forked from cerc-io/ipld-eth-server
55 lines
1.3 KiB
Go
55 lines
1.3 KiB
Go
package pep
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import (
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"errors"
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"github.com/ethereum/go-ethereum"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/core/types"
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"github.com/vulcanize/vulcanizedb/pkg/core"
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"math/big"
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)
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var (
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ErrMultipleLogs = errors.New("multiple matching logs found in block")
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ErrNoMatchingLog = errors.New("no matching log")
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)
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type IPepFetcher interface {
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FetchPepValue(header core.Header) (string, error)
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}
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type PepFetcher struct {
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blockChain core.BlockChain
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}
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func NewPepFetcher(chain core.BlockChain) PepFetcher {
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return PepFetcher{
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blockChain: chain,
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}
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}
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func (fetcher PepFetcher) FetchPepValue(header core.Header) (string, error) {
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blockNumber := big.NewInt(header.BlockNumber)
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query := ethereum.FilterQuery{
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FromBlock: blockNumber,
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ToBlock: blockNumber,
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Addresses: []common.Address{common.HexToAddress(PepAddress)},
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Topics: [][]common.Hash{{common.HexToHash(LogValueTopic0)}},
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}
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logs, err := fetcher.blockChain.GetEthLogsWithCustomQuery(query)
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return fetcher.getLogValue(logs, err)
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}
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func (fetcher PepFetcher) getLogValue(logs []types.Log, err error) (string, error) {
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if err != nil {
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return "", err
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}
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if len(logs) < 1 {
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return "", ErrNoMatchingLog
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}
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if len(logs) > 1 {
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return "", ErrMultipleLogs
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}
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return string(logs[0].Data), nil
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}
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