feat:#10 added new minimal backend

datamanager/backend/tools/hook/hook.go

@@ -0,0 +1,59 @@
+package hook
+
+import (
+	"datamanager/backend/tools/security"
+	"errors"
+	"fmt"
+	"sync"
+)
+
+type Handler[T any] func(e T) error
+type handlerPair[T any] struct {
+	id      string
+	handler Handler[T]
+}
+
+type Hook[T any] struct {
+	mux      sync.RWMutex
+	handlers []*handlerPair[T]
+}
+
+var StopPropagation = errors.New("event hook propagation stopped")
+
+func (h *Hook[T]) Trigger(data T, oneOffHandlers ...Handler[T]) error {
+	h.mux.RLock()
+
+	handlers := make([]*handlerPair[T], 0, len(h.handlers)+len(oneOffHandlers))
+	handlers = append(handlers, h.handlers...)
+
+	// append the one off handlers
+	for i, oneOff := range oneOffHandlers {
+		handlers = append(handlers, &handlerPair[T]{
+			id:      fmt.Sprintf("@%d", i),
+			handler: oneOff,
+		})
+	}
+
+	// unlock is not deferred to avoid deadlocks in case Trigger
+	// is called recursively by the handlers
+	h.mux.RUnlock()
+
+	for _, item := range handlers {
+		err := item.handler(data)
+		if err == nil {
+			continue
+		}
+
+		if errors.Is(err, StopPropagation) {
+			return nil
+		}
+
+		return err
+	}
+
+	return nil
+}
+
+func generateHookId() string {
+	return security.PseudorandomString(8)
+}