// File: @balancer-labs/v2-interfaces/contracts/solidity-utils/helpers/BalancerErrors.sol



// 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 <0.9.0;

// 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;
    uint256 internal constant INSUFFICIENT_DATA = 105;

    // 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;
    uint256 internal constant ADD_OR_REMOVE_BPT = 354;
    uint256 internal constant INVALID_CIRCUIT_BREAKER_BOUNDS = 355;
    uint256 internal constant CIRCUIT_BREAKER_TRIPPED = 356;
    uint256 internal constant MALICIOUS_QUERY_REVERT = 357;
    uint256 internal constant JOINS_EXITS_DISABLED = 358;

    // 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;
    uint256 internal constant BURN_FROM_ZERO = 444;

    // 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;

    // FeeSplitter
    uint256 internal constant SPLITTER_FEE_PERCENTAGE_TOO_HIGH = 700;

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

// File: @balancer-labs/v2-interfaces/contracts/solidity-utils/helpers/IOptionalOnlyCaller.sol



// 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 <0.9.0;

/**
 * @dev Interface for the OptionalOnlyCaller helper, used to opt in to a caller
 * verification for a given address to methods that are otherwise callable by any address.
 */
interface IOptionalOnlyCaller {
    /**
     * @dev Emitted every time setOnlyCallerCheck is called.
     */
    event OnlyCallerOptIn(address user, bool enabled);

    /**
     * @dev Enables / disables verification mechanism for caller.
     * @param enabled - True if caller verification shall be enabled, false otherwise.
     */
    function setOnlyCallerCheck(bool enabled) external;

    function setOnlyCallerCheckWithSignature(
        address user,
        bool enabled,
        bytes memory signature
    ) external;

    /**
     * @dev Returns true if caller verification is enabled for the given user, false otherwise.
     */
    function isOnlyCallerEnabled(address user) external view returns (bool);
}

// File: @balancer-labs/v2-interfaces/contracts/solidity-utils/helpers/ISignaturesValidator.sol



// 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 <0.9.0;

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

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

// File: @balancer-labs/v2-interfaces/contracts/solidity-utils/openzeppelin/IERC1271.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (interfaces/IERC1271.sol)

pragma solidity >=0.7.0 <0.9.0;

/**
 * @dev Interface of the ERC1271 standard signature validation method for
 * contracts as defined in https://eips.ethereum.org/EIPS/eip-1271[ERC-1271].
 *
 * _Available since v4.1._
 */
interface IERC1271 {
    /**
     * @dev Should return whether the signature provided is valid for the provided data
     * @param hash      Hash of the data to be signed
     * @param signature Signature byte array associated with _data
     */
    function isValidSignature(bytes32 hash, bytes memory signature) external view returns (bytes4 magicValue);
}

// File: @balancer-labs/v2-interfaces/contracts/solidity-utils/openzeppelin/IERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.7.0 <0.9.0;

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

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

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

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

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

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

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

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

// File: @balancer-labs/v2-solidity-utils/contracts/helpers/EOASignaturesValidator.sol



// 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;
    }
}

// File: @balancer-labs/v2-solidity-utils/contracts/helpers/InputHelpers.sol



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

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

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

pragma solidity ^0.7.0;

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

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

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

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

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

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

// File: @balancer-labs/v2-solidity-utils/contracts/helpers/OptionalOnlyCaller.sol



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

import "./SignaturesValidator.sol";

abstract contract OptionalOnlyCaller is IOptionalOnlyCaller, SignaturesValidator {
    mapping(address => bool) private _isOnlyCallerEnabled;

    bytes32 private constant _SET_ONLY_CALLER_CHECK_TYPEHASH = keccak256(
        "SetOnlyCallerCheck(address user,bool enabled,uint256 nonce)"
    );

    /**
     * @dev Reverts if the verification mechanism is enabled and the given address is not the caller.
     * @param user - Address to validate as the only allowed caller, if the verification is enabled.
     */
    modifier optionalOnlyCaller(address user) {
        _verifyCaller(user);
        _;
    }

    function setOnlyCallerCheck(bool enabled) external override {
        _setOnlyCallerCheck(msg.sender, enabled);
    }

    function setOnlyCallerCheckWithSignature(
        address user,
        bool enabled,
        bytes memory signature
    ) external override {
        bytes32 structHash = keccak256(abi.encode(_SET_ONLY_CALLER_CHECK_TYPEHASH, user, enabled, getNextNonce(user)));
        _ensureValidSignature(user, structHash, signature, Errors.INVALID_SIGNATURE);
        _setOnlyCallerCheck(user, enabled);
    }

    function _setOnlyCallerCheck(address user, bool enabled) private {
        _isOnlyCallerEnabled[user] = enabled;
        emit OnlyCallerOptIn(user, enabled);
    }

    function isOnlyCallerEnabled(address user) external view override returns (bool) {
        return _isOnlyCallerEnabled[user];
    }

    function _verifyCaller(address user) private view {
        if (_isOnlyCallerEnabled[user]) {
            _require(msg.sender == user, Errors.SENDER_NOT_ALLOWED);
        }
    }
}

// File: @balancer-labs/v2-solidity-utils/contracts/helpers/SignaturesValidator.sol



// 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/IERC1271.sol";

import "./EOASignaturesValidator.sol";
import "../openzeppelin/Address.sol";

/**
 * @dev Utility for signing Solidity function calls.
 */
abstract contract SignaturesValidator is EOASignaturesValidator {
    using Address for address;

    function _isValidSignature(
        address account,
        bytes32 digest,
        bytes memory signature
    ) internal view virtual override returns (bool) {
        if (account.isContract()) {
            return IERC1271(account).isValidSignature(digest, signature) == IERC1271.isValidSignature.selector;
        } else {
            return super._isValidSignature(account, digest, signature);
        }
    }
}

// File: @balancer-labs/v2-solidity-utils/contracts/math/Math.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.7.0;

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

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow checks.
 * Adapted from OpenZeppelin's SafeMath library.
 */
library Math {
    // solhint-disable no-inline-assembly

    /**
     * @dev Returns the absolute value of a signed integer.
     */
    function abs(int256 a) internal pure returns (uint256 result) {
        // Equivalent to:
        // result = a > 0 ? uint256(a) : uint256(-a)
        assembly {
            let s := sar(255, a)
            result := sub(xor(a, s), s)
        }
    }

    /**
     * @dev Returns the addition of two unsigned integers of 256 bits, reverting on overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        _require(c >= a, Errors.ADD_OVERFLOW);
        return c;
    }

    /**
     * @dev Returns the addition of two signed integers, reverting on overflow.
     */
    function add(int256 a, int256 b) internal pure returns (int256) {
        int256 c = a + b;
        _require((b >= 0 && c >= a) || (b < 0 && c < a), Errors.ADD_OVERFLOW);
        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers of 256 bits, reverting on overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        _require(b <= a, Errors.SUB_OVERFLOW);
        uint256 c = a - b;
        return c;
    }

    /**
     * @dev Returns the subtraction of two signed integers, reverting on overflow.
     */
    function sub(int256 a, int256 b) internal pure returns (int256) {
        int256 c = a - b;
        _require((b >= 0 && c <= a) || (b < 0 && c > a), Errors.SUB_OVERFLOW);
        return c;
    }

    /**
     * @dev Returns the largest of two numbers of 256 bits.
     */
    function max(uint256 a, uint256 b) internal pure returns (uint256 result) {
        // Equivalent to:
        // result = (a < b) ? b : a;
        assembly {
            result := sub(a, mul(sub(a, b), lt(a, b)))
        }
    }

    /**
     * @dev Returns the smallest of two numbers of 256 bits.
     */
    function min(uint256 a, uint256 b) internal pure returns (uint256 result) {
        // Equivalent to `result = (a < b) ? a : b`
        assembly {
            result := sub(a, mul(sub(a, b), gt(a, b)))
        }
    }

    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a * b;
        _require(a == 0 || c / a == b, Errors.MUL_OVERFLOW);
        return c;
    }

    function div(
        uint256 a,
        uint256 b,
        bool roundUp
    ) internal pure returns (uint256) {
        return roundUp ? divUp(a, b) : divDown(a, b);
    }

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

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

        // Equivalent to:
        // result = a == 0 ? 0 : 1 + (a - 1) / b;
        assembly {
            result := mul(iszero(iszero(a)), add(1, div(sub(a, 1), b)))
        }
    }
}

// File: @balancer-labs/v2-solidity-utils/contracts/openzeppelin/Address.sol



// SPDX-License-Identifier: MIT

// Based on the Address library from OpenZeppelin Contracts, altered by removing the `isContract` checks on
// `functionCall` and `functionDelegateCall` in order to save gas, as the recipients are known to be contracts.

pragma solidity ^0.7.0;

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

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        // solhint-disable-next-line no-inline-assembly
        assembly {
            size := extcodesize(account)
        }
        return size > 0;
    }

    // solhint-disable max-line-length

    /**
     * @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://diligence.consensys.net/posts/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/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        _require(address(this).balance >= amount, Errors.ADDRESS_INSUFFICIENT_BALANCE);

        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (bool success, ) = recipient.call{ value: amount }("");
        _require(success, Errors.ADDRESS_CANNOT_SEND_VALUE);
    }

    /**
     * @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, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * 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:
     *
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call(data);
        return verifyCallResult(success, returndata);
    }

    // solhint-enable max-line-length

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but passing some native ETH as msg.value to the call.
     *
     * _Available since v3.4._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value
    ) internal returns (bytes memory) {
        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{ value: value }(data);
        return verifyCallResult(success, returndata);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResult(success, returndata);
    }

    /**
     * @dev Tool to verify that a low level call was successful, and revert if it wasn't, either by bubbling up the
     * revert reason or using the one provided.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(bool success, bytes memory returndata) internal pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            // 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
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                _revert(Errors.LOW_LEVEL_CALL_FAILED);
            }
        }
    }
}

// File: @balancer-labs/v2-solidity-utils/contracts/openzeppelin/EIP712.sol



// 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));
    }

    // solc-ignore-next-line func-mutability
    function _getChainId() private view returns (uint256 chainId) {
        // solhint-disable-next-line no-inline-assembly
        assembly {
            chainId := chainid()
        }
    }
}

// File: @balancer-labs/v2-solidity-utils/contracts/openzeppelin/ReentrancyGuard.sol



// SPDX-License-Identifier: MIT

// Based on the ReentrancyGuard library from OpenZeppelin Contracts, altered to reduce bytecode size.
// Modifier code is inlined by the compiler, which causes its code to appear multiple times in the codebase. By using
// private functions, we achieve the same end result with slightly higher runtime gas costs, but reduced bytecode size.

pragma solidity ^0.7.0;

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

/**
 * @dev Contract module that helps prevent reentrant calls to a function.
 *
 * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
 * available, which can be applied to functions to make sure there are no nested
 * (reentrant) calls to them.
 *
 * Note that because there is a single `nonReentrant` guard, functions marked as
 * `nonReentrant` may not call one another. This can be worked around by making
 * those functions `private`, and then adding `external` `nonReentrant` entry
 * points to them.
 *
 * TIP: If you would like to learn more about reentrancy and alternative ways
 * to protect against it, check out our blog post
 * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
 */
abstract contract ReentrancyGuard {
    // Booleans are more expensive than uint256 or any type that takes up a full
    // word because each write operation emits an extra SLOAD to first read the
    // slot's contents, replace the bits taken up by the boolean, and then write
    // back. This is the compiler's defense against contract upgrades and
    // pointer aliasing, and it cannot be disabled.

    // The values being non-zero value makes deployment a bit more expensive,
    // but in exchange the refund on every call to nonReentrant will be lower in
    // amount. Since refunds are capped to a percentage of the total
    // transaction's gas, it is best to keep them low in cases like this one, to
    // increase the likelihood of the full refund coming into effect.
    uint256 private constant _NOT_ENTERED = 1;
    uint256 private constant _ENTERED = 2;

    uint256 private _status;

    constructor() {
        _status = _NOT_ENTERED;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and make it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        _enterNonReentrant();
        _;
        _exitNonReentrant();
    }

    function _enterNonReentrant() private {
        // On the first call to nonReentrant, _status will be _NOT_ENTERED
        _require(_status != _ENTERED, Errors.REENTRANCY);

        // Any calls to nonReentrant after this point will fail
        _status = _ENTERED;
    }

    function _exitNonReentrant() private {
        // By storing the original value once again, a refund is triggered (see
        // https://eips.ethereum.org/EIPS/eip-2200)
        _status = _NOT_ENTERED;
    }
}

// File: @balancer-labs/v2-solidity-utils/contracts/openzeppelin/SafeERC20.sol



// SPDX-License-Identifier: MIT

// Based on the ReentrancyGuard library from OpenZeppelin Contracts, altered to reduce gas costs.
// The `safeTransfer` and `safeTransferFrom` functions assume that `token` is a contract (an account with code), and
// work differently from the OpenZeppelin version if it is not.

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";

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 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 {

    function safeApprove(
        IERC20 token,
        address to,
        uint256 value
    ) internal {
        // Some contracts need their allowance reduced to 0 before setting it to an arbitrary amount.
        if (value != 0 && token.allowance(address(this), address(to)) != 0) {
            _callOptionalReturn(address(token), abi.encodeWithSelector(token.approve.selector, to, 0));
        }

        _callOptionalReturn(address(token), abi.encodeWithSelector(token.approve.selector, to, value));
    }

    function safeTransfer(
        IERC20 token,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(address(token), abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(
        IERC20 token,
        address from,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(address(token), abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @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).
     *
     * WARNING: `token` is assumed to be a contract: calls to EOAs will *not* revert.
     */
    function _callOptionalReturn(address 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.
        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = token.call(data);

        // If the low-level call didn't succeed we return whatever was returned from it.
        // solhint-disable-next-line no-inline-assembly
        assembly {
            if eq(success, 0) {
                returndatacopy(0, 0, returndatasize())
                revert(0, returndatasize())
            }
        }

        // Finally we check the returndata size is either zero or true - note that this check will always pass for EOAs
        _require(returndata.length == 0 || abi.decode(returndata, (bool)), Errors.SAFE_ERC20_CALL_FAILED);
    }
}

// File: @balancer-labs/v2-solidity-utils/contracts/openzeppelin/SafeMath.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.7.0;

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

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        _require(c >= a, Errors.ADD_OVERFLOW);

        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, Errors.SUB_OVERFLOW);
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(
        uint256 a,
        uint256 b,
        uint256 errorCode
    ) internal pure returns (uint256) {
        _require(b <= a, errorCode);
        uint256 c = a - b;

        return c;
    }
}

// File: contracts/interfaces/IRewardDistributor.sol



// 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 <0.9.0;
pragma experimental ABIEncoderV2;

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

import "./IVotingEscrow.sol";

/**
 * @title Reward Distributor
 * @notice Distributes any tokens transferred to the contract (e.g. Protocol rewards and any token emissions) among veBPT
 * holders proportionally based on a snapshot of the week at which the tokens are sent to the RewardDistributor contract.
 * @dev Supports distributing arbitrarily many different tokens. In order to start distributing a new token to veBPT
 * holders simply transfer the tokens to the `RewardDistributor` contract and then call `checkpointToken`.
 */
interface IRewardDistributor {
    event TokenCheckpointed(
        IERC20 token,
        uint256 amount,
        uint256 lastCheckpointTimestamp
    );
    event TokensClaimed(
        address user,
        IERC20 token,
        uint256 amount,
        uint256 userTokenTimeCursor
    );
    event TokenAdded(address indexed token);

    /**
     * @notice Returns the VotingEscrow (veBPT) token contract
     */
    function getVotingEscrow() external view returns (IVotingEscrow);

    /**
     * @notice Returns the global time cursor representing the most earliest uncheckpointed week.
     */
    function getTimeCursor() external view returns (uint256);

    /**
     * @notice Returns the user-level time cursor representing the most earliest uncheckpointed week.
     * @param user - The address of the user to query.
     */
    function getUserTimeCursor(address user) external view returns (uint256);

    /**
     * @notice Returns the token-level time cursor storing the timestamp at up to which tokens have been distributed.
     * @param token - The ERC20 token address to query.
     */
    function getTokenTimeCursor(IERC20 token) external view returns (uint256);

    /**
     * @notice Returns the user-level time cursor storing the timestamp of the latest token distribution claimed.
     * @param user - The address of the user to query.
     * @param token - The ERC20 token address to query.
     */
    function getUserTokenTimeCursor(
        address user,
        IERC20 token
    ) external view returns (uint256);

    /**
     * @notice Returns the user's cached balance of veBPT as of the provided timestamp.
     * @dev Only timestamps which fall on Thursdays 00:00:00 UTC will return correct values.
     * This function requires `user` to have been checkpointed past `timestamp` so that their balance is cached.
     * @param user - The address of the user of which to read the cached balance of.
     * @param timestamp - The timestamp at which to read the `user`'s cached balance at.
     */
    function getUserBalanceAtTimestamp(
        address user,
        uint256 timestamp
    ) external view returns (uint256);

    /**
     * @notice Returns the cached total supply of veBPT as of the provided timestamp.
     * @dev Only timestamps which fall on Thursdays 00:00:00 UTC will return correct values.
     * This function requires the contract to have been checkpointed past `timestamp` so that the supply is cached.
     * @param timestamp - The timestamp at which to read the cached total supply at.
     */
    function getTotalSupplyAtTimestamp(
        uint256 timestamp
    ) external view returns (uint256);

    /**
     * @notice Returns the RewardDistributor's cached balance of `token`.
     */
    function getTokenLastBalance(IERC20 token) external view returns (uint256);

    /**
     * @notice Returns the amount of `token` which the RewardDistributor received in the week beginning at `timestamp`.
     * @param token - The ERC20 token address to query.
     * @param timestamp - The timestamp corresponding to the beginning of the week of interest.
     */
    function getTokensDistributedInWeek(
        IERC20 token,
        uint256 timestamp
    ) external view returns (uint256);

    // Depositing

    /**
     * @notice Deposits tokens to be distributed in the current week.
     * @dev Sending tokens directly to the RewardDistributor instead of using `depositTokens` may result in tokens being
     * retroactively distributed to past weeks, or for the distribution to carry over to future weeks.
     *
     * If for some reason `depositTokens` cannot be called, in order to ensure that all tokens are correctly distributed
     * manually call `checkpointToken` before and after the token transfer.
     * @param token - The ERC20 token address to distribute.
     * @param amount - The amount of tokens to deposit.
     */
    function depositToken(IERC20 token, uint256 amount) external;

    /**
     * @notice Deposits tokens to be distributed in the current week.
     * @dev A version of `depositToken` which supports depositing multiple `tokens` at once.
     * See `depositToken` for more details.
     * @param tokens - An array of ERC20 token addresses to distribute.
     * @param amounts - An array of token amounts to deposit.
     */
    function depositTokens(
        IERC20[] calldata tokens,
        uint256[] calldata amounts
    ) external;

    // Checkpointing

    /**
     * @notice Caches the total supply of veBPT at the beginning of each week.
     * This function will be called automatically before claiming tokens to ensure the contract is properly updated.
     */
    function checkpoint() external;

    /**
     * @notice Caches the user's balance of veBPT at the beginning of each week.
     * This function will be called automatically before claiming tokens to ensure the contract is properly updated.
     * @param user - The address of the user to be checkpointed.
     */
    function checkpointUser(address user) external;

    /**
     * @notice Assigns any newly-received tokens held by the RewardDistributor to weekly distributions.
     * @dev Any `token` balance held by the RewardDistributor above that which is returned by `getTokenLastBalance`
     * will be distributed evenly across the time period since `token` was last checkpointed.
     *
     * This function will be called automatically before claiming tokens to ensure the contract is properly updated.
     * @param token - The ERC20 token address to be checkpointed.
     */
    function checkpointToken(IERC20 token) external;

    /**
     * @notice Assigns any newly-received tokens held by the RewardDistributor to weekly distributions.
     * @dev A version of `checkpointToken` which supports checkpointing multiple tokens.
     * See `checkpointToken` for more details.
     * @param tokens - An array of ERC20 token addresses to be checkpointed.
     */
    function checkpointTokens(IERC20[] calldata tokens) external;

    // Claiming

    /**
     * @notice Claims all pending distributions of the provided token for a user.
     * @dev It's not necessary to explicitly checkpoint before calling this function, it will ensure the RewardDistributor
     * is up to date before calculating the amount of tokens to be claimed.
     * @param user - The user on behalf of which to claim.
     * @param token - The ERC20 token address to be claimed.
     * @return The amount of `token` sent to `user` as a result of claiming.
     */
    function claimToken(address user, IERC20 token) external returns (uint256);

    /**
     * @notice Claims a number of tokens on behalf of a user.
     * @dev A version of `claimToken` which supports claiming multiple `tokens` on behalf of `user`.
     * See `claimToken` for more details.
     * @param user - The user on behalf of which to claim.
     * @param tokens - An array of ERC20 token addresses to be claimed.
     * @return An array of the amounts of each token in `tokens` sent to `user` as a result of claiming.
     */
    function claimTokens(
        address user,
        IERC20[] calldata tokens
    ) external returns (uint256[] memory);
}
// File: contracts/interfaces/IVotingEscrow.sol



// 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 <0.9.0;
pragma experimental ABIEncoderV2;

// solhint-disable func-name-mixedcase

interface IVotingEscrow {
    struct Point {
        int128 bias;
        int128 slope; // - dweight / dt
        uint256 ts;
        uint256 blk; // block
    }

    function epoch() external view returns (uint256);

    function admin() external view returns (address);

    function future_admin() external view returns (address);

    function apply_smart_wallet_checker() external;

    function apply_transfer_ownership() external;

    // function balanceOf(address addr, uint256 _t) external view returns (uint256);
    function balanceOf(
        address user,
        uint256 timestamp
    ) external view returns (uint256);

    function balanceOfAt(
        address addr,
        uint256 _block
    ) external view returns (uint256);

    function checkpoint() external;

    function commit_smart_wallet_checker(address addr) external;

    function commit_transfer_ownership(address addr) external;

    function create_lock(uint256 _value, uint256 _unlock_time) external;

    function decimals() external view returns (uint256);

    function deposit_for(address _addr, uint256 _value) external;

    function get_last_user_slope(address addr) external view returns (int128);

    function increase_amount(uint256 _value) external;

    function increase_unlock_time(uint256 _unlock_time) external;

    function locked__end(address _addr) external view returns (uint256);

    function name() external view returns (string memory);

    function point_history(
        uint256 timestamp
    ) external view returns (Point memory);

    function symbol() external view returns (string memory);

    function token() external view returns (address);

    function totalSupply(uint256 t) external view returns (uint256);

    function totalSupplyAt(uint256 _block) external view returns (uint256);

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

    function user_point_history__ts(
        address _addr,
        uint256 _idx
    ) external view returns (uint256);

    function user_point_history(
        address user,
        uint256 timestamp
    ) external view returns (Point memory);

    function withdraw() external;
}
// File: contracts/RewardDistributor.sol



// 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 {IVotingEscrow} from "./interfaces/IVotingEscrow.sol";
import {IRewardDistributor} from "./interfaces/IRewardDistributor.sol";
import "@balancer-labs/v2-solidity-utils/contracts/openzeppelin/ReentrancyGuard.sol";
import "@balancer-labs/v2-solidity-utils/contracts/helpers/OptionalOnlyCaller.sol";
import "@balancer-labs/v2-solidity-utils/contracts/helpers/InputHelpers.sol";
import "@balancer-labs/v2-solidity-utils/contracts/openzeppelin/SafeERC20.sol";
import "@balancer-labs/v2-solidity-utils/contracts/openzeppelin/SafeMath.sol";
import "@balancer-labs/v2-solidity-utils/contracts/math/Math.sol";

// solhint-disable not-rely-on-time

/**
 * @title Reward Distributor
 * @notice Distributes any tokens transferred to the contract among veBPT holders
 * proportionally based on a snapshot of the week at which the tokens are sent to the RewardDistributor contract.
 * @dev Supports distributing arbitrarily many different tokens. In order to start distributing a new token to veBPT
 * holders simply transfer the tokens to the `RewardDistributor` contract and then call `checkpointToken`.
 */
contract RewardDistributor is
    IRewardDistributor,
    OptionalOnlyCaller,
    ReentrancyGuard
{
    using SafeMath for uint256;
    using SafeERC20 for IERC20;

    bool public isInitialized;
    IVotingEscrow private _votingEscrow;

    uint256 private _startTime;

    // Global State
    uint256 private _timeCursor;
    mapping(uint256 => uint256) private _veSupplyCache;

    address public admin;
    address[] private _rewardTokens;
    mapping(address => bool) public allowedRewardTokens;

    /**
     * @notice Event emitted when the admin role is transferred
     * @param newAdmin The address of the new admin
     */
    event AdminTransferred(address indexed newAdmin);

    // Token State

    // `startTime` and `timeCursor` are both timestamps so comfortably fit in a uint64.
    // `cachedBalance` will comfortably fit the total supply of any meaningful token.
    // Should more than 2^128 tokens be sent to this contract then checkpointing this token will fail until enough
    // tokens have been claimed to bring the total balance back below 2^128.
    struct TokenState {
        uint64 startTime;
        uint64 timeCursor;
        uint128 cachedBalance;
    }

    mapping(IERC20 => TokenState) private _tokenState;
    mapping(IERC20 => mapping(uint256 => uint256)) private _tokensPerWeek;

    // User State

    // `startTime` and `timeCursor` are timestamps so will comfortably fit in a uint64.
    // For `lastEpochCheckpointed` to overflow would need over 2^128 transactions to the VotingEscrow contract.
    struct UserState {
        uint64 startTime;
        uint64 timeCursor;
        uint128 lastEpochCheckpointed;
    }

    mapping(address => UserState) internal _userState;
    mapping(address => mapping(uint256 => uint256))
        private _userBalanceAtTimestamp;
    mapping(address => mapping(IERC20 => uint256)) private _userTokenTimeCursor;

    constructor() EIP712("RewardDistributor", "1") {}

    modifier onlyAdmin() {
        require(admin == msg.sender, "not admin");
        _;
    }

    function initialize(
        IVotingEscrow votingEscrow,
        uint256 startTime,
        address admin_
    ) external {
        require(!isInitialized, "only once");
        isInitialized = true;

        require (admin_ != address(0), "zero address");
        admin = admin_;
        
        _votingEscrow = votingEscrow;

        startTime = _roundDownTimestamp(startTime);
        uint256 currentWeek = _roundDownTimestamp(block.timestamp);
        require(startTime >= currentWeek, "Cannot start before current week");
        if (startTime == currentWeek) {
            // We assume that `votingEscrow` has been deployed in a week previous to this one.
            // If `votingEscrow` did not have a non-zero supply at the beginning of the current week
            // then any tokens which are distributed this week will be lost permanently.
            require(
                votingEscrow.totalSupply(currentWeek) > 0,
                "Zero total supply results in lost tokens"
            );
        }
        _startTime = startTime;
        _timeCursor = startTime;
    }

    /**
     * @notice Returns the VotingEscrow (veBPT) token contract
     */
    function getVotingEscrow()
        external
        view
        override
        returns (IVotingEscrow)
    {
        return _votingEscrow;
    }

    /**
     * @notice Returns the global time cursor representing the most earliest uncheckpointed week.
     */
    function getTimeCursor() external view override returns (uint256) {
        return _timeCursor;
    }

    /**
     * @notice Returns the user-level time cursor representing the most earliest uncheckpointed week.
     * @param user - The address of the user to query.
     */
    function getUserTimeCursor(
        address user
    ) external view override returns (uint256) {
        return _userState[user].timeCursor;
    }

    /**
     * @notice Returns the token-level time cursor storing the timestamp at up to which tokens have been distributed.
     * @param token - The ERC20 token address to query.
     */
    function getTokenTimeCursor(
        IERC20 token
    ) external view override returns (uint256) {
        return _tokenState[token].timeCursor;
    }

    /**
     * @notice Returns the user-level time cursor storing the timestamp of the latest token distribution claimed.
     * @param user - The address of the user to query.
     * @param token - The ERC20 token address to query.
     */
    function getUserTokenTimeCursor(
        address user,
        IERC20 token
    ) external view override returns (uint256) {
        return _getUserTokenTimeCursor(user, token);
    }

    /**
     * @notice Returns the user's cached balance of veBPT as of the provided timestamp.
     * @dev Only timestamps which fall on Thursdays 00:00:00 UTC will return correct values.
     * This function requires `user` to have been checkpointed past `timestamp` so that their balance is cached.
     * @param user - The address of the user of which to read the cached balance of.
     * @param timestamp - The timestamp at which to read the `user`'s cached balance at.
     */
    function getUserBalanceAtTimestamp(
        address user,
        uint256 timestamp
    ) external view override returns (uint256) {
        return _userBalanceAtTimestamp[user][timestamp];
    }

    /**
     * @notice Returns the cached total supply of veBPT as of the provided timestamp.
     * @dev Only timestamps which fall on Thursdays 00:00:00 UTC will return correct values.
     * This function requires the contract to have been checkpointed past `timestamp` so that the supply is cached.
     * @param timestamp - The timestamp at which to read the cached total supply at.
     */
    function getTotalSupplyAtTimestamp(
        uint256 timestamp
    ) external view override returns (uint256) {
        return _veSupplyCache[timestamp];
    }

    /**
     * @notice Returns the RewardDistributor's cached balance of `token`.
     */
    function getTokenLastBalance(
        IERC20 token
    ) external view override returns (uint256) {
        return _tokenState[token].cachedBalance;
    }

    /**
     * @notice Returns the amount of `token` which the RewardDistributor received in the week beginning at `timestamp`.
     * @param token - The ERC20 token address to query.
     * @param timestamp - The timestamp corresponding to the beginning of the week of interest.
     */
    function getTokensDistributedInWeek(
        IERC20 token,
        uint256 timestamp
    ) external view override returns (uint256) {
        return _tokensPerWeek[token][timestamp];
    }

    // Depositing

    /**
     * @notice Deposits tokens to be distributed in the current week.
     * @dev Sending tokens directly to the RewardDistributor instead of using `depositToken` may result in tokens being
     * retroactively distributed to past weeks, or for the distribution to carry over to future weeks.
     *
     * If for some reason `depositToken` cannot be called, in order to ensure that all tokens are correctly distributed
     * manually call `checkpointToken` before and after the token transfer.
     * @param token - The ERC20 token address to distribute.
     * @param amount - The amount of tokens to deposit.
     */
    function depositToken(
        IERC20 token,
        uint256 amount
    ) external override nonReentrant {
        require(allowedRewardTokens[address(token)], "token not allowed");
        _checkpointToken(token, false);
        token.safeTransferFrom(msg.sender, address(this), amount);
        _checkpointToken(token, true);
    }

    /**
     * @notice Deposits tokens to be distributed in the current week.
     * @dev A version of `depositToken` which supports depositing multiple `tokens` at once.
     * See `depositToken` for more details.
     * @param tokens - An array of ERC20 token addresses to distribute.
     * @param amounts - An array of token amounts to deposit.
     */
    function depositTokens(
        IERC20[] calldata tokens,
        uint256[] calldata amounts
    ) external override nonReentrant {
        InputHelpers.ensureInputLengthMatch(tokens.length, amounts.length);

        uint256 length = tokens.length;
        for (uint256 i = 0; i < length; ++i) {
            require(allowedRewardTokens[address(tokens[i])], "token not allowed");
            _checkpointToken(tokens[i], false);
            tokens[i].safeTransferFrom(msg.sender, address(this), amounts[i]);
            _checkpointToken(tokens[i], true);
        }
    }

    // Checkpointing

    /**
     * @notice Caches the total supply of veBPT at the beginning of each week.
     * This function will be called automatically before claiming tokens to ensure the contract is properly updated.
     */
    function checkpoint() external override nonReentrant {
        _checkpointTotalSupply();
    }

    /**
     * @notice Caches the user's balance of veBPT at the beginning of each week.
     * This function will be called automatically before claiming tokens to ensure the contract is properly updated.
     * @param user - The address of the user to be checkpointed.
     */
    function checkpointUser(address user) external override nonReentrant {
        _checkpointUserBalance(user);
    }

    /**
     * @notice Assigns any newly-received tokens held by the RewardDistributor to weekly distributions.
     * @dev Any `token` balance held by the RewardDistributor above that which is returned by `getTokenLastBalance`
     * will be distributed evenly across the time period since `token` was last checkpointed.
     *
     * This function will be called automatically before claiming tokens to ensure the contract is properly updated.
     * @param token - The ERC20 token address to be checkpointed.
     */
    function checkpointToken(IERC20 token) external override nonReentrant {
        _checkpointToken(token, true);
    }

    /**
     * @notice Assigns any newly-received tokens held by the RewardDistributor to weekly distributions.
     * @dev A version of `checkpointToken` which supports checkpointing multiple tokens.
     * See `checkpointToken` for more details.
     * @param tokens - An array of ERC20 token addresses to be checkpointed.
     */
    function checkpointTokens(
        IERC20[] calldata tokens
    ) external override nonReentrant {
        uint256 tokensLength = tokens.length;
        for (uint256 i = 0; i < tokensLength; ++i) {
            _checkpointToken(tokens[i], true);
        }
    }

    // Claiming

    /**
     * @notice Claims all pending distributions of the provided token for a user.
     * @dev It's not necessary to explicitly checkpoint before calling this function, it will ensure the RewardDistributor
     * is up to date before calculating the amount of tokens to be claimed.
     * @param user - The user on behalf of which to claim.
     * @param token - The ERC20 token address to be claimed.
     * @return The amount of `token` sent to `user` as a result of claiming.
     */
    function claimToken(
        address user,
        IERC20 token
    )
        external
        override
        nonReentrant
        optionalOnlyCaller(user)
        returns (uint256)
    {
        _checkpointTotalSupply();
        _checkpointUserBalance(user);
        _checkpointToken(token, false);

        uint256 amount = _claimToken(user, token);
        return amount;
    }

    /**
     * @notice Claims a number of tokens on behalf of a user.
     * @dev A version of `claimToken` which supports claiming multiple `tokens` on behalf of `user`.
     * See `claimToken` for more details.
     * @param user - The user on behalf of which to claim.
     * @param tokens - An array of ERC20 token addresses to be claimed.
     * @return An array of the amounts of each token in `tokens` sent to `user` as a result of claiming.
     */
    function claimTokens(
        address user,
        IERC20[] calldata tokens
    )
        external
        override
        nonReentrant
        optionalOnlyCaller(user)
        returns (uint256[] memory)
    {
        _checkpointTotalSupply();
        _checkpointUserBalance(user);

        uint256 tokensLength = tokens.length;
        uint256[] memory amounts = new uint256[](tokensLength);
        for (uint256 i = 0; i < tokensLength; ++i) {
            _checkpointToken(tokens[i], false);
            amounts[i] = _claimToken(user, tokens[i]);
        }

        return amounts;
    }

    // Internal functions

    /**
     * @dev It is required that both the global, token and user state have been properly checkpointed
     * before calling this function.
     */
    function _claimToken(
        address user,
        IERC20 token
    ) internal returns (uint256) {
        TokenState storage tokenState = _tokenState[token];
        uint256 nextUserTokenWeekToClaim = _getUserTokenTimeCursor(user, token);

        // The first week which cannot be correctly claimed is the earliest of:
        // - A) The global or user time cursor (whichever is earliest), rounded up to the end of the week.
        // - B) The token time cursor, rounded down to the beginning of the week.
        //
        // This prevents the two failure modes:
        // - A) A user may claim a week for which we have not processed their balance, resulting in tokens being locked.
        // - B) A user may claim a week which then receives more tokens to be distributed. However the user has
        //      already claimed for that week so their share of these new tokens are lost.
        uint256 firstUnclaimableWeek = Math.min(
            _roundUpTimestamp(
                Math.min(_timeCursor, _userState[user].timeCursor)
            ),
            _roundDownTimestamp(tokenState.timeCursor)
        );

        mapping(uint256 => uint256) storage tokensPerWeek = _tokensPerWeek[
            token
        ];
        mapping(uint256 => uint256)
            storage userBalanceAtTimestamp = _userBalanceAtTimestamp[user];

        uint256 amount;
        for (uint256 i = 0; i < 20; ++i) {
            // We clearly cannot claim for `firstUnclaimableWeek` and so we break here.
            if (nextUserTokenWeekToClaim >= firstUnclaimableWeek) break;

            amount +=
                (tokensPerWeek[nextUserTokenWeekToClaim] *
                    userBalanceAtTimestamp[nextUserTokenWeekToClaim]) /
                _veSupplyCache[nextUserTokenWeekToClaim];
            nextUserTokenWeekToClaim += 1 weeks;
        }
        // Update the stored user-token time cursor to prevent this user claiming this week again.
        _userTokenTimeCursor[user][token] = nextUserTokenWeekToClaim;

        if (amount > 0) {
            // For a token to be claimable it must have been added to the cached balance so this is safe.
            tokenState.cachedBalance = uint128(
                tokenState.cachedBalance - amount
            );
            token.safeTransfer(user, amount);
            emit TokensClaimed(user, token, amount, nextUserTokenWeekToClaim);
        }

        return amount;
    }

    /**
     * @dev Calculate the amount of `token` to be distributed to `_votingEscrow` holders since the last checkpoint.
     */
    function _checkpointToken(IERC20 token, bool force) internal {
        TokenState storage tokenState = _tokenState[token];
        uint256 lastTokenTime = tokenState.timeCursor;
        uint256 timeSinceLastCheckpoint;
        if (lastTokenTime == 0) {
            // If it's the first time we're checkpointing this token then start distributing from now.
            // Also mark at which timestamp users should start attempts to claim this token from.
            lastTokenTime = block.timestamp;
            tokenState.startTime = uint64(_roundDownTimestamp(block.timestamp));

            // Prevent someone from assigning tokens to an inaccessible week.
            require(
                block.timestamp > _startTime,
                "Reward distribution has not started yet"
            );
        } else {
            timeSinceLastCheckpoint = block.timestamp - lastTokenTime;

            if (!force) {
                // Checkpointing N times within a single week is completely equivalent to checkpointing once at the end.
                // We then want to get as close as possible to a single checkpoint every Wed 23:59 UTC to save gas.

                // We then skip checkpointing if we're in the same week as the previous checkpoint.
                bool alreadyCheckpointedThisWeek = _roundDownTimestamp(
                    block.timestamp
                ) == _roundDownTimestamp(lastTokenTime);
                // However we want to ensure that all of this week's rewards are assigned to the current week without
                // overspilling into the next week. To mitigate this, we checkpoint if we're near the end of the week.
                bool nearingEndOfWeek = _roundUpTimestamp(block.timestamp) -
                    block.timestamp <
                    1 days;

                // This ensures that we checkpoint once at the beginning of the week and again for each user interaction
                // towards the end of the week to give an accurate final reading of the balance.
                if (alreadyCheckpointedThisWeek && !nearingEndOfWeek) {
                    return;
                }
            }
        }

        tokenState.timeCursor = uint64(block.timestamp);

        uint256 tokenBalance = token.balanceOf(address(this));
        uint256 newTokensToDistribute = tokenBalance.sub(
            tokenState.cachedBalance
        );
        if (newTokensToDistribute == 0) return;
        require(
            tokenBalance <= type(uint128).max,
            "Maximum token balance exceeded"
        );
        tokenState.cachedBalance = uint128(tokenBalance);

        uint256 firstIncompleteWeek = _roundDownTimestamp(lastTokenTime);
        uint256 nextWeek = 0;

        // Distribute `newTokensToDistribute` evenly across the time period from `lastTokenTime` to now.
        // These tokens are assigned to weeks proportionally to how much of this period falls into each week.
        mapping(uint256 => uint256) storage tokensPerWeek = _tokensPerWeek[
            token
        ];
        for (uint256 i = 0; i < 20; ++i) {
            // This is safe as we're incrementing a timestamp.
            nextWeek = firstIncompleteWeek + 1 weeks;
            if (block.timestamp < nextWeek) {
                // `firstIncompleteWeek` is now the beginning of the current week, i.e. this is the final iteration.
                if (
                    timeSinceLastCheckpoint == 0 &&
                    block.timestamp == lastTokenTime
                ) {
                    tokensPerWeek[firstIncompleteWeek] += newTokensToDistribute;
                } else {
                    // block.timestamp >= lastTokenTime by definition.
                    tokensPerWeek[firstIncompleteWeek] +=
                        (newTokensToDistribute *
                            (block.timestamp - lastTokenTime)) /
                        timeSinceLastCheckpoint;
                }
                // As we've caught up to the present then we should now break.
                break;
            } else {
                // We've gone a full week or more without checkpointing so need to distribute tokens to previous weeks.
                if (timeSinceLastCheckpoint == 0 && nextWeek == lastTokenTime) {
                    // It shouldn't be possible to enter this block
                    tokensPerWeek[firstIncompleteWeek] += newTokensToDistribute;
                } else {
                    // nextWeek > lastTokenTime by definition.
                    tokensPerWeek[firstIncompleteWeek] +=
                        (newTokensToDistribute * (nextWeek - lastTokenTime)) /
                        timeSinceLastCheckpoint;
                }
            }

            // We've now "checkpointed" up to the beginning of next week so must update timestamps appropriately.
            lastTokenTime = nextWeek;
            firstIncompleteWeek = nextWeek;
        }

        emit TokenCheckpointed(token, newTokensToDistribute, lastTokenTime);
    }

    /**
     * @dev Cache the `user`'s balance of `_votingEscrow` at the beginning of each new week
     */
    function _checkpointUserBalance(address user) internal {
        uint256 maxUserEpoch = _votingEscrow.user_point_epoch(user);

        // If user has no epochs then they have never locked veBPT.
        // They clearly will not then receive rewards.
        if (maxUserEpoch == 0) return;

        UserState storage userState = _userState[user];

        // `nextWeekToCheckpoint` represents the timestamp of the beginning of the first week
        // which we haven't checkpointed the user's VotingEscrow balance yet.
        uint256 nextWeekToCheckpoint = userState.timeCursor;

        uint256 userEpoch;
        if (nextWeekToCheckpoint == 0) {
            // First checkpoint for user so need to do the initial binary search
            userEpoch = _findTimestampUserEpoch(
                user,
                _startTime,
                0,
                maxUserEpoch
            );
        } else {
            if (nextWeekToCheckpoint >= block.timestamp) {
                // User has checkpointed the current week already so perform early return.
                // This prevents a user from processing epochs created later in this week, however this is not an issue
                // as if a significant number of these builds up then the user will skip past them with a binary search.
                return;
            }

            // Otherwise use the value saved from last time
            userEpoch = userState.lastEpochCheckpointed;

            // This optimizes a scenario common for power users, which have frequent `VotingEscrow` interactions in
            // the same week. We assume that any such user is also claiming rewards every week, and so we only perform
            // a binary search here rather than integrating it into the main search algorithm, effectively skipping
            // most of the week's irrelevant checkpoints.
            // The slight tradeoff is that users who have multiple infrequent `VotingEscrow` interactions and also don't
            // claim frequently will also perform the binary search, despite it not leading to gas savings.
            if (maxUserEpoch - userEpoch > 20) {
                userEpoch = _findTimestampUserEpoch(
                    user,
                    nextWeekToCheckpoint,
                    userEpoch,
                    maxUserEpoch
                );
            }
        }

        // Epoch 0 is always empty so bump onto the next one so that we start on a valid epoch.
        if (userEpoch == 0) {
            userEpoch = 1;
        }

        IVotingEscrow.Point memory nextUserPoint = _votingEscrow
            .user_point_history(user, userEpoch);

        // If this is the first checkpoint for the user, calculate the first week they're eligible for.
        // i.e. the timestamp of the first Thursday after they locked.
        // If this is earlier then the first distribution then fast forward to then.
        if (nextWeekToCheckpoint == 0) {
            // Disallow checkpointing before `startTime`.
            require(
                block.timestamp > _startTime,
                "Reward distribution has not started yet"
            );
            nextWeekToCheckpoint = Math.max(
                _startTime,
                _roundUpTimestamp(nextUserPoint.ts)
            );
            userState.startTime = uint64(nextWeekToCheckpoint);
        }

        // It's safe to increment `userEpoch` and `nextWeekToCheckpoint` in this loop as epochs and timestamps
        // are always much smaller than 2^256 and are being incremented by small values.
        IVotingEscrow.Point memory currentUserPoint;
        for (uint256 i = 0; i < 50; ++i) {
            if (
                nextWeekToCheckpoint >= nextUserPoint.ts &&
                userEpoch <= maxUserEpoch
            ) {
                // The week being considered is contained in a user epoch after that described by `currentUserPoint`.
                // We then shift `nextUserPoint` into `currentUserPoint` and query the Point for the next user epoch.
                // We do this in order to step though epochs until we find the first epoch starting after
                // `nextWeekToCheckpoint`, making the previous epoch the one that contains `nextWeekToCheckpoint`.
                userEpoch += 1;
                currentUserPoint = nextUserPoint;
                if (userEpoch > maxUserEpoch) {
                    nextUserPoint = IVotingEscrow.Point(0, 0, 0, 0);
                } else {
                    nextUserPoint = _votingEscrow.user_point_history(
                        user,
                        userEpoch
                    );
                }
            } else {
                // The week being considered lies inside the user epoch described by `oldUserPoint`
                // we can then use it to calculate the user's balance at the beginning of the week.
                if (nextWeekToCheckpoint >= block.timestamp) {
                    // Break if we're trying to cache the user's balance at a timestamp in the future.
                    // We only perform this check here to ensure that we can still process checkpoints created
                    // in the current week.
                    break;
                }

                int128 dt = int128(nextWeekToCheckpoint - currentUserPoint.ts);
                uint256 userBalance = currentUserPoint.bias >
                    currentUserPoint.slope * dt
                    ? uint256(
                        currentUserPoint.bias - currentUserPoint.slope * dt
                    )
                    : 0;

                // User's lock has expired and they haven't relocked yet.
                if (userBalance == 0 && userEpoch > maxUserEpoch) {
                    nextWeekToCheckpoint = _roundUpTimestamp(block.timestamp);
                    break;
                }

                // User had a nonzero lock and so is eligible to collect rewards.
                _userBalanceAtTimestamp[user][
                    nextWeekToCheckpoint
                ] = userBalance;

                nextWeekToCheckpoint += 1 weeks;
            }
        }

        // We subtract off 1 from the userEpoch to step back once so that on the next attempt to checkpoint
        // the current `currentUserPoint` will be loaded as `nextUserPoint`. This ensures that we can't skip over the
        // user epoch containing `nextWeekToCheckpoint`.
        // userEpoch > 0 so this is safe.
        userState.lastEpochCheckpointed = uint64(userEpoch - 1);
        userState.timeCursor = uint64(nextWeekToCheckpoint);
    }

    /**
     * @dev Cache the totalSupply of VotingEscrow token at the beginning of each new week
     */
    function _checkpointTotalSupply() internal {
        uint256 nextWeekToCheckpoint = _timeCursor;
        uint256 weekStart = _roundDownTimestamp(block.timestamp);

        // We expect `timeCursor == weekStart + 1 weeks` when fully up to date.
        if (nextWeekToCheckpoint > weekStart || weekStart == block.timestamp) {
            // We've already checkpointed up to this week so perform early return
            return;
        }

        _votingEscrow.checkpoint();

        // Step through the each week and cache the total supply at beginning of week on this contract
        for (uint256 i = 0; i < 20; ++i) {
            if (nextWeekToCheckpoint > weekStart) break;

            _veSupplyCache[nextWeekToCheckpoint] = _votingEscrow.totalSupply(
                nextWeekToCheckpoint
            );

            // This is safe as we're incrementing a timestamp
            nextWeekToCheckpoint += 1 weeks;
        }
        // Update state to the end of the current week (`weekStart` + 1 weeks)
        _timeCursor = nextWeekToCheckpoint;
    }

    // Helper functions

    /**
     * @dev Wrapper around `_userTokenTimeCursor` which returns the start timestamp for `token`
     * if `user` has not attempted to interact with it previously.
     */
    function _getUserTokenTimeCursor(
        address user,
        IERC20 token
    ) internal view returns (uint256) {
        uint256 userTimeCursor = _userTokenTimeCursor[user][token];
        if (userTimeCursor > 0) return userTimeCursor;
        // This is the first time that the user has interacted with this token.
        // We then start from the latest out of either when `user` first locked veBPT or `token` was first checkpointed.
        return
            Math.max(_userState[user].startTime, _tokenState[token].startTime);
    }

    /**
     * @dev Return the user epoch number for `user` corresponding to the provided `timestamp`
     */
    function _findTimestampUserEpoch(
        address user,
        uint256 timestamp,
        uint256 minUserEpoch,
        uint256 maxUserEpoch
    ) internal view returns (uint256) {
        uint256 min = minUserEpoch;
        uint256 max = maxUserEpoch;

        // Perform binary search through epochs to find epoch containing `timestamp`
        for (uint256 i = 0; i < 128; ++i) {
            if (min >= max) break;

            // Algorithm assumes that inputs are less than 2^128 so this operation is safe.
            // +2 avoids getting stuck in min == mid < max
            uint256 mid = (min + max + 2) / 2;
            IVotingEscrow.Point memory pt = _votingEscrow
                .user_point_history(user, mid);
            if (pt.ts <= timestamp) {
                min = mid;
            } else {
                // max > min so this is safe.
                max = mid - 1;
            }
        }
        return min;
    }

    /**
     * @dev Rounds the provided timestamp down to the beginning of the previous week (Thurs 00:00 UTC)
     */
    function _roundDownTimestamp(
        uint256 timestamp
    ) private pure returns (uint256) {
        // Division by zero or overflows are impossible here.
        return (timestamp / 1 weeks) * 1 weeks;
    }

    /**
     * @dev Rounds the provided timestamp up to the beginning of the next week (Thurs 00:00 UTC)
     */
    function _roundUpTimestamp(
        uint256 timestamp
    ) private pure returns (uint256) {
        // Overflows are impossible here for all realistic inputs.
        return _roundDownTimestamp(timestamp + 1 weeks - 1);
    }

    function addAllowedRewardTokens(address[] calldata tokens) external onlyAdmin {
        for (uint256 i = 0; i < tokens.length; i++) {
            require(!allowedRewardTokens[tokens[i]], "already exist");
            allowedRewardTokens[tokens[i]] = true;
            _rewardTokens.push(tokens[i]);
            emit TokenAdded(tokens[i]);
        }
    }

    /**
     * @notice Returns the list of allowed reward tokens
     * @return An array of addresses of the allowed reward tokens
     */
    function getAllowedRewardTokens() external view returns (address[] memory) {
        return _rewardTokens;
    }

    /**
     * @notice Transfers the admin role to a new address
     * @param newAdmin The address of the new admin
     */
    function transferAdmin(address newAdmin) external onlyAdmin {
        require (newAdmin != address(0), "zero address");
        admin = newAdmin;
        emit AdminTransferred(newAdmin);
    }
}