// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (utils/Address.sol)

pragma solidity ^0.8.20;

import {Errors} from "./Errors.sol";

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev There's no code at `target` (it is not a contract).
     */
    error AddressEmptyCode(address target);

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://consensys.net/diligence/blog/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.8.20/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        if (address(this).balance < amount) {
            revert Errors.InsufficientBalance(address(this).balance, amount);
        }

        (bool success, ) = recipient.call{value: amount}("");
        if (!success) {
            revert Errors.FailedCall();
        }
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain `call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason or custom error, it is bubbled
     * up by this function (like regular Solidity function calls). However, if
     * the call reverted with no returned reason, this function reverts with a
     * {Errors.FailedCall} error.
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        if (address(this).balance < value) {
            revert Errors.InsufficientBalance(address(this).balance, value);
        }
        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResultFromTarget(target, success, returndata);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResultFromTarget(target, success, returndata);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResultFromTarget(target, success, returndata);
    }

    /**
     * @dev Tool to verify that a low level call to smart-contract was successful, and reverts if the target
     * was not a contract or bubbling up the revert reason (falling back to {Errors.FailedCall}) in case
     * of an unsuccessful call.
     */
    function verifyCallResultFromTarget(
        address target,
        bool success,
        bytes memory returndata
    ) internal view returns (bytes memory) {
        if (!success) {
            _revert(returndata);
        } else {
            // only check if target is a contract if the call was successful and the return data is empty
            // otherwise we already know that it was a contract
            if (returndata.length == 0 && target.code.length == 0) {
                revert AddressEmptyCode(target);
            }
            return returndata;
        }
    }

    /**
     * @dev Tool to verify that a low level call was successful, and reverts if it wasn't, either by bubbling the
     * revert reason or with a default {Errors.FailedCall} error.
     */
    function verifyCallResult(bool success, bytes memory returndata) internal pure returns (bytes memory) {
        if (!success) {
            _revert(returndata);
        } else {
            return returndata;
        }
    }

    /**
     * @dev Reverts with returndata if present. Otherwise reverts with {Errors.FailedCall}.
     */
    function _revert(bytes memory returndata) private pure {
        // Look for revert reason and bubble it up if present
        if (returndata.length > 0) {
            // The easiest way to bubble the revert reason is using memory via assembly
            /// @solidity memory-safe-assembly
            assembly {
                let returndata_size := mload(returndata)
                revert(add(32, returndata), returndata_size)
            }
        } else {
            revert Errors.FailedCall();
        }
    }
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This contract is a modified version of the Pendle VeHistoryLib Library
// https://github.com/pendle-finance/pendle-core-v2-public/

pragma solidity ^0.8.0;

import "./VoteEscrowLib.sol";
import "./WeekMath.sol";

struct Checkpoint {
  uint128 timestamp;
  VeBalance value;
}

library Checkpoints {
  struct History {
    Checkpoint[] _checkpoints;
  }

  function length(History storage self) internal view returns (uint256) {
    return self._checkpoints.length;
  }

  function get(History storage self, uint256 index) internal view returns (Checkpoint memory) {
    return self._checkpoints[index];
  }

  function push(History storage self, VeBalance memory value) internal {
    uint256 pos = self._checkpoints.length;
    if (pos > 0 && self._checkpoints[pos - 1].timestamp == WeekMath.getCurrentWeekStart()) {
      self._checkpoints[pos - 1].value = value;
    } else {
      self._checkpoints.push(Checkpoint({timestamp: WeekMath.getCurrentWeekStart(), value: value}));
    }
  }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.20;

/**
 * @dev Collection of common custom errors used in multiple contracts
 *
 * IMPORTANT: Backwards compatibility is not guaranteed in future versions of the library.
 * It is recommended to avoid relying on the error API for critical functionality.
 */
library Errors {
    /**
     * @dev The ETH balance of the account is not enough to perform the operation.
     */
    error InsufficientBalance(uint256 balance, uint256 needed);

    /**
     * @dev A call to an address target failed. The target may have reverted.
     */
    error FailedCall();

    /**
     * @dev The deployment failed.
     */
    error FailedDeployment();
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (interfaces/IERC1363.sol)

pragma solidity ^0.8.20;

import {IERC20} from "./IERC20.sol";
import {IERC165} from "./IERC165.sol";

/**
 * @title IERC1363
 * @dev Interface of the ERC-1363 standard as defined in the https://eips.ethereum.org/EIPS/eip-1363[ERC-1363].
 *
 * Defines an extension interface for ERC-20 tokens that supports executing code on a recipient contract
 * after `transfer` or `transferFrom`, or code on a spender contract after `approve`, in a single transaction.
 */
interface IERC1363 is IERC20, IERC165 {
    /*
     * Note: the ERC-165 identifier for this interface is 0xb0202a11.
     * 0xb0202a11 ===
     *   bytes4(keccak256('transferAndCall(address,uint256)')) ^
     *   bytes4(keccak256('transferAndCall(address,uint256,bytes)')) ^
     *   bytes4(keccak256('transferFromAndCall(address,address,uint256)')) ^
     *   bytes4(keccak256('transferFromAndCall(address,address,uint256,bytes)')) ^
     *   bytes4(keccak256('approveAndCall(address,uint256)')) ^
     *   bytes4(keccak256('approveAndCall(address,uint256,bytes)'))
     */

    /**
     * @dev Moves a `value` amount of tokens from the caller's account to `to`
     * and then calls {IERC1363Receiver-onTransferReceived} on `to`.
     * @param to The address which you want to transfer to.
     * @param value The amount of tokens to be transferred.
     * @return A boolean value indicating whether the operation succeeded unless throwing.
     */
    function transferAndCall(address to, uint256 value) external returns (bool);

    /**
     * @dev Moves a `value` amount of tokens from the caller's account to `to`
     * and then calls {IERC1363Receiver-onTransferReceived} on `to`.
     * @param to The address which you want to transfer to.
     * @param value The amount of tokens to be transferred.
     * @param data Additional data with no specified format, sent in call to `to`.
     * @return A boolean value indicating whether the operation succeeded unless throwing.
     */
    function transferAndCall(address to, uint256 value, bytes calldata data) external returns (bool);

    /**
     * @dev Moves a `value` amount of tokens from `from` to `to` using the allowance mechanism
     * and then calls {IERC1363Receiver-onTransferReceived} on `to`.
     * @param from The address which you want to send tokens from.
     * @param to The address which you want to transfer to.
     * @param value The amount of tokens to be transferred.
     * @return A boolean value indicating whether the operation succeeded unless throwing.
     */
    function transferFromAndCall(address from, address to, uint256 value) external returns (bool);

    /**
     * @dev Moves a `value` amount of tokens from `from` to `to` using the allowance mechanism
     * and then calls {IERC1363Receiver-onTransferReceived} on `to`.
     * @param from The address which you want to send tokens from.
     * @param to The address which you want to transfer to.
     * @param value The amount of tokens to be transferred.
     * @param data Additional data with no specified format, sent in call to `to`.
     * @return A boolean value indicating whether the operation succeeded unless throwing.
     */
    function transferFromAndCall(address from, address to, uint256 value, bytes calldata data) external returns (bool);

    /**
     * @dev Sets a `value` amount of tokens as the allowance of `spender` over the
     * caller's tokens and then calls {IERC1363Spender-onApprovalReceived} on `spender`.
     * @param spender The address which will spend the funds.
     * @param value The amount of tokens to be spent.
     * @return A boolean value indicating whether the operation succeeded unless throwing.
     */
    function approveAndCall(address spender, uint256 value) external returns (bool);

    /**
     * @dev Sets a `value` amount of tokens as the allowance of `spender` over the
     * caller's tokens and then calls {IERC1363Spender-onApprovalReceived} on `spender`.
     * @param spender The address which will spend the funds.
     * @param value The amount of tokens to be spent.
     * @param data Additional data with no specified format, sent in call to `spender`.
     * @return A boolean value indicating whether the operation succeeded unless throwing.
     */
    function approveAndCall(address spender, uint256 value, bytes calldata data) external returns (bool);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (interfaces/IERC165.sol)

pragma solidity ^0.8.20;

import {IERC165} from "../utils/introspection/IERC165.sol";

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.20;

/**
 * @dev Interface of the ERC-20 standard as defined in the ERC.
 */
interface IERC20 {
    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

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

    /**
     * @dev Returns the value of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

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

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

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

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

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

// SPDX-License-Identifier: GPL-3.0-or-later

pragma solidity ^0.8.0;

/// Utils /////
import "../libraries/VoteEscrowLib.sol";
import "../libraries/CheckpointsLib.sol";

///@title VoteEscrow Contract Interface
///@notice This contract is a modified version of the Pendle IPVotingEscrowMainchain interface
///        https://github.com/pendle-finance/pendle-core-v2-public/
interface IVoteEscrow {
  /*//////////////////////////////////////////////////////////////
                             EVENTS
  //////////////////////////////////////////////////////////////*/

  event UpdateLock(address indexed user, uint128 amount, uint128 expiry);
  event Withdraw(address indexed user, uint128 amount);

  /*//////////////////////////////////////////////////////////////
                             EXTERNAL
  //////////////////////////////////////////////////////////////*/

  function updateLock(uint128 additionalAmountToLock, uint128 expiry) external returns (uint128);

  function withdraw() external returns (uint128);

  function totalSupplyAt(uint128 timestamp) external view returns (uint128);

  function balanceOf(address user) external view returns (uint128);

  function positionData(address user) external view returns (uint128 amount, uint128 expiry);

  function totalSupplyStored() external view returns (uint128);

  function totalSupplyCurrent() external returns (uint128);

  function totalSupplyAndBalanceCurrent(address user) external returns (uint128, uint128);

  function getUserHistoryLength(address user) external view returns (uint256);

  function getUserHistoryAt(address user, uint256 index) external view returns (Checkpoint memory);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (token/ERC20/utils/SafeERC20.sol)

pragma solidity ^0.8.20;

import {IERC20} from "../IERC20.sol";
import {IERC1363} from "../../../interfaces/IERC1363.sol";
import {Address} from "../../../utils/Address.sol";

/**
 * @title SafeERC20
 * @dev Wrappers around ERC-20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using Address for address;

    /**
     * @dev An operation with an ERC-20 token failed.
     */
    error SafeERC20FailedOperation(address token);

    /**
     * @dev Indicates a failed `decreaseAllowance` request.
     */
    error SafeERC20FailedDecreaseAllowance(address spender, uint256 currentAllowance, uint256 requestedDecrease);

    /**
     * @dev Transfer `value` amount of `token` from the calling contract to `to`. If `token` returns no value,
     * non-reverting calls are assumed to be successful.
     */
    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeCall(token.transfer, (to, value)));
    }

    /**
     * @dev Transfer `value` amount of `token` from `from` to `to`, spending the approval given by `from` to the
     * calling contract. If `token` returns no value, non-reverting calls are assumed to be successful.
     */
    function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeCall(token.transferFrom, (from, to, value)));
    }

    /**
     * @dev Increase the calling contract's allowance toward `spender` by `value`. If `token` returns no value,
     * non-reverting calls are assumed to be successful.
     */
    function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 oldAllowance = token.allowance(address(this), spender);
        forceApprove(token, spender, oldAllowance + value);
    }

    /**
     * @dev Decrease the calling contract's allowance toward `spender` by `requestedDecrease`. If `token` returns no
     * value, non-reverting calls are assumed to be successful.
     */
    function safeDecreaseAllowance(IERC20 token, address spender, uint256 requestedDecrease) internal {
        unchecked {
            uint256 currentAllowance = token.allowance(address(this), spender);
            if (currentAllowance < requestedDecrease) {
                revert SafeERC20FailedDecreaseAllowance(spender, currentAllowance, requestedDecrease);
            }
            forceApprove(token, spender, currentAllowance - requestedDecrease);
        }
    }

    /**
     * @dev Set the calling contract's allowance toward `spender` to `value`. If `token` returns no value,
     * non-reverting calls are assumed to be successful. Meant to be used with tokens that require the approval
     * to be set to zero before setting it to a non-zero value, such as USDT.
     */
    function forceApprove(IERC20 token, address spender, uint256 value) internal {
        bytes memory approvalCall = abi.encodeCall(token.approve, (spender, value));

        if (!_callOptionalReturnBool(token, approvalCall)) {
            _callOptionalReturn(token, abi.encodeCall(token.approve, (spender, 0)));
            _callOptionalReturn(token, approvalCall);
        }
    }

    /**
     * @dev Performs an {ERC1363} transferAndCall, with a fallback to the simple {ERC20} transfer if the target has no
     * code. This can be used to implement an {ERC721}-like safe transfer that rely on {ERC1363} checks when
     * targeting contracts.
     *
     * Reverts if the returned value is other than `true`.
     */
    function transferAndCallRelaxed(IERC1363 token, address to, uint256 value, bytes memory data) internal {
        if (to.code.length == 0) {
            safeTransfer(token, to, value);
        } else if (!token.transferAndCall(to, value, data)) {
            revert SafeERC20FailedOperation(address(token));
        }
    }

    /**
     * @dev Performs an {ERC1363} transferFromAndCall, with a fallback to the simple {ERC20} transferFrom if the target
     * has no code. This can be used to implement an {ERC721}-like safe transfer that rely on {ERC1363} checks when
     * targeting contracts.
     *
     * Reverts if the returned value is other than `true`.
     */
    function transferFromAndCallRelaxed(
        IERC1363 token,
        address from,
        address to,
        uint256 value,
        bytes memory data
    ) internal {
        if (to.code.length == 0) {
            safeTransferFrom(token, from, to, value);
        } else if (!token.transferFromAndCall(from, to, value, data)) {
            revert SafeERC20FailedOperation(address(token));
        }
    }

    /**
     * @dev Performs an {ERC1363} approveAndCall, with a fallback to the simple {ERC20} approve if the target has no
     * code. This can be used to implement an {ERC721}-like safe transfer that rely on {ERC1363} checks when
     * targeting contracts.
     *
     * NOTE: When the recipient address (`to`) has no code (i.e. is an EOA), this function behaves as {forceApprove}.
     * Opposedly, when the recipient address (`to`) has code, this function only attempts to call {ERC1363-approveAndCall}
     * once without retrying, and relies on the returned value to be true.
     *
     * Reverts if the returned value is other than `true`.
     */
    function approveAndCallRelaxed(IERC1363 token, address to, uint256 value, bytes memory data) internal {
        if (to.code.length == 0) {
            forceApprove(token, to, value);
        } else if (!token.approveAndCall(to, value, data)) {
            revert SafeERC20FailedOperation(address(token));
        }
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address-functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data);
        if (returndata.length != 0 && !abi.decode(returndata, (bool))) {
            revert SafeERC20FailedOperation(address(token));
        }
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     *
     * This is a variant of {_callOptionalReturn} that silents catches all reverts and returns a bool instead.
     */
    function _callOptionalReturnBool(IERC20 token, bytes memory data) private returns (bool) {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We cannot use {Address-functionCall} here since this should return false
        // and not revert is the subcall reverts.

        (bool success, bytes memory returndata) = address(token).call(data);
        return success && (returndata.length == 0 || abi.decode(returndata, (bool))) && address(token).code.length > 0;
    }
}

// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity ^0.8.17;

/// Utils /////
import "openzeppelin-contracts/contracts/token/ERC20/utils/SafeERC20.sol";

import "./interfaces/IVoteEscrow.sol";
import "./libraries/VoteEscrowLib.sol";
import "./libraries/WeekMath.sol";
import "./libraries/CheckpointsLib.sol";

///@title VoteEscrow Contract
///@notice This is a modified version of the Pendle VotingEscrowPendleMainchain contract
///        as well as VotingEscrowTokenBase
///        https://github.com/pendle-finance/pendle-core-v2-public/
contract VoteEscrow is IVoteEscrow {
  using SafeERC20 for IERC20;
  using VoteEscrowLib for VeBalance;
  using VoteEscrowLib for LockedPosition;
  using Checkpoints for Checkpoints.History;

  /*//////////////////////////////////////////////////////////////
                             STORAGE
  //////////////////////////////////////////////////////////////*/

  IERC20 public immutable FYDE;

  uint128 public constant WEEK = 1 weeks;
  uint128 public constant MAX_LOCK_TIME = 104 weeks;
  uint128 public constant MIN_LOCK_TIME = 1 weeks;

  VeBalance internal _totalSupply;

  mapping(address => LockedPosition) public positionData;

  uint128 public lastSlopeChangeAppliedAt;

  // [wTime] => slopeChanges
  mapping(uint128 => uint128) public slopeChanges;

  // Saving totalSupply checkpoint for each week, later can be used for reward accounting
  // [wTime] => totalSupply
  mapping(uint128 => uint128) public totalSupplyAt;

  // Saving VeBalance checkpoint for users of each week, can later use binary search
  // to ask for their vePendle balance at any wTime
  mapping(address => Checkpoints.History) internal userHistory;

  /*//////////////////////////////////////////////////////////////
                           CONSTRUCTOR
  //////////////////////////////////////////////////////////////*/

  constructor(address _FYDE) {
    FYDE = IERC20(_FYDE);
    lastSlopeChangeAppliedAt = WeekMath.getCurrentWeekStart();
  }

  /*//////////////////////////////////////////////////////////////
                             ERRORS
  //////////////////////////////////////////////////////////////*/

  error WeekMathInvalidTime(uint256 wTime);

  error UpdateExpiryMustBeCurrent();
  error UpdateExpiryMustIncrease();
  error UpdateExpiryTooLong();
  error UpdateExpiryTooShort();

  error VoteEscrowZeroAmount();
  error VoteEscrowNotExpired();

  /*//////////////////////////////////////////////////////////////
                             EXTERNAL
  //////////////////////////////////////////////////////////////*/

  /**
   * @notice increases the lock position of a user (amount and/or expiry). Applicable even when
   * user has no position or the current position has expired.
   * @param additionalAmountToLock pendle amount to be pulled in from user to lock.
   * @param newExpiry new lock expiry. Must be a valid week beginning, and resulting lock
   * duration (since `block.timestamp`) must be within the allowed range.
   * @dev Will revert if resulting position has zero lock amount.
   * @dev See `_increasePosition()` for details on inner workings.
   * @dev Sidechain broadcasting is not bundled since it can be done anytime after.
   */
  function updateLock(uint128 additionalAmountToLock, uint128 newExpiry)
    public
    returns (uint128 newVeBalance)
  {
    address user = msg.sender;

    if (!WeekMath.isValidWTime(newExpiry)) revert WeekMathInvalidTime(newExpiry);
    if (WeekMath.isCurrentlyExpired(newExpiry)) revert UpdateExpiryMustBeCurrent();

    if (newExpiry < positionData[user].expiry) revert UpdateExpiryMustIncrease();

    if (newExpiry > block.timestamp + MAX_LOCK_TIME) revert UpdateExpiryTooLong();
    if (newExpiry < block.timestamp + MIN_LOCK_TIME) revert UpdateExpiryTooShort();

    uint128 newTotalAmountLocked = additionalAmountToLock + positionData[user].amount;
    if (newTotalAmountLocked == 0) revert VoteEscrowZeroAmount();

    uint128 additionalDurationToLock = newExpiry - positionData[user].expiry;

    if (additionalAmountToLock > 0) {
      FYDE.safeTransferFrom(user, address(this), additionalAmountToLock);
    }

    newVeBalance = _increasePosition(user, additionalAmountToLock, additionalDurationToLock);

    emit UpdateLock(user, newTotalAmountLocked, newExpiry);
  }

  /**
   * @notice Withdraws an expired lock position, returns locked PENDLE back to user
   * @dev reverts if position is not expired, or if no locked PENDLE to withdraw
   * @dev broadcast is not bundled since it can be done anytime after
   */
  function withdraw() external returns (uint128 amount) {
    address user = msg.sender;

    if (!_isPositionExpired(user)) revert VoteEscrowNotExpired();
    amount = positionData[user].amount;

    if (amount == 0) revert VoteEscrowZeroAmount();

    delete positionData[user];

    FYDE.safeTransfer(user, amount);

    emit Withdraw(user, amount);
  }

  /*//////////////////////////////////////////////////////////////
                             GETTERS
  //////////////////////////////////////////////////////////////*/

  function balanceOf(address user) public view returns (uint128) {
    return positionData[user].convertToVeBalance().getCurrentValue();
  }

  function totalSupplyStored() external view returns (uint128) {
    return _totalSupply.getCurrentValue();
  }

  function totalSupplyCurrent() public returns (uint128) {
    (VeBalance memory supply,) = _applySlopeChange();
    return supply.getCurrentValue();
  }

  function totalSupplyAndBalanceCurrent(address user) external returns (uint128, uint128) {
    return (totalSupplyCurrent(), balanceOf(user));
  }

  function getUserHistoryLength(address user) external view returns (uint256) {
    return userHistory[user].length();
  }

  function getUserHistoryAt(address user, uint256 index) external view returns (Checkpoint memory) {
    return userHistory[user].get(index);
  }

  /*//////////////////////////////////////////////////////////////
                             INTERNAL
  //////////////////////////////////////////////////////////////*/

  /**
   * @notice increase the locking position of the user
   * @dev works by simply removing the old position from all relevant data (as if the user has
   * never locked) and then add in the new position
   */
  function _increasePosition(address user, uint128 amountToIncrease, uint128 durationToIncrease)
    internal
    returns (uint128)
  {
    LockedPosition memory oldPosition = positionData[user];

    (VeBalance memory newSupply,) = _applySlopeChange();

    if (!WeekMath.isCurrentlyExpired(oldPosition.expiry)) {
      // remove old position not yet expired
      VeBalance memory oldBalance = oldPosition.convertToVeBalance();
      newSupply = newSupply.sub(oldBalance);
      slopeChanges[oldPosition.expiry] -= oldBalance.slope;
    }

    LockedPosition memory newPosition =
      LockedPosition(oldPosition.amount + amountToIncrease, oldPosition.expiry + durationToIncrease);

    VeBalance memory newBalance = newPosition.convertToVeBalance();
    // add new position
    newSupply = newSupply.add(newBalance);
    slopeChanges[newPosition.expiry] += newBalance.slope;

    _totalSupply = newSupply;
    positionData[user] = newPosition;
    userHistory[user].push(newBalance);
    return newBalance.getCurrentValue();
  }

  /**
   * @notice updates the totalSupply, processing all slope changes of past weeks. At the same time,
   * set the finalized totalSupplyAt
   */
  function _applySlopeChange() internal returns (VeBalance memory, uint128) {
    VeBalance memory supply = _totalSupply;
    uint128 wTime = lastSlopeChangeAppliedAt;
    uint128 currentWeekStart = WeekMath.getCurrentWeekStart();

    if (wTime >= currentWeekStart) return (supply, wTime);

    while (wTime < currentWeekStart) {
      wTime += WEEK;
      supply = supply.sub(slopeChanges[wTime], wTime);
      totalSupplyAt[wTime] = supply.getValueAt(wTime);
    }

    _totalSupply = supply;
    lastSlopeChangeAppliedAt = wTime;

    return (supply, wTime);
  }

  function _isPositionExpired(address user) internal view returns (bool) {
    return WeekMath.isCurrentlyExpired(positionData[user].expiry);
  }
}

// SPDX-License-Identifier: Unkown
// This contract is a modified version of the Pendle VeBalanceLib Library
// https://github.com/pendle-finance/pendle-core-v2-public/

pragma solidity ^0.8.19;

struct VeBalance {
  uint128 bias;
  uint128 slope;
}

struct LockedPosition {
  uint128 amount;
  uint128 expiry;
}

error ZeroSlope(uint128 bias, uint128 slope);

library VoteEscrowLib {
  uint128 internal constant MAX_LOCK_TIME = 104 weeks;

  function add(VeBalance memory a, VeBalance memory b) internal pure returns (VeBalance memory res) {
    res.bias = a.bias + b.bias;
    res.slope = a.slope + b.slope;
  }

  function sub(VeBalance memory a, VeBalance memory b) internal pure returns (VeBalance memory res) {
    res.bias = a.bias - b.bias;
    res.slope = a.slope - b.slope;
  }

  function sub(VeBalance memory a, uint128 slope, uint128 expiry)
    internal
    pure
    returns (VeBalance memory res)
  {
    res.slope = a.slope - slope;
    res.bias = a.bias - slope * expiry;
  }

  function isExpired(VeBalance memory a) internal view returns (bool) {
    return a.slope * uint128(block.timestamp) >= a.bias;
  }

  function getCurrentValue(VeBalance memory a) internal view returns (uint128) {
    if (isExpired(a)) return 0;
    return getValueAt(a, uint128(block.timestamp));
  }

  function getValueAt(VeBalance memory a, uint128 t) internal pure returns (uint128) {
    if (a.slope * t > a.bias) return 0;
    return a.bias - a.slope * t;
  }

  function getExpiry(VeBalance memory a) internal pure returns (uint128) {
    if (a.slope == 0) revert ZeroSlope(a.bias, a.slope);
    return a.bias / a.slope;
  }

  function convertToVeBalance(LockedPosition memory position)
    internal
    pure
    returns (VeBalance memory res)
  {
    res.slope = position.amount / MAX_LOCK_TIME;
    res.bias = res.slope * position.expiry;
  }
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This contract is a modified version of the Pendle WeekMath Library
// https://github.com/pendle-finance/pendle-core-v2-public/

pragma solidity ^0.8.20;

library WeekMath {
  uint128 internal constant WEEK = 7 days;

  function getWeekStartTimestamp(uint128 timestamp) internal pure returns (uint128) {
    return (timestamp / WEEK) * WEEK;
  }

  function getCurrentWeekStart() internal view returns (uint128) {
    return getWeekStartTimestamp(uint128(block.timestamp));
  }

  function isValidWTime(uint256 time) internal pure returns (bool) {
    return time % WEEK == 0;
  }

  function isCurrentlyExpired(uint256 expiry) internal view returns (bool) {
    return (expiry <= block.timestamp);
  }
}

{
  "compilationTarget": {
    "src/VoteEscrow.sol": "VoteEscrow"
  },
  "evmVersion": "cancun",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": true,
    "runs": 200
  },
  "remappings": [
    ":@openzeppelin/contracts-upgradeable/=lib/openzeppelin-contracts-upgradeable/contracts/",
    ":@openzeppelin/contracts/=lib/openzeppelin-contracts/contracts/",
    ":ds-test/=lib/solmate/lib/ds-test/src/",
    ":erc4626-tests/=lib/openzeppelin-contracts-upgradeable/lib/erc4626-tests/",
    ":forge-std/=lib/forge-std/src/",
    ":halmos-cheatcodes/=lib/openzeppelin-contracts-upgradeable/lib/halmos-cheatcodes/src/",
    ":murky/=lib/murky/",
    ":openzeppelin-contracts-upgradeable/=lib/openzeppelin-contracts-upgradeable/",
    ":openzeppelin-contracts/=lib/openzeppelin-contracts/",
    ":solidity-stringutils/=lib/surl/lib/solidity-stringutils/",
    ":solmate/=lib/solmate/src/",
    ":surl/=lib/surl/"
  ]
}