Merge pull request #7 from enviodev/decoder-example

 Add an example of decoding transfer events using the built-in decoder.

examples/erc721_events_decoded.go

@@ -0,0 +1,109 @@
+package main
+
+/*
+ This is a fun example of decoding ERC721 events with the built-in decoder.  We use the Clovers.network contracts as an example, which are tokens that are minted by players who work out a symetric othelo game. View more at https://clovers.network
+*/
+import (
+	"context"
+	"fmt"
+	"math/big"
+	"time"
+
+	hypersyncgo "github.com/enviodev/hypersync-client-go"
+	"github.com/enviodev/hypersync-client-go/contracts"
+	"github.com/enviodev/hypersync-client-go/decoder"
+	"github.com/enviodev/hypersync-client-go/logger"
+	"github.com/enviodev/hypersync-client-go/options"
+	"github.com/enviodev/hypersync-client-go/types"
+	"github.com/enviodev/hypersync-client-go/utils"
+	"github.com/ethereum/go-ethereum/common"
+	"go.uber.org/zap"
+)
+
+func main() {
+	opts := options.Options{
+		Blockchains: []options.Node{
+			{
+				Type:        utils.EthereumNetwork,
+				NetworkId:   utils.EthereumNetworkID,
+				Endpoint:    "https://eth.hypersync.xyz",
+				RpcEndpoint: "https://eth.rpc.hypersync.xyz",
+			},
+		},
+	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	hsClient, err := hypersyncgo.NewHyper(ctx, opts)
+	if err != nil {
+		logger.L().Error("failed to create hyper client", zap.Error(err))
+		return
+	}
+
+	client, found := hsClient.GetClient(utils.EthereumNetworkID)
+	if !found {
+		logger.L().Error("failure to discover hyper client", zap.Error(err))
+		return
+	}
+
+	startBlock := big.NewInt(20000000)
+	endBlock := big.NewInt(20865800)
+
+	logger.L().Info("Fetching USDC transfer logs", zap.Any("start_block", startBlock), zap.Any("end_block", endBlock))
+
+	// Clovers Transfer event signature: Transfer(address,address,uint256)
+	selections := []types.LogSelection{
+		{
+			Address: []common.Address{common.HexToAddress("0xB55C5cAc5014C662fDBF21A2C59Cd45403C482Fd")}, // Clovers contract address
+			Topics: [][]common.Hash{
+				{common.HexToHash("0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef")}, // Transfer event signature
+			},
+		},
+	}
+
+	batchSize := big.NewInt(50)
+	bStream, bsErr := client.StreamLogsInRange(ctx, startBlock, endBlock, selections, options.DefaultStreamOptionsWithBatchSize(batchSize))
+	if bsErr != nil {
+		logger.L().Error("failure to execute hyper client stream in range", zap.Error(bsErr))
+		return
+	}
+
+	// Load contracts manager to decode logs
+	cManager, cErr := contracts.NewManagerWithDefaults()
+	if cErr != nil {
+		logger.L().Error("failed to load contracts manager", zap.Error(cErr))
+		return
+	}
+
+	contract, cdErr := cManager.GetByStandard(utils.EthereumNetworkID, utils.Erc721)
+	if cdErr != nil {
+		logger.L().Error("failed to get ERC721 interface for Clovers contract", zap.Error(cdErr))
+		return
+	}
+
+	for {
+		select {
+		case cErr := <-bStream.Err():
+			logger.L().Error("stream error", zap.Error(cErr))
+			return
+		case response := <-bStream.Channel():
+			for _, log := range response.GetLogs() {
+				dLog, dlErr := decoder.DecodeEthereumLogWithContract(log, contract)
+				if dlErr != nil {
+					logger.L().Error("failed to decode log", zap.Error(dlErr))
+					continue
+				}
+
+				fmt.Printf("Decoded Clovers event: %+v\n", dLog)
+			}
+			bStream.Ack()
+		case <-bStream.Done():
+			logger.L().Info("Stream request successfully completed")
+			return
+		case <-time.After(15 * time.Second):
+			logger.L().Error("Timeout: no logs received in the last 15s")
+			return
+		}
+	}
+}