// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (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
     * ====
     *
     * [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://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "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 functionCall(target, data, "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");
        require(isContract(target), "Address: call to non-contract");

        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResult(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) {
        require(isContract(target), "Address: static call to non-contract");

        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResult(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) {
        require(isContract(target), "Address: delegate call to non-contract");

        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason 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 {
            // 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

                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;
pragma abicoder v1;

import "@openzeppelin/contracts/interfaces/IERC1271.sol";

library ECDSA {
    function recover(bytes32 hash, uint8 v, bytes32 r, bytes32 s) internal view returns(address signer) {
        /// @solidity memory-safe-assembly
        assembly { // solhint-disable-line no-inline-assembly
            let ptr := mload(0x40)

            mstore(ptr, hash)
            mstore(add(ptr, 0x20), v)
            mstore(add(ptr, 0x40), r)
            mstore(add(ptr, 0x60), s)
            if staticcall(gas(), 0x1, ptr, 0x80, 0, 0x20) {
                signer := mload(0)
            }
        }
    }

    function recover(bytes32 hash, bytes32 r, bytes32 vs) internal view returns(address signer) {
        /// @solidity memory-safe-assembly
        assembly { // solhint-disable-line no-inline-assembly
            let ptr := mload(0x40)

            mstore(ptr, hash)
            mstore(add(ptr, 0x20), add(27, shr(255, vs)))
            mstore(add(ptr, 0x40), r)
            mstore(add(ptr, 0x60), shr(1, shl(1, vs)))
            if staticcall(gas(), 0x1, ptr, 0x80, 0, 0x20) {
                signer := mload(0)
            }
        }
    }

    function recover(bytes32 hash, bytes calldata signature) internal view returns(address signer) {
        /// @solidity memory-safe-assembly
        assembly { // solhint-disable-line no-inline-assembly
            let ptr := mload(0x40)

            // memory[ptr:ptr+0x80] = (hash, v, r, s)
            switch signature.length
            case 65 {
                // memory[ptr+0x20:ptr+0x80] = (v, r, s)
                mstore(add(ptr, 0x20), byte(0, calldataload(add(signature.offset, 0x40))))
                calldatacopy(add(ptr, 0x40), signature.offset, 0x40)
            }
            case 64 {
                // memory[ptr+0x20:ptr+0x80] = (v, r, s)
                let vs := calldataload(add(signature.offset, 0x20))
                mstore(add(ptr, 0x20), add(27, shr(255, vs)))
                calldatacopy(add(ptr, 0x40), signature.offset, 0x20)
                mstore(add(ptr, 0x60), shr(1, shl(1, vs)))
            }
            default {
                ptr := 0
            }

            if ptr {
                if gt(mload(add(ptr, 0x60)), 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0) {
                    ptr := 0
                }

                if ptr {
                    // memory[ptr:ptr+0x20] = (hash)
                    mstore(ptr, hash)

                    if staticcall(gas(), 0x1, ptr, 0x80, 0, 0x20) {
                        signer := mload(0)
                    }
                }
            }
        }
    }

    function recoverOrIsValidSignature(address signer, bytes32 hash, bytes calldata signature) internal view returns(bool success) {
        if ((signature.length == 64 || signature.length == 65) && recover(hash, signature) == signer) {
            return true;
        }
        return isValidSignature(signer, hash, signature);
    }

    function recoverOrIsValidSignature(address signer, bytes32 hash, uint8 v, bytes32 r, bytes32 s) internal view returns(bool success) {
        if (recover(hash, v, r, s) == signer) {
            return true;
        }
        return isValidSignature(signer, hash, v, r, s);
    }

    function recoverOrIsValidSignature(address signer, bytes32 hash, bytes32 r, bytes32 vs) internal view returns(bool success) {
        if (recover(hash, r, vs) == signer) {
            return true;
        }
        return isValidSignature(signer, hash, r, vs);
    }

    function recoverOrIsValidSignature65(address signer, bytes32 hash, bytes32 r, bytes32 vs) internal view returns(bool success) {
        if (recover(hash, r, vs) == signer) {
            return true;
        }
        return isValidSignature65(signer, hash, r, vs);
    }

    function isValidSignature(address signer, bytes32 hash, bytes calldata signature) internal view returns(bool success) {
        // (bool success, bytes memory data) = signer.staticcall(abi.encodeWithSelector(IERC1271.isValidSignature.selector, hash, signature));
        // return success && data.length >= 4 && abi.decode(data, (bytes4)) == IERC1271.isValidSignature.selector;
        bytes4 selector = IERC1271.isValidSignature.selector;
        /// @solidity memory-safe-assembly
        assembly { // solhint-disable-line no-inline-assembly
            let ptr := mload(0x40)
            let len := add(0x64, signature.length)

            mstore(ptr, selector)
            mstore(add(ptr, 0x04), hash)
            mstore(add(ptr, 0x24), 0x40)
            mstore(add(ptr, 0x44), signature.length)
            calldatacopy(add(ptr, 0x64), signature.offset, signature.length)
            mstore(0, 0)
            if staticcall(gas(), signer, ptr, len, 0, 0x20) {
                success := eq(selector, mload(0))
            }
        }
    }

    function isValidSignature(address signer, bytes32 hash, uint8 v, bytes32 r, bytes32 s) internal view returns(bool success) {
        bytes4 selector = IERC1271.isValidSignature.selector;
        /// @solidity memory-safe-assembly
        assembly { // solhint-disable-line no-inline-assembly
            let ptr := mload(0x40)
            let len := add(0x64, 65)

            mstore(ptr, selector)
            mstore(add(ptr, 0x04), hash)
            mstore(add(ptr, 0x24), 0x40)
            mstore(add(ptr, 0x44), 65)
            mstore(add(ptr, 0x64), r)
            mstore(add(ptr, 0x84), s)
            mstore8(add(ptr, 0xa4), v)
            mstore(0, 0)
            if staticcall(gas(), signer, ptr, len, 0, 0x20) {
                success := eq(selector, mload(0))
            }
        }
    }

    function isValidSignature(address signer, bytes32 hash, bytes32 r, bytes32 vs) internal view returns(bool success) {
        // (bool success, bytes memory data) = signer.staticcall(abi.encodeWithSelector(IERC1271.isValidSignature.selector, hash, abi.encodePacked(r, vs)));
        // return success && data.length >= 4 && abi.decode(data, (bytes4)) == IERC1271.isValidSignature.selector;
        bytes4 selector = IERC1271.isValidSignature.selector;
        /// @solidity memory-safe-assembly
        assembly { // solhint-disable-line no-inline-assembly
            let ptr := mload(0x40)
            let len := add(0x64, 64)

            mstore(ptr, selector)
            mstore(add(ptr, 0x04), hash)
            mstore(add(ptr, 0x24), 0x40)
            mstore(add(ptr, 0x44), 64)
            mstore(add(ptr, 0x64), r)
            mstore(add(ptr, 0x84), vs)
            mstore(0, 0)
            if staticcall(gas(), signer, ptr, len, 0, 0x20) {
                success := eq(selector, mload(0))
            }
        }
    }

    function isValidSignature65(address signer, bytes32 hash, bytes32 r, bytes32 vs) internal view returns(bool success) {
        // (bool success, bytes memory data) = signer.staticcall(abi.encodeWithSelector(IERC1271.isValidSignature.selector, hash, abi.encodePacked(r, vs & ~uint256(1 << 255), uint8(vs >> 255))));
        // return success && data.length >= 4 && abi.decode(data, (bytes4)) == IERC1271.isValidSignature.selector;
        bytes4 selector = IERC1271.isValidSignature.selector;
        /// @solidity memory-safe-assembly
        assembly { // solhint-disable-line no-inline-assembly
            let ptr := mload(0x40)
            let len := add(0x64, 65)

            mstore(ptr, selector)
            mstore(add(ptr, 0x04), hash)
            mstore(add(ptr, 0x24), 0x40)
            mstore(add(ptr, 0x44), 65)
            mstore(add(ptr, 0x64), r)
            mstore(add(ptr, 0x84), shr(1, shl(1, vs)))
            mstore8(add(ptr, 0xa4), add(27, shr(255, vs)))
            mstore(0, 0)
            if staticcall(gas(), signer, ptr, len, 0, 0x20) {
                success := eq(selector, mload(0))
            }
        }
    }

    function toEthSignedMessageHash(bytes32 hash) internal pure returns (bytes32 res) {
        // 32 is the length in bytes of hash, enforced by the type signature above
        // return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", hash));
        /// @solidity memory-safe-assembly
        assembly { // solhint-disable-line no-inline-assembly
            mstore(0, 0x19457468657265756d205369676e6564204d6573736167653a0a333200000000) // "\x19Ethereum Signed Message:\n32"
            mstore(28, hash)
            res := keccak256(0, 60)
        }
    }

    function toTypedDataHash(bytes32 domainSeparator, bytes32 structHash) internal pure returns (bytes32 res) {
        // return keccak256(abi.encodePacked("\x19\x01", domainSeparator, structHash));
        /// @solidity memory-safe-assembly
        assembly { // solhint-disable-line no-inline-assembly
            let ptr := mload(0x40)
            mstore(ptr, 0x1901000000000000000000000000000000000000000000000000000000000000) // "\x19\x01"
            mstore(add(ptr, 0x02), domainSeparator)
            mstore(add(ptr, 0x22), structHash)
            res := keccak256(ptr, 66)
        }
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;
pragma abicoder v1;


interface IDaiLikePermit {
    function permit(address holder, address spender, uint256 nonce, uint256 expiry, bool allowed, uint8 v, bytes32 r, bytes32 s) external;
}

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

pragma solidity ^0.8.0;

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

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (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

pragma solidity ^0.8.0;
pragma abicoder v1;

// Allows anyone to claim a token if they exist in a merkle root.
interface ISignatureMerkleDrop128 {
    // Returns the address of the token distributed by this contract.
    function token() external view returns (address);
    // Returns the merkle root of the merkle tree containing account balances available to claim.
    function merkleRoot() external view returns (bytes16);
    // Returns the tree depth of the merkle tree containing account balances available to claim.
    function depth() external view returns (uint256);
    // Claim the given amount of the token to the given address. Reverts if the inputs are invalid.
    function claim(address receiver, uint256 amount, bytes calldata merkleProof, bytes calldata signature) external;
    // Verifies that given leaf and merkle proof matches given merkle root and returns leaf index.
    function verify(bytes calldata proof, bytes16 root, bytes16 leaf) external view returns (bool valid, uint256 index);
    // Returns true if the index has been marked claimed.
    function isClaimed(uint256 index) external view returns (bool);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (utils/math/Math.sol)

pragma solidity ^0.8.0;

/**
 * @dev Standard math utilities missing in the Solidity language.
 */
library Math {
    /**
     * @dev Returns the largest of two numbers.
     */
    function max(uint256 a, uint256 b) internal pure returns (uint256) {
        return a >= b ? a : b;
    }

    /**
     * @dev Returns the smallest of two numbers.
     */
    function min(uint256 a, uint256 b) internal pure returns (uint256) {
        return a < b ? a : b;
    }

    /**
     * @dev Returns the average of two numbers. The result is rounded towards
     * zero.
     */
    function average(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b) / 2 can overflow.
        return (a & b) + (a ^ b) / 2;
    }

    /**
     * @dev Returns the ceiling of the division of two numbers.
     *
     * This differs from standard division with `/` in that it rounds up instead
     * of rounding down.
     */
    function ceilDiv(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b - 1) / b can overflow on addition, so we distribute.
        return a / b + (a % b == 0 ? 0 : 1);
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (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 Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing 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

pragma solidity ^0.8.0;
pragma abicoder v1;

library RevertReasonForwarder {
    function reRevert() internal pure {
        // bubble up revert reason from latest external call
        /// @solidity memory-safe-assembly
        assembly { // solhint-disable-line no-inline-assembly
            let ptr := mload(0x40)
            returndatacopy(ptr, 0, returndatasize())
            revert(ptr, returndatasize())
        }
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;
pragma abicoder v1;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/extensions/draft-IERC20Permit.sol";
import "../interfaces/IDaiLikePermit.sol";
import "../libraries/RevertReasonForwarder.sol";

library SafeERC20 {
    error SafeTransferFailed();
    error SafeTransferFromFailed();
    error ForceApproveFailed();
    error SafeIncreaseAllowanceFailed();
    error SafeDecreaseAllowanceFailed();
    error SafePermitBadLength();

    // Ensures method do not revert or return boolean `true`, admits call to non-smart-contract
    function safeTransferFrom(IERC20 token, address from, address to, uint256 amount) internal {
        bytes4 selector = token.transferFrom.selector;
        bool success;
        /// @solidity memory-safe-assembly
        assembly { // solhint-disable-line no-inline-assembly
            let data := mload(0x40)

            mstore(data, selector)
            mstore(add(data, 0x04), from)
            mstore(add(data, 0x24), to)
            mstore(add(data, 0x44), amount)
            let status := call(gas(), token, 0, data, 100, 0x0, 0x20)
            success := and(status, or(iszero(returndatasize()), and(gt(returndatasize(), 31), eq(mload(0), 1))))
        }
        if (!success) {
            revert SafeTransferFromFailed();
        }
    }

    // Ensures method do not revert or return boolean `true`, admits call to non-smart-contract
    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        if (!_makeCall(token, token.transfer.selector, to, value)) {
            revert SafeTransferFailed();
        }
    }

    // If `approve(from, to, amount)` fails, try to `approve(from, to, 0)` before retry
    function forceApprove(IERC20 token, address spender, uint256 value) internal {
        if (!_makeCall(token, token.approve.selector, spender, value)) {
            if (!_makeCall(token, token.approve.selector, spender, 0) ||
                !_makeCall(token, token.approve.selector, spender, value))
            {
                revert ForceApproveFailed();
            }
        }
    }

    function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 allowance = token.allowance(address(this), spender);
        if (value > type(uint256).max - allowance) revert SafeIncreaseAllowanceFailed();
        forceApprove(token, spender, allowance + value);
    }

    function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 allowance = token.allowance(address(this), spender);
        if (value > allowance) revert SafeDecreaseAllowanceFailed();
        forceApprove(token, spender, allowance - value);
    }

    function safePermit(IERC20 token, bytes calldata permit) internal {
        bool success;
        if (permit.length == 32 * 7) {
            // solhint-disable-next-line avoid-low-level-calls
            success = _makeCalldataCall(token, IERC20Permit.permit.selector, permit);
        } else if (permit.length == 32 * 8) {
            // solhint-disable-next-line avoid-low-level-calls
            success = _makeCalldataCall(token, IDaiLikePermit.permit.selector, permit);
        } else {
            revert SafePermitBadLength();
        }

        if (!success) {
            RevertReasonForwarder.reRevert();
        }
    }

    function _makeCall(IERC20 token, bytes4 selector, address to, uint256 amount) private returns(bool done) {
        /// @solidity memory-safe-assembly
        assembly { // solhint-disable-line no-inline-assembly
            let data := mload(0x40)

            mstore(data, selector)
            mstore(add(data, 0x04), to)
            mstore(add(data, 0x24), amount)
            let success := call(gas(), token, 0, data, 68, 0x0, 0x20)
            done := and(
                success,
                or(
                    iszero(returndatasize()),
                    and(gt(returndatasize(), 31), eq(mload(0), 1))
                )
            )
        }
    }

    function _makeCalldataCall(IERC20 token, bytes4 selector, bytes calldata args) private returns(bool done) {
        /// @solidity memory-safe-assembly
        assembly { // solhint-disable-line no-inline-assembly
            let len := add(4, args.length)
            let data := mload(0x40)

            mstore(data, selector)
            calldatacopy(add(data, 0x04), args.offset, args.length)
            let success := call(gas(), token, 0, data, len, 0x0, 0x20)
            done := and(
                success,
                or(
                    iszero(returndatasize()),
                    and(gt(returndatasize(), 31), eq(mload(0), 1))
                )
            )
        }
    }
}

// SPDX-License-Identifier: MIT

pragma solidity 0.8.15;
pragma abicoder v1;

import "@openzeppelin/contracts/utils/math/Math.sol";
import "@openzeppelin/contracts/utils/Address.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "@1inch/solidity-utils/contracts/libraries/SafeERC20.sol";
import "@1inch/solidity-utils/contracts/libraries/ECDSA.sol";

import "./interfaces/ISignatureMerkleDrop128.sol";

contract SignatureMerkleDrop128 is ISignatureMerkleDrop128, Ownable {
    using Address for address payable;
    using SafeERC20 for IERC20;

    address public immutable override token;
    bytes16 public immutable override merkleRoot;
    uint256 public immutable override depth;

    // This is a packed array of booleans.
    mapping(uint256 => uint256) private _claimedBitMap;

    uint256 private constant _CLAIM_GAS_COST = 60000;

    receive() external payable {}  // solhint-disable-line no-empty-blocks

    constructor(address token_, bytes16 merkleRoot_, uint256 depth_) {
        token = token_;
        merkleRoot = merkleRoot_;
        depth = depth_;
    }

    function claim(address receiver, uint256 amount, bytes calldata merkleProof, bytes calldata signature) external override {
        bytes32 signedHash = ECDSA.toEthSignedMessageHash(keccak256(abi.encodePacked(receiver)));
        address account = ECDSA.recover(signedHash, signature);
        // Verify the merkle proof.
        bytes16 node = bytes16(keccak256(abi.encodePacked(account, amount)));
        (bool valid, uint256 index) = _verifyAsm(merkleProof, merkleRoot, node);
        require(valid, "MD: Invalid proof");
        _invalidate(index);
        IERC20(token).safeTransfer(receiver, amount);
        _cashback();
    }

    function verify(bytes calldata proof, bytes16 root, bytes16 leaf) external view returns (bool valid, uint256 index) {
        return _verifyAsm(proof, root, leaf);
    }

    function isClaimed(uint256 index) external view override returns (bool) {
        uint256 claimedWordIndex = index / 256;
        uint256 claimedBitIndex = index % 256;
        uint256 claimedWord = _claimedBitMap[claimedWordIndex];
        uint256 mask = (1 << claimedBitIndex);
        return claimedWord & mask == mask;
    }

    function _cashback() private {
        uint256 balance = address(this).balance;
        if (balance > 0) {
            // solhint-disable-next-line avoid-tx-origin
            payable(tx.origin).sendValue(Math.min(block.basefee * _CLAIM_GAS_COST, balance));
        }
    }

    function _invalidate(uint256 index) private {
        uint256 claimedWordIndex = index >> 8;
        uint256 claimedBitIndex = index & 0xff;
        uint256 claimedWord = _claimedBitMap[claimedWordIndex];
        uint256 newClaimedWord = claimedWord | (1 << claimedBitIndex);
        require(claimedWord != newClaimedWord, "MD: Drop already claimed");
        _claimedBitMap[claimedWordIndex] = newClaimedWord;
    }

    function _verifyAsm(bytes calldata proof, bytes16 root, bytes16 leaf) private view returns (bool valid, uint256 index) {
        /// @solidity memory-safe-assembly
        assembly {  // solhint-disable-line no-inline-assembly
            let ptr := proof.offset
            let mask := 1

            for { let end := add(ptr, proof.length) } lt(ptr, end) { ptr := add(ptr, 0x10) } {
                let node := calldataload(ptr)

                switch lt(leaf, node)
                case 1 {
                    mstore(0x00, leaf)
                    mstore(0x10, node)
                }
                default {
                    mstore(0x00, node)
                    mstore(0x10, leaf)
                    index := or(mask, index)
                }

                leaf := keccak256(0x00, 0x20)
                mask := shl(1, mask)
            }

            valid := iszero(shr(128, xor(root, leaf)))
        }
        unchecked {
            index <<= depth - proof.length / 16;
        }
    }

    function rescueFunds(address token_, uint256 amount) external onlyOwner {
        if (token_ == address(0)) {
            payable(msg.sender).sendValue(amount);
        } else {
            IERC20(token_).safeTransfer(msg.sender, amount);
        }
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/draft-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);
}

{
  "compilationTarget": {
    "contracts/SignatureMerkleDrop128.sol": "SignatureMerkleDrop128"
  },
  "evmVersion": "london",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs",
    "useLiteralContent": true
  },
  "optimizer": {
    "enabled": true,
    "runs": 1000000
  },
  "remappings": []
}