implement OutputV0AtBlock

engine/engine.go

@@ -34,13 +34,27 @@ func (e *ExChainAPI) BlockRefByNumber(ctx context.Context, num uint64) (eth.Bloc
 }
 
 func (e *ExChainAPI) FetchReceipts(ctx context.Context, blockHash common.Hash) (eth.BlockInfo, types.Receipts, error) {
-	//TODO implement me
-	panic("implement me")
+	return nil, nil, errors.New("FetchReceipts is not implemented in exchain currently")
 }
 
 func (e *ExChainAPI) OutputV0AtBlock(ctx context.Context, blockHash common.Hash) (*eth.OutputV0, error) {
-	//TODO implement me
-	panic("implement me")
+	blk := e.chain.BlockByHash(blockHash)
+	if blk == nil {
+		return nil, errors.New("block not found in exchain")
+	}
+	wblk := wrapper.NewBlkWrapper(blk)
+	root := eth.Bytes32{}
+	storageRoot := eth.Bytes32{}
+
+	// todo: vicotor implement this.
+	copy(root[:], wblk.Header().AppRoot)
+	copy(storageRoot[:], wblk.Header().AppRoot)
+
+	return &eth.OutputV0{
+		BlockHash:                wblk.Hash(),
+		StateRoot:                root,
+		MessagePasserStorageRoot: storageRoot,
+	}, nil
 }
 
 func (e *ExChainAPI) GetPayload(id eth.PayloadInfo) (*eth.ExecutionPayloadEnvelope, error) {