package registerreward

import "sync"

// registerRewardNoticeHub 维护本地调试页订阅的通知监听器。
// 这里使用进程内广播，目的是在不接入 App IM SDK 的前提下，也能验证
// “注册成功 -> Go 发奖 -> Go 发 REGISTER_REWARD_GRANTED 通知”这条链路是否打通。
type registerRewardNoticeHub struct {
	mu          sync.RWMutex
	subscribers map[int64]map[chan RegisterRewardNoticeEvent]struct{}
	recent      map[int64][]RegisterRewardNoticeEvent
}

// newRegisterRewardNoticeHub 创建进程内通知广播中心。
func newRegisterRewardNoticeHub() *registerRewardNoticeHub {
	return &registerRewardNoticeHub{
		subscribers: make(map[int64]map[chan RegisterRewardNoticeEvent]struct{}),
		recent:      make(map[int64][]RegisterRewardNoticeEvent),
	}
}

// subscribe 按 userId 订阅注册奖励通知镜像。
func (h *registerRewardNoticeHub) subscribe(userID int64) (<-chan RegisterRewardNoticeEvent, func()) {
	stream := make(chan RegisterRewardNoticeEvent, 16)

	h.mu.Lock()
	recent := append([]RegisterRewardNoticeEvent(nil), h.recent[userID]...)
	if _, ok := h.subscribers[userID]; !ok {
		h.subscribers[userID] = make(map[chan RegisterRewardNoticeEvent]struct{})
	}
	h.subscribers[userID][stream] = struct{}{}
	h.mu.Unlock()

	for _, event := range recent {
		select {
		case stream <- event:
		default:
		}
	}

	cancel := func() {
		h.mu.Lock()
		defer h.mu.Unlock()

		group, ok := h.subscribers[userID]
		if !ok {
			return
		}

		if _, exists := group[stream]; exists {
			delete(group, stream)
			close(stream)
		}

		if len(group) == 0 {
			delete(h.subscribers, userID)
		}
	}

	return stream, cancel
}

// publish 把通知镜像广播给当前用户的所有本地订阅者。
// 这里使用非阻塞写入，避免测试页断开或消费变慢时反向卡住正式发奖链路。
func (h *registerRewardNoticeHub) publish(event RegisterRewardNoticeEvent) {
	if event.UserID <= 0 {
		return
	}

	h.mu.Lock()
	h.recent[event.UserID] = append(h.recent[event.UserID], event)
	if len(h.recent[event.UserID]) > 10 {
		h.recent[event.UserID] = append([]RegisterRewardNoticeEvent(nil), h.recent[event.UserID][len(h.recent[event.UserID])-10:]...)
	}
	group := h.subscribers[event.UserID]
	targets := make([]chan RegisterRewardNoticeEvent, 0, len(group))
	for stream := range group {
		targets = append(targets, stream)
	}
	h.mu.Unlock()

	for _, stream := range targets {
		select {
		case stream <- event:
		default:
		}
	}
}

// SubscribeDebugNotices 给本地测试页提供注册奖励通知订阅能力。
func (s *RegisterRewardService) SubscribeDebugNotices(userID int64) (<-chan RegisterRewardNoticeEvent, func()) {
	if s == nil || s.debug == nil {
		closed := make(chan RegisterRewardNoticeEvent)
		close(closed)
		return closed, func() {}
	}
	return s.debug.subscribe(userID)
}

// publishDebugNotice 把刚刚触发的 REGISTER_REWARD_GRANTED 镜像到本地调试流。
func (s *RegisterRewardService) publishDebugNotice(event RegisterRewardNoticeEvent) {
	if s == nil || s.debug == nil {
		return
	}
	s.debug.publish(event)
}