Add listener support to event service and notify on event creation

event/event.go

@@ -3,23 +3,67 @@ package event
 import (
 	"context"
 	"fmt"
+	"sync"
 
 	. "git.gorlug.de/code/ersteller"
 	"git.gorlug.de/code/ersteller/schema/ent"
 )
 
+type Listener interface {
+	OnEvent(ctx context.Context, userId int, name string, data any)
+}
+
 type Service struct {
 	entClient *ent.Client
+	listeners []Listener
+	mu        sync.RWMutex
 }
 
 func NewService(entClient *ent.Client) *Service {
 	return &Service{
 		entClient: entClient,
+		listeners: make([]Listener, 0),
+	}
+}
+
+func (s *Service) AddListener(listener Listener) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	s.listeners = append(s.listeners, listener)
+}
+
+func (s *Service) RemoveListener(listener Listener) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	for i, l := range s.listeners {
+		if l == listener {
+			s.listeners = append(s.listeners[:i], s.listeners[i+1:]...)
+			return
+		}
+	}
+}
+
+func (s *Service) notifyListeners(ctx context.Context, userId int, name string, data any) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	for _, listener := range s.listeners {
+		go listener.OnEvent(ctx, userId, name, data)
 	}
 }
 
 func (s *Service) Create(htmxContext HtmxContext, name string, data any) error {
-	return Create(s.entClient, htmxContext, name, data)
+	err := Create(s.entClient, htmxContext, name, data)
+	if err == nil {
+		var userId int
+		ok, authContext := htmxContext.GetAuthContext()
+		if ok {
+			userId = authContext.UserId
+		} else {
+			userId = -1
+		}
+		s.notifyListeners(htmxContext.GetGoContext(), userId, name, data)
+	}
+	return err
 }
 
 func Should(err error) {
@@ -39,6 +83,11 @@ func Create(entClient *ent.Client, c HtmxContext, name string, data any) error {
 
 func CreateWithSession(entClient *ent.Client, ctx context.Context,
 	auth AuthContext, name string, data any) error {
+	return CreateWithSessionAndNotify(entClient, ctx, auth, name, data, nil)
+}
+
+func CreateWithSessionAndNotify(entClient *ent.Client, ctx context.Context,
+	auth AuthContext, name string, data any, service *Service) error {
 	Debug("event", name, data)
 	var mapData JSONB
 	if data == nil {
@@ -58,5 +107,8 @@ func CreateWithSession(entClient *ent.Client, ctx context.Context,
 	if err != nil {
 		return fmt.Errorf("failed to create event: %w", err)
 	}
+	if service != nil {
+		service.notifyListeners(ctx, auth.UserId, name, data)
+	}
 	return nil
 }