library SushiSwapLibrary {
  using SafeMath for uint256;

  // returns sorted token addresses, used to handle return values from pairs sorted in this order
  function sortTokens(address tokenA, address tokenB)
    internal
    pure
    returns (address token0, address token1)
  {
    require(tokenA != tokenB, "UniswapV2Library: IDENTICAL_ADDRESSES");
    (token0, token1) = tokenA < tokenB ? (tokenA, tokenB) : (tokenB, tokenA);
    require(token0 != address(0), "UniswapV2Library: ZERO_ADDRESS");
  }

  // calculates the CREATE2 address for a pair without making any external calls
  function pairFor(
    address factory,
    address tokenA,
    address tokenB
  ) internal pure returns (address pair) {
    (address token0, address token1) = sortTokens(tokenA, tokenB);
    pair = address(
      uint160(
        uint256(
          keccak256(
            abi.encodePacked(
              hex"ff",
              factory,
              keccak256(abi.encodePacked(token0, token1)),
              hex"e18a34eb0e04b04f7a0ac29a6e80748dca96319b42c54d679cb821dca90c6303" // init code hash
            )
          )
        )
      )
    );
  }

  // fetches and sorts the reserves for a pair
  function getReserves(
    address factory,
    address tokenA,
    address tokenB
  ) internal view returns (uint256 reserveA, uint256 reserveB) {
    (address token0, ) = sortTokens(tokenA, tokenB);
    (uint256 reserve0, uint256 reserve1, ) =
      IUniswapV2Pair(pairFor(factory, tokenA, tokenB)).getReserves();
    (reserveA, reserveB) = tokenA == token0
      ? (reserve0, reserve1)
      : (reserve1, reserve0);
  }

  // given some amount of an asset and pair reserves, returns an equivalent amount of the other asset
  function quote(
    uint256 amountA,
    uint256 reserveA,
    uint256 reserveB
  ) internal pure returns (uint256 amountB) {
    require(amountA > 0, "UniswapV2Library: INSUFFICIENT_AMOUNT");
    require(
      reserveA > 0 && reserveB > 0,
      "UniswapV2Library: INSUFFICIENT_LIQUIDITY"
    );
    amountB = amountA.mul(reserveB) / reserveA;
  }

  // given an input amount of an asset and pair reserves, returns the maximum output amount of the other asset
  function getAmountOut(
    uint256 amountIn,
    uint256 reserveIn,
    uint256 reserveOut
  ) internal pure returns (uint256 amountOut) {
    require(amountIn > 0, "UniswapV2Library: INSUFFICIENT_INPUT_AMOUNT");
    require(
      reserveIn > 0 && reserveOut > 0,
      "UniswapV2Library: INSUFFICIENT_LIQUIDITY"
    );
    uint256 amountInWithFee = amountIn.mul(997);
    uint256 numerator = amountInWithFee.mul(reserveOut);
    uint256 denominator = reserveIn.mul(1000).add(amountInWithFee);
    amountOut = numerator / denominator;
  }

  // given an output amount of an asset and pair reserves, returns a required input amount of the other asset
  function getAmountIn(
    uint256 amountOut,
    uint256 reserveIn,
    uint256 reserveOut
  ) internal pure returns (uint256 amountIn) {
    require(amountOut > 0, "UniswapV2Library: INSUFFICIENT_OUTPUT_AMOUNT");
    require(
      reserveIn > 0 && reserveOut > 0,
      "UniswapV2Library: INSUFFICIENT_LIQUIDITY"
    );
    uint256 numerator = reserveIn.mul(amountOut).mul(1000);
    uint256 denominator = reserveOut.sub(amountOut).mul(997);
    amountIn = (numerator / denominator).add(1);
  }

  // performs chained getAmountOut calculations on any number of pairs
  function getAmountsOut(
    address factory,
    uint256 amountIn,
    address[] memory path
  ) internal view returns (uint256[] memory amounts) {
    require(path.length >= 2, "UniswapV2Library: INVALID_PATH");
    amounts = new uint256[](path.length);
    amounts[0] = amountIn;
    for (uint256 i; i < path.length - 1; i++) {
      (uint256 reserveIn, uint256 reserveOut) =
        getReserves(factory, path[i], path[i + 1]);
      amounts[i + 1] = getAmountOut(amounts[i], reserveIn, reserveOut);
    }
  }

  // performs chained getAmountIn calculations on any number of pairs
  function getAmountsIn(
    address factory,
    uint256 amountOut,
    address[] memory path
  ) internal view returns (uint256[] memory amounts) {
    require(path.length >= 2, "UniswapV2Library: INVALID_PATH");
    amounts = new uint256[](path.length);
    amounts[amounts.length - 1] = amountOut;
    for (uint256 i = path.length - 1; i > 0; i--) {
      (uint256 reserveIn, uint256 reserveOut) =
        getReserves(factory, path[i - 1], path[i]);
      amounts[i - 1] = getAmountIn(amounts[i], reserveIn, reserveOut);
    }
  }
}
function getAmountIn(
  uint256 amountOut,
  uint256 reserveIn,
  uint256 reserveOut
) internal pure returns (uint256 amountIn) {
  require(amountOut > 0, "UniswapV2Library: INSUFFICIENT_OUTPUT_AMOUNT");
  require(
    reserveIn > 0 && reserveOut > 0,
    "UniswapV2Library: INSUFFICIENT_LIQUIDITY"
  );
  uint256 numerator = reserveIn.mul(amountOut).mul(1000);
  uint256 denominator = reserveOut.sub(amountOut).mul(997);
  amountIn = (numerator / denominator).add(1);
}

// given an output amount of an asset and pair reserves, returns a required input amount of the other asset