middleware factory interface

contracts/hooks/middleware/MiddlewareRemove.sol

@@ -11,6 +11,7 @@ import {Proxy} from "@openzeppelin/contracts/proxy/Proxy.sol";
 import {BaseMiddleware} from "./BaseMiddleware.sol";
 import {BaseHook} from "../../BaseHook.sol";
 import {console} from "../../../lib/forge-std/src/console.sol";
+import {BalanceDeltaLibrary} from "@uniswap/v4-core/src/types/BalanceDelta.sol";
 
 contract MiddlewareRemove is BaseMiddleware {
     bytes internal constant ZERO_BYTES = bytes("");
@@ -40,6 +41,7 @@ contract MiddlewareRemove is BaseMiddleware {
         console.log("afterRemoveLiquidity middleware");
         (bool success, bytes memory returnData) = implementation.delegatecall{gas: gasLimit}(msg.data);
         console.log(success);
-        return BaseHook.afterRemoveLiquidity.selector;
+        // hook cannot return delta
+        return (BaseHook.afterRemoveLiquidity.selector, BalanceDeltaLibrary.ZERO_DELTA);
     }
 }

contracts/interfaces/IMiddlewareFactory.sol

@@ -1,62 +1,16 @@
 // SPDX-License-Identifier: UNLICENSED
 pragma solidity ^0.8.19;
 
-interface IUniswapV3Factory {
-    event MiddlewareCreated(
-        address implementation,
-        address middleware
-    );
+interface IMiddlewareFactory {
+    event MiddlewareCreated(address implementation, address middleware);
 
-    /// @notice Emitted when a new fee amount is enabled for middleware creation via the factory
-    /// @param fee The enabled fee, denominated in hundredths of a bip
-    /// @param tickSpacing The minimum number of ticks between initialized ticks for middlewares created with the given fee
-    event FeeAmountEnabled(uint24 indexed fee, int24 indexed tickSpacing);
+    /// @notice Returns the implementation address for a given middleware
+    /// @param middleware The middleware address
+    /// @return implementation The implementation address
+    function getImplementation(address middleware) external view returns (address implementation);
 
-    /// @notice Returns the current owner of the factory
-    /// @dev Can be changed by the current owner via setOwner
-    /// @return The address of the factory owner
-    function owner() external view returns (address);
-
-    /// @notice Returns the tick spacing for a given fee amount, if enabled, or 0 if not enabled
-    /// @dev A fee amount can never be removed, so this value should be hard coded or cached in the calling context
-    /// @param fee The enabled fee, denominated in hundredths of a bip. Returns 0 in case of unenabled fee
-    /// @return The tick spacing
-    function feeAmountTickSpacing(uint24 fee) external view returns (int24);
-
-    /// @notice Returns the middleware address for a given pair of tokens and a fee, or address 0 if it does not exist
-    /// @dev tokenA and tokenB may be passed in either token0/token1 or token1/token0 order
-    /// @param tokenA The contract address of either token0 or token1
-    /// @param tokenB The contract address of the other token
-    /// @param fee The fee collected upon every swap in the middleware, denominated in hundredths of a bip
-    /// @return middleware The middleware address
-    function getMiddleware(
-        address tokenA,
-        address tokenB,
-        uint24 fee
-    ) external view returns (address middleware);
-
-    /// @notice Creates a middleware for the given two tokens and fee
-    /// @param tokenA One of the two tokens in the desired middleware
-    /// @param tokenB The other of the two tokens in the desired middleware
-    /// @param fee The desired fee for the middleware
-    /// @dev tokenA and tokenB may be passed in either order: token0/token1 or token1/token0. tickSpacing is retrieved
-    /// from the fee. The call will revert if the middleware already exists, the fee is invalid, or the token arguments
-    /// are invalid.
+    /// @notice Creates a middleware for the given implementation
+    /// @param implementation The implementation address
     /// @return middleware The address of the newly created middleware
-    function createMiddleware(
-        address tokenA,
-        address tokenB,
-        uint24 fee
-    ) external returns (address middleware);
-
-    /// @notice Updates the owner of the factory
-    /// @dev Must be called by the current owner
-    /// @param _owner The new owner of the factory
-    function setOwner(address _owner) external;
-
-    /// @notice Enables a fee amount with the given tickSpacing
-    /// @dev Fee amounts may never be removed once enabled
-    /// @param fee The fee amount to enable, denominated in hundredths of a bip (i.e. 1e-6)
-    /// @param tickSpacing The spacing between ticks to be enforced for all middlewares created with the given fee amount
-    function enableFeeAmount(uint24 fee, int24 tickSpacing) external;
-}
+    function createMiddleware(address implementation) external returns (address middleware);
+}