Backfill Frob log events

pkg/transformers/shared/fetcher.go

@@ -0,0 +1,51 @@
+// Copyright 2018 Vulcanize
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package shared
+
+import (
+	"math/big"
+
+	"github.com/ethereum/go-ethereum"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/types"
+
+	"github.com/vulcanize/vulcanizedb/pkg/core"
+)
+
+type LogFetcher interface {
+	FetchLogs(contractAddress string, topics [][]common.Hash, blockNumber int64) ([]types.Log, error)
+}
+
+type Fetcher struct {
+	blockChain core.BlockChain
+}
+
+func NewFetcher(blockchain core.BlockChain) Fetcher {
+	return Fetcher{
+		blockChain: blockchain,
+	}
+}
+
+func (fetcher Fetcher) FetchLogs(contractAddress string, topics [][]common.Hash, blockNumber int64) ([]types.Log, error) {
+	block := big.NewInt(blockNumber)
+	address := common.HexToAddress(contractAddress)
+	query := ethereum.FilterQuery{
+		FromBlock: block,
+		ToBlock:   block,
+		Addresses: []common.Address{address},
+		Topics:    topics,
+	}
+	return fetcher.blockChain.GetEthLogsWithCustomQuery(query)
+}