feat(SwapRouter): add swap router

src/CellarRouter.sol

@@ -4,7 +4,7 @@ pragma solidity 0.8.13;
 import { ERC20 } from "@solmate/tokens/ERC20.sol";
 import { SafeTransferLib } from "@solmate/utils/SafeTransferLib.sol";
 import { ERC4626 } from "./base/ERC4626.sol";
-import { ISwapRouter as UniswapV3Router } from "./interfaces/ISwapRouter.sol";
+import { IUniswapV3Router as UniswapV3Router } from "./interfaces/IUniswapV3Router.sol";
 import { IUniswapV2Router02 as UniswapV2Router } from "./interfaces/IUniswapV2Router02.sol";
 import { ICellarRouter } from "./interfaces/ICellarRouter.sol";
 

src/SwapRouter.sol

@@ -0,0 +1,100 @@
+// SPDX-License-Identifier: Apache-2.0
+pragma solidity 0.8.13;
+
+import { ERC20 } from "@solmate/tokens/ERC20.sol";
+import { SafeTransferLib } from "@solmate/utils/SafeTransferLib.sol";
+import { IUniswapV2Router02 as UniswapV2Router } from "./interfaces/IUniswapV2Router02.sol";
+import { IUniswapV3Router as UniswapV3Router } from "./interfaces/IUniswapV3Router.sol";
+
+contract SwapRouter {
+    using SafeTransferLib for ERC20;
+
+    enum Exchanges {
+        UNIV2,
+        UNIV3
+    }
+    /** @notice Planned additions 
+        BALANCERV2,
+        CURVE,
+        ONEINCH
+    */
+    mapping(Exchanges => bytes4) public idToSelector;
+
+    // ========================================== CONSTRUCTOR ==========================================
+
+    /**
+     * @notice Uniswap V2 swap router contract. Used for swapping if pool fees are not specified.
+     */
+    UniswapV2Router public immutable uniswapV2Router; // 0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D
+
+    /**
+     * @notice Uniswap V3 swap router contract. Used for swapping if pool fees are specified.
+     */
+    UniswapV3Router public immutable uniswapV3Router; // 0xE592427A0AEce92De3Edee1F18E0157C05861564
+
+    /**
+     *
+     */
+    constructor(UniswapV2Router _uniswapV2Router, UniswapV3Router _uniswapV3Router) {
+        //set up all exchanges
+        uniswapV2Router = _uniswapV2Router;
+        uniswapV3Router = _uniswapV3Router;
+
+        //set up mapping between ids and selectors
+        idToSelector[Exchanges.UNIV2] = SwapRouter(this).swapWithUniV2.selector;
+        idToSelector[Exchanges.UNIV3] = SwapRouter(this).swapWithUniV3.selector;
+    }
+
+    // ======================================= SWAP OPERATIONS =======================================
+
+    function swap(Exchanges id, bytes memory swapData) external returns (uint256 swapOutAmount) {
+        (bool success, bytes memory result) = address(this).call(abi.encodeWithSelector(idToSelector[id], swapData));
+        require(success, "Failed to perform swap");
+        swapOutAmount = abi.decode(result, (uint256));
+    }
+
+    function swapWithUniV2(bytes memory swapData) public returns (uint256 swapOutAmount) {
+        (address[] memory path, uint256 assets, uint256 assetsOutMin, address recipient) = abi.decode(
+            swapData,
+            (address[], uint256, uint256, address)
+        );
+        ERC20 assetIn = ERC20(path[0]);
+        // Approve assets to be swapped through the router.
+        assetIn.safeApprove(address(uniswapV2Router), assets);
+
+        // Execute the swap.
+        uint256[] memory amountsOut = uniswapV2Router.swapExactTokensForTokens(
+            assets,
+            assetsOutMin,
+            path,
+            recipient,
+            block.timestamp + 60
+        );
+        swapOutAmount = amountsOut[1];
+    }
+
+    function swapWithUniV3(bytes memory swapData) public returns (uint256 swapOutAmount) {
+        (address[] memory path, uint24[] memory poolFees, uint256 assets, uint256 assetsOutMin, address recipient) = abi
+            .decode(swapData, (address[], uint24[], uint256, uint256, address));
+        ERC20 assetIn = ERC20(path[0]);
+
+        // Approve assets to be swapped through the router.
+        assetIn.safeApprove(address(uniswapV3Router), assets);
+
+        // Encode swap parameters.
+        bytes memory encodePackedPath = abi.encodePacked(address(assetIn));
+        for (uint256 i = 1; i < path.length; i++)
+            encodePackedPath = abi.encodePacked(encodePackedPath, poolFees[i - 1], path[i]);
+
+        // Execute the swap.
+        swapOutAmount = uniswapV3Router.exactInput(
+            UniswapV3Router.ExactInputParams({
+                path: encodePackedPath,
+                recipient: recipient,
+                deadline: block.timestamp + 60,
+                amountIn: assets,
+                amountOutMinimum: assetsOutMin
+            })
+        );
+    }
+}

src/interfaces/ISwapRouter.sol → src/interfaces/IUniswapV3Router.sol

@@ -22,7 +22,7 @@ interface IUniswapV3SwapCallback {
 
 /// @title Router token swapping functionality
 /// @notice Functions for swapping tokens via Uniswap V3
-interface ISwapRouter is IUniswapV3SwapCallback {
+interface IUniswapV3Router is IUniswapV3SwapCallback {
     struct ExactInputSingleParams {
         address tokenIn;
         address tokenOut;

src/mocks/MockSwapRouter.sol

@@ -3,7 +3,7 @@ pragma solidity 0.8.13;
 
 import { ERC20 } from "@solmate/tokens/ERC20.sol";
 import { Math } from "src/utils/Math.sol";
-import { ISwapRouter } from "../interfaces/ISwapRouter.sol";
+import { IUniswapV3Router } from "../interfaces/IUniswapV3Router.sol";
 
 library BytesLib {
     function slice(
@@ -202,7 +202,7 @@ contract MockSwapRouter {
         return amountOut;
     }
 
-    function exactInput(ISwapRouter.ExactInputParams memory params) external returns (uint256) {
+    function exactInput(IUniswapV3Router.ExactInputParams memory params) external returns (uint256) {
         (address tokenIn, address tokenOut, ) = params.path.decodeFirstPool();
 
         while (params.path.hasMultiplePools()) {

test/CellarRouter.t.sol

@@ -4,7 +4,7 @@ pragma solidity 0.8.13;
 import { ERC20 } from "@solmate/tokens/ERC20.sol";
 import { ERC4626 } from "src/base/ERC4626.sol";
 import { CellarRouter } from "src/CellarRouter.sol";
-import { ISwapRouter as UniswapV3Router } from "src/interfaces/ISwapRouter.sol";
+import { IUniswapV3Router as UniswapV3Router } from "src/interfaces/IUniswapV3Router.sol";
 import { IUniswapV2Router02 as UniswapV2Router } from "src/interfaces/IUniswapV2Router02.sol";
 import { MockERC20 } from "src/mocks/MockERC20.sol";
 import { MockERC4626 } from "src/mocks/MockERC4626.sol";