// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;

/// @notice Signature verification helper that supports both ECDSA signatures from EOAs
/// and ERC1271 signatures from smart contract wallets like Argent and Gnosis safe.
/// @author Solady (https://github.com/vectorized/solady/blob/main/src/utils/ext/zksync/SignatureCheckerLib.sol)
/// @author Modified from OpenZeppelin (https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/utils/cryptography/SignatureChecker.sol)
///
/// @dev Note:
/// - The signature checking functions use the ecrecover precompile (0x1).
/// - Unlike ECDSA signatures, contract signatures are revocable.
/// - As of Solady version 0.0.134, all `bytes signature` variants accept both
///   regular 65-byte `(r, s, v)` and EIP-2098 `(r, vs)` short form signatures.
///   See: https://eips.ethereum.org/EIPS/eip-2098
///   This is for calldata efficiency on smart accounts prevalent on L2s.
///
/// WARNING! Do NOT use signatures as unique identifiers:
/// - Use a nonce in the digest to prevent replay attacks on the same contract.
/// - Use EIP-712 for the digest to prevent replay attacks across different chains and contracts.
///   EIP-712 also enables readable signing of typed data for better user safety.
/// This implementation does NOT check if a signature is non-malleable.
library SignatureCheckerLib {
    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*               SIGNATURE CHECKING OPERATIONS                */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Returns whether `signature` is valid for `signer` and `hash`.
    /// If `signer.code.length == 0`, then validate with `ecrecover`, else
    /// it will validate with ERC1271 on `signer`.
    function isValidSignatureNow(address signer, bytes32 hash, bytes memory signature)
        internal
        view
        returns (bool isValid)
    {
        if (signer == address(0)) return isValid;
        /// @solidity memory-safe-assembly
        assembly {
            function copy(dst_, src_, n_) {
                for { let i_ := 0 } lt(i_, n_) { i_ := add(0x20, i_) } {
                    mstore(add(dst_, i_), mload(add(src_, i_)))
                }
            }
            let m := mload(0x40)
            for {} 1 {} {
                if iszero(extcodesize(signer)) {
                    switch mload(signature)
                    case 64 {
                        let vs := mload(add(signature, 0x40))
                        mstore(0x20, add(shr(255, vs), 27)) // `v`.
                        mstore(0x60, shr(1, shl(1, vs))) // `s`.
                    }
                    case 65 {
                        mstore(0x20, byte(0, mload(add(signature, 0x60)))) // `v`.
                        mstore(0x60, mload(add(signature, 0x40))) // `s`.
                    }
                    default { break }
                    mstore(0x00, hash)
                    mstore(0x40, mload(add(signature, 0x20))) // `r`.
                    let recovered := mload(staticcall(gas(), 1, 0x00, 0x80, 0x01, 0x20))
                    isValid := gt(returndatasize(), shl(96, xor(signer, recovered)))
                    mstore(0x60, 0) // Restore the zero slot.
                    mstore(0x40, m) // Restore the free memory pointer.
                    break
                }
                let f := shl(224, 0x1626ba7e)
                mstore(m, f) // `bytes4(keccak256("isValidSignature(bytes32,bytes)"))`.
                mstore(add(m, 0x04), hash)
                let d := add(m, 0x24)
                mstore(d, 0x40) // The offset of the `signature` in the calldata.
                // Copy the `signature` over.
                let n := add(0x20, mload(signature))
                copy(add(m, 0x44), signature, n)
                isValid := staticcall(gas(), signer, m, add(n, 0x44), d, 0x20)
                isValid := and(eq(mload(d), f), isValid)
                break
            }
        }
    }

    /// @dev Returns whether `signature` is valid for `signer` and `hash`.
    /// If `signer.code.length == 0`, then validate with `ecrecover`, else
    /// it will validate with ERC1271 on `signer`.
    function isValidSignatureNowCalldata(address signer, bytes32 hash, bytes calldata signature)
        internal
        view
        returns (bool isValid)
    {
        if (signer == address(0)) return isValid;
        /// @solidity memory-safe-assembly
        assembly {
            let m := mload(0x40)
            for {} 1 {} {
                if iszero(extcodesize(signer)) {
                    switch signature.length
                    case 64 {
                        let vs := calldataload(add(signature.offset, 0x20))
                        mstore(0x20, add(shr(255, vs), 27)) // `v`.
                        mstore(0x40, calldataload(signature.offset)) // `r`.
                        mstore(0x60, shr(1, shl(1, vs))) // `s`.
                    }
                    case 65 {
                        mstore(0x20, byte(0, calldataload(add(signature.offset, 0x40)))) // `v`.
                        calldatacopy(0x40, signature.offset, 0x40) // `r`, `s`.
                    }
                    default { break }
                    mstore(0x00, hash)
                    let recovered := mload(staticcall(gas(), 1, 0x00, 0x80, 0x01, 0x20))
                    isValid := gt(returndatasize(), shl(96, xor(signer, recovered)))
                    mstore(0x60, 0) // Restore the zero slot.
                    mstore(0x40, m) // Restore the free memory pointer.
                    break
                }
                let f := shl(224, 0x1626ba7e)
                mstore(m, f) // `bytes4(keccak256("isValidSignature(bytes32,bytes)"))`.
                mstore(add(m, 0x04), hash)
                let d := add(m, 0x24)
                mstore(d, 0x40) // The offset of the `signature` in the calldata.
                mstore(add(m, 0x44), signature.length)
                // Copy the `signature` over.
                calldatacopy(add(m, 0x64), signature.offset, signature.length)
                isValid := staticcall(gas(), signer, m, add(signature.length, 0x64), d, 0x20)
                isValid := and(eq(mload(d), f), isValid)
                break
            }
        }
    }

    /// @dev Returns whether the signature (`r`, `vs`) is valid for `signer` and `hash`.
    /// If `signer.code.length == 0`, then validate with `ecrecover`, else
    /// it will validate with ERC1271 on `signer`.
    function isValidSignatureNow(address signer, bytes32 hash, bytes32 r, bytes32 vs)
        internal
        view
        returns (bool isValid)
    {
        if (signer == address(0)) return isValid;
        /// @solidity memory-safe-assembly
        assembly {
            let m := mload(0x40)
            for {} 1 {} {
                if iszero(extcodesize(signer)) {
                    mstore(0x00, hash)
                    mstore(0x20, add(shr(255, vs), 27)) // `v`.
                    mstore(0x40, r) // `r`.
                    mstore(0x60, shr(1, shl(1, vs))) // `s`.
                    let recovered := mload(staticcall(gas(), 1, 0x00, 0x80, 0x01, 0x20))
                    isValid := gt(returndatasize(), shl(96, xor(signer, recovered)))
                    mstore(0x60, 0) // Restore the zero slot.
                    mstore(0x40, m) // Restore the free memory pointer.
                    break
                }
                let f := shl(224, 0x1626ba7e)
                mstore(m, f) // `bytes4(keccak256("isValidSignature(bytes32,bytes)"))`.
                mstore(add(m, 0x04), hash)
                let d := add(m, 0x24)
                mstore(d, 0x40) // The offset of the `signature` in the calldata.
                mstore(add(m, 0x44), 65) // Length of the signature.
                mstore(add(m, 0x64), r) // `r`.
                mstore(add(m, 0x84), shr(1, shl(1, vs))) // `s`.
                mstore8(add(m, 0xa4), add(shr(255, vs), 27)) // `v`.
                isValid := staticcall(gas(), signer, m, 0xa5, d, 0x20)
                isValid := and(eq(mload(d), f), isValid)
                break
            }
        }
    }

    /// @dev Returns whether the signature (`v`, `r`, `s`) is valid for `signer` and `hash`.
    /// If `signer.code.length == 0`, then validate with `ecrecover`, else
    /// it will validate with ERC1271 on `signer`.
    function isValidSignatureNow(address signer, bytes32 hash, uint8 v, bytes32 r, bytes32 s)
        internal
        view
        returns (bool isValid)
    {
        if (signer == address(0)) return isValid;
        /// @solidity memory-safe-assembly
        assembly {
            let m := mload(0x40)
            for {} 1 {} {
                if iszero(extcodesize(signer)) {
                    mstore(0x00, hash)
                    mstore(0x20, and(v, 0xff)) // `v`.
                    mstore(0x40, r) // `r`.
                    mstore(0x60, s) // `s`.
                    let recovered := mload(staticcall(gas(), 1, 0x00, 0x80, 0x01, 0x20))
                    isValid := gt(returndatasize(), shl(96, xor(signer, recovered)))
                    mstore(0x60, 0) // Restore the zero slot.
                    mstore(0x40, m) // Restore the free memory pointer.
                    break
                }
                let f := shl(224, 0x1626ba7e)
                mstore(m, f) // `bytes4(keccak256("isValidSignature(bytes32,bytes)"))`.
                mstore(add(m, 0x04), hash)
                let d := add(m, 0x24)
                mstore(d, 0x40) // The offset of the `signature` in the calldata.
                mstore(add(m, 0x44), 65) // Length of the signature.
                mstore(add(m, 0x64), r) // `r`.
                mstore(add(m, 0x84), s) // `s`.
                mstore8(add(m, 0xa4), v) // `v`.
                isValid := staticcall(gas(), signer, m, 0xa5, d, 0x20)
                isValid := and(eq(mload(d), f), isValid)
                break
            }
        }
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                     ERC1271 OPERATIONS                     */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    // Note: These ERC1271 operations do NOT have an ECDSA fallback.

    /// @dev Returns whether `signature` is valid for `hash` for an ERC1271 `signer` contract.
    function isValidERC1271SignatureNow(address signer, bytes32 hash, bytes memory signature)
        internal
        view
        returns (bool isValid)
    {
        /// @solidity memory-safe-assembly
        assembly {
            function copy(dst_, src_, n_) {
                for { let i_ := 0 } lt(i_, n_) { i_ := add(0x20, i_) } {
                    mstore(add(dst_, i_), mload(add(src_, i_)))
                }
            }
            let m := mload(0x40)
            let f := shl(224, 0x1626ba7e)
            mstore(m, f) // `bytes4(keccak256("isValidSignature(bytes32,bytes)"))`.
            mstore(add(m, 0x04), hash)
            let d := add(m, 0x24)
            mstore(d, 0x40) // The offset of the `signature` in the calldata.
            // Copy the `signature` over.
            let n := add(0x20, mload(signature))
            copy(add(m, 0x44), signature, n)
            isValid := staticcall(gas(), signer, m, add(n, 0x44), d, 0x20)
            isValid := and(eq(mload(d), f), isValid)
        }
    }

    /// @dev Returns whether `signature` is valid for `hash` for an ERC1271 `signer` contract.
    function isValidERC1271SignatureNowCalldata(
        address signer,
        bytes32 hash,
        bytes calldata signature
    ) internal view returns (bool isValid) {
        /// @solidity memory-safe-assembly
        assembly {
            let m := mload(0x40)
            let f := shl(224, 0x1626ba7e)
            mstore(m, f) // `bytes4(keccak256("isValidSignature(bytes32,bytes)"))`.
            mstore(add(m, 0x04), hash)
            let d := add(m, 0x24)
            mstore(d, 0x40) // The offset of the `signature` in the calldata.
            mstore(add(m, 0x44), signature.length)
            // Copy the `signature` over.
            calldatacopy(add(m, 0x64), signature.offset, signature.length)
            isValid := staticcall(gas(), signer, m, add(signature.length, 0x64), d, 0x20)
            isValid := and(eq(mload(d), f), isValid)
        }
    }

    /// @dev Returns whether the signature (`r`, `vs`) is valid for `hash`
    /// for an ERC1271 `signer` contract.
    function isValidERC1271SignatureNow(address signer, bytes32 hash, bytes32 r, bytes32 vs)
        internal
        view
        returns (bool isValid)
    {
        /// @solidity memory-safe-assembly
        assembly {
            let m := mload(0x40)
            let f := shl(224, 0x1626ba7e)
            mstore(m, f) // `bytes4(keccak256("isValidSignature(bytes32,bytes)"))`.
            mstore(add(m, 0x04), hash)
            let d := add(m, 0x24)
            mstore(d, 0x40) // The offset of the `signature` in the calldata.
            mstore(add(m, 0x44), 65) // Length of the signature.
            mstore(add(m, 0x64), r) // `r`.
            mstore(add(m, 0x84), shr(1, shl(1, vs))) // `s`.
            mstore8(add(m, 0xa4), add(shr(255, vs), 27)) // `v`.
            isValid := staticcall(gas(), signer, m, 0xa5, d, 0x20)
            isValid := and(eq(mload(d), f), isValid)
        }
    }

    /// @dev Returns whether the signature (`v`, `r`, `s`) is valid for `hash`
    /// for an ERC1271 `signer` contract.
    function isValidERC1271SignatureNow(address signer, bytes32 hash, uint8 v, bytes32 r, bytes32 s)
        internal
        view
        returns (bool isValid)
    {
        /// @solidity memory-safe-assembly
        assembly {
            let m := mload(0x40)
            let f := shl(224, 0x1626ba7e)
            mstore(m, f) // `bytes4(keccak256("isValidSignature(bytes32,bytes)"))`.
            mstore(add(m, 0x04), hash)
            let d := add(m, 0x24)
            mstore(d, 0x40) // The offset of the `signature` in the calldata.
            mstore(add(m, 0x44), 65) // Length of the signature.
            mstore(add(m, 0x64), r) // `r`.
            mstore(add(m, 0x84), s) // `s`.
            mstore8(add(m, 0xa4), v) // `v`.
            isValid := staticcall(gas(), signer, m, 0xa5, d, 0x20)
            isValid := and(eq(mload(d), f), isValid)
        }
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                     HASHING OPERATIONS                     */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Returns an Ethereum Signed Message, created from a `hash`.
    /// This produces a hash corresponding to the one signed with the
    /// [`eth_sign`](https://eth.wiki/json-rpc/API#eth_sign)
    /// JSON-RPC method as part of EIP-191.
    function toEthSignedMessageHash(bytes32 hash) internal pure returns (bytes32 result) {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x20, hash) // Store into scratch space for keccak256.
            mstore(0x00, "\x00\x00\x00\x00\x19Ethereum Signed Message:\n32") // 28 bytes.
            result := keccak256(0x04, 0x3c) // `32 * 2 - (32 - 28) = 60 = 0x3c`.
        }
    }

    /// @dev Returns an Ethereum Signed Message, created from `s`.
    /// This produces a hash corresponding to the one signed with the
    /// [`eth_sign`](https://eth.wiki/json-rpc/API#eth_sign)
    /// JSON-RPC method as part of EIP-191.
    /// Note: Supports lengths of `s` up to 999999 bytes.
    function toEthSignedMessageHash(bytes memory s) internal pure returns (bytes32 result) {
        /// @solidity memory-safe-assembly
        assembly {
            let sLength := mload(s)
            let o := 0x20
            mstore(o, "\x19Ethereum Signed Message:\n") // 26 bytes, zero-right-padded.
            mstore(0x00, 0x00)
            // Convert the `s.length` to ASCII decimal representation: `base10(s.length)`.
            for { let temp := sLength } 1 {} {
                o := sub(o, 1)
                mstore8(o, add(48, mod(temp, 10)))
                temp := div(temp, 10)
                if iszero(temp) { break }
            }
            let n := sub(0x3a, o) // Header length: `26 + 32 - o`.
            // Throw an out-of-offset error (consumes all gas) if the header exceeds 32 bytes.
            returndatacopy(returndatasize(), returndatasize(), gt(n, 0x20))
            mstore(s, or(mload(0x00), mload(n))) // Temporarily store the header.
            result := keccak256(add(s, sub(0x20, n)), add(n, sLength))
            mstore(s, sLength) // Restore the length.
        }
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                   EMPTY CALLDATA HELPERS                   */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Returns an empty calldata bytes.
    function emptySignature() internal pure returns (bytes calldata signature) {
        /// @solidity memory-safe-assembly
        assembly {
            signature.length := 0
        }
    }
}