// SPDX-License-Identifier: MIT
pragma solidity ^0.7.0;

/**
 * @title Bytes
 * @dev Helper methods to transform bytes to other solidity types.
 */
library BytesHelper {
  /**
   * @dev Truncate bytes array if its size is more than 20 bytes.
   * NOTE: This function does not perform any checks on the received parameter.
   * Make sure that the _bytes argument has a correct length, not less than 20 bytes.
   * A case when _bytes has length less than 20 will lead to the undefined behaviour,
   * since assembly will read data from memory that is not related to the _bytes argument.
   * @param _bytes to be converted to address type
   * @return addr address included in the firsts 20 bytes of the bytes array in parameter.
   */
  function bytesToAddress(bytes memory _bytes) internal pure returns (address addr) {
    assembly {
      addr := mload(add(_bytes, 20))
    }
  }

  /**
   * @param _bytes it's 32 length slice to be converted to uint type
   * @param _start start index of slice
   * @return x uint included in the 32 length slice of the bytes array in parameter.
   */
  function sliceToUint(bytes memory _bytes, uint256 _start) internal pure returns (uint256 x) {
    require(_bytes.length >= _start + 32, "slicing out of range");
    assembly {
      x := mload(add(_bytes, add(0x20, _start)))
    }
  }
}