[OP] - Aligning OpStackParentHashesFetcher with the latest Optimism stack

src/core/x-rollup-messaging/parent-hashes-fetchers/OpStackParentHashesFetcher.sol

@@ -2,18 +2,22 @@
 pragma solidity ^0.8.19;
 
 import {IParentHashFetcher} from "../interfaces/IParentHashFetcher.sol";
-import {IL2OutputOracle} from "./interfaces/IL2OutputOracle.sol";
+import {IDisputeGameFactory} from "./interfaces/IDisputeGameFactory.sol";
+import {DisputeGameStatus} from "../../lib/Types.sol";
+import {GameType} from "../../lib/Types.sol";
 
 /// @title OpStackParentHashesFetcher
 /// @notice Fetches parent hashes for the an OP stack based chain, settling to the chain where this contract is deployed
 /// @notice for example if deployed on Ethereum, it will fetch parent hashes for Optimism/Base
 contract OpStackParentHashesFetcher is IParentHashFetcher {
-    IL2OutputOracle public immutable l2OutputOracle;
+    IDisputeGameFactory public immutable disputeGameFactory;
     uint256 public immutable chainId;
+    GameType public immutable respectedGameType;
 
-    constructor(IL2OutputOracle _l2OutputOracle, uint256 _chainId) {
-        l2OutputOracle = _l2OutputOracle;
+    constructor(IDisputeGameFactory _disputeGameFactory, uint256 _chainId, GameType _respectedGameType) {
+        disputeGameFactory = _disputeGameFactory;
         chainId = _chainId;
+        respectedGameType = _respectedGameType;
     }
 
     function fetchParentHash(bytes memory ctx)
@@ -22,20 +26,31 @@ contract OpStackParentHashesFetcher is IParentHashFetcher {
         override
         returns (uint256 fetchedForBlock, bytes32 parentHash)
     {
-        (uint256 l2OutputIndex, bytes memory outputRootPreimage) = abi.decode(ctx, (uint256, bytes));
-        IL2OutputOracle.OutputProposal memory outputProposal = l2OutputOracle.getL2Output(l2OutputIndex);
+        (uint256 startSearchGameIndex, bytes memory outputRootPreimage) = abi.decode(ctx, (uint256, bytes));
+
+        // Fetch the latest dispute game
+        IDisputeGameFactory.GameSearchResult memory game = disputeGameFactory.findLatestGames(
+            respectedGameType,
+            startSearchGameIndex,
+            1
+        )[0];
+
+        require(game.metadata != bytes32(0), "ERR_GAME_NOT_FOUND");
+        require(game.status == DisputeGameStatus.DEFENDER_WINS, "ERR_GAME_NOT_RESOLVED");
 
         // To see the preimage structure and why it is valid, see:
         // https://github.com/ethereum-optimism/optimism/blob/c24298e798f40003f752d12710aa1cad63ad66d1/packages/contracts-bedrock/src/libraries/Hashing.sol#L114
         // https://github.com/ethereum-optimism/optimism/blob/c24298e798f40003f752d12710aa1cad63ad66d1/packages/contracts-bedrock/src/libraries/Types.sol#L25
 
         // Ensure that the passed preimage matches the output proposal root
-        require(outputProposal.outputRoot == keccak256(outputRootPreimage), "ERR_INVALID_OUTPUT_PROPOSAL");
+        require(game.rootClaim == keccak256(outputRootPreimage), "ERR_INVALID_OUTPUT_PROPOSAL");
+
 
         // Decode the values from the preimage
         (,,, bytes32 latestBlockhash) = abi.decode(outputRootPreimage, (bytes32, bytes32, bytes32, bytes32));
-
-        fetchedForBlock = outputProposal.l2BlockNumber + 1;
+
+        // The block number is encoded in the game metadata
+        fetchedForBlock = uint256(uint160(bytes20(game.metadata))) + 1;
         parentHash = latestBlockhash;
     }
 }

src/core/x-rollup-messaging/parent-hashes-fetchers/interfaces/IDisputeGameFactory.sol

@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0
+pragma solidity ^0.8.19;
+
+import {GameType} from "../../../lib/Types.sol";
+import {DisputeGameStatus} from "../../../lib/Types.sol";
+
+interface IDisputeGameFactory {
+    struct GameSearchResult {
+        uint256 index;
+        bytes32 metadata;
+        uint64 timestamp;
+        bytes32 rootClaim;
+        bytes extraData;
+        DisputeGameStatus status;
+    }
+
+    function findLatestGames(
+        GameType gameType,
+        uint256 start,
+        uint256 n
+    ) external view returns (GameSearchResult[] memory games);
+}

src/lib/Types.sol

@@ -18,4 +18,12 @@ library Types {
         STORAGE_ROOT,
         CODE_HASH
     }
+
+    enum DisputeGameStatus {
+        IN_PROGRESS,
+        CHALLENGER_WINS,
+        DEFENDER_WINS
+    }
+
+    type GameType is uint32;
 }