refactor event handling to support multiple handlers and improve default behavior

event/event_bus.go

@@ -2,11 +2,13 @@ package event
 
 import (
 	"errors"
+	"fmt"
 	"reflect"
+	"strings"
 )
 
-type HandlerInst interface {
-	Default(event any) (err error)
+type Default struct {
+	Val any
 }
 
 type OnStart struct{}
@@ -14,32 +16,48 @@ type OnLoopCycle struct{}
 
 var HandlerDone = errors.New("handler done")
 
-func FindHandlers(inst HandlerInst) (handlers map[reflect.Type]reflect.Value) {
-	handlers = make(map[reflect.Type]reflect.Value)
-	t := reflect.TypeOf(inst)
-	v := reflect.ValueOf(inst)
-	for i := 0; i < t.NumMethod(); i++ {
-		method := t.Method(i)
-		if method.Type.NumIn() != 2 || method.Type.NumOut() != 1 {
-			continue
+func FindHandlers(insts []any) (handlers map[reflect.Type][]reflect.Value) {
+	handlers = make(map[reflect.Type][]reflect.Value)
+	for _, inst := range insts {
+		t := reflect.TypeOf(inst)
+		v := reflect.ValueOf(inst)
+		for i := 0; i < t.NumMethod(); i++ {
+			method := t.Method(i)
+			if strings.HasPrefix(method.Name, "On") {
+				if method.Type.NumIn() != 2 || method.Type.NumOut() != 1 || method.Type.Out(0) != reflect.TypeFor[error]() {
+					fmt.Println("Invalid event handler signature:", method.Name)
+					continue
+				}
+			} else {
+				continue
+			}
+			eventType := method.Type.In(1)
+			handlers[eventType] = append(handlers[eventType], v.Method(i))
 		}
-		if method.Type.Out(0) != reflect.TypeFor[error]() {
-			continue
-		}
-		eventType := method.Type.In(1)
-		handlers[eventType] = v.Method(i)
 	}
 	return
 }
 
-func Fire(inst HandlerInst, event any, handlers map[reflect.Type]reflect.Value) (err error) {
-	if handler, ok := handlers[reflect.TypeOf(event)]; ok {
-		errV := handler.Call([]reflect.Value{reflect.ValueOf(event)})[0]
-		if !errV.IsNil() {
-			err = errV.Interface().(error)
+func FireFound(event any, handlersMap map[reflect.Type][]reflect.Value) (found bool, err error) {
+	var handlers []reflect.Value
+	if handlers, found = handlersMap[reflect.TypeOf(event)]; found {
+		for _, handler := range handlers {
+			errV := handler.Call([]reflect.Value{reflect.ValueOf(event)})[0]
+			if !errV.IsNil() {
+				err = errV.Interface().(error)
+			}
 		}
-	} else {
-		err = inst.Default(event)
+	}
+	return
+}
+
+func Fire(event any, handlersMap map[reflect.Type][]reflect.Value) (err error) {
+	found, err := FireFound(event, handlersMap)
+	if err != nil {
+		return
+	}
+	if !found {
+		_, err = FireFound(Default{event}, handlersMap)
 	}
 	return
 }