// 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
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

pragma solidity ^0.8.0;

/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "@openzeppelin/contracts/security/Pausable.sol";
import "./interfaces/IDackiePool.sol";

contract DackieFlexiblePool is Ownable, Pausable {
    using SafeERC20 for IERC20;

    struct UserInfo {
        uint256 shares; // number of shares for a user
        uint256 lastDepositedTime; // keeps track of deposited time for potential penalty
        uint256 cakeAtLastUserAction; // keeps track of dackie deposited at the last user action
        uint256 lastUserActionTime; // keeps track of the last user action time
    }

    IERC20 public immutable token; // Cake token
    IDackiePool public immutable cakePool; //Cake pool

    mapping(address => UserInfo) public userInfo;

    uint256 public totalShares;
    address public admin;
    address public treasury;
    bool public staking = true;

    uint256 public constant MAX_PERFORMANCE_FEE = 2000; // 20%
    uint256 public constant MAX_WITHDRAW_FEE = 500; // 5%
    uint256 public constant MAX_WITHDRAW_FEE_PERIOD = 1 weeks; // 1 week
    uint256 public constant MAX_WITHDRAW_AMOUNT_BOOSTER = 10010; // 1.001
    uint256 public constant MIN_DEPOSIT_AMOUNT = 0.00001 ether;
    uint256 public constant MIN_WITHDRAW_AMOUNT = 0.00001 ether;
    uint256 public constant MIN_WITHDRAW_AMOUNT_BOOSTER = 10000; // 1

    //When call dackiepool.withdrawByAmount function,there will be a loss of precision, so need to withdraw more.
    uint256 public withdrawAmountBooster = 10001; // 1.0001
    uint256 public performanceFee = 200; // 2%
    uint256 public withdrawFee = 10; // 0.1%
    uint256 public withdrawFeePeriod = 72 hours; // 3 days

    event DepositDackie(address indexed sender, uint256 amount, uint256 shares, uint256 lastDepositedTime);
    event WithdrawShares(address indexed sender, uint256 amount, uint256 shares);
    event ChargePerformanceFee(address indexed sender, uint256 amount, uint256 shares);
    event ChargeWithdrawFee(address indexed sender, uint256 amount);
    event Pause();
    event Unpause();
    event NewAdmin(address admin);
    event NewTreasury(address treasury);
    event NewPerformanceFee(uint256 performanceFee);
    event NewWithdrawFee(uint256 withdrawFee);
    event NewWithdrawFeePeriod(uint256 withdrawFeePeriod);
    event NewWithdrawAmountBooster(uint256 withdrawAmountBooster);

    /**
     * @notice Constructor
     * @param _token: DACKIE token contract
     * @param _dackiePool: DackiePool contract
     * @param _admin: address of the admin
     * @param _treasury: address of the treasury (collects fees)
     */
    constructor(
        IERC20 _token,
        IDackiePool _dackiePool,
        address _admin,
        address _treasury
    ) {
        token = _token;
        cakePool = _dackiePool;
        admin = _admin;
        treasury = _treasury;

        // Infinite approve
        IERC20(_token).safeApprove(address(_dackiePool), type(uint256).max);
    }

    /**
     * @notice Checks if the msg.sender is the admin address
     */
    modifier onlyAdmin() {
        require(msg.sender == admin, "admin: wut?");
        _;
    }

    /**
     * @notice Deposits funds into the Dackie Flexible Pool.
     * @dev Only possible when contract not paused.
     * @param _amount: number of tokens to deposit (in DACKIE)
     */
    function deposit(uint256 _amount) external whenNotPaused {
        require(staking, "Not allowed to stake");
        require(_amount > MIN_DEPOSIT_AMOUNT, "Deposit amount must be greater than MIN_DEPOSIT_AMOUNT");
        UserInfo storage user = userInfo[msg.sender];
        //charge performanceFee
        bool chargeFeeFromDeposite;
        uint256 currentPerformanceFee;
        uint256 performanceFeeShares;
        if (user.shares > 0) {
            uint256 totalAmount = (user.shares * balanceOf()) / totalShares;
            uint256 earnAmount = totalAmount - user.cakeAtLastUserAction;
            currentPerformanceFee = (earnAmount * performanceFee) / 10000;
            if (currentPerformanceFee > 0) {
                performanceFeeShares = (currentPerformanceFee * totalShares) / balanceOf();
                user.shares -= performanceFeeShares;
                totalShares -= performanceFeeShares;
                if (_amount >= currentPerformanceFee) {
                    chargeFeeFromDeposite = true;
                } else {
                    // withdrawByAmount have a MIN_WITHDRAW_AMOUNT limit ,so need to withdraw more than MIN_WITHDRAW_AMOUNT.
                    uint256 withdrawAmount = currentPerformanceFee < MIN_WITHDRAW_AMOUNT
                        ? MIN_WITHDRAW_AMOUNT
                        : currentPerformanceFee;
                    //There will be a loss of precision when call withdrawByAmount, so need to withdraw more.
                    withdrawAmount = (withdrawAmount * withdrawAmountBooster) / 10000;
                    cakePool.withdrawByAmount(withdrawAmount);

                    currentPerformanceFee = available() >= currentPerformanceFee ? currentPerformanceFee : available();
                    token.safeTransfer(treasury, currentPerformanceFee);
                    emit ChargePerformanceFee(msg.sender, currentPerformanceFee, performanceFeeShares);
                }
            }
        }
        uint256 pool = balanceOf();
        token.safeTransferFrom(msg.sender, address(this), _amount);
        if (chargeFeeFromDeposite) {
            token.safeTransfer(treasury, currentPerformanceFee);
            emit ChargePerformanceFee(msg.sender, currentPerformanceFee, performanceFeeShares);
            pool -= currentPerformanceFee;
        }
        uint256 currentShares;
        if (totalShares != 0) {
            currentShares = (_amount * totalShares) / pool;
        } else {
            currentShares = _amount;
        }

        user.shares += currentShares;
        user.lastDepositedTime = block.timestamp;

        totalShares += currentShares;

        _earn();

        user.cakeAtLastUserAction = (user.shares * balanceOf()) / totalShares;
        user.lastUserActionTime = block.timestamp;

        emit DepositDackie(msg.sender, _amount, currentShares, block.timestamp);
    }

    /**
     * @notice Withdraws funds from the Dackie Flexible Pool
     * @param _shares: Number of shares to withdraw
     */
    function withdraw(uint256 _shares) public {
        UserInfo storage user = userInfo[msg.sender];
        require(_shares > 0, "Nothing to withdraw");
        require(_shares <= user.shares, "Withdraw amount exceeds balance");
        //charge performanceFee
        uint256 totalAmount = (user.shares * balanceOf()) / totalShares;
        uint256 earnAmount = totalAmount - user.cakeAtLastUserAction;
        uint256 currentPerformanceFee;
        uint256 performanceFeeShares;
        if (earnAmount > 0) {
            currentPerformanceFee = (earnAmount * performanceFee) / 10000;
            performanceFeeShares = (currentPerformanceFee * totalShares) / balanceOf();
            user.shares -= performanceFeeShares;
            totalShares -= performanceFeeShares;
        }
        //Update withdraw shares
        if (_shares > user.shares) {
            _shares = user.shares;
        }
        //The current pool balance should not include currentPerformanceFee.
        uint256 currentAmount = (_shares * (balanceOf() - currentPerformanceFee)) / totalShares;
        user.shares -= _shares;
        totalShares -= _shares;
        uint256 withdrawAmount = currentAmount + currentPerformanceFee;
        if (staking) {
            // withdrawByAmount have a MIN_WITHDRAW_AMOUNT limit ,so need to withdraw more than MIN_WITHDRAW_AMOUNT.
            withdrawAmount = withdrawAmount < MIN_WITHDRAW_AMOUNT ? MIN_WITHDRAW_AMOUNT : withdrawAmount;
            //There will be a loss of precision when call withdrawByAmount, so need to withdraw more.
            withdrawAmount = (withdrawAmount * withdrawAmountBooster) / 10000;
            cakePool.withdrawByAmount(withdrawAmount);
        }

        uint256 currentWithdrawFee;
        if (block.timestamp < user.lastDepositedTime + withdrawFeePeriod) {
            currentWithdrawFee = (currentAmount * withdrawFee) / 10000;
            currentAmount -= currentWithdrawFee;
        }
        //Combine two fees to reduce gas
        uint256 totalFee = currentPerformanceFee + currentWithdrawFee;
        if (totalFee > 0) {
            totalFee = available() >= totalFee ? totalFee : available();
            token.safeTransfer(treasury, totalFee);
            if (currentPerformanceFee > 0) {
                emit ChargePerformanceFee(msg.sender, currentPerformanceFee, performanceFeeShares);
            }
            if (currentWithdrawFee > 0) {
                emit ChargeWithdrawFee(msg.sender, currentWithdrawFee);
            }
        }

        currentAmount = available() >= currentAmount ? currentAmount : available();
        token.safeTransfer(msg.sender, currentAmount);

        if (user.shares > 0) {
            user.cakeAtLastUserAction = (user.shares * balanceOf()) / totalShares;
        } else {
            user.cakeAtLastUserAction = 0;
        }

        user.lastUserActionTime = block.timestamp;

        emit WithdrawShares(msg.sender, currentAmount, _shares);
    }

    /**
     * @notice Withdraws all funds for a user
     */
    function withdrawAll() external {
        withdraw(userInfo[msg.sender].shares);
    }

    /**
     * @notice Sets admin address
     * @dev Only callable by the contract owner.
     */
    function setAdmin(address _admin) external onlyOwner {
        require(_admin != address(0), "Cannot be zero address");
        admin = _admin;
        emit NewAdmin(admin);
    }

    /**
     * @notice Sets treasury address
     * @dev Only callable by the contract owner.
     */
    function setTreasury(address _treasury) external onlyOwner {
        require(_treasury != address(0), "Cannot be zero address");
        treasury = _treasury;
        emit NewTreasury(treasury);
    }

    /**
     * @notice Sets performance fee
     * @dev Only callable by the contract admin.
     */
    function setPerformanceFee(uint256 _performanceFee) external onlyAdmin {
        require(_performanceFee <= MAX_PERFORMANCE_FEE, "performanceFee cannot be more than MAX_PERFORMANCE_FEE");
        performanceFee = _performanceFee;
        emit NewPerformanceFee(performanceFee);
    }

    /**
     * @notice Sets withdraw fee
     * @dev Only callable by the contract admin.
     */
    function setWithdrawFee(uint256 _withdrawFee) external onlyAdmin {
        require(_withdrawFee <= MAX_WITHDRAW_FEE, "withdrawFee cannot be more than MAX_WITHDRAW_FEE");
        withdrawFee = _withdrawFee;
        emit NewWithdrawFee(withdrawFee);
    }

    /**
     * @notice Sets withdraw fee period
     * @dev Only callable by the contract admin.
     */
    function setWithdrawFeePeriod(uint256 _withdrawFeePeriod) external onlyAdmin {
        require(
            _withdrawFeePeriod <= MAX_WITHDRAW_FEE_PERIOD,
            "withdrawFeePeriod cannot be more than MAX_WITHDRAW_FEE_PERIOD"
        );
        withdrawFeePeriod = _withdrawFeePeriod;
        emit NewWithdrawFeePeriod(withdrawFeePeriod);
    }

    /**
     * @notice Sets withdraw amount booster
     * @dev Only callable by the contract admin.
     */
    function setWithdrawAmountBooster(uint256 _withdrawAmountBooster) external onlyAdmin {
        require(
            _withdrawAmountBooster >= MIN_WITHDRAW_AMOUNT_BOOSTER,
            "withdrawAmountBooster cannot be less than MIN_WITHDRAW_AMOUNT_BOOSTER"
        );
        require(
            _withdrawAmountBooster <= MAX_WITHDRAW_AMOUNT_BOOSTER,
            "withdrawAmountBooster cannot be more than MAX_WITHDRAW_AMOUNT_BOOSTER"
        );
        withdrawAmountBooster = _withdrawAmountBooster;
        emit NewWithdrawAmountBooster(withdrawAmountBooster);
    }

    /**
     * @notice Withdraws from Dackie Pool without caring about rewards.
     * @dev EMERGENCY ONLY. Only callable by the contract admin.
     */
    function emergencyWithdraw() external onlyAdmin {
        require(staking, "No staking dackie");
        staking = false;
        cakePool.withdrawAll();
    }

    /**
     * @notice Withdraw unexpected tokens sent to the Dackie Flexible Pool
     */
    function inCaseTokensGetStuck(address _token) external onlyAdmin {
        require(_token != address(token), "Token cannot be same as deposit token");

        uint256 amount = IERC20(_token).balanceOf(address(this));
        IERC20(_token).safeTransfer(msg.sender, amount);
    }

    /**
     * @notice Triggers stopped state
     * @dev Only possible when contract not paused.
     */
    function pause() external onlyAdmin whenNotPaused {
        _pause();
        emit Pause();
    }

    /**
     * @notice Returns to normal state
     * @dev Only possible when contract is paused.
     */
    function unpause() external onlyAdmin whenPaused {
        _unpause();
        emit Unpause();
    }

    /**
     * @notice Calculates the price per share
     */
    function getPricePerFullShare() external view returns (uint256) {
        return totalShares == 0 ? 1e18 : (balanceOf() * 1e18) / totalShares;
    }

    /**
     * @notice Custom logic for how much the pool to be borrowed
     * @dev The contract puts 100% of the tokens to work.
     */
    function available() public view returns (uint256) {
        return token.balanceOf(address(this));
    }

    /**
     * @notice Calculates the total underlying tokens
     * @dev It includes tokens held by the contract and held in DackiePool
     */
    function balanceOf() public view returns (uint256) {
        (uint256 shares, , , , , , , , ) = cakePool.userInfo(address(this));
        uint256 pricePerFullShare = cakePool.getPricePerFullShare();

        return token.balanceOf(address(this)) + (shares * pricePerFullShare) / 1e18;
    }

    /**
     * @notice Deposits tokens into DackiePool to earn staking rewards
     */
    function _earn() internal {
        uint256 bal = available();
        if (bal > 0) {
            cakePool.deposit(bal, 0);
        }
    }
}

//SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

interface IDackiePool {
    function userInfo(address _user)
        external
        view
        returns (
            uint256,
            uint256,
            uint256,
            uint256,
            uint256,
            uint256,
            uint256,
            bool,
            uint256
        );

    function getPricePerFullShare() external view returns (uint256);

    function totalLockedAmount() external view returns (uint256);

    function totalShares() external view returns (uint256);

    function BOOST_WEIGHT() external view returns (uint256);

    function MAX_LOCK_DURATION() external view returns (uint256);

    function deposit(uint256 _amount, uint256 _lockDuration) external;

    function withdrawByAmount(uint256 _amount) external;

    function withdraw(uint256 _shares) external;

    function withdrawAll() external;
}

// 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 v4.9.0) (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);
}

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

pragma solidity ^0.8.0;

import "../utils/Context.sol";

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _transferOwnership(_msgSender());
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby disabling any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _transferOwnership(address(0));
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (security/Pausable.sol)

pragma solidity ^0.8.0;

import "../utils/Context.sol";

/**
 * @dev Contract module which allows children to implement an emergency stop
 * mechanism that can be triggered by an authorized account.
 *
 * This module is used through inheritance. It will make available the
 * modifiers `whenNotPaused` and `whenPaused`, which can be applied to
 * the functions of your contract. Note that they will not be pausable by
 * simply including this module, only once the modifiers are put in place.
 */
abstract contract Pausable is Context {
    /**
     * @dev Emitted when the pause is triggered by `account`.
     */
    event Paused(address account);

    /**
     * @dev Emitted when the pause is lifted by `account`.
     */
    event Unpaused(address account);

    bool private _paused;

    /**
     * @dev Initializes the contract in unpaused state.
     */
    constructor() {
        _paused = false;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is not paused.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    modifier whenNotPaused() {
        _requireNotPaused();
        _;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is paused.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    modifier whenPaused() {
        _requirePaused();
        _;
    }

    /**
     * @dev Returns true if the contract is paused, and false otherwise.
     */
    function paused() public view virtual returns (bool) {
        return _paused;
    }

    /**
     * @dev Throws if the contract is paused.
     */
    function _requireNotPaused() internal view virtual {
        require(!paused(), "Pausable: paused");
    }

    /**
     * @dev Throws if the contract is not paused.
     */
    function _requirePaused() internal view virtual {
        require(paused(), "Pausable: not paused");
    }

    /**
     * @dev Triggers stopped state.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    function _pause() internal virtual whenNotPaused {
        _paused = true;
        emit Paused(_msgSender());
    }

    /**
     * @dev Returns to normal state.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    function _unpause() internal virtual whenPaused {
        _paused = false;
        emit Unpaused(_msgSender());
    }
}

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

pragma solidity ^0.8.0;

import "../IERC20.sol";
import "../extensions/IERC20Permit.sol";
import "../../../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));
    }
}

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  "evmVersion": "london",
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