// File: @openzeppelin/contracts/token/ERC20/extensions/IERC20Permit.sol



// 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);
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol



// 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);
}

// File: @openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (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. Compatible with tokens that require the approval to be set to
     * 0 before setting it to a non-zero value.
     */
    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));
    }
}

// File: @openzeppelin/contracts/utils/Address.sol



// 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);
        }
    }
}

// File: @openzeppelin/contracts/utils/math/SafeMath.sol



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

pragma solidity ^0.8.0;

// CAUTION
// This version of SafeMath should only be used with Solidity 0.8 or later,
// because it relies on the compiler's built in overflow checks.

/**
 * @dev Wrappers over Solidity's arithmetic operations.
 *
 * NOTE: `SafeMath` is generally not needed starting with Solidity 0.8, since the compiler
 * now has built in overflow checking.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            uint256 c = a + b;
            if (c < a) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b > a) return (false, 0);
            return (true, a - b);
        }
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
            // benefit is lost if 'b' is also tested.
            // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
            if (a == 0) return (true, 0);
            uint256 c = a * b;
            if (c / a != b) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a / b);
        }
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a % b);
        }
    }

    /**
     * @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) {
        return a + b;
    }

    /**
     * @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 a - b;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        return a * b;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator.
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return a % b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {trySub}.
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        unchecked {
            require(b <= a, errorMessage);
            return a - b;
        }
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        unchecked {
            require(b > 0, errorMessage);
            return a / b;
        }
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting with custom message when dividing by zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryMod}.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        unchecked {
            require(b > 0, errorMessage);
            return a % b;
        }
    }
}

// File: contracts/interfaces/AggregatorInterface.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.18;

interface AggregatorInterface {
	function latestAnswer() external view returns (int256);

	function latestTimestamp() external view returns (uint256);

	function latestRound() external view returns (uint256);

	function getAnswer(uint256 roundId) external view returns (int256);

	function getTimestamp(uint256 roundId) external view returns (uint256);

	function latestRoundData()
		external
		view
		returns (
			uint80 roundId,
			int256 answer,
			uint256 startedAt,
			uint256 updatedAt,
			uint80 answeredInRound
		);

	event AnswerUpdated(int256 indexed current, uint256 indexed roundId, uint256 updatedAt);

	event NewRound(uint256 indexed roundId, address indexed startedBy, uint256 startedAt);
}

// File: contracts/interfaces/ICurve.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.18;

interface ICurve {
	function exchange(int128 i, int128 j, uint256 dx, uint256 min_dy) external;

	function exchange_underlying(int128 i, int128 j, uint256 dx, uint256 min_dy) external;

	function get_dy(int128 i, int128 j, uint256 dx) external view returns (uint256);

	function get_dy_underlying(int128 i, int128 j, uint256 dx) external view returns (uint256);

	function coins(uint256 i) external view returns (address);
}

// File: contracts/LiquidatePool.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.18;

import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "@openzeppelin/contracts/utils/math/SafeMath.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

import "./interfaces/ICurve.sol";
import "./interfaces/AggregatorInterface.sol";

contract LiquidatePool {
	using SafeERC20 for IERC20;
	using SafeMath for uint256;

	// used to redeem stbt
	address public mxpRedeemPool;

	address public admin;
	// ustpool
	address public ustpool;
	// stbt address
	IERC20 public stbt;
	// usdc address
	IERC20 public usdc;
	// STBT curve pool
	// Mainnet: 0x892D701d94a43bDBCB5eA28891DaCA2Fa22A690b
	ICurve curvePool;

	// Used to calculate the fee base.
	uint256 public constant FEE_COEFFICIENT = 1e8;
	// Max fee rates can't over then 1%
	uint256 public constant maxLiquidateFeeRate = FEE_COEFFICIENT / 100;
	uint256 public constant maxLiquidateMXPFeeRate = FEE_COEFFICIENT / 100;
	// liquidateFeeRate: 0.1% => 100000 (10 ** 5)
	// liquidateFeeRate: 10% => 10000000 (10 ** 7)
	// liquidateFeeRate: 100% => 100000000 (10 ** 8)
	// It's used when call liquidate method.
	uint256 public liquidateFeeRate;
	uint256 public liquidateMXPFeeRate;
	// Fee Collector, used to receive fee.
	address public feeCollector;

	// liquidation index.
	uint256 public liquidationIndex;
	// the time for liquidation.
	uint256 public processPeriod;

	struct LiquidationDetail {
		uint256 id;
		uint256 timestamp;
		address user;
		uint256 repayAmount;
		uint256 receiveAmountAfterFee;
		uint256 MXPFee;
		uint256 protocolFee;
		// False not withdraw, or True.
		bool isDone;
	}

	// Mapping from liquidation index to liquidationDetail.
	mapping(uint256 => LiquidationDetail) public liquidationDetails;

	// mint threshold for underlying token
	uint256 public mintThreshold;
	// redeem threshold for STBT
	uint256 public redeemThreshold;
	// target price
	int256 public lowerPrice;
	int256 public upperPrice;
	// priceFeed be using check USDC is pegged
	AggregatorInterface public priceFeed;
	// coins , [DAI, USDC, USDT]
	// see https://etherscan.io/address/0x892D701d94a43bDBCB5eA28891DaCA2Fa22A690b#code
	address[3] public coins;

	event liquidateRequested(
		uint256 id,
		uint256 timestamp,
		address indexed user,
		uint256 repayAmount,
		uint256 underlyingAmount,
		uint256 receiveAmountAfterFee,
		uint256 MXPFee,
		uint256 protocolFee
	);
	event FinalizeLiquidation(
		address indexed user,
		uint256 amount,
		uint256 protocolFee,
		uint256 id
	);

	event ProcessPeriodChanged(uint256 newProcessPeriod);
	event FeeCollectorChanged(address newFeeCollector);
	event LiquidateFeeRateChanged(uint256 newLiquidateFeeRate);
	event RedeemMXPFeeRateChanged(uint256 newRedeemMXPFeeRate);
	event RedeemPoolChanged(address newRedeemPool);
	event CurvePoolChanged(address newCurvePool);
	event RedeemThresholdChanged(uint256 newRedeemThreshold);
	event PegPriceChanged(int256 lowerPrice, int256 upperPrice);

	constructor(
		address _admin,
		address _ustpool,
		address _mxpRedeemPool,
		address _stbt,
		address _usdc,
		address _priceFeed,
		address[3] memory _coins
	) {
		require(_admin != address(0), "!_admin");
		require(_ustpool != address(0), "!_ustpool");
		require(_mxpRedeemPool != address(0), "!_mxpRedeemPool");
		require(_stbt != address(0), "!_stbt");
		require(_usdc != address(0), "!_usdc");
		require(_priceFeed != address(0), "!_priceFeed");

		admin = _admin;
		ustpool = _ustpool;
		mxpRedeemPool = _mxpRedeemPool;
		stbt = IERC20(_stbt);
		usdc = IERC20(_usdc);
		priceFeed = AggregatorInterface(_priceFeed);
		coins = _coins;
	}

	modifier onlyAdmin() {
		require(msg.sender == admin, "only admin");
		_;
	}

	/**
	 * @dev to set the period of processing
	 * @param _processPeriod the period of processing. it's second.
	 */
	function setProcessPeriod(uint256 _processPeriod) external onlyAdmin {
		require(_processPeriod <= 7 days, "should be less than 7 days");
		processPeriod = _processPeriod;
		emit ProcessPeriodChanged(processPeriod);
	}

	/**
	 * @dev to set the collector of fee
	 * @param _feeCollector the address of collector
	 */
	function setFeeCollector(address _feeCollector) external onlyAdmin {
		require(_feeCollector != address(0), "!_feeCollector");
		feeCollector = _feeCollector;
		emit FeeCollectorChanged(feeCollector);
	}

	/**
	 * @dev to set the rate of liquidate fee
	 * @param _liquidateFeeRate the rate. it should be multiply 10**6
	 */
	function setLiquidateFeeRate(uint256 _liquidateFeeRate) external onlyAdmin {
		require(
			_liquidateFeeRate <= maxLiquidateFeeRate,
			"Liquidate fee rate should be less than 1%."
		);
		liquidateFeeRate = _liquidateFeeRate;
		emit LiquidateFeeRateChanged(liquidateFeeRate);
	}

	/**
	 * @dev to set the rate of MP redeem fee
	 * @param _liquidateMXPFeeRate the rate. it should be multiply 10**6
	 */
	function setRedeemMXPFeeRate(uint256 _liquidateMXPFeeRate) external onlyAdmin {
		require(
			_liquidateMXPFeeRate <= maxLiquidateMXPFeeRate,
			"redeem MXP fee rate should be less than 1%."
		);
		liquidateMXPFeeRate = _liquidateMXPFeeRate;
		emit RedeemMXPFeeRateChanged(liquidateMXPFeeRate);
	}

	/**
	 * @dev to set the redeem pool
	 * @param _redeemPool the address of redeem pool
	 */
	function setRedeemPool(address _redeemPool) external onlyAdmin {
		require(_redeemPool != address(0), "!_redeemPool");
		mxpRedeemPool = _redeemPool;
		emit RedeemPoolChanged(mxpRedeemPool);
	}

	/**
	 * @dev to set the stbt curve pool
	 * @param _curvePool the address of curve pool
	 */
	function setCurvePool(address _curvePool) external onlyAdmin {
		require(_curvePool != address(0), "!_curvePool");
		curvePool = ICurve(_curvePool);
		emit CurvePoolChanged(_curvePool);
	}

	/**
	 * @dev to set the redeem threshold
	 * @param amount the amount of redeem threshold
	 */
	function setRedeemThreshold(uint256 amount) external onlyAdmin {
		redeemThreshold = amount;
		emit RedeemThresholdChanged(redeemThreshold);
	}

	/**
	 * @dev to set the price
	 * @param _lowerPrice the lower price of usdc
	 * @param _upperPrice the upper price of usdc
	 */
	function setPegPrice(int256 _lowerPrice, int256 _upperPrice) external onlyAdmin {
		lowerPrice = _lowerPrice;
		upperPrice = _upperPrice;
		emit PegPriceChanged(lowerPrice, upperPrice);
	}

	/**
	 * @dev get the exchange amount out from curve
	 * @param stbtAmount amount of stbt
	 * @param j token of index for curve pool
	 */
	function getFlashLiquidateAmountOutFromCurve(
		uint256 stbtAmount,
		int128 j
	) public view returns (uint256) {
		// From stbt to others
		return curvePool.get_dy_underlying(0, j, stbtAmount);
	}

	/// @notice get price feed answer
	function latestRoundData()
		public
		view
		returns (
			uint80 roundId,
			int256 answer,
			uint256 startedAt,
			uint256 updatedAt,
			uint80 answeredInRound
		)
	{
		return priceFeed.latestRoundData();
	}

	function _checkChainlinkResponse() internal view returns (bool) {
		(uint80 roundId, int256 answer, , uint256 updatedAt, ) = priceFeed.latestRoundData();
		// Check for an invalid roundId that is 0
		if (roundId == 0) {
			return false;
		}
		// Check for an invalid timeStamp that is 0, or in the future
		if (updatedAt == 0 || updatedAt > block.timestamp) {
			return false;
		}
		// depeg
		if (answer < lowerPrice || answer > upperPrice) {
			return false;
		}

		return true;
	}

	/**
	 * @dev Transfer a give amout of stbt to matrixport's mint pool
	 * @param caller the address of liquidator
	 * @param stbtAmount the amout of stbt
	 */
	function liquidateSTBT(address caller, uint256 stbtAmount) external {
		require(msg.sender == ustpool, "unauthorized");
		require(_checkChainlinkResponse(), "depeg");
		require(stbtAmount >= redeemThreshold, "less than redeemThreshold.");
		stbt.safeTransfer(mxpRedeemPool, stbtAmount);

		// convert to USDC amount.
		uint256 underlyingAmount = stbtAmount.div(1e12);

		uint256 liquidateFeeAmount = underlyingAmount.mul(liquidateFeeRate).div(FEE_COEFFICIENT);
		uint256 liquidateMXPFeeAmount = underlyingAmount.mul(liquidateMXPFeeRate).div(
			FEE_COEFFICIENT
		);
		uint256 amountAfterFee = underlyingAmount.sub(liquidateFeeAmount).sub(
			liquidateMXPFeeAmount
		);

		liquidationIndex++;
		liquidationDetails[liquidationIndex] = LiquidationDetail({
			id: liquidationIndex,
			timestamp: block.timestamp,
			user: caller,
			repayAmount: stbtAmount,
			receiveAmountAfterFee: amountAfterFee,
			MXPFee: liquidateMXPFeeAmount,
			protocolFee: liquidateFeeAmount,
			isDone: false
		});

		emit liquidateRequested(
			liquidationIndex,
			block.timestamp,
			caller,
			stbtAmount,
			underlyingAmount,
			amountAfterFee,
			liquidateMXPFeeAmount,
			liquidateFeeAmount
		);
	}

	/**
	 * @dev Transfer a give amout of stbt to matrixport's mint pool
	 * @param stbtAmount the amout of stbt
	 * @param j token of index for curve pool
	 * @param minReturn the minimum amount of return
	 * @param receiver used to receive token
	 */
	function flashLiquidateSTBTByCurve(
		uint256 stbtAmount,
		int128 j,
		uint256 minReturn,
		address receiver
	) external {
		require(msg.sender == ustpool, "unauthorized");
		require(j > 0, "out of range");
		require(j < 4, "out of range");

		// From stbt to others
		uint256 dy = curvePool.get_dy_underlying(0, j, stbtAmount);
		require(dy >= minReturn, "!minReturn");
		stbt.approve(address(curvePool), stbtAmount);
		curvePool.exchange_underlying(0, j, stbtAmount, dy);

		// choose from coin list.
		// Ensure that the transaction cannot succeed when the curve pool is maliciously replaced.
		IERC20 targetToken = IERC20(coins[uint256(int256(j - 1))]);

		uint256 feeAmount = dy.mul(liquidateFeeRate).div(FEE_COEFFICIENT);
		uint256 amountAfterFee = dy.sub(feeAmount);
		targetToken.safeTransfer(receiver, amountAfterFee);
		targetToken.safeTransfer(feeCollector, feeAmount);
	}

	/**
	 * @dev finalize liquidation
	 * @param _id the id of liquidation details
	 */
	function finalizeLiquidationById(uint256 _id) external {
		require(liquidationDetails[_id].user == msg.sender, "Not yours.");
		require(liquidationDetails[_id].isDone == false, "Withdrawn");
		require(
			liquidationDetails[_id].timestamp + processPeriod <= block.timestamp,
			"Not done yet."
		);

		uint256 receiveAmountAfterFee = liquidationDetails[_id].receiveAmountAfterFee;
		uint256 protocolFee = liquidationDetails[_id].protocolFee;

		liquidationDetails[_id].isDone = true;

		// the MXP fee had been charge.
		usdc.safeTransfer(msg.sender, receiveAmountAfterFee);
		usdc.safeTransfer(feeCollector, protocolFee);

		emit FinalizeLiquidation(msg.sender, receiveAmountAfterFee, protocolFee, _id);
	}
}