receipts: add new FetchReceiptTokenTransfers method to fetch and decode logs

Author: pkieltyka

receipts/token_transfers.go

@@ -0,0 +1,99 @@
+package receipts
+
+import (
+	"context"
+	"math/big"
+
+	"github.com/0xsequence/ethkit/ethrpc"
+	"github.com/0xsequence/ethkit/go-ethereum/common"
+	"github.com/0xsequence/ethkit/go-ethereum/core/types"
+	"github.com/0xsequence/go-sequence/contracts/gen/tokens"
+)
+
+// FetchReceiptTokenTransfers fetches the transaction receipt for the given transaction hash
+// and decodes any token transfer events (ERC20) that occurred within that transaction. TODOXXX: we
+// currently only support ERC20 token transfers, but we can extend this to support ERC721 and ERC1155 as well.
+func FetchReceiptTokenTransfers(ctx context.Context, provider *ethrpc.Provider, transactionHash common.Hash) (*types.Receipt, TokenTransfers, error) {
+	receipt, err := provider.TransactionReceipt(ctx, transactionHash)
+	if err != nil {
+		return nil, nil, err
+	}
+	if receipt == nil {
+		return nil, nil, nil
+	}
+
+	transferTopic := common.HexToHash("0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef")
+	polLogTransferTopic := common.HexToHash("0xe6497e3ee548a3372136af2fcb0696db31fc6cf20260707645068bd3fe97f3c4")
+
+	var decoded []*TokenTransfer
+
+	for _, log := range receipt.Logs {
+		if len(log.Topics) == 0 {
+			continue
+		}
+		if log.Topics[0] != transferTopic && log.Topics[0] != polLogTransferTopic {
+			continue
+		}
+
+		if log.Topics[0] == transferTopic {
+			filterer, err := tokens.NewIERC20Filterer(log.Address, provider)
+			if err == nil {
+				if ev, err := filterer.ParseTransfer(*log); err == nil && ev != nil {
+					decoded = append(decoded, &TokenTransfer{From: ev.From, To: ev.To, Value: ev.Value, Raw: *log})
+					continue
+				}
+			}
+		}
+
+		// TODO: need to try all of the various versions of this.. and we may as well support ERC721 and ERC1155 too
+		// note: "indexed" args, etc.
+
+		if len(log.Topics) >= 3 {
+			from := common.BytesToAddress(log.Topics[1].Bytes())
+			to := common.BytesToAddress(log.Topics[2].Bytes())
+			value := new(big.Int).SetBytes(log.Data)
+			decoded = append(decoded, &TokenTransfer{From: from, To: to, Value: value, Raw: *log})
+		}
+	}
+
+	return receipt, decoded, nil
+}
+
+type TokenTransfer struct {
+	From  common.Address
+	To    common.Address
+	Value *big.Int
+	Raw   types.Log
+}
+
+type TokenTransfers []*TokenTransfer
+
+func (t TokenTransfers) FilterTokenTransfersByContractAddress(ctx context.Context, contract common.Address) TokenTransfers {
+	var out TokenTransfers
+	for _, transfer := range t {
+		if transfer.Raw.Address == contract {
+			out = append(out, transfer)
+		}
+	}
+	return out
+}
+
+func (t TokenTransfers) FilterTokenTransfersByFromAddress(ctx context.Context, from common.Address) TokenTransfers {
+	var out TokenTransfers
+	for _, transfer := range t {
+		if transfer.From == from {
+			out = append(out, transfer)
+		}
+	}
+	return out
+}
+
+func (t TokenTransfers) FilterTokenTransfersByToAddress(ctx context.Context, to common.Address) TokenTransfers {
+	var out TokenTransfers
+	for _, transfer := range t {
+		if transfer.To == to {
+			out = append(out, transfer)
+		}
+	}
+	return out
+}

receipts/token_transfers_test.go

@@ -0,0 +1,27 @@
+package receipts_test
+
+import (
+	"context"
+	"testing"
+
+	"github.com/0xsequence/ethkit/ethrpc"
+	"github.com/0xsequence/ethkit/go-ethereum/common"
+	"github.com/0xsequence/go-sequence/receipts"
+	"github.com/davecgh/go-spew/spew"
+	"github.com/stretchr/testify/require"
+)
+
+func TestFetchReceiptTokenTransfers(t *testing.T) {
+	// txnHash := https://polygonscan.com/tx/0x252419983224542bfb07dab75808fa57186a7a269d0d267ae655eb7ef037fdd5
+	provider, err := ethrpc.NewProvider("https://nodes.sequence.app/polygon")
+	require.NoError(t, err)
+
+	txnHash := common.HexToHash("0x252419983224542bfb07dab75808fa57186a7a269d0d267ae655eb7ef037fdd5")
+
+	receipt, transfers, err := receipts.FetchReceiptTokenTransfers(context.Background(), provider, txnHash)
+	require.NoError(t, err)
+	require.NotNil(t, receipt)
+	require.Greater(t, len(transfers), 0)
+
+	spew.Dump(transfers)
+}