[WIP] Exact Output for Trident Router

contracts/TridentRouter.sol

@@ -10,6 +10,7 @@ import {IMasterDeployer} from "./interfaces/IMasterDeployer.sol";
 import {IPool} from "./interfaces/IPool.sol";
 import {ITridentRouter} from "./interfaces/ITridentRouter.sol";
 import {IWETH9} from "./interfaces/IWETH9.sol";
+import {TridentRouterLibrary} from "./libraries/TridentRouterLibrary.sol";
 
 /// @dev Custom Errors
 error NotWethSender();
@@ -64,6 +65,22 @@ contract TridentRouter is ITridentRouter, SelfPermit, Multicall {
         if (amountOut < params.amountOutMinimum) revert TooLittleReceived();
     }
 
+    /// @notice Swaps token B to token A directly. Swaps are done on `bento` tokens.
+    /// @param params This includes the address of token B, pool, amount of token B to swap,
+    /// maximum amount of token A for the swap and data required by the pool for the swap.
+    /// @dev Ensure that the pool is trusted before calling this function. The pool can steal users' tokens.
+    function exactOutputSingle(ExactOutputSingleParams calldata params) public payable returns (uint256 amountIn) {
+        amountIn = TridentRouterLibrary.getAmountIn(params.pool, params.amountOut, params.tokenOut);
+
+        if (amountIn > params.amountInMaximum) revert TooLittleReceived();
+
+        address tokenIn = abi.decode(params.data, (address));
+
+        bento.transfer(tokenIn, msg.sender, params.pool, amountIn);
+
+        IPool(params.pool).swap(params.data);
+    }
+
     /// @notice Swaps token A to token B indirectly by using multiple hops.
     /// @param params This includes the addresses of the tokens, pools, amount of token A to swap,
     /// minimum amount of token B after the swap and data required by the pools for the swaps.
@@ -84,6 +101,26 @@ contract TridentRouter is ITridentRouter, SelfPermit, Multicall {
         if (amountOut < params.amountOutMinimum) revert TooLittleReceived();
     }
 
+    /// @notice Swaps token B to token A indirectly by using multiple hops.
+    /// @param params This includes the addresses of the tokens, pools, amount of token B to swap,
+    /// maximum amount of token A for the swap and data required by the pools for the swaps.
+    /// @dev Ensure that the pools are trusted before calling this function. The pools can steal users' tokens.
+    function exactOutput(ExactOutputParams calldata params) public payable returns (uint256 amountIn) {
+        amountIn = TridentRouterLibrary.getAmountsIn(params.path, params.tokenOut, params.amountOut)[0];
+
+        if (amountIn > params.amountInMaximum) revert TooLittleReceived();
+
+        address tokenIn = abi.decode(params.path[0].data, (address));
+
+        bento.transfer(tokenIn, msg.sender, params.path[0].pool, amountIn);
+
+        uint256 n = params.path.length;
+
+        for (uint256 i = 0; i < n; i = _increment(i)) {
+            IPool(params.path[i].pool).swap(params.path[i].data);
+        }
+    }
+
     /// @notice Swaps token A to token B directly. It's the same as `exactInputSingle` except
     /// it takes raw ERC-20 tokens from the users and deposits them into `bento`.
     /// @param params This includes the address of token A, pool, amount of token A to swap,
@@ -98,6 +135,23 @@ contract TridentRouter is ITridentRouter, SelfPermit, Multicall {
         if (amountOut < params.amountOutMinimum) revert TooLittleReceived();
     }
 
+    /// @notice Swaps token B to token A directly. It's the same as `exactOutputSingle` except
+    /// it takes raw ERC-20 tokens from the users and deposits them into `bento`.
+    /// @param params This includes the address of token B, pool, amount of token B to swap,
+    /// minimum amount of token A for the swap and data required by the pool for the swap.
+    /// @dev Ensure that the pool is trusted before calling this function. The pool can steal users' tokens.
+    function exactOutputSingleWithNativeTokens(ExactOutputSingleParams calldata params) public payable returns (uint256 amountIn) {
+        amountIn = TridentRouterLibrary.getAmountIn(params.pool, params.amountOut, params.tokenOut);
+
+        if (amountIn > params.amountInMaximum) revert TooLittleReceived();
+
+        address tokenIn = abi.decode(params.data, (address));
+
+        _depositToBentoBox(tokenIn, params.pool, amountIn);
+
+        IPool(params.pool).swap(params.data);
+    }
+
     /// @notice Swaps token A to token B indirectly by using multiple hops. It's the same as `exactInput` except
     /// it takes raw ERC-20 tokens from the users and deposits them into `bento`.
     /// @param params This includes the addresses of the tokens, pools, amount of token A to swap,
@@ -117,6 +171,27 @@ contract TridentRouter is ITridentRouter, SelfPermit, Multicall {
         if (amountOut < params.amountOutMinimum) revert TooLittleReceived();
     }
 
+    /// @notice Swaps token B to token A indirectly by using multiple hops. It's the same as `exactOutput` except
+    /// it takes raw ERC-20 tokens from the users and deposits them into `bento`.
+    /// @param params This includes the addresses of the tokens, pools, amount of token B to swap,
+    /// maximum amount of token A for the swap and data required by the pools for the swaps.
+    /// @dev Ensure that the pools are trusted before calling this function. The pools can steal users' tokens.
+    function exactOutputWithNativeToken(ExactOutputParams calldata params) public payable returns (uint256 amountIn) {
+        amountIn = TridentRouterLibrary.getAmountsIn(params.path, params.tokenOut, params.amountOut)[0];
+
+        if (amountIn > params.amountInMaximum) revert TooLittleReceived();
+
+        address tokenIn = abi.decode(params.path[0].data, (address));
+
+        _depositToBentoBox(tokenIn, params.path[0].pool, amountIn);
+
+        uint256 n = params.path.length;
+
+        for (uint256 i = 0; i < n; i = _increment(i)) {
+            IPool(params.path[i].pool).swap(params.path[i].data);
+        }
+    }
+
     /// @notice Swaps multiple input tokens to multiple output tokens using multiple paths, in different percentages.
     /// For example, you can swap 50 DAI + 100 USDC into 60% ETH and 40% BTC.
     /// @param params This includes everything needed for the swap. Look at the `ComplexPathParams` struct for more details.

contracts/interfaces/ITridentRouter.sol

@@ -24,6 +24,21 @@ interface ITridentRouter {
         Path[] path;
     }
 
+    struct ExactOutputSingleParams {
+        uint256 amountOut;
+        uint256 amountInMaximum;
+        address pool;
+        address tokenOut;
+        bytes data;
+    }
+
+    struct ExactOutputParams {
+        address tokenOut;
+        uint256 amountOut;
+        uint256 amountInMaximum;
+        Path[] path;
+    }
+
     struct TokenInput {
         address token;
         bool native;

contracts/libraries/TridentRouterLibrary.sol

@@ -0,0 +1,42 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+pragma solidity >=0.8.0;
+
+import "../interfaces/ITridentRouter.sol";
+import "../interfaces/IPool.sol";
+
+library TridentRouterLibrary {
+    /// @notice Get Amount In from the pool
+    /// @param pool Pool address
+    /// @param amountOut Amount out required
+    /// @param tokenOut Token out required
+    function getAmountIn(
+        address pool,
+        uint256 amountOut,
+        address tokenOut
+    ) internal view returns (uint256 amountIn) {
+        bytes memory data = abi.encode(tokenOut, amountOut);
+        amountIn = IPool(pool).getAmountIn(data);
+    }
+
+    /// @notice Get Amount In multihop
+    /// @param path Path for the hops (pool addresses)
+    /// @param tokenOut Token out required
+    /// @param amountOut Amount out required
+    function getAmountsIn(
+        ITridentRouter.Path[] memory path,
+        address tokenOut,
+        uint256 amountOut
+    ) internal view returns (uint256[] memory amounts) {
+        amounts = new uint256[](path.length + 1);
+        amounts[amounts.length - 1] = amountOut;
+
+        for (uint256 i = path.length; i > 0; i--) {
+            uint256 amountIn = getAmountIn(path[i - 1].pool, amounts[i], tokenOut);
+            amounts[i - 1] = amountIn;
+            if (i > 1) {
+                (tokenOut) = abi.decode(path[i - 1].data, (address));
+            }
+        }
+    }
+}