ERC4626 Router

contracts/helper/ERC4626Router.sol

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+// SPDX-License-Identifier: MIT
+pragma solidity 0.8.24;
+
+import { IERC4626, IERC20 } from "@openzeppelin/contracts/token/ERC20/extensions/ERC4626.sol";
+import { SafeERC20 } from "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
+
+contract ERC4626Router {
+    error ERC4626Router__InvalidOptions();
+    error ERC4626Router__InvalidVaultChain();
+
+    /**
+     * @notice Deposits into a list of chained ERC4626 vaults.
+     * @param vaults List of ERC4626 compatible vaults to deposit into.
+     * @param amount The initial amount to be deposited in the first vault.
+     * @dev Every following vault must have the previous vault as the underlying.
+     */
+    function depositChained(IERC4626[] memory vaults, uint256 amount) external {
+        uint256 vaultCount = vaults.length;
+
+        // Let's make sure there's vaults and amounts to deposit.
+        if (vaultCount == 0 || amount == 0) {
+            revert ERC4626Router__InvalidOptions();
+        }
+
+        // While looping through the vaults...
+        for (uint256 i = 0; i < vaultCount; i++) {
+            // Let's get the vault and asset details
+            IERC4626 vault = vaults[i];
+            IERC20 asset = IERC20(vault.asset());
+
+            // If it's the first vault, we need to transfer the base asset to the contract
+            if (i == 0) {
+                SafeERC20.safeTransferFrom(asset, msg.sender, address(this), amount);
+            }
+
+            // Figure out the deposit amount for the vault
+            // Note: This also accounts for any assets that were transferred to the contract
+            uint256 depositAmount = asset.balanceOf(address(this));
+            asset.approve(address(vault), depositAmount);
+
+            if (i != vaultCount - 1) {
+                // If it's not the last vault, we deposit while minting to the contract.
+                vault.deposit(depositAmount, address(this));
+
+                // Let's make sure the asset required for the next vault is actually the vault we're depositing into.
+                if (vaults[i + 1].asset() != address(vault)) {
+                    revert ERC4626Router__InvalidVaultChain();
+                }
+            } else {
+                // If it's the last vault, we deposit minting directly to the user.
+                vault.deposit(depositAmount, msg.sender);
+            }
+        }
+    }
+}