feat: WebSocket based implementation of server sent events for cache busting (#527)

* rough implementation of WS based event system for server side notifications of mutation

* fix test construction

* fix deadlock on event bus

* disable linter error

* add item mutation events

* remove old event bus code

* refactor event system to use composables

* refresh items table when new item is added

* fix create form errors

* cleanup unnecessary calls

* fix importer erorrs + limit fn calls on import

backend/internal/core/services/reporting/eventbus/eventbus.go

@@ -0,0 +1,85 @@
+// / Package eventbus provides an interface for event bus.
+package eventbus
+
+import (
+	"sync"
+
+	"github.com/google/uuid"
+)
+
+type Event string
+
+const (
+	EventLabelMutation    Event = "label.mutation"
+	EventLocationMutation Event = "location.mutation"
+	EventItemMutation     Event = "item.mutation"
+)
+
+type GroupMutationEvent struct {
+	GID uuid.UUID
+}
+
+type eventData struct {
+	event Event
+	data  any
+}
+
+type EventBus struct {
+	started bool
+	ch      chan eventData
+
+	mu          sync.RWMutex
+	subscribers map[Event][]func(any)
+}
+
+func New() *EventBus {
+	return &EventBus{
+		ch: make(chan eventData, 10),
+		subscribers: map[Event][]func(any){
+			EventLabelMutation:    {},
+			EventLocationMutation: {},
+      EventItemMutation:     {},
+		},
+	}
+}
+
+func (e *EventBus) Run() {
+	if e.started {
+		panic("event bus already started")
+	}
+
+	e.started = true
+
+	for event := range e.ch {
+		e.mu.RLock()
+		arr, ok := e.subscribers[event.event]
+		e.mu.RUnlock()
+
+		if !ok {
+			continue
+		}
+
+		for _, fn := range arr {
+			fn(event.data)
+		}
+	}
+}
+
+func (e *EventBus) Publish(event Event, data any) {
+	e.ch <- eventData{
+		event: event,
+		data:  data,
+	}
+}
+
+func (e *EventBus) Subscribe(event Event, fn func(any)) {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+
+	arr, ok := e.subscribers[event]
+	if !ok {
+		panic("event not found")
+	}
+
+	e.subscribers[event] = append(arr, fn)
+}