Cryo Explorer Ethereum Mainnet

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.17;

import "contracts/token/ERC20/IERC20.sol";
import "contracts/utils/Address.sol";
import "contracts/token/ERC20/utils/SafeERC20.sol";

import {IEscrow, IGauge, IFeeDistribution, IMetaRegistry, IGaugeController} from "contracts/interfaces/Curve.sol";
import {IProxy, SafeProxy} from "contracts/interfaces/IProxy.sol";

contract StrategyProxy {
    using SafeERC20 for IERC20;
    using Address for address;
    using SafeProxy for IProxy;

    uint constant WEEK = 1 weeks;

    /// @notice Yearn's voter proxy. Typically referred to as "voter".
    IProxy public constant proxy =
        IProxy(0xF147b8125d2ef93FB6965Db97D6746952a133934);

    /// @notice Curve's token minter.
    address public constant mintr = 0xd061D61a4d941c39E5453435B6345Dc261C2fcE0;

    /// @notice Curve's CRV token address.
    address public constant crv = 0xD533a949740bb3306d119CC777fa900bA034cd52;

    /// @notice Curve's crvUSD address (weekly fees paid in this token).
    IERC20 public constant crvUSD =
        IERC20(0xf939E0A03FB07F59A73314E73794Be0E57ac1b4E);

    /// @notice Curve's fee distributor contract.
    IFeeDistribution public constant feeDistribution =
        IFeeDistribution(0xD16d5eC345Dd86Fb63C6a9C43c517210F1027914);

    /// @notice Curve's vote-escrowed Curve address.
    IEscrow public constant veCRV =
        IEscrow(0x5f3b5DfEb7B28CDbD7FAba78963EE202a494e2A2);

    /// @notice Curve's meta-registry. Can pull data from the many existing curve registries.
    IMetaRegistry public constant metaRegistry =
        IMetaRegistry(0xF98B45FA17DE75FB1aD0e7aFD971b0ca00e379fC);

    /// @notice Curve's gauge controller.
    IGaugeController public constant gaugeController =
        IGaugeController(0x2F50D538606Fa9EDD2B11E2446BEb18C9D5846bB);

    /// @notice Look up the strategy approved for a given Curve gauge.
    mapping(address => address) public strategies;

    /// @notice Check if a gauge reward token is approved for claiming.
    mapping(address => bool) public rewardTokenApproved;

    /// @notice Check if an address is an approved voter for gauge weights.
    mapping(address => bool) public voters;

    /// @notice Check if an address is an approved locker of CRV tokens.
    mapping(address => bool) public lockers;

    /// @notice Check if an address is an approved admin fee claimer.
    address public adminFeeRecipient;

    /// @notice Current governance address.
    address public governance;

    /// @notice Check if an address is an approved factory for deploying Curve voter strategies.
    mapping(address => bool) public approvedFactories;

    // Events so that indexers can keep track of key actions
    event GovernanceSet(address indexed governance);
    event AdminFeeRecipientSet(address indexed recipient);
    event StrategyApproved(address indexed gauge, address indexed strategy);
    event StrategyRevoked(address indexed gauge, address indexed strategy);
    event VoterApprovalSet(address indexed voter, bool indexed approved);
    event LockerApprovalSet(address indexed locker, bool indexed approved);
    event RewardTokenApprovalSet(address indexed token, bool indexed approved);
    event FactoryApproved(address indexed factory, bool indexed approved);
    event TokenClaimed(
        address indexed token,
        address indexed recipient,
        uint balance
    );

    constructor(address _adminFeeRecipient) {
        require(_adminFeeRecipient != address(0), "Empty admin fee recipient");
        governance = msg.sender;
        adminFeeRecipient = _adminFeeRecipient;
    }

    /**
     * @notice Approve curve vault factory addresses.
     * @dev Must be called by governance. Multiple factories possible (Curve LP, Curve Lend).
     * @param _factory Address to set as a curve vault factory.
     * @param _approved Whether the address is allowed factory permissions (to approve strategies).
     */
    function approveFactory(address _factory, bool _approved) external {
        require(msg.sender == governance, "!governance");
        approvedFactories[_factory] = _approved;
        emit FactoryApproved(_factory, _approved);
    }

    /**
     * @notice Set governance address.
     * @dev Must be called by current governance.
     * @param _governance Address to set as governance.
     */
    function setGovernance(address _governance) external {
        require(msg.sender == governance, "!governance");
        require(_governance != governance, "already set");
        governance = _governance;
        emit GovernanceSet(_governance);
    }

    /**
     * @notice Set recipient of weekly crvUSD admin fees.
     * @dev Only a single address can be approved at any time. Must be called by governance.
     * @param _recipient Address to approve for fees.
     */
    function setAdminFeeRecipient(address _recipient) external {
        require(msg.sender == governance, "!governance");
        require(_recipient != address(0), "zero address");
        adminFeeRecipient = _recipient;
        emit AdminFeeRecipientSet(_recipient);
    }

    /**
     * @notice Add strategy to a gauge.
     * @dev Must be called by governance or factory.
     * @param _gauge Gauge to permit strategy on.
     * @param _strategy Strategy to approve on gauge.
     */
    function approveStrategy(address _gauge, address _strategy) external {
        require(
            msg.sender == governance || approvedFactories[msg.sender],
            "!access"
        );
        require(_strategy != address(0), "disallow zero");
        require(strategies[_gauge] != _strategy, "already approved");
        // @dev The following call should fail gracefully on older gauges that don't implement this interface.
        proxy.execute(
            _gauge,
            0,
            abi.encodeWithSignature("set_rewards_receiver(address)", _strategy)
        );
        strategies[_gauge] = _strategy;
        emit StrategyApproved(_gauge, _strategy);
    }

    /**
     * @notice Clear any previously approved strategy to a gauge.
     * @dev Must be called by governance.
     * @param _gauge Gauge from which to remove strategy.
     */
    function revokeStrategy(address _gauge) external {
        require(msg.sender == governance, "!governance");
        address _strategy = strategies[_gauge];
        require(_strategy != address(0), "already revoked");
        // @dev The following call should fail gracefully on older gauges that don't implement this interface.
        proxy.execute(
            _gauge,
            0,
            abi.encodeWithSignature("set_rewards_receiver(address)", address(0))
        );
        strategies[_gauge] = address(0);
        emit StrategyRevoked(_gauge, _strategy);
    }

    /**
     * @notice Approve an address for voting on gauge weights.
     * @dev Must be called by governance.
     * @param _voter Voter to add.
     * @param _approved Whether the address is allowed to vote.
     */
    function approveVoter(address _voter, bool _approved) external {
        require(msg.sender == governance, "!governance");
        voters[_voter] = _approved;
        emit VoterApprovalSet(_voter, _approved);
    }

    /**
     * @notice Approve an address for locking CRV.
     * @dev Must be called by governance.
     * @param _locker Locker to add.
     * @param _approved Whether the address is allowed to lock.
     */
    function approveLocker(address _locker, bool _approved) external {
        require(msg.sender == governance, "!governance");
        lockers[_locker] = _approved;
        emit LockerApprovalSet(_locker, _approved);
    }

    /**
     * @notice Lock CRV into veCRV contract.
     * @dev Must be called by governance or locker.
     */
    function lock() external {
        require(msg.sender == governance || lockers[msg.sender], "!locker");
        uint256 amount = IERC20(crv).balanceOf(address(proxy));
        if (amount > 0) proxy.increaseAmount(amount);
    }

    /**
     * @notice Extend veCRV lock time to maximum amount of 4 years.
     * @dev Must be called by governance or locker.
     */
    function maxLock() external {
        require(msg.sender == governance || lockers[msg.sender], "!locker");
        uint max = block.timestamp + (365 days * 4);
        uint lock_end = veCRV.locked__end(address(proxy));
        if (lock_end < (max / WEEK) * WEEK) {
            proxy.safeExecute(
                address(veCRV),
                0,
                abi.encodeWithSignature("increase_unlock_time(uint256)", max)
            );
        }
    }

    /**
     * @notice Vote on a gauge.
     * @dev Must be called by governance or voter.
     * @param _gauge The gauge to vote on.
     * @param _weight Weight to vote with.
     */
    function vote(address _gauge, uint256 _weight) external {
        require(msg.sender == governance || voters[msg.sender], "!voter");
        _vote(_gauge, _weight);
    }

    /**
     * @notice Vote on a multiple gauges.
     * @dev Must be called by governance or voter.
     * @param _gauges List of gauges to vote on.
     * @param _weights List of weight to vote with.
     */
    function voteMany(
        address[] calldata _gauges,
        uint256[] calldata _weights
    ) external {
        require(msg.sender == governance || voters[msg.sender], "!voter");
        require(_gauges.length == _weights.length, "!mismatch");
        for (uint256 i = 0; i < _gauges.length; i++) {
            _vote(_gauges[i], _weights[i]);
        }
    }

    function _vote(address _gauge, uint256 _weight) internal {
        proxy.safeExecute(
            address(gaugeController),
            0,
            abi.encodeWithSignature(
                "vote_for_gauge_weights(address,uint256)",
                _gauge,
                _weight
            )
        );
    }

    /**
     * @notice Withdraw exact amount of LPs from gauge.
     * @dev Must be called by the strategy approved for the given gauge.
     * @param _gauge The gauge from which to withdraw.
     * @param _token The LP token to withdraw from gauge.
     * @param _amount The exact amount of LPs with withdraw.
     */
    function withdraw(
        address _gauge,
        address _token,
        uint256 _amount
    ) public returns (uint256) {
        require(strategies[_gauge] == msg.sender, "!strategy");
        uint256 _balance = IERC20(_token).balanceOf(address(proxy));
        proxy.safeExecute(
            _gauge,
            0,
            abi.encodeWithSignature("withdraw(uint256)", _amount)
        );
        _balance = IERC20(_token).balanceOf(address(proxy)) - _balance;
        proxy.safeExecute(
            _token,
            0,
            abi.encodeWithSignature(
                "transfer(address,uint256)",
                msg.sender,
                _balance
            )
        );
        return _balance;
    }

    /**
     * @notice Find Yearn voter's full balance within a given gauge.
     * @param _gauge The gauge from which to check balance.
     */
    function balanceOf(address _gauge) public view returns (uint256) {
        return IERC20(_gauge).balanceOf(address(proxy));
    }

    /**
     * @notice Withdraw full balance of voter's LPs from gauge.
     * @param _gauge The gauge from which to withdraw.
     * @param _token The LP token to withdraw from gauge.
     */
    function withdrawAll(
        address _gauge,
        address _token
    ) external returns (uint256) {
        return withdraw(_gauge, _token, balanceOf(_gauge));
    }

    /**
     * @notice Takes care of depositing Curve LPs into gauge.
     * @dev Strategy must first transfer LPs to this contract prior to calling.
     *   Must be called by strategy approved for this gauge.
     * @param _gauge The gauge to deposit LP token into.
     * @param _token The LP token to deposit into gauge.
     */
    function deposit(address _gauge, address _token) external {
        require(strategies[_gauge] == msg.sender, "!strategy");
        uint256 _balance = IERC20(_token).balanceOf(address(this));
        IERC20(_token).safeTransfer(address(proxy), _balance);
        _balance = IERC20(_token).balanceOf(address(proxy));

        proxy.safeExecute(
            _token,
            0,
            abi.encodeWithSignature("approve(address,uint256)", _gauge, 0)
        );
        proxy.safeExecute(
            _token,
            0,
            abi.encodeWithSignature(
                "approve(address,uint256)",
                _gauge,
                _balance
            )
        );
        proxy.safeExecute(
            _gauge,
            0,
            abi.encodeWithSignature("deposit(uint256)", _balance)
        );
    }

    /**
     * @notice Abstracts the CRV minting and transfers to an approved strategy with CRV earnings.
     * @dev Designed to be called within the harvest function of a strategy.
     * @param _gauge The gauge which this strategy is claiming CRV from.
     */
    function harvest(address _gauge) external {
        require(strategies[_gauge] == msg.sender, "!strategy");
        uint256 _balance = IERC20(crv).balanceOf(address(proxy));
        proxy.safeExecute(
            mintr,
            0,
            abi.encodeWithSignature("mint(address)", _gauge)
        );
        _balance = IERC20(crv).balanceOf(address(proxy)) - _balance;
        proxy.safeExecute(
            crv,
            0,
            abi.encodeWithSignature(
                "transfer(address,uint256)",
                msg.sender,
                _balance
            )
        );
    }

    /**
     * @notice Claim share of weekly admin fees from Curve fee distributor.
     * @dev Admin fees become available every Thursday at 00:00 UTC
     * @return Amount of crvUSD claimed.
     */
    function claimAdminFees() external returns (uint) {
        require(msg.sender == adminFeeRecipient, "!authorized");
        return _claimAdminFees(adminFeeRecipient);
    }

    /**
     * @notice Allow governance to claim weekly admin fees from Curve fee distributor.
     * @param _recipient Where to send the crvUSD.
     * @return Amount of crvUSD claimed.
     */
    function claimAdminFeesTo(address _recipient) external returns (uint) {
        require(msg.sender == governance, "!governance");
        return _claimAdminFees(_recipient);
    }

    function _claimAdminFees(address _recipient) internal returns (uint) {
        address p = address(proxy);
        uint balance = crvUSD.balanceOf(p);
        if (!canClaim()) {
            return balance > 1e18 ? _transferBalance(crvUSD, _recipient) : 0;
        }

        for (uint i; i < 10; i++) {
            // @dev max 10 tries is up to 500 weeks of history.
            feeDistribution.claim(p);
            if (crvUSD.balanceOf(p) > balance) break;
        }
        return _transferBalance(crvUSD, _recipient);
    }

    /**
     * @notice Cast a DAO vote
     * @dev Allows for casting a vote in either the admin or parameter DAO.
     * @param _target The address of the DAO contract
     * @param _voteId Vote identifier
     * @param _support true/false
     */
    function dao_vote(
        address _target,
        uint _voteId,
        bool _support
    ) external returns (uint amount) {
        require(voters[msg.sender] || msg.sender == governance, "!voter");
        require(
            _target == 0xE478de485ad2fe566d49342Cbd03E49ed7DB3356 ||
                _target == 0xBCfF8B0b9419b9A88c44546519b1e909cF330399,
            "invalid dao contract"
        );
        bytes memory data = abi.encodeWithSignature(
            "vote(uint256,bool,bool)",
            _voteId,
            _support,
            false
        );
        proxy.safeExecute(_target, 0, data);
    }

    /**
     * @notice Check if any admin fees are available for claim.
     * @return Whether admin fees are claimable.
     */
    function canClaim() public view returns (bool) {
        uint weekStart = (block.timestamp / WEEK) * WEEK;
        uint lastClaimWeek = feeDistribution.time_cursor_of(address(proxy));
        uint lastCheckpoint = feeDistribution.last_token_time();
        if (
            block.timestamp > lastClaimWeek + WEEK && lastCheckpoint > weekStart
        ) return true;
        return false;
    }

    /**
     * @notice Claim non-CRV token incentives from the gauge and transfer to strategy.
     * @dev There are two claim methods:
     *  - new (preferred): strategy is set as recipient in gauge contract. Rewards are forwarded directly to strategy.
     *  - legacy: fallback method for old gauges that do not support rewards_receiver interface. In this case, reward
     *    tokens are sent to voter and then swept to strategy.
     * @param _gauge The gauge which this strategy is claiming rewards.
     * @param _token The token to be claimed to the approved strategy.
     */
    function claimRewards(address _gauge, address _token) external {
        if (_claimRewards(_gauge)) return;
        address[] memory tokens = new address[](1);
        tokens[0] = _token;
        _legacyClaimRewards(_gauge, tokens);
    }

    /**
     * @notice Claim non-CRV token incentives from the gauge and transfer to strategy.
     * @dev Must be called by the strategy approved for the given gauge.
     * @param _gauge The gauge which this strategy is claiming rewards.
     * @param _tokens The token(s) to be claimed to the approved strategy.
     */
    function claimManyRewards(
        address _gauge,
        address[] memory _tokens
    ) external {
        if (_claimRewards(_gauge)) return;
        _legacyClaimRewards(_gauge, _tokens);
    }

    // use this internal function to eliminate the need for transfers when claiming extra rewards
    function _claimRewards(address _gauge) internal returns (bool) {
        require(strategies[_gauge] == msg.sender, "!strategy");
        IGauge(_gauge).claim_rewards(address(proxy));
        try IGauge(_gauge).rewards_receiver(address(proxy)) returns (
            address receiver
        ) {
            require(receiver == msg.sender, "strategy not reward receiver"); // Reverts txn if fails.
        } catch {
            return false;
        }
        return true;
    }

    function _legacyClaimRewards(
        address _gauge,
        address[] memory _tokens
    ) internal {
        for (uint256 i; i < _tokens.length; ++i) {
            require(rewardTokenApproved[_tokens[i]], "!approvedToken");
            _transferBalance(IERC20(_tokens[i]), msg.sender);
        }
    }

    /**
     * @notice Approve reward tokens to be claimed by strategies.
     * @dev Must be called by governance. Only required for legacy gauges without rewards_receiver interface.
     * @param _token The token to be claimed.
     * @param _approved Whether a reward token is approved to be claimed.
     */
    function approveRewardToken(address _token, bool _approved) external {
        require(msg.sender == governance, "!governance");
        if (_approved) require(_isSafeToken(_token), "!safeToken");
        require(rewardTokenApproved[_token] != _approved, "No approval change");
        rewardTokenApproved[_token] = _approved;
        emit RewardTokenApprovalSet(_token, _approved);
    }

    // make sure a strategy can't yoink gauge or LP tokens.
    function _isSafeToken(address _token) internal view returns (bool) {
        if (_token == crv || _token == address(crvUSD)) return false;
        try gaugeController.gauge_types(_token) {
            return false;
        } catch {} // @dev: Since we expect try should fail, proceed without any catch logic error here.
        address pool = metaRegistry.get_pool_from_lp_token(_token);
        if (pool != address(0)) return false;
        return true;
    }

    function _transferBalance(
        IERC20 _token,
        address _recipient
    ) internal returns (uint) {
        uint balance = _token.balanceOf(address(proxy));
        if (balance == 0) return 0;
        proxy.safeExecute(
            address(_token),
            0,
            abi.encodeWithSignature(
                "transfer(address,uint256)",
                _recipient,
                balance
            )
        );
        return balance;
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (utils/Address.sol)

pragma solidity ^0.8.1;

/**
 * @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
     *
     * Furthermore, `isContract` will also return true if the target contract within
     * the same transaction is already scheduled for destruction by `SELFDESTRUCT`,
     * which only has an effect at the end of a transaction.
     * ====
     *
     * [IMPORTANT]
     * ====
     * You shouldn't rely on `isContract` to protect against flash loan attacks!
     *
     * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
     * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
     * constructor.
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize/address.code.length, which returns 0
        // for contracts in construction, since the code is only stored at the end
        // of the constructor execution.

        return account.code.length > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://consensys.net/diligence/blog/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.8.0/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, "Address: insufficient balance");

        (bool success, ) = recipient.call{value: amount}("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @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:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResultFromTarget(target, success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResultFromTarget(target, success, returndata, errorMessage);
    }

    /**
     * @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) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResultFromTarget(target, success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verify that a low level call to smart-contract was successful, and revert (either by bubbling
     * the revert reason or using the provided one) in case of unsuccessful call or if target was not a contract.
     *
     * _Available since v4.8._
     */
    function verifyCallResultFromTarget(
        address target,
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        if (success) {
            if (returndata.length == 0) {
                // only check isContract if the call was successful and the return data is empty
                // otherwise we already know that it was a contract
                require(isContract(target), "Address: call to non-contract");
            }
            return returndata;
        } else {
            _revert(returndata, errorMessage);
        }
    }

    /**
     * @dev Tool to verify that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason or using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            _revert(returndata, errorMessage);
        }
    }

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

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.17;

interface ICurveFi {
    function get_virtual_price() external view returns (uint256);

    function add_liquidity(
        // EURs
        uint256[2] calldata amounts,
        uint256 min_mint_amount
    ) external;

    function add_liquidity(
        // sBTC pool
        uint256[3] calldata amounts,
        uint256 min_mint_amount
    ) external;

    function add_liquidity(
        // bUSD pool
        uint256[4] calldata amounts,
        uint256 min_mint_amount
    ) external;

    function remove_liquidity_imbalance(uint256[4] calldata amounts, uint256 max_burn_amount) external;

    function remove_liquidity(uint256 _amount, uint256[4] calldata amounts) external;

    function remove_liquidity_one_coin(
        uint256 _token_amount,
        int128 i,
        uint256 min_amount
    ) external;

    function exchange(
        int128 from,
        int128 to,
        uint256 _from_amount,
        uint256 _min_to_amount
    ) external;

    function exchange_underlying(
        int128 from,
        int128 to,
        uint256 _from_amount,
        uint256 _min_to_amount
    ) external;

    function balances(int128) external view returns (uint256);

    function get_dy(
        int128 from,
        int128 to,
        uint256 _from_amount
    ) external view returns (uint256);
}

interface Zap {
    function remove_liquidity_one_coin(
        uint256,
        int128,
        uint256
    ) external;
}

interface IGauge {
    function deposit(uint256) external;
    function balanceOf(address) external view returns (uint256);
    function withdraw(uint256) external;
    function claim_rewards(address) external;
    function reward_tokens(uint256) external view returns (address);
    function rewards_receiver(address) external view returns (address);
}

interface IFeeDistribution {
    function claim(address) external returns (uint);
    function claim_many(address[20] calldata) external returns (bool);
    function last_token_time() external view returns (uint256);
    function time_cursor() external view returns (uint256);
    function time_cursor_of(address) external view returns (uint256);
}

interface IEscrow {
    function increase_unlock_time(uint256 _time) external;
    function locked__end(address user) external returns (uint);
}

interface IMetaRegistry {
    function get_pool_from_lp_token(address _lp) external view returns (address);
}

interface IGaugeController {
    function gauge_types(address _gauge) external view returns (int128);
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.17;

interface IProxy {
    function execute(
        address to,
        uint256 value,
        bytes calldata data
    ) external returns (bool, bytes memory);

    function increaseAmount(uint256) external;
}

library SafeProxy {
    function safeExecute(
        IProxy proxy,
        address to,
        uint256 value,
        bytes memory data
    ) internal {
        (bool success, ) = proxy.execute(to, value, data);
        require(success);
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

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

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

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.3) (token/ERC20/utils/SafeERC20.sol)

pragma solidity ^0.8.0;

import "contracts/token/ERC20/IERC20.sol";
import "contracts/token/ERC20/extensions/IERC20Permit.sol";
import "contracts/utils/Address.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 {
    using Address for address;

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

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

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(IERC20 token, address spender, uint256 value) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        require(
            (value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

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

    /**
     * @dev Decrease the calling contract's allowance toward `spender` by `value`. If `token` returns no value,
     * non-reverting calls are assumed to be successful.
     */
    function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        unchecked {
            uint256 oldAllowance = token.allowance(address(this), spender);
            require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, oldAllowance - value));
        }
    }

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

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

    /**
     * @dev Use a ERC-2612 signature to set the `owner` approval toward `spender` on `token`.
     * Revert on invalid signature.
     */
    function safePermit(
        IERC20Permit token,
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal {
        uint256 nonceBefore = token.nonces(owner);
        token.permit(owner, spender, value, deadline, v, r, s);
        uint256 nonceAfter = token.nonces(owner);
        require(nonceAfter == nonceBefore + 1, "SafeERC20: permit did not succeed");
    }

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

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        require(returndata.length == 0 || abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
    }

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

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

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (token/ERC20/extensions/IERC20Permit.sol)

pragma solidity ^0.8.0;

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

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

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