// SPDX-License-Identifier: MIT
pragma solidity ^0.6.12;

/**
 * @title ECDSA library
 *
 * @dev Based on https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v3.3.0/contracts/cryptography/ECDSA.sol#L26
 */
library ECDSALib {
  function recoverAddress(
    bytes32 messageHash,
    bytes memory signature
  )
    internal
    pure
    returns (address)
  {
    address result = address(0);

    if (signature.length == 65) {
      bytes32 r;
      bytes32 s;
      uint8 v;

      // solhint-disable-next-line no-inline-assembly
      assembly {
        r := mload(add(signature, 0x20))
        s := mload(add(signature, 0x40))
        v := byte(0, mload(add(signature, 0x60)))
      }

      if (v < 27) {
        v += 27;
      }

      if (v == 27 || v == 28) {
        result = ecrecover(messageHash, v, r, s);
      }
    }

    return result;
  }

  function toEthereumSignedMessageHash(
    bytes32 messageHash
  )
    internal
    pure
    returns (bytes32)
  {
    return keccak256(abi.encodePacked(
      "\x19Ethereum Signed Message:\n32",
      messageHash
    ));
  }
}