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

/// @notice Gas optimized ECDSA wrapper.
/// @author Solady (https://github.com/vectorized/solady/blob/main/src/utils/ECDSA.sol)
/// @author Modified from Solmate (https://github.com/transmissions11/solmate/blob/main/src/utils/ECDSA.sol)
/// @author Modified from OpenZeppelin (https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/utils/cryptography/ECDSA.sol)
///
/// @dev Note:
/// - The recovery functions use the ecrecover precompile (0x1).
/// - As of Solady version 0.0.68, the `recover` variants will revert upon recovery failure.
///   This is for more safety by default.
///   Use the `tryRecover` variants if you need to get the zero address back
///   upon recovery failure instead.
/// - 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 directly use signatures as unique identifiers:
/// - The recovery operations do NOT check if a signature is non-malleable.
/// - 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.
/// - If you need a unique hash from a signature, please use the `canonicalHash` functions.
library ECDSA {
    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                         CONSTANTS                          */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev The order of the secp256k1 elliptic curve.
    uint256 internal constant N = 0xfffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141;

    /// @dev `N/2 + 1`. Used for checking the malleability of the signature.
    uint256 private constant _HALF_N_PLUS_1 =
        0x7fffffffffffffffffffffffffffffff5d576e7357a4501ddfe92f46681b20a1;

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                        CUSTOM ERRORS                       */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev The signature is invalid.
    error InvalidSignature();

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

    /// @dev Recovers the signer's address from a message digest `hash`, and the `signature`.
    function recover(bytes32 hash, bytes memory signature) internal view returns (address result) {
        /// @solidity memory-safe-assembly
        assembly {
            for { let m := mload(0x40) } 1 {
                mstore(0x00, 0x8baa579f) // `InvalidSignature()`.
                revert(0x1c, 0x04)
            } {
                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 { continue }
                mstore(0x00, hash)
                mstore(0x40, mload(add(signature, 0x20))) // `r`.
                result := mload(staticcall(gas(), 1, 0x00, 0x80, 0x01, 0x20))
                mstore(0x60, 0) // Restore the zero slot.
                mstore(0x40, m) // Restore the free memory pointer.
                // `returndatasize()` will be `0x20` upon success, and `0x00` otherwise.
                if returndatasize() { break }
            }
        }
    }

    /// @dev Recovers the signer's address from a message digest `hash`, and the `signature`.
    function recoverCalldata(bytes32 hash, bytes calldata signature)
        internal
        view
        returns (address result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            for { let m := mload(0x40) } 1 {
                mstore(0x00, 0x8baa579f) // `InvalidSignature()`.
                revert(0x1c, 0x04)
            } {
                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) // Copy `r` and `s`.
                }
                default { continue }
                mstore(0x00, hash)
                result := mload(staticcall(gas(), 1, 0x00, 0x80, 0x01, 0x20))
                mstore(0x60, 0) // Restore the zero slot.
                mstore(0x40, m) // Restore the free memory pointer.
                // `returndatasize()` will be `0x20` upon success, and `0x00` otherwise.
                if returndatasize() { break }
            }
        }
    }

    /// @dev Recovers the signer's address from a message digest `hash`,
    /// and the EIP-2098 short form signature defined by `r` and `vs`.
    function recover(bytes32 hash, bytes32 r, bytes32 vs) internal view returns (address result) {
        /// @solidity memory-safe-assembly
        assembly {
            let m := mload(0x40) // Cache the free memory pointer.
            mstore(0x00, hash)
            mstore(0x20, add(shr(255, vs), 27)) // `v`.
            mstore(0x40, r)
            mstore(0x60, shr(1, shl(1, vs))) // `s`.
            result := mload(staticcall(gas(), 1, 0x00, 0x80, 0x01, 0x20))
            // `returndatasize()` will be `0x20` upon success, and `0x00` otherwise.
            if iszero(returndatasize()) {
                mstore(0x00, 0x8baa579f) // `InvalidSignature()`.
                revert(0x1c, 0x04)
            }
            mstore(0x60, 0) // Restore the zero slot.
            mstore(0x40, m) // Restore the free memory pointer.
        }
    }

    /// @dev Recovers the signer's address from a message digest `hash`,
    /// and the signature defined by `v`, `r`, `s`.
    function recover(bytes32 hash, uint8 v, bytes32 r, bytes32 s)
        internal
        view
        returns (address result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            let m := mload(0x40) // Cache the free memory pointer.
            mstore(0x00, hash)
            mstore(0x20, and(v, 0xff))
            mstore(0x40, r)
            mstore(0x60, s)
            result := mload(staticcall(gas(), 1, 0x00, 0x80, 0x01, 0x20))
            // `returndatasize()` will be `0x20` upon success, and `0x00` otherwise.
            if iszero(returndatasize()) {
                mstore(0x00, 0x8baa579f) // `InvalidSignature()`.
                revert(0x1c, 0x04)
            }
            mstore(0x60, 0) // Restore the zero slot.
            mstore(0x40, m) // Restore the free memory pointer.
        }
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                   TRY-RECOVER OPERATIONS                   */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    // WARNING!
    // These functions will NOT revert upon recovery failure.
    // Instead, they will return the zero address upon recovery failure.
    // It is critical that the returned address is NEVER compared against
    // a zero address (e.g. an uninitialized address variable).

    /// @dev Recovers the signer's address from a message digest `hash`, and the `signature`.
    function tryRecover(bytes32 hash, bytes memory signature)
        internal
        view
        returns (address result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            for { let m := mload(0x40) } 1 {} {
                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`.
                pop(staticcall(gas(), 1, 0x00, 0x80, 0x40, 0x20))
                mstore(0x60, 0) // Restore the zero slot.
                // `returndatasize()` will be `0x20` upon success, and `0x00` otherwise.
                result := mload(xor(0x60, returndatasize()))
                mstore(0x40, m) // Restore the free memory pointer.
                break
            }
        }
    }

    /// @dev Recovers the signer's address from a message digest `hash`, and the `signature`.
    function tryRecoverCalldata(bytes32 hash, bytes calldata signature)
        internal
        view
        returns (address result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            for { let m := mload(0x40) } 1 {} {
                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) // Copy `r` and `s`.
                }
                default { break }
                mstore(0x00, hash)
                pop(staticcall(gas(), 1, 0x00, 0x80, 0x40, 0x20))
                mstore(0x60, 0) // Restore the zero slot.
                // `returndatasize()` will be `0x20` upon success, and `0x00` otherwise.
                result := mload(xor(0x60, returndatasize()))
                mstore(0x40, m) // Restore the free memory pointer.
                break
            }
        }
    }

    /// @dev Recovers the signer's address from a message digest `hash`,
    /// and the EIP-2098 short form signature defined by `r` and `vs`.
    function tryRecover(bytes32 hash, bytes32 r, bytes32 vs)
        internal
        view
        returns (address result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            let m := mload(0x40) // Cache the free memory pointer.
            mstore(0x00, hash)
            mstore(0x20, add(shr(255, vs), 27)) // `v`.
            mstore(0x40, r)
            mstore(0x60, shr(1, shl(1, vs))) // `s`.
            pop(staticcall(gas(), 1, 0x00, 0x80, 0x40, 0x20))
            mstore(0x60, 0) // Restore the zero slot.
            // `returndatasize()` will be `0x20` upon success, and `0x00` otherwise.
            result := mload(xor(0x60, returndatasize()))
            mstore(0x40, m) // Restore the free memory pointer.
        }
    }

    /// @dev Recovers the signer's address from a message digest `hash`,
    /// and the signature defined by `v`, `r`, `s`.
    function tryRecover(bytes32 hash, uint8 v, bytes32 r, bytes32 s)
        internal
        view
        returns (address result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            let m := mload(0x40) // Cache the free memory pointer.
            mstore(0x00, hash)
            mstore(0x20, and(v, 0xff))
            mstore(0x40, r)
            mstore(0x60, s)
            pop(staticcall(gas(), 1, 0x00, 0x80, 0x40, 0x20))
            mstore(0x60, 0) // Restore the zero slot.
            // `returndatasize()` will be `0x20` upon success, and `0x00` otherwise.
            result := mload(xor(0x60, returndatasize()))
            mstore(0x40, m) // Restore the free memory pointer.
        }
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                     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://ethereum.org/en/developers/docs/apis/json-rpc/#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://ethereum.org/en/developers/docs/apis/json-rpc/#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.
        }
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                  CANONICAL HASH FUNCTIONS                  */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    // The following functions return the hash of the signature in its canonicalized format,
    // which is the 65-byte `abi.encodePacked(r, s, uint8(v))`, where `v` is either 27 or 28.
    // If `s` is greater than `N / 2` then it will be converted to `N - s`
    // and the `v` value will be flipped.
    // If the signature has an invalid length, or if `v` is invalid,
    // a uniquely corrupt hash will be returned.
    // These functions are useful for "poor-mans-VRF".

    /// @dev Returns the canonical hash of `signature`.
    function canonicalHash(bytes memory signature) internal pure returns (bytes32 result) {
        /// @solidity memory-safe-assembly
        assembly {
            let l := mload(signature)
            for {} 1 {} {
                mstore(0x00, mload(add(signature, 0x20))) // `r`.
                let s := mload(add(signature, 0x40))
                let v := mload(add(signature, 0x41))
                if eq(l, 64) {
                    v := add(shr(255, s), 27)
                    s := shr(1, shl(1, s))
                }
                if iszero(lt(s, _HALF_N_PLUS_1)) {
                    v := xor(v, 7)
                    s := sub(N, s)
                }
                mstore(0x21, v)
                mstore(0x20, s)
                result := keccak256(0x00, 0x41)
                mstore(0x21, 0) // Restore the overwritten part of the free memory pointer.
                break
            }

            // If the length is neither 64 nor 65, return a uniquely corrupted hash.
            if iszero(lt(sub(l, 64), 2)) {
                // `bytes4(keccak256("InvalidSignatureLength"))`.
                result := xor(keccak256(add(signature, 0x20), l), 0xd62f1ab2)
            }
        }
    }

    /// @dev Returns the canonical hash of `signature`.
    function canonicalHashCalldata(bytes calldata signature)
        internal
        pure
        returns (bytes32 result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            for {} 1 {} {
                mstore(0x00, calldataload(signature.offset)) // `r`.
                let s := calldataload(add(signature.offset, 0x20))
                let v := calldataload(add(signature.offset, 0x21))
                if eq(signature.length, 64) {
                    v := add(shr(255, s), 27)
                    s := shr(1, shl(1, s))
                }
                if iszero(lt(s, _HALF_N_PLUS_1)) {
                    v := xor(v, 7)
                    s := sub(N, s)
                }
                mstore(0x21, v)
                mstore(0x20, s)
                result := keccak256(0x00, 0x41)
                mstore(0x21, 0) // Restore the overwritten part of the free memory pointer.
                break
            }
            // If the length is neither 64 nor 65, return a uniquely corrupted hash.
            if iszero(lt(sub(signature.length, 64), 2)) {
                calldatacopy(mload(0x40), signature.offset, signature.length)
                // `bytes4(keccak256("InvalidSignatureLength"))`.
                result := xor(keccak256(mload(0x40), signature.length), 0xd62f1ab2)
            }
        }
    }

    /// @dev Returns the canonical hash of `signature`.
    function canonicalHash(bytes32 r, bytes32 vs) internal pure returns (bytes32 result) {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x00, r) // `r`.
            let v := add(shr(255, vs), 27)
            let s := shr(1, shl(1, vs))
            mstore(0x21, v)
            mstore(0x20, s)
            result := keccak256(0x00, 0x41)
            mstore(0x21, 0) // Restore the overwritten part of the free memory pointer.
        }
    }

    /// @dev Returns the canonical hash of `signature`.
    function canonicalHash(uint8 v, bytes32 r, bytes32 s) internal pure returns (bytes32 result) {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x00, r) // `r`.
            if iszero(lt(s, _HALF_N_PLUS_1)) {
                v := xor(v, 7)
                s := sub(N, s)
            }
            mstore(0x21, v)
            mstore(0x20, s)
            result := keccak256(0x00, 0x41)
            mstore(0x21, 0) // Restore the overwritten part of the free memory pointer.
        }
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                   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
        }
    }
}