// File: contracts/GiddyForwarder.sol



// SPDX-License-Identifier:MIT
pragma solidity ^0.8.2;
pragma abicoder v2;

import "@openzeppelin/contracts/utils/cryptography/ECDSA.sol";
import "./interfaces/IForwarder.sol";

contract GiddyForwarder is IForwarder {
    using ECDSA for bytes32;

    string public constant GENERIC_PARAMS = "address from,address to,uint256 value,uint256 gas,uint256 nonce,bytes data,uint256 validUntil";

    string public constant EIP712_DOMAIN_TYPE = "EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)";

    mapping(bytes32 => bool) public typeHashes;
    mapping(bytes32 => bool) public domains;

    // Nonces of senders, used to prevent replay attacks
    mapping(address => uint256) private nonces;

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

    function getNonce(address from)
    public view override
    returns (uint256) {
        return nonces[from];
    }

    constructor() {

        string memory requestType = string(abi.encodePacked("ForwardRequest(", GENERIC_PARAMS, ")"));
        registerRequestTypeInternal(requestType);
    }

    function verify(
        ForwardRequest calldata req,
        bytes32 domainSeparator,
        bytes32 requestTypeHash,
        bytes calldata suffixData,
        bytes calldata sig)
    external override view {

        _verifyNonce(req);
        _verifySig(req, domainSeparator, requestTypeHash, suffixData, sig);
    }

    function execute(
        ForwardRequest calldata req,
        bytes32 domainSeparator,
        bytes32 requestTypeHash,
        bytes calldata suffixData,
        bytes calldata sig
    )
    external payable
    override
    returns (bool success, bytes memory ret) {
        _verifySig(req, domainSeparator, requestTypeHash, suffixData, sig);
        _verifyAndUpdateNonce(req);

        require(req.validUntil == 0 || req.validUntil > block.number, "FWD: request expired");

        uint gasForTransfer = 0;
        if ( req.value != 0 ) {
            gasForTransfer = 40000; //buffer in case we need to move eth after the transaction.
        }
        bytes memory callData = abi.encodePacked(req.data, req.from);
        require(gasleft()*63/64 >= req.gas + gasForTransfer, "FWD: insufficient gas");
        // solhint-disable-next-line avoid-low-level-calls
        (success,ret) = req.to.call{gas : req.gas, value : req.value}(callData);
        if ( req.value != 0 && address(this).balance>0 ) {
            // can't fail: req.from signed (off-chain) the request, so it must be an EOA...
            payable(req.from).transfer(address(this).balance);
        }

        return (success,ret);
    }


    function _verifyNonce(ForwardRequest calldata req) internal view {
        require(nonces[req.from] == req.nonce, "FWD: nonce mismatch");
    }

    function _verifyAndUpdateNonce(ForwardRequest calldata req) internal {
        require(nonces[req.from]++ == req.nonce, "FWD: nonce mismatch");
    }

    function registerRequestType(string calldata typeName, string calldata typeSuffix) external override {

        for (uint i = 0; i < bytes(typeName).length; i++) {
            bytes1 c = bytes(typeName)[i];
            require(c != "(" && c != ")", "FWD: invalid typename");
        }

        string memory requestType = string(abi.encodePacked(typeName, "(", GENERIC_PARAMS, ",", typeSuffix));
        registerRequestTypeInternal(requestType);
    }

    function registerDomainSeparator(string calldata name, string calldata version) external override {
        uint256 chainId;
        /* solhint-disable-next-line no-inline-assembly */
        assembly { chainId := chainid() }

        bytes memory domainValue = abi.encode(
            keccak256(bytes(EIP712_DOMAIN_TYPE)),
            keccak256(bytes(name)),
            keccak256(bytes(version)),
            chainId,
            address(this));

        bytes32 domainHash = keccak256(domainValue);

        domains[domainHash] = true;
        emit DomainRegistered(domainHash, domainValue);
    }

    function registerRequestTypeInternal(string memory requestType) internal {

        bytes32 requestTypehash = keccak256(bytes(requestType));
        typeHashes[requestTypehash] = true;
        emit RequestTypeRegistered(requestTypehash, requestType);
    }

    function _verifySig(
        ForwardRequest calldata req,
        bytes32 domainSeparator,
        bytes32 requestTypeHash,
        bytes calldata suffixData,
        bytes calldata sig)
    internal
    view
    {
        require(domains[domainSeparator], "FWD: unregistered domain sep.");
        require(typeHashes[requestTypeHash], "FWD: unregistered typehash");
        bytes32 digest = keccak256(abi.encodePacked(
                "\x19\x01", domainSeparator,
                keccak256(_getEncoded(req, requestTypeHash, suffixData))
            ));
        require(digest.recover(sig) == req.from, "FWD: signature mismatch");
    }

    function _getEncoded(
        ForwardRequest calldata req,
        bytes32 requestTypeHash,
        bytes calldata suffixData
    )
    public
    pure
    returns (
        bytes memory
    ) {
        // we use encodePacked since we append suffixData as-is, not as dynamic param.
        // still, we must make sure all first params are encoded as abi.encode()
        // would encode them - as 256-bit-wide params.
        return abi.encodePacked(
            requestTypeHash,
            uint256(uint160(req.from)),
            uint256(uint160(req.to)),
            req.value,
            req.gas,
            req.nonce,
            keccak256(req.data),
            req.validUntil,
            suffixData
        );
    }
}
// File: @openzeppelin/contracts/utils/cryptography/ECDSA.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Elliptic Curve Digital Signature Algorithm (ECDSA) operations.
 *
 * These functions can be used to verify that a message was signed by the holder
 * of the private keys of a given address.
 */
library ECDSA {
    enum RecoverError {
        NoError,
        InvalidSignature,
        InvalidSignatureLength,
        InvalidSignatureS,
        InvalidSignatureV
    }

    function _throwError(RecoverError error) private pure {
        if (error == RecoverError.NoError) {
            return; // no error: do nothing
        } else if (error == RecoverError.InvalidSignature) {
            revert("ECDSA: invalid signature");
        } else if (error == RecoverError.InvalidSignatureLength) {
            revert("ECDSA: invalid signature length");
        } else if (error == RecoverError.InvalidSignatureS) {
            revert("ECDSA: invalid signature 's' value");
        } else if (error == RecoverError.InvalidSignatureV) {
            revert("ECDSA: invalid signature 'v' value");
        }
    }

    /**
     * @dev Returns the address that signed a hashed message (`hash`) with
     * `signature` or error string. This address can then be used for verification purposes.
     *
     * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
     * this function rejects them by requiring the `s` value to be in the lower
     * half order, and the `v` value to be either 27 or 28.
     *
     * IMPORTANT: `hash` _must_ be the result of a hash operation for the
     * verification to be secure: it is possible to craft signatures that
     * recover to arbitrary addresses for non-hashed data. A safe way to ensure
     * this is by receiving a hash of the original message (which may otherwise
     * be too long), and then calling {toEthSignedMessageHash} on it.
     *
     * Documentation for signature generation:
     * - with https://web3js.readthedocs.io/en/v1.3.4/web3-eth-accounts.html#sign[Web3.js]
     * - with https://docs.ethers.io/v5/api/signer/#Signer-signMessage[ethers]
     *
     * _Available since v4.3._
     */
    function tryRecover(bytes32 hash, bytes memory signature) internal pure returns (address, RecoverError) {
        // Check the signature length
        // - case 65: r,s,v signature (standard)
        // - case 64: r,vs signature (cf https://eips.ethereum.org/EIPS/eip-2098) _Available since v4.1._
        if (signature.length == 65) {
            bytes32 r;
            bytes32 s;
            uint8 v;
            // ecrecover takes the signature parameters, and the only way to get them
            // currently is to use assembly.
            assembly {
                r := mload(add(signature, 0x20))
                s := mload(add(signature, 0x40))
                v := byte(0, mload(add(signature, 0x60)))
            }
            return tryRecover(hash, v, r, s);
        } else if (signature.length == 64) {
            bytes32 r;
            bytes32 vs;
            // ecrecover takes the signature parameters, and the only way to get them
            // currently is to use assembly.
            assembly {
                r := mload(add(signature, 0x20))
                vs := mload(add(signature, 0x40))
            }
            return tryRecover(hash, r, vs);
        } else {
            return (address(0), RecoverError.InvalidSignatureLength);
        }
    }

    /**
     * @dev Returns the address that signed a hashed message (`hash`) with
     * `signature`. This address can then be used for verification purposes.
     *
     * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
     * this function rejects them by requiring the `s` value to be in the lower
     * half order, and the `v` value to be either 27 or 28.
     *
     * IMPORTANT: `hash` _must_ be the result of a hash operation for the
     * verification to be secure: it is possible to craft signatures that
     * recover to arbitrary addresses for non-hashed data. A safe way to ensure
     * this is by receiving a hash of the original message (which may otherwise
     * be too long), and then calling {toEthSignedMessageHash} on it.
     */
    function recover(bytes32 hash, bytes memory signature) internal pure returns (address) {
        (address recovered, RecoverError error) = tryRecover(hash, signature);
        _throwError(error);
        return recovered;
    }

    /**
     * @dev Overload of {ECDSA-tryRecover} that receives the `r` and `vs` short-signature fields separately.
     *
     * See https://eips.ethereum.org/EIPS/eip-2098[EIP-2098 short signatures]
     *
     * _Available since v4.3._
     */
    function tryRecover(
        bytes32 hash,
        bytes32 r,
        bytes32 vs
    ) internal pure returns (address, RecoverError) {
        bytes32 s;
        uint8 v;
        assembly {
            s := and(vs, 0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff)
            v := add(shr(255, vs), 27)
        }
        return tryRecover(hash, v, r, s);
    }

    /**
     * @dev Overload of {ECDSA-recover} that receives the `r and `vs` short-signature fields separately.
     *
     * _Available since v4.2._
     */
    function recover(
        bytes32 hash,
        bytes32 r,
        bytes32 vs
    ) internal pure returns (address) {
        (address recovered, RecoverError error) = tryRecover(hash, r, vs);
        _throwError(error);
        return recovered;
    }

    /**
     * @dev Overload of {ECDSA-tryRecover} that receives the `v`,
     * `r` and `s` signature fields separately.
     *
     * _Available since v4.3._
     */
    function tryRecover(
        bytes32 hash,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal pure returns (address, RecoverError) {
        // EIP-2 still allows signature malleability for ecrecover(). Remove this possibility and make the signature
        // unique. Appendix F in the Ethereum Yellow paper (https://ethereum.github.io/yellowpaper/paper.pdf), defines
        // the valid range for s in (301): 0 < s < secp256k1n ÷ 2 + 1, and for v in (302): v ∈ {27, 28}. Most
        // signatures from current libraries generate a unique signature with an s-value in the lower half order.
        //
        // If your library generates malleable signatures, such as s-values in the upper range, calculate a new s-value
        // with 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 - s1 and flip v from 27 to 28 or
        // vice versa. If your library also generates signatures with 0/1 for v instead 27/28, add 27 to v to accept
        // these malleable signatures as well.
        if (uint256(s) > 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0) {
            return (address(0), RecoverError.InvalidSignatureS);
        }
        if (v != 27 && v != 28) {
            return (address(0), RecoverError.InvalidSignatureV);
        }

        // If the signature is valid (and not malleable), return the signer address
        address signer = ecrecover(hash, v, r, s);
        if (signer == address(0)) {
            return (address(0), RecoverError.InvalidSignature);
        }

        return (signer, RecoverError.NoError);
    }

    /**
     * @dev Overload of {ECDSA-recover} that receives the `v`,
     * `r` and `s` signature fields separately.
     */
    function recover(
        bytes32 hash,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal pure returns (address) {
        (address recovered, RecoverError error) = tryRecover(hash, v, r, s);
        _throwError(error);
        return recovered;
    }

    /**
     * @dev Returns an Ethereum Signed Message, created from a `hash`. This
     * produces hash corresponding to the one signed with the
     * https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
     * JSON-RPC method as part of EIP-191.
     *
     * See {recover}.
     */
    function toEthSignedMessageHash(bytes32 hash) internal pure returns (bytes32) {
        // 32 is the length in bytes of hash,
        // enforced by the type signature above
        return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", hash));
    }

    /**
     * @dev Returns an Ethereum Signed Typed Data, created from a
     * `domainSeparator` and a `structHash`. This produces hash corresponding
     * to the one signed with the
     * https://eips.ethereum.org/EIPS/eip-712[`eth_signTypedData`]
     * JSON-RPC method as part of EIP-712.
     *
     * See {recover}.
     */
    function toTypedDataHash(bytes32 domainSeparator, bytes32 structHash) internal pure returns (bytes32) {
        return keccak256(abi.encodePacked("\x19\x01", domainSeparator, structHash));
    }
}

// File: contracts/interfaces/IForwarder.sol



// SPDX-License-Identifier:MIT
pragma solidity >=0.7.6;
pragma abicoder v2;

interface IForwarder {

    struct ForwardRequest {
        address from;
        address to;
        uint256 value;
        uint256 gas;
        uint256 nonce;
        bytes data;
        uint256 validUntil;
    }

    event DomainRegistered(bytes32 indexed domainSeparator, bytes domainValue);

    event RequestTypeRegistered(bytes32 indexed typeHash, string typeStr);

    function getNonce(address from)
    external view
    returns(uint256);

    /**
     * verify the transaction would execute.
     * validate the signature and the nonce of the request.
     * revert if either signature or nonce are incorrect.
     * also revert if domainSeparator or requestTypeHash are not registered.
     */
    function verify(
        ForwardRequest calldata forwardRequest,
        bytes32 domainSeparator,
        bytes32 requestTypeHash,
        bytes calldata suffixData,
        bytes calldata signature
    ) external view;

    /**
     * execute a transaction
     * @param forwardRequest - all transaction parameters
     * @param domainSeparator - domain used when signing this request
     * @param requestTypeHash - request type used when signing this request.
     * @param suffixData - the extension data used when signing this request.
     * @param signature - signature to validate.
     *
     * the transaction is verified, and then executed.
     * the success and ret of "call" are returned.
     * This method would revert only verification errors. target errors
     * are reported using the returned "success" and ret string
     */
    function execute(
        ForwardRequest calldata forwardRequest,
        bytes32 domainSeparator,
        bytes32 requestTypeHash,
        bytes calldata suffixData,
        bytes calldata signature
    )
    external payable
    returns (bool success, bytes memory ret);

    /**
     * Register a new Request typehash.
     * @param typeName - the name of the request type.
     * @param typeSuffix - any extra data after the generic params.
     *  (must add at least one param. The generic ForwardRequest type is always registered by the constructor)
     */
    function registerRequestType(string calldata typeName, string calldata typeSuffix) external;

    /**
     * Register a new domain separator.
     * The domain separator must have the following fields: name,version,chainId, verifyingContract.
     * the chainId is the current network's chainId, and the verifyingContract is this forwarder.
     * This method is given the domain name and version to create and register the domain separator value.
     * @param name the domain's display name
     * @param version the domain/protocol version
     */
    function registerDomainSeparator(string calldata name, string calldata version) external;
}