feat: implement handler interface, add example emitter (stdout)

internal/chain/revert.go

@@ -5,51 +5,8 @@ import (
 	"math/big"
 
 	"github.com/celo-org/celo-blockchain/common"
-	"github.com/celo-org/celo-blockchain/core/types"
-	"github.com/grassrootseconomics/w3-celo"
-	"github.com/grassrootseconomics/w3-celo/module/eth"
 )
 
 func (c *Chain) GetRevertReason(ctx context.Context, txHash common.Hash, blockNumber *big.Int) (string, error) {
 	return c.provider.SimulateRevertedTx(ctx, txHash, blockNumber)
 }
-
-func (c *Chain) TestDecodeTransfer(ctx context.Context, logs []*types.Log) {
-	signature := "Transfer(address indexed _from, address indexed _to, uint256 _value)"
-
-	eventTransfer := w3.MustNewEvent(signature)
-
-	for _, log := range logs {
-		if log.Topics[0] == w3.H("0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef") {
-			var (
-				from  common.Address
-				to    common.Address
-				value big.Int
-
-				tokenSymbol   string
-				tokenDecimals big.Int
-			)
-
-			if err := c.provider.Client.CallCtx(
-				ctx,
-				eth.CallFunc(log.Address, w3.MustNewFunc("symbol()", "string")).Returns(&tokenSymbol),
-				eth.CallFunc(log.Address, w3.MustNewFunc("decimals()", "uint256")).Returns(&tokenDecimals),
-			); err != nil {
-				c.logg.Error("token details fetcher", "error", err)
-			}
-
-			if err := eventTransfer.DecodeArgs(log, &from, &to, &value); err != nil {
-				c.logg.Error("event decoder", "error", err)
-			}
-
-			c.logg.Info("transfer event",
-				"hash", log.TxHash,
-				"token", tokenSymbol,
-				"from", from,
-				"to", to,
-				"value", value.Uint64(),
-			)
-		}
-	}
-
-}

internal/emitter/emitter.go

@@ -0,0 +1,15 @@
+package emitter
+
+import (
+	"log/slog"
+
+	"github.com/grassrootseconomics/celo-tracker/internal/handler"
+)
+
+func New(logg *slog.Logger) handler.EmitterEmitFunc {
+	stdOutEmitter := &LogEmitter{
+		logg: logg,
+	}
+
+	return stdOutEmitter.Emit
+}

internal/emitter/stdout.go

@@ -0,0 +1,24 @@
+package emitter
+
+import (
+	"context"
+	"encoding/json"
+	"log/slog"
+)
+
+type (
+	LogEmitter struct {
+		logg *slog.Logger
+	}
+)
+
+func (l *LogEmitter) Emit(_ context.Context, payload []byte) error {
+	var event map[string]interface{}
+
+	if err := json.Unmarshal(payload, &event); err != nil {
+		return err
+	}
+
+	l.logg.Info("emitted event", "json_payload", event)
+	return nil
+}

internal/handler/handler.go

@@ -0,0 +1,27 @@
+package handler
+
+import (
+	"context"
+
+	"github.com/celo-org/celo-blockchain/core/types"
+	"github.com/grassrootseconomics/w3-celo"
+)
+
+type (
+	EmitterEmitFunc func(context.Context, []byte) error
+
+	Handler interface {
+		Handle(context.Context, *types.Log, EmitterEmitFunc) error
+	}
+)
+
+func New() []Handler {
+	transferHandler := &TransferHandler{
+		topicHash: w3.H("0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef"),
+		event:     w3.MustNewEvent("Transfer(address indexed _from, address indexed _to, uint256 _value)"),
+	}
+
+	return []Handler{
+		transferHandler,
+	}
+}

internal/handler/transfer.go

@@ -0,0 +1,55 @@
+package handler
+
+import (
+	"context"
+	"encoding/json"
+	"math/big"
+
+	"github.com/celo-org/celo-blockchain/common"
+	"github.com/celo-org/celo-blockchain/core/types"
+	"github.com/grassrootseconomics/w3-celo"
+)
+
+type (
+	TransferHandler struct {
+		topicHash common.Hash
+		event     *w3.Event
+	}
+
+	TransferEvent struct {
+		Contract string
+		From     string
+		To       string
+		Value    uint64
+	}
+)
+
+func (h *TransferHandler) Handle(ctx context.Context, log *types.Log, emitFn EmitterEmitFunc) error {
+	if log.Topics[0] == h.topicHash {
+		var (
+			from  common.Address
+			to    common.Address
+			value big.Int
+		)
+
+		if err := h.event.DecodeArgs(log, &from, &to, &value); err != nil {
+			return err
+		}
+
+		transferEvent := &TransferEvent{
+			Contract: log.Address.Hex(),
+			From:     from.Hex(),
+			To:       to.Hex(),
+			Value:    value.Uint64(),
+		}
+
+		jsonData, err := json.Marshal(transferEvent)
+		if err != nil {
+			return err
+		}
+
+		return emitFn(ctx, jsonData)
+	}
+
+	return nil
+}

internal/processor/block.go

@@ -5,6 +5,7 @@ import (
 
 	"github.com/celo-org/celo-blockchain/common"
 	"github.com/celo-org/celo-blockchain/core/types"
+	"github.com/grassrootseconomics/celo-tracker/internal/emitter"
 )
 
 func (p *Processor) processBlock(ctx context.Context, block types.Block) error {
@@ -24,8 +25,11 @@ func (p *Processor) processBlock(ctx context.Context, block types.Block) error {
 
 	for i, receipt := range receiptsResp {
 		if receipt.Status > 0 {
-			// test transfers
-			p.chain.TestDecodeTransfer(ctx, receipt.Logs)
+			for _, log := range receipt.Logs {
+				if err := p.handleLogs(ctx, log); err != nil {
+					p.logg.Error("hanlder error", "error", err)
+				}
+			}
 		} else {
 			revertReason, _ := p.chain.GetRevertReason(ctx, receipt.TxHash, receipt.BlockNumber)
 			p.logg.Debug("tx reverted", "hash", receipt.TxHash, "revert_reason", revertReason, "input_data", common.Bytes2Hex(txs[i].Data()))
@@ -40,3 +44,14 @@ func (p *Processor) processBlock(ctx context.Context, block types.Block) error {
 
 	return nil
 }
+
+func (p *Processor) handleLogs(ctx context.Context, log *types.Log) error {
+	defaultEmitter := emitter.New(p.logg)
+
+	for _, handler := range p.handlers {
+		if err := handler.Handle(ctx, log, defaultEmitter); err != nil {
+			return err
+		}
+	}
+	return nil
+}

internal/processor/processor.go

@@ -10,6 +10,7 @@ import (
 	"github.com/ef-ds/deque/v2"
 	"github.com/grassrootseconomics/celo-tracker/internal/chain"
 	"github.com/grassrootseconomics/celo-tracker/internal/db"
+	"github.com/grassrootseconomics/celo-tracker/internal/handler"
 	"github.com/grassrootseconomics/celo-tracker/internal/pool"
 	"github.com/grassrootseconomics/celo-tracker/internal/stats"
 )
@@ -31,6 +32,7 @@ type (
 		stats       *stats.Stats
 		db          *db.DB
 		quit        chan struct{}
+		handlers    []handler.Handler
 	}
 )
 
@@ -47,6 +49,7 @@ func NewProcessor(o ProcessorOpts) *Processor {
 		stats:       o.Stats,
 		db:          o.DB,
 		quit:        make(chan struct{}),
+		handlers:    handler.New(),
 	}
 }