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| // Copyright (C) 2020 Zerion Inc. <https://zerion.io> | ||
| // | ||
| // This program is free software: you can redistribute it and/or modify | ||
| // it under the terms of the GNU General Public License as published by | ||
| // the Free Software Foundation, either version 3 of the License, or | ||
| // (at your option) any later version. | ||
| // | ||
| // This program is distributed in the hope that it will be useful, | ||
| // but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
| // GNU General Public License for more details. | ||
| // | ||
| // You should have received a copy of the GNU General Public License | ||
| // along with this program. If not, see <https://www.gnu.org/licenses/>. | ||
| // | ||
| // SPDX-License-Identifier: LGPL-3.0-only | ||
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| pragma solidity 0.8.12; | ||
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| import { IERC20 } from "@openzeppelin/contracts/token/ERC20/IERC20.sol"; | ||
| import { SafeERC20 } from "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol"; | ||
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| import { ICaller } from "../interfaces/ICaller.sol"; | ||
| import { IUniswapV2Pair } from "../interfaces/IUniswapV2Pair.sol"; | ||
| import { IWETH9 } from "../interfaces/IWETH9.sol"; | ||
| import { Base } from "../shared/Base.sol"; | ||
| import { SwapType } from "../shared/Enums.sol"; | ||
| import { BadToken, InconsistentPairsAndDirectionsLengths, InsufficientBalance, LowReserve, ZeroAmountIn, ZeroAmountOut, ZeroLength } from "../shared/Errors.sol"; | ||
| import { TokensHandler } from "../shared/TokensHandler.sol"; | ||
| import { Weth } from "../shared/Weth.sol"; | ||
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| /** | ||
| * @title Uniswap caller that executes swaps on UniswapV2-like pools | ||
| */ | ||
| contract UniswapV2SinglePoolCaller is ICaller, TokensHandler, Weth { | ||
| address internal constant ETH = 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE; | ||
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| /** | ||
| * @notice Sets Wrapped Ether address for the current chain | ||
| * @param weth Wrapped Ether address | ||
| */ | ||
| constructor(address weth) Weth(weth) { | ||
| // solhint-disable-previous-line no-empty-blocks | ||
| } | ||
|
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| /** | ||
| * @notice Main external function: | ||
| * executes swap using Uniswap-like pools and returns tokens to the account | ||
| * @param callerCallData ABI-encoded parameters: | ||
| * - inputToken Address of the token that should be spent | ||
| * - outputToken Address of the token that should be returned | ||
| * - pair Uniswap V2 like pair | ||
| * - swapType Whether input or output amount is fixed | ||
| * - fixedSideAmount Amount of the token which is fixed (see `swapType`) | ||
| * @dev Implementation of Caller interface function | ||
| */ | ||
| function callBytes(bytes calldata callerCallData) external override { | ||
| ( | ||
| address inputToken, | ||
| address outputToken, | ||
| address pair, | ||
| SwapType swapType, | ||
| uint256 fixedSideAmount | ||
| ) = abi.decode(callerCallData, (address, address, address, SwapType, uint256)); | ||
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| address inputTokenERC20 = (inputToken == ETH) ? getWeth() : inputToken; | ||
| // Positive direction means `inputTokenERC20 == token0` | ||
| bool direction = (inputTokenERC20 == IUniswapV2Pair(pair).token0()); | ||
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| (uint256 inputTokenAmount, uint256 outputTokenAmount) = swapType == SwapType.FixedInputs | ||
| ? (fixedSideAmount, getAmountOut(fixedSideAmount, pair, direction)) | ||
| : (getAmountIn(fixedSideAmount, pair, direction), fixedSideAmount); | ||
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| // Transfer input tokens to the pair | ||
| { | ||
| uint256 balance = Base.getBalance(inputToken); | ||
| if (balance < inputTokenAmount) revert InsufficientBalance(balance, inputTokenAmount); | ||
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| if (inputToken == ETH) depositEth(inputTokenAmount); | ||
| SafeERC20.safeTransfer(IERC20(inputTokenERC20), pair, inputTokenAmount); | ||
| } | ||
|
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| // Do the swap via the given pair | ||
| IUniswapV2Pair(pair).swap( | ||
| direction ? uint256(0) : outputTokenAmount, | ||
| direction ? outputTokenAmount : uint256(0), | ||
| (outputToken == ETH) ? address(this) : msg.sender, | ||
| bytes("") | ||
| ); | ||
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| // Unwrap weth if necessary | ||
| if (outputToken == ETH) withdrawEth(); | ||
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| // In case of non-zero input token, transfer the remaining amount back to `msg.sender` | ||
| Base.transfer(inputToken, msg.sender, Base.getBalance(inputToken)); | ||
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| // In case of non-zero output token, transfer the total balance to `msg.sender` | ||
| Base.transfer(outputToken, msg.sender, Base.getBalance(outputToken)); | ||
| } | ||
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| /** | ||
| * @notice Wraps Ether | ||
| */ | ||
| function depositEth(uint256 amount) internal { | ||
| address weth = getWeth(); | ||
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| if (amount > 0) IWETH9(weth).deposit{ value: amount }(); | ||
| } | ||
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| /** | ||
| * @notice Unwraps Wrapped Ether (if necessary) | ||
| */ | ||
| function withdrawEth() internal { | ||
| address weth = getWeth(); | ||
| uint256 wethBalance = IERC20(weth).balanceOf(address(this)); | ||
| // The check always passes, however, left for unusual cases | ||
| if (wethBalance > uint256(0)) IWETH9(weth).withdraw(wethBalance); | ||
| } | ||
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| /** | ||
| * @notice Calculates the required amount for one swap in case of fixed output amount | ||
| * @param amountOut Amount of the token returned after the swap | ||
| * @param pair Uniswap-like pair | ||
| * @param direction Exchange direction (`true` means token0 -> token1) | ||
| * @return amountIn Amount required for the swap | ||
| * @dev Repeats Uniswap's getAmountIn calculations | ||
| */ | ||
| function getAmountIn( | ||
| uint256 amountOut, | ||
| address pair, | ||
| bool direction | ||
| ) internal view returns (uint256 amountIn) { | ||
| if (amountOut == uint256(0)) revert ZeroAmountOut(); | ||
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| (uint256 reserveIn, uint256 reserveOut) = getReserves(pair, direction); | ||
| if (reserveOut < amountOut) revert LowReserve(reserveOut, amountOut); | ||
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| uint256 numerator = reserveIn * amountOut * 1000; | ||
| uint256 denominator = (reserveOut - amountOut) * 997; | ||
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| return (numerator / denominator) + 1; | ||
| } | ||
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| /** | ||
| * @notice Calculates the returned amount for one swap in case of fixed input amount | ||
| * @param amountIn Amount of the token provided for the swap | ||
| * @param pair Uniswap-like pair | ||
| * @param direction Exchange direction (`true` means token0 -> token1) | ||
| * @return amountOut Amount returned after the swap | ||
| * @dev Repeats Uniswap's getAmountIn calculations | ||
| */ | ||
| function getAmountOut( | ||
| uint256 amountIn, | ||
| address pair, | ||
| bool direction | ||
| ) internal view returns (uint256 amountOut) { | ||
| if (amountIn == uint256(0)) revert ZeroAmountIn(); | ||
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| (uint256 reserveIn, uint256 reserveOut) = getReserves(pair, direction); | ||
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| uint256 amountInWithFee = amountIn * 997; | ||
| uint256 numerator = amountInWithFee * reserveOut; | ||
| uint256 denominator = (reserveIn * 1000) + amountInWithFee; | ||
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| return numerator / denominator; | ||
| } | ||
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| /** | ||
| * @notice Returns pool's reserves in 'correct' order (input token, output token) | ||
| * @param pair Uniswap-like pair | ||
| * @param direction Exchange direction (`true` means token0 -> token1) | ||
| * @return reserveIn Pool reserve for input token | ||
| * @return reserveOut Pool reserve for output token | ||
| */ | ||
| function getReserves( | ||
| address pair, | ||
| bool direction | ||
| ) internal view returns (uint256 reserveIn, uint256 reserveOut) { | ||
| (uint256 reserve0, uint256 reserve1, ) = IUniswapV2Pair(pair).getReserves(); | ||
| (reserveIn, reserveOut) = direction ? (reserve0, reserve1) : (reserve1, reserve0); | ||
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| return (reserveIn, reserveOut); | ||
| } | ||
| } |
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