fix: Make permit2 permit an action in the universal router

--- don't change below this line ---
ENG-4286 Took 1 hour 35 minutes

foundry/test/GasTest.t.sol

@@ -11,11 +11,13 @@ import {IERC20} from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
 import {Currency} from "../lib/v4-core/src/types/Currency.sol";
 import {IHooks} from "../lib/v4-core/src/interfaces/IHooks.sol";
 import "forge-std/Test.sol";
+import "@permit2/src/interfaces/IAllowanceTransfer.sol";
 
 contract Commands {
     uint256 constant V2_SWAP_EXACT_IN = 0x08;
     uint256 constant V3_SWAP_EXACT_IN = 0x00;
     uint256 constant V4_SWAP = 0x10;
+    uint256 constant PERMIT2_PERMIT = 0x0a;
 }
 
 // A gas test to compare the gas usage of the UniversalRouter with the TychoRouter
@@ -51,24 +53,26 @@ contract GasTest is Commands, Test, Constants {
         bool isPermit2 = true;
         uint256 amountIn = 10 ** 18;
 
-        bytes memory commands =
+        bytes memory commands = abi.encodePacked(
-            abi.encodePacked(uint8(Commands.V2_SWAP_EXACT_IN));
+            uint8(Commands.PERMIT2_PERMIT), uint8(Commands.V2_SWAP_EXACT_IN)
+        );
+
+        vm.startPrank(ALICE);
+        (
+            IAllowanceTransfer.PermitSingle memory permitSingle,
+            bytes memory signature
+        ) = handlePermit2Approval(WETH_ADDR, amountIn);
 
         address[] memory path = new address[](2);
         path[0] = WETH_ADDR;
         path[1] = DAI_ADDR;
 
-        bytes[] memory inputs = new bytes[](1);
+        bytes[] memory inputs = new bytes[](2);
-        inputs[0] = abi.encode(BOB, amountIn, uint256(0), path, isPermit2);
+        inputs[0] = abi.encode(permitSingle, signature);
+        inputs[1] = abi.encode(ALICE, amountIn, uint256(0), path, isPermit2);
+
+        deal(WETH_ADDR, ALICE, amountIn);
 
-        deal(WETH_ADDR, address(this), amountIn);
-        IERC20(WETH_ADDR).approve(PERMIT2_ADDRESS, amountIn);
-        permit2.approve(
-            WETH_ADDR,
-            address(universalRouter),
-            uint160(amountIn),
-            uint48(block.timestamp + 1000)
-        );
         universalRouter.execute(commands, inputs, block.timestamp + 1000);
     }
 
@@ -93,23 +97,25 @@ contract GasTest is Commands, Test, Constants {
         bool isPermit2 = true;
         uint256 amountIn = 10 ** 18;
 
-        bytes memory commands =
+        bytes memory commands = abi.encodePacked(
-            abi.encodePacked(uint8(Commands.V3_SWAP_EXACT_IN));
+            uint8(Commands.PERMIT2_PERMIT), uint8(Commands.V3_SWAP_EXACT_IN)
+        );
+
+        vm.startPrank(ALICE);
+        (
+            IAllowanceTransfer.PermitSingle memory permitSingle,
+            bytes memory signature
+        ) = handlePermit2Approval(WETH_ADDR, amountIn);
 
         uint24 poolFee = 3000;
         bytes memory path = abi.encodePacked(WETH_ADDR, poolFee, DAI_ADDR);
 
-        bytes[] memory inputs = new bytes[](1);
+        bytes[] memory inputs = new bytes[](2);
-        inputs[0] = abi.encode(BOB, amountIn, uint256(0), path, isPermit2);
+        inputs[0] = abi.encode(permitSingle, signature);
+        inputs[1] = abi.encode(ALICE, amountIn, uint256(0), path, isPermit2);
+
+        deal(WETH_ADDR, ALICE, amountIn);
 
-        deal(WETH_ADDR, address(this), amountIn);
-        IERC20(WETH_ADDR).approve(PERMIT2_ADDRESS, amountIn);
-        permit2.approve(
-            WETH_ADDR,
-            address(universalRouter),
-            uint160(amountIn),
-            uint48(block.timestamp + 1000)
-        );
         universalRouter.execute(commands, inputs, block.timestamp + 1000);
     }
 
@@ -118,7 +124,9 @@ contract GasTest is Commands, Test, Constants {
         uint128 amountOutMinimum = uint128(0);
         uint256 deadline = block.timestamp + 1000;
 
-        bytes memory commands = abi.encodePacked(uint8(Commands.V4_SWAP));
+        bytes memory commands = abi.encodePacked(
+            uint8(Commands.PERMIT2_PERMIT), uint8(Commands.V4_SWAP)
+        );
 
         bytes memory actions = abi.encodePacked(
             uint8(Actions.SWAP_EXACT_IN_SINGLE),
@@ -126,6 +134,12 @@ contract GasTest is Commands, Test, Constants {
             uint8(Actions.TAKE_ALL)
         );
 
+        vm.startPrank(ALICE);
+        (
+            IAllowanceTransfer.PermitSingle memory permitSingle,
+            bytes memory signature
+        ) = handlePermit2Approval(USDE_ADDR, amountIn);
+
         PoolKey memory key = PoolKey({
             currency0: Currency.wrap(USDE_ADDR),
             currency1: Currency.wrap(USDT_ADDR),
@@ -148,14 +162,71 @@ contract GasTest is Commands, Test, Constants {
         params[1] = abi.encode(key.currency0, amountIn);
         params[2] = abi.encode(key.currency1, amountOutMinimum);
 
-        bytes[] memory inputs = new bytes[](1);
+        bytes[] memory inputs = new bytes[](2);
-        inputs[0] = abi.encode(actions, params);
+        inputs[0] = abi.encode(permitSingle, signature);
+        inputs[1] = abi.encode(actions, params);
+
+        deal(USDE_ADDR, ALICE, amountIn);
 
-        deal(USDE_ADDR, address(this), amountIn);
-        IERC20(USDE_ADDR).approve(PERMIT2_ADDRESS, amountIn);
-        permit2.approve(
-            USDE_ADDR, address(universalRouter), amountIn, uint48(deadline)
-        );
         universalRouter.execute(commands, inputs, deadline);
     }
+
+    function handlePermit2Approval(address tokenIn, uint256 amount_in)
+        internal
+        returns (IAllowanceTransfer.PermitSingle memory, bytes memory)
+    {
+        IERC20(tokenIn).approve(PERMIT2_ADDRESS, amount_in);
+        IAllowanceTransfer.PermitSingle memory permitSingle = IAllowanceTransfer
+            .PermitSingle({
+            details: IAllowanceTransfer.PermitDetails({
+                token: tokenIn,
+                amount: uint160(amount_in),
+                expiration: uint48(block.timestamp + 1 days),
+                nonce: 0
+            }),
+            spender: UNIVERSAL_ROUTER,
+            sigDeadline: block.timestamp + 1 days
+        });
+
+        bytes memory signature = signPermit2(permitSingle, ALICE_PK);
+        return (permitSingle, signature);
+    }
+
+    function signPermit2(
+        IAllowanceTransfer.PermitSingle memory permit,
+        uint256 privateKey
+    ) internal view returns (bytes memory) {
+        bytes32 _PERMIT_DETAILS_TYPEHASH = keccak256(
+            "PermitDetails(address token,uint160 amount,uint48 expiration,uint48 nonce)"
+        );
+        bytes32 _PERMIT_SINGLE_TYPEHASH = keccak256(
+            "PermitSingle(PermitDetails details,address spender,uint256 sigDeadline)PermitDetails(address token,uint160 amount,uint48 expiration,uint48 nonce)"
+        );
+        bytes32 domainSeparator = keccak256(
+            abi.encode(
+                keccak256(
+                    "EIP712Domain(string name,uint256 chainId,address verifyingContract)"
+                ),
+                keccak256("Permit2"),
+                block.chainid,
+                PERMIT2_ADDRESS
+            )
+        );
+        bytes32 detailsHash =
+            keccak256(abi.encode(_PERMIT_DETAILS_TYPEHASH, permit.details));
+        bytes32 permitHash = keccak256(
+            abi.encode(
+                _PERMIT_SINGLE_TYPEHASH,
+                detailsHash,
+                permit.spender,
+                permit.sigDeadline
+            )
+        );
+
+        bytes32 digest =
+            keccak256(abi.encodePacked("\x19\x01", domainSeparator, permitHash));
+        (uint8 v, bytes32 r, bytes32 s) = vm.sign(privateKey, digest);
+
+        return abi.encodePacked(r, s, v);
+    }
 }