package events

import (
	"sync"

	"github.com/google/uuid"
)

type IEventHandler interface {
	Publish(event IEvent) error
	Subscribe(event EventType, handle func(event IEvent)) ISubscription
}

func NewEventHandler() IEventHandler {
	handler := &eventHandler{
		subscribers: make(map[EventType]map[string]func(IEvent)),
		mu:          sync.Mutex{},
	}
	return handler
}

type eventHandler struct {
	subscribers map[EventType]map[string]func(IEvent)
	mu          sync.Mutex
}

func (handler *eventHandler) Publish(event IEvent) error {
	for eventType, handles := range handler.subscribers {
		if event.Typ() == eventType {
			for _, handle := range handles {
				handle(event)
			}
		}
	}
	return nil
}

func (handler *eventHandler) Subscribe(eventType EventType, handle func(event IEvent)) ISubscription {
	handler.mu.Lock()
	defer handler.mu.Unlock()

	id := uuid.NewString()
	if handler.subscribers[eventType] == nil {
		handler.subscribers[eventType] = make(map[string]func(IEvent))
	}
	handler.subscribers[eventType][id] = handle
	return newSubscription(func() {
		handler.mu.Lock()
		defer handler.mu.Unlock()

		delete(handler.subscribers[eventType], id)
		if len(handler.subscribers[eventType]) < 1 {
			delete(handler.subscribers, eventType)
		}
	})
}