageUserBalance(noop);
    }

    /**
     * @dev Updates the old rate for the token at `index` (including BPT). Assumes `index` is valid.
     */
    function _updateOldRate(uint256 index) internal {
        bytes32 cache = _tokenRateCaches[index];
        _tokenRateCaches[index] = cache.updateOldRate();
    }

    /**
     * @dev Returns the rate for a given token. All token rates are fixed-point values with 18 decimals.
     * If there is no rate provider for the provided token, it returns FixedPoint.ONE.
     */
    function getTokenRate(IERC20 token) external view returns (uint256) {
        return _getTokenRate(_getTokenIndex(token));
    }

    function _getTokenRate(uint256 index) internal view virtual returns (uint256) {
        // We optimize for the scenario where all tokens have rate providers, except the BPT (which never has a rate
        // provider). Therefore, we return early if `token` is the BPT, and otherwise optimistically read the cache
        // expecting that it will not be empty (instead of e.g. fetching the provider to avoid a cache read, since
        // we don't need the provider at all).

        if (index == getBptIndex()) {
            return FixedPoint.ONE;
        }

        bytes32 tokenRateCache = _tokenRateCaches[index];
        return tokenRateCache == bytes32(0) ? FixedPoint.ONE : tokenRateCache.getCurrentRate();
    }

    /**
     * @dev Returns the cached value for token's rate. Reverts if the token doesn't belong to the pool or has no rate
     * provider.
     */
    function getTokenRateCache(IERC20 token)
        external
        view
        returns (
            uint256 rate,
            uint256 oldRate,
            uint256 duration,
            uint256 expires
        )
    {
        bytes32 cache = _tokenRateCaches[_getTokenIndex(token)];

        // A zero cache indicates that the token doesn't have a rate provider associated with it.
        _require(cache != bytes32(0), Errors.TOKEN_DOES_NOT_HAVE_RATE_PROVIDER);

        rate = cache.getCurrentRate();
        oldRate = cache.getOldRate();
        (duration, expires) = cache.getTimestamps();
    }

    /**
     * @dev Sets a new duration for a token rate cache.
     * Note this function also updates the current cached value.
     *
     * This function will revert when called within a Vault context (i.e. in the middle of a join or an exit).
     *
     * This function depends on `getRate` via the rate provider, which may be calculated incorrectly in the middle of a
     * join or an exit because the state of the pool could be out of sync with the state of the Vault.
     *
     * It will also revert if there was no rate provider set initially.
     *
     * See https://forum.balancer.fi/t/reentrancy-vulnerability-scope-expanded/4345 for reference.
     *
     * @param duration Number of seconds until the current token rate is fetched again.
     */
    function setTokenRateCacheDuration(IERC20 token, uint256 duration) external authenticate whenNotInVaultContext {
        uint256 index = _getTokenIndex(token);
        IRateProvider provider = _getRateProvider(index);
        _require(address(provider) != address(0), Errors.TOKEN_DOES_NOT_HAVE_RATE_PROVIDER);
        _updateTokenRateCache(index, provider, duration);
        emit TokenRateProviderSet(index, provider, duration);
    }

    /**
     * @dev Forces a rate cache hit for a token.
     *
     * This function will revert when called within a Vault context (i.e. in the middle of a join or an exit).
     *
     * This function depends on `getRate` via the rate provider, which may be calculated incorrectly in the middle of a
     * join or an exit because the state of the pool could be out of sync with the state of the Vault.
     *
     * It will also revert if the requested token does not have an associated rate provider.
     *
     * See https://forum.balancer.fi/t/reentrancy-vulnerability-scope-expanded/4345 for reference.
     */
    function updateTokenRateCache(IERC20 token) external whenNotInVaultContext {
        uint256 index = _getTokenIndex(token);

        IRateProvider provider = _getRateProvider(index);
        _require(address(provider) != address(0), Errors.TOKEN_DOES_NOT_HAVE_RATE_PROVIDER);
        uint256 duration = _tokenRateCaches[index].getDuration();
        _updateTokenRateCache(index, provider, duration);
    }

    /**
     * @dev Internal function to update a token rate cache for a known provider and duration.
     * It trusts the given values, and does not perform any checks.
     */
    function _updateTokenRateCache(
        uint256 index,
        IRateProvider provider,
        uint256 duration
    ) internal virtual {
        uint256 rate = provider.getRate();
        bytes32 cache = _tokenRateCaches[index];

        _tokenRateCaches[index] = cache.updateRateAndDuration(rate, duration);

        emit TokenRateCacheUpdated(index, rate);
    }

    /**
     * @dev Caches the rates of all tokens if necessary
     */
    function _cacheTokenRatesIfNecessary() internal {
        uint256 totalTokens = _getTotalTokens();
        for (uint256 i = 0; i < totalTokens; ++i) {
            _cacheTokenRateIfNecessary(i);
        }
    }

    /**
     * @dev Caches the rate for a token if necessary. It ignores the call if there is no provider set.
     */
    function _cacheTokenRateIfNecessary(uint256 index) internal {
        // We optimize for the scenario where all tokens have rate providers, except the BPT (which never has a rate
        // provider). Therefore, we return early if token is BPT, and otherwise optimistically read the cache expecting
        // that it will not be empty (instead of e.g. fetching the provider to avoid a cache read in situations where
        // we might not need the provider if the cache is still valid).

        if (index == getBptIndex()) return;

        bytes32 cache = _tokenRateCaches[index];
        if (cache != bytes32(0)) {
            (uint256 duration, uint256 expires) = cache.getTimestamps();
            if (block.timestamp > expires) {
                // solhint-disable-previous-line not-rely-on-time
                _updateTokenRateCache(index, _getRateProvider(index), duration);
            }
        }
    }

    // To compute the yield protocol fees, we need the oldRate for all tokens, even if the exempt flag is not set.
    // We do need to ensure the token has a rate provider before updating; otherwise it will not be in the cache.
    function _updateOldRates() internal {
        uint256 totalTokens = _getTotalTokens();
        for (uint256 i = 0; i < totalTokens; ++i) {
            if (_hasRateProvider(i)) _updateOldRate(i);
        }
    }

    /**
     * @dev Apply the token ratios to a set of balances, only if they have a rate provider.
     * The `balances` array is assumed to not include BPT to ensure that token indices align.
     */
    function _getAdjustedBalances(uint256[] memory balances) internal view returns (uint256[] memory) {
        uint256 totalTokensWithoutBpt = balances.length;
        uint256[] memory adjustedBalances = new uint256[](totalTokensWithoutBpt);

        for (uint256 i = 0; i < totalTokensWithoutBpt; ++i) {
            uint256 skipBptIndex = i >= getBptIndex() ? i + 1 : i;
            adjustedBalances[i] = _hasRateProvider(skipBptIndex)
                ? _adjustedBalance(balances[i], _tokenRateCaches[skipBptIndex])
                : balances[i];
        }

        return adjustedBalances;
    }

    // Compute balance * oldRate/currentRate, doing division last to minimize rounding error.
    function _adjustedBalance(uint256 balance, bytes32 cache) private pure returns (uint256) {
        return Math.divDown(Math.mul(balance, cache.getOldRate()), cache.getCurrentRate());
    }

    // Scaling Factors

    /**
     * @dev Overrides scaling factor getter to compute the tokens' rates.
     */
    function _scalingFactors() internal view virtual override returns (uint256[] memory) {
        // There is no need to check the arrays length since both are based on `_getTotalTokens`
        uint256 totalTokens = _getTotalTokens();
        uint256[] memory scalingFactors = new uint256[](totalTokens);

        for (uint256 i = 0; i < totalTokens; ++i) {
            scalingFactors[i] = _getScalingFactor(i).mulDown(_getTokenRate(i));
        }

        return scalingFactors;
    }

    /**
     * @dev Overrides only owner action to allow setting the cache duration for the token rates
     */
    function _isOwnerOnlyAction(bytes32 actionId) internal view virtual override returns (bool) {
        return (actionId == getActionId(this.setTokenRateCacheDuration.selector)) || super._isOwnerOnlyAction(actionId);
    }
}

// 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/openzeppelin/IERC20.sol";
import "@balancer-labs/v2-interfaces/contracts/pool-utils/IRateProvider.sol";

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

import "./StableMath.sol";

abstract contract ComposableStablePoolStorage is BasePool {
    using FixedPoint for uint256;
    using WordCodec for bytes32;

    struct StorageParams {
        IERC20[] registeredTokens;
        IRateProvider[] tokenRateProviders;
        bool exemptFromYieldProtocolFeeFlag;
    }

    // This minimum refers not to the total tokens, but rather to the non-BPT tokens. The minimum value for _totalTokens
    // is therefore _MIN_NON_BPT_TOKENS + 1.
    uint256 private constant _MIN_NON_BPT_TOKENS = 2;

    // The Pool will register n+1 tokens, where n are the actual tokens in the Pool, and the other one is the BPT
    // itself.
    uint256 private immutable _totalTokens;

    // The index of BPT in the tokens and balances arrays, i.e. its index when calling IVault.registerTokens().
    uint256 private immutable _bptIndex;

    // These are the registered tokens: one of them will be the BPT.
    IERC20 private immutable _token0;
    IERC20 private immutable _token1;
    IERC20 private immutable _token2;
    IERC20 private immutable _token3;
    IERC20 private immutable _token4;
    IERC20 private immutable _token5;

    // All token balances are normalized to behave as if the token had 18 decimals. We assume a token's decimals will
    // not change throughout its lifetime, and store the corresponding scaling factor for each at construction time.
    // These factors are always greater than or equal to one: tokens with more than 18 decimals are not supported.

    uint256 internal immutable _scalingFactor0;
    uint256 internal immutable _scalingFactor1;
    uint256 internal immutable _scalingFactor2;
    uint256 internal immutable _scalingFactor3;
    uint256 internal immutable _scalingFactor4;
    uint256 internal immutable _scalingFactor5;

    // Rate Providers accommodate tokens with a known price ratio, such as Compound's cTokens.

    IRateProvider internal immutable _rateProvider0;
    IRateProvider internal immutable _rateProvider1;
    IRateProvider internal immutable _rateProvider2;
    IRateProvider internal immutable _rateProvider3;
    IRateProvider internal immutable _rateProvider4;
    IRateProvider internal immutable _rateProvider5;

    // This is a bitmap which allows querying whether a token at a particular index:
    // - has a rate provider associated with it.
    // - is exempt from yield protocol fees.
    // This is required as the data stored in this bitmap is computed from values in immutable storage,
    // without this bitmap we would have to manually search through token by token to reach these values.
    // The data structure is as follows:
    //
    // [  unused  | rate provider flags | exemption flags ]
    // [ 244 bits |        6 bits       |     6 bits      ]
    bytes32 private immutable _rateProviderInfoBitmap;

    // Indicates whether all the tokens from the pool are exempt from yield protocol fee or not.
    bool private immutable _exemptFromYieldProtocolFee;

    uint256 private constant _RATE_PROVIDER_FLAGS_OFFSET = 6;

    constructor(StorageParams memory params) {
        // BasePool checks that the Pool has at least two tokens, but since one of them is the BPT (this contract), we
        // need to check ourselves that there are at least creator-supplied tokens (i.e. the minimum number of total
        // tokens for this contract is actually three, including the BPT).
        uint256 totalTokens = params.registeredTokens.length;
        _require(totalTokens > _MIN_NON_BPT_TOKENS, Errors.MIN_TOKENS);
        InputHelpers.ensureInputLengthMatch(totalTokens - 1, params.tokenRateProviders.length);

        _totalTokens = totalTokens;

        // Immutable variables cannot be initialized inside an if statement, so we must do conditional assignments
        _token0 = params.registeredTokens[0];
        _token1 = params.registeredTokens[1];
        _token2 = params.registeredTokens[2];
        _token3 = totalTokens > 3 ? params.registeredTokens[3] : IERC20(0);
        _token4 = totalTokens > 4 ? params.registeredTokens[4] : IERC20(0);
        _token5 = totalTokens > 5 ? params.registeredTokens[5] : IERC20(0);

        _scalingFactor0 = _computeScalingFactor(params.registeredTokens[0]);
        _scalingFactor1 = _computeScalingFactor(params.registeredTokens[1]);
        _scalingFactor2 = _computeScalingFactor(params.registeredTokens[2]);
        _scalingFactor3 = totalTokens > 3 ? _computeScalingFactor(params.registeredTokens[3]) : 0;
        _scalingFactor4 = totalTokens > 4 ? _computeScalingFactor(params.registeredTokens[4]) : 0;
        _scalingFactor5 = totalTokens > 5 ? _computeScalingFactor(params.registeredTokens[5]) : 0;

        // The Vault keeps track of all Pool tokens in a specific order: we need to know what the index of BPT is in
        // this ordering to be able to identify it when balances arrays are received. Since the tokens array is sorted,
        // we need to find the correct BPT index in the array returned by `_insertSorted()`.
        // See `IVault.getPoolTokens()` for more information regarding token ordering.
        uint256 bptIndex;
        for (
            bptIndex = params.registeredTokens.length - 1;
            bptIndex > 0 && params.registeredTokens[bptIndex] > IERC20(this);
            bptIndex--
        ) {
            // solhint-disable-previous-line no-empty-blocks
        }
        _bptIndex = bptIndex;

        // The rate providers are stored as immutable state variables, and for simplicity when accessing those we'll
        // reference them by token index in the full base tokens plus BPT set (i.e. the tokens the Pool registers). Due
        // to immutable variables requiring an explicit assignment instead of defaulting to an empty value, it is
        // simpler to create a new memory array with the values we want to assign to the immutable state variables.
        IRateProvider[] memory rateProviders = new IRateProvider[](params.registeredTokens.length);

        bytes32 rateProviderInfoBitmap;

        // The exemptFromYieldFlag should never be set on a token without a rate provider.
        // This would cause division by zero errors downstream.
        for (uint256 i = 0; i < params.registeredTokens.length; ++i) {
            if (i < bptIndex) {
                rateProviders[i] = params.tokenRateProviders[i];
            } else if (i != bptIndex) {
                rateProviders[i] = params.tokenRateProviders[i - 1];
            } else {
                // do nothing for i == bptIndex
                continue;
            }
            // Store whether token has rate provider
            rateProviderInfoBitmap = rateProviderInfoBitmap.insertBool(
                rateProviders[i] != IRateProvider(0),
                _RATE_PROVIDER_FLAGS_OFFSET + i
            );
            // Store whether token is exempt from yield fees (only with rate providers).
            if (params.exemptFromYieldProtocolFeeFlag && rateProviders[i] != IRateProvider(0)) {
                rateProviderInfoBitmap = rateProviderInfoBitmap.insertBool(true, i);
            }
        }

        // Either all tokens are exempt, or none of them are. This is defined by the input parameter.
        _exemptFromYieldProtocolFee = params.exemptFromYieldProtocolFeeFlag;

        // Immutable variables cannot be initialized inside an if statement, so we must do conditional assignments
        _rateProvider0 = rateProviders[0];
        _rateProvider1 = rateProviders[1];
        _rateProvider2 = rateProviders[2];
        _rateProvider3 = (rateProviders.length > 3) ? rateProviders[3] : IRateProvider(0);
        _rateProvider4 = (rateProviders.length > 4) ? rateProviders[4] : IRateProvider(0);
        _rateProvider5 = (rateProviders.length > 5) ? rateProviders[5] : IRateProvider(0);

        _rateProviderInfoBitmap = rateProviderInfoBitmap;
    }

    // Tokens

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

    function _getMaxTokens() internal pure override returns (uint256) {
        // The BPT will be one of the Pool tokens, but it is unaffected by the Stable 5 token limit.
        return StableMath._MAX_STABLE_TOKENS + 1;
    }

    function getBptIndex() public view returns (uint256) {
        return _bptIndex;
    }

    function _getTokenIndex(IERC20 token) internal view returns (uint256) {
        if (token == _token0) return 0;
        if (token == _token1) return 1;
        if (token == _token2) return 2;
        if (token == _token3) return 3;
        if (token == _token4) return 4;
        if (token == _token5) return 5;

        _revert(Errors.INVALID_TOKEN);
    }

    function _scalingFactor(IERC20) internal view virtual override returns (uint256) {
        // We never use a single token's scaling factor by itself, we always process the entire array at once.
        // Therefore we don't bother providing an implementation for this.
        _revert(Errors.UNIMPLEMENTED);
    }

    // Index helpers

    // Convert from an index into an array including BPT (the Vault's registered token list), to an index
    // into an array excluding BPT (usually from user input, such as amountsIn/Out).
    // `index` must not be the BPT token index itself.
    function _skipBptIndex(uint256 index) internal view returns (uint256) {
        // Currently this is never called with an index passed in from user input, so this check
        // should not be necessary. Included for completion (and future proofing).
        _require(index != getBptIndex(), Errors.OUT_OF_BOUNDS);

        return index < getBptIndex() ? index : index.sub(1);
    }

    /**
     * @dev Remove the item at `_bptIndex` from an arbitrary array (e.g., amountsIn).
     */
    function _dropBptItem(uint256[] memory amounts) internal view returns (uint256[] memory) {
        uint256[] memory amountsWithoutBpt = new uint256[](amounts.length - 1);
        for (uint256 i = 0; i < amountsWithoutBpt.length; i++) {
            amountsWithoutBpt[i] = amounts[i < getBptIndex() ? i : i + 1];
        }

        return amountsWithoutBpt;
    }

    /**
     * @dev Same as `_dropBptItem`, except the virtual supply is also returned, and `balances` is assumed to be the
     * current Pool balances (including BPT).
     */
    function _dropBptItemFromBalances(uint256[] memory registeredBalances)
        internal
        view
        returns (uint256, uint256[] memory)
    {
        return (_getVirtualSupply(registeredBalances[getBptIndex()]), _dropBptItem(registeredBalances));
    }

    // Convert from an index into an array excluding BPT (usually from user input, such as amountsIn/Out),
    // to an index into an array including BPT (the Vault's registered token list).
    // `index` must not be the BPT token index itself, if it is the last element, and the result must be
    // in the range of registered tokens.
    function _addBptIndex(uint256 index) internal view returns (uint256 registeredIndex) {
        // This can be called from an index passed in from user input.
        registeredIndex = index < getBptIndex() ? index : index.add(1);

        // TODO: `indexWithBpt != getBptIndex()` follows from above line and so can be removed.
        _require(registeredIndex < _totalTokens && registeredIndex != getBptIndex(), Errors.OUT_OF_BOUNDS);
    }

    /**
     * @dev Take an array of arbitrary values the size of the token set without BPT, and insert the given
     * bptAmount at the bptIndex location.
     *
     * The caller is responsible for ensuring the `amounts` input array is sized properly; this function
     * performs no checks.
     */
    function _addBptItem(uint256[] memory amounts, uint256 bptAmount)
        internal
        view
        returns (uint256[] memory registeredTokenAmounts)
    {
        registeredTokenAmounts = new uint256[](amounts.length + 1);
        for (uint256 i = 0; i < registeredTokenAmounts.length; i++) {
            registeredTokenAmounts[i] = i == getBptIndex() ? bptAmount : amounts[i < getBptIndex() ? i : i - 1];
        }
    }

    // Rate Providers

    function _getScalingFactor(uint256 index) internal view returns (uint256) {
        if (index == 0) return _scalingFactor0;
        if (index == 1) return _scalingFactor1;
        if (index == 2) return _scalingFactor2;
        if (index == 3) return _scalingFactor3;
        if (index == 4) return _scalingFactor4;
        if (index == 5) return _scalingFactor5;
        else {
            _revert(Errors.INVALID_TOKEN);
        }
    }

    /**
     * @dev Returns the rate providers configured for each token (in the same order as registered).
     */
    function getRateProviders() external view returns (IRateProvider[] memory) {
        uint256 totalTokens = _getTotalTokens();
        IRateProvider[] memory providers = new IRateProvider[](totalTokens);

        for (uint256 i = 0; i < totalTokens; ++i) {
            providers[i] = _getRateProvider(i);
        }

        return providers;
    }

    function _getRateProvider(uint256 index) internal view returns (IRateProvider) {
        if (index == 0) return _rateProvider0;
        if (index == 1) return _rateProvider1;
        if (index == 2) return _rateProvider2;
        if (index == 3) return _rateProvider3;
        if (index == 4) return _rateProvider4;
        if (index == 5) return _rateProvider5;
        else {
            _revert(Errors.INVALID_TOKEN);
        }
    }

    /**
     * @notice Return true if the token at this index has a rate provider
     */
    function _hasRateProvider(uint256 tokenIndex) internal view returns (bool) {
        return _rateProviderInfoBitmap.decodeBool(_RATE_PROVIDER_FLAGS_OFFSET + tokenIndex);
    }

    /**
     * @notice Return true if all tokens are exempt from yield fees.
     */
    function isExemptFromYieldProtocolFee() public view returns (bool) {
        return _exemptFromYieldProtocolFee;
    }

    /**
     * @dev Returns whether the token is exempt from protocol fees on the yield.
     * If the BPT token is passed in (which doesn't make much sense, but shouldn't fail,
     * since it is a valid pool token), the corresponding flag will be false.
     */
    function isTokenExemptFromYieldProtocolFee(IERC20 token) external view returns (bool) {
        return _exemptFromYieldProtocolFee && _hasRateProvider(_getTokenIndex(token));
    }

    // Virtual Supply

    /**
     * @dev Returns the number of tokens in circulation.
     *
     * WARNING: in the vast majority of cases this is not a useful value, since it does not include the debt the Pool
     * accrued in the form of unminted BPT for the ProtocolFeesCollector. Look into `getActualSupply()` and how that's
     * different.
     *
     * 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 regular
     * joins/exit functions, the totalSupply can change as BPT are minted for joins or burned for exits.
     */
    function _getVirtualSupply(uint256 bptBalance) internal view returns (uint256) {
        // 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 amount of BPT supply in circulation) is defined as:
        // virtualSupply = totalSupply() - _balances[_bptIndex]
        return totalSupply().sub(bptBalance);
    }
}

// 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/helpers/BalancerErrors.sol";
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 _findTokenIndex(IERC20[] memory tokens, IERC20 token) pure returns (uint256) {
    // Note that while we know tokens are initially sorted, we cannot assume this will hold throughout
    // the pool's lifetime, as pools with mutable tokens can append and remove tokens in any order.
    uint256 tokensLength = tokens.length;
    for (uint256 i = 0; i < tokensLength; i++) {
        if (tokens[i] == token) {
            return i;
        }
    }

    _revert(Errors.INVALID_TOKEN);
}

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);
}