refactor: decouple router to allow adding custom log and input data handlers

pkg/router/router.go

@@ -0,0 +1,88 @@
+package router
+
+import (
+	"context"
+
+	"github.com/celo-org/celo-blockchain/common"
+	"github.com/celo-org/celo-blockchain/core/types"
+	"github.com/grassrootseconomics/celo-tracker/pkg/event"
+)
+
+type (
+	Callback    func(context.Context, event.Event) error
+	HandlerFunc func(context.Context, interface{}, Callback) error
+
+	LogPayload struct {
+		Log       *types.Log
+		Timestamp uint64
+	}
+
+	LogRouteEntry struct {
+		Name        string
+		Signature   common.Hash
+		HandlerFunc HandlerFunc
+	}
+
+	InputDataPayload struct {
+		From            string
+		InputData       string
+		Block           uint64
+		ContractAddress string
+		Timestamp       uint64
+		TxHash          string
+	}
+
+	InputDataEntry struct {
+		Name        string
+		Signature   string
+		HandlerFunc HandlerFunc
+	}
+
+	Router struct {
+		logHandlers       map[common.Hash]LogRouteEntry
+		inputDataHandlers map[string]InputDataEntry
+	}
+)
+
+func New() *Router {
+	return &Router{
+		logHandlers:       make(map[common.Hash]LogRouteEntry),
+		inputDataHandlers: make(map[string]InputDataEntry),
+	}
+}
+
+func (r *Router) RegisterLogRoute(signature common.Hash, handlerFunc HandlerFunc) {
+	r.logHandlers[signature] = LogRouteEntry{
+		Signature:   signature,
+		HandlerFunc: handlerFunc,
+	}
+}
+
+func (r *Router) RegisterInputDataRoute(signature string, handlerFunc HandlerFunc) {
+	r.inputDataHandlers[signature] = InputDataEntry{
+		Signature:   signature,
+		HandlerFunc: handlerFunc,
+	}
+}
+
+func (r *Router) ProcessLog(ctx context.Context, payload LogPayload, cb Callback) error {
+	handler, ok := r.logHandlers[payload.Log.Topics[0]]
+	if ok {
+		return handler.HandlerFunc(ctx, payload, cb)
+	}
+
+	return nil
+}
+
+func (r *Router) ProcessInputData(ctx context.Context, payload InputDataPayload, cb Callback) error {
+	if len(payload.InputData) < 8 {
+		return nil
+	}
+
+	handler, ok := r.inputDataHandlers[payload.InputData[:8]]
+	if ok {
+		return handler.HandlerFunc(ctx, payload, cb)
+	}
+
+	return nil
+}