feat: subaccount design using spend function

snapshots/BenchmarkTest.json

@@ -16,11 +16,11 @@
   "testERC20Transfer_ERC4337MinimalAccount": "171509",
   "testERC20Transfer_ERC4337MinimalAccount_AppSponsor": "168500",
   "testERC20Transfer_ERC4337MinimalAccount_ERC20SelfPay": "199831",
-  "testERC20Transfer_IthacaAccount": "128059",
-  "testERC20Transfer_IthacaAccountWithSpendLimits": "193602",
-  "testERC20Transfer_IthacaAccount_AppSponsor": "138595",
-  "testERC20Transfer_IthacaAccount_AppSponsor_ERC20": "143884",
-  "testERC20Transfer_IthacaAccount_ERC20SelfPay": "128548",
+  "testERC20Transfer_IthacaAccount": "128232",
+  "testERC20Transfer_IthacaAccountWithSpendLimits": "193695",
+  "testERC20Transfer_IthacaAccount_AppSponsor": "138724",
+  "testERC20Transfer_IthacaAccount_AppSponsor_ERC20": "144025",
+  "testERC20Transfer_IthacaAccount_ERC20SelfPay": "128721",
   "testERC20Transfer_Safe4337": "197561",
   "testERC20Transfer_Safe4337_AppSponsor": "191725",
   "testERC20Transfer_Safe4337_ERC20SelfPay": "221464",
@@ -29,25 +29,25 @@
   "testERC20Transfer_ZerodevKernel_ERC20SelfPay": "235489",
   "testERC20Transfer_batch100_AlchemyModularAccount": "10109066",
   "testERC20Transfer_batch100_AlchemyModularAccount_ERC20SelfPay": "11609298",
-  "testERC20Transfer_batch100_IthacaAccount": "7531912",
-  "testERC20Transfer_batch100_IthacaAccount_AppSponsor": "8140216",
-  "testERC20Transfer_batch100_IthacaAccount_AppSponsor_ERC20": "7966120",
-  "testERC20Transfer_batch100_IthacaAccount_ERC20SelfPay": "7353064",
+  "testERC20Transfer_batch100_IthacaAccount": "7549092",
+  "testERC20Transfer_batch100_IthacaAccount_AppSponsor": "8152996",
+  "testERC20Transfer_batch100_IthacaAccount_AppSponsor_ERC20": "7979008",
+  "testERC20Transfer_batch100_IthacaAccount_ERC20SelfPay": "7370352",
   "testERC20Transfer_batch100_ZerodevKernel": "12631318",
   "testERC20Transfer_batch100_ZerodevKernel_ERC20SelfPay": "14149937",
   "testNativeTransfer_AlchemyModularAccount": "180829",
   "testNativeTransfer_CoinbaseSmartWallet": "178916",
-  "testNativeTransfer_IthacaAccount": "129415",
-  "testNativeTransfer_IthacaAccount_AppSponsor": "139982",
-  "testNativeTransfer_IthacaAccount_ERC20SelfPay": "137204",
+  "testNativeTransfer_IthacaAccount": "129588",
+  "testNativeTransfer_IthacaAccount_AppSponsor": "140111",
+  "testNativeTransfer_IthacaAccount_ERC20SelfPay": "137377",
   "testNativeTransfer_Safe4337": "198595",
   "testNativeTransfer_ZerodevKernel": "208635",
   "testUniswapV2Swap_AlchemyModularAccount": "238647",
   "testUniswapV2Swap_CoinbaseSmartWallet": "237451",
   "testUniswapV2Swap_ERC4337MinimalAccount": "230691",
-  "testUniswapV2Swap_IthacaAccount": "187179",
-  "testUniswapV2Swap_IthacaAccount_AppSponsor": "197691",
-  "testUniswapV2Swap_IthacaAccount_ERC20SelfPay": "192480",
+  "testUniswapV2Swap_IthacaAccount": "187376",
+  "testUniswapV2Swap_IthacaAccount_AppSponsor": "197832",
+  "testUniswapV2Swap_IthacaAccount_ERC20SelfPay": "192665",
   "testUniswapV2Swap_Safe4337": "257333",
   "testUniswapV2Swap_ZerodevKernel": "266367"
 }

src/IthacaAccount.sol

@@ -92,6 +92,8 @@ contract IthacaAccount is IIthacaAccount, EIP712, GuardedExecutor {
         mapping(bytes32 => LibStorage.Bump) keyExtraStorage;
         /// @dev Nonce management when porto account acts as paymaster.
         mapping(bytes32 => bool) paymasterNonces;
+        /// @dev Mapping of approved spends to their IDs
+        mapping(uint256 => Spend) spends;
     }
 
     /// @dev Returns the storage pointer.
@@ -139,6 +141,9 @@ contract IthacaAccount is IIthacaAccount, EIP712, GuardedExecutor {
     /// @dev The paymaster nonce has already been used.
     error PaymasterNonceError();
 
+    /// @dev The spend has expired.
+    error Expired();
+
     ////////////////////////////////////////////////////////////////////////
     // Events
     ////////////////////////////////////////////////////////////////////////
@@ -592,6 +597,80 @@ contract IthacaAccount is IIthacaAccount, EIP712, GuardedExecutor {
         if (!$.keyHashes.remove(keyHash)) revert KeyDoesNotExist();
     }
 
+    ////////////////////////////////////////////////////////////////////////
+    // Spend/SubAccount Functions
+    ////////////////////////////////////////////////////////////////////////
+
+    struct Spend {
+        /// @dev If the spender is a parent, then it can sweep ALL funds from the account.
+        bool isParent;
+        /// @dev The expiry of the spend.
+        uint32 expiry;
+        /// @dev The `msg.sender` which is calling spend.
+        address spender;
+        /// @dev Mapping of tokens to their spending limits.
+        mapping(address token => uint256 limit) limits;
+    }
+
+    /// @dev This function can be used to give safe spending permissions to any entity.
+    /// In the `parentAccount` <> `subAccount` architecture, this function is used for -
+    /// * In the parent account, subaccounts can use this function to JIT pull funds.
+    /// * In the sub account, parent accounts can use this function to sweep back leftover funds.
+    /// Note: This spend function only supports ERC20 tokens.
+    /// We will have to create a spend function for all types of tokens we want to support.
+    function spend(
+        uint256 spendId,
+        address[] calldata tokens,
+        uint256[] calldata amounts,
+        address recipient
+    ) public payable virtual {
+        Spend storage _spend = _getAccountStorage().spends[spendId];
+
+        // Spend can only be called by the authorized spender
+        if (msg.sender != _spend.spender) {
+            revert Unauthorized();
+        }
+
+        // If the spender is a parent, then it can sweep any amount of funds from the account.
+        if (_spend.isParent) {
+            for (uint256 i = 0; i < tokens.length; i++) {
+                TokenTransferLib.safeTransfer(tokens[i], recipient, amounts[i]);
+            }
+        } else {
+            if (block.timestamp > _spend.expiry) {
+                revert Expired();
+            }
+
+            for (uint256 i = 0; i < tokens.length; i++) {
+                address token = tokens[i];
+                // Ensure that the spending is within the specified limits
+                _spend.limits[token] -= amounts[i];
+
+                TokenTransferLib.safeTransfer(token, recipient, amounts[i]);
+            }
+        }
+    }
+
+    /// @dev Sets the spend for the `spendId`.
+    /// Note: Values are overridden for existing spends, instead of adding.
+    function setSpend(
+        uint256 spendId,
+        bool isParent,
+        uint32 expiry,
+        address spender,
+        address[] calldata tokens,
+        uint256[] calldata limits
+    ) public virtual onlyThis {
+        Spend storage _spend = _getAccountStorage().spends[spendId];
+
+        _spend.isParent = isParent;
+        _spend.expiry = expiry;
+        _spend.spender = spender;
+        for (uint256 i = 0; i < tokens.length; i++) {
+            _spend.limits[tokens[i]] = limits[i];
+        }
+    }
+
     ////////////////////////////////////////////////////////////////////////
     // Orchestrator Functions
     ////////////////////////////////////////////////////////////////////////
@@ -755,6 +834,6 @@ contract IthacaAccount is IIthacaAccount, EIP712, GuardedExecutor {
         returns (string memory name, string memory version)
     {
         name = "IthacaAccount";
-        version = "0.5.10";
+        version = "0.5.11";
     }
 }