package ckwk

import (
	"ckwk/pkg/log"
	"context"
	"sync"
	"time"

	"github.com/google/uuid"
	"go.uber.org/zap"
)

type SessionManager struct {
	mu            sync.RWMutex
	sessions      map[string]SessionItem
	userToSession map[string]string
}

type SessionItem struct {
	Instance  *WK
	LastValue time.Time
	cancel    context.CancelFunc
}

func NewSessionManager() *SessionManager {
	return &SessionManager{
		sessions:      make(map[string]SessionItem),
		userToSession: make(map[string]string),
	}
}

// removeSession 取消 context、删除双 map 条目、记日志
func (m *SessionManager) removeSession(sessionID string, item SessionItem) {
	if item.cancel != nil {
		item.cancel()
	}
	userKey := item.Instance.UserKey()
	delete(m.userToSession, userKey)
	delete(m.sessions, sessionID)
	log.Info("删除 Session", zap.String("id", sessionID))
}

// Store: 保存 session 并返回 session id
func (m *SessionManager) Store(wk *WK) string {
	m.mu.Lock()
	defer m.mu.Unlock()

	userKey := wk.UserKey()
	if oldID, exists := m.userToSession[userKey]; exists {
		item := m.sessions[oldID]
		if item.cancel != nil {
			item.cancel()
		}

		ctx, cancel := context.WithCancel(context.Background())
		item.LastValue = time.Now()
		wk.bindSession(m, oldID)
		item.Instance = wk
		item.cancel = cancel
		m.sessions[oldID] = item

		log.Info("用户已存在，复用旧 Session",
			zap.String("id", oldID),
			zap.String("user", userKey),
		)

		go m.KeepAlive(ctx, oldID)

		return oldID
	}

	sessionID := uuid.New().String()
	ctx, cancel := context.WithCancel(context.Background())
	wk.bindSession(m, sessionID)

	m.userToSession[userKey] = sessionID
	m.sessions[sessionID] = SessionItem{
		Instance:  wk,
		LastValue: time.Now(),
		cancel:    cancel,
	}

	log.Info("创建新 Session", zap.String("id", sessionID))

	go m.KeepAlive(ctx, sessionID)

	return sessionID
}

// Get: 获取指定 session id 的 wk
func (m *SessionManager) Get(sessionID string) (*WK, bool) {
	m.mu.RLock()
	item, ok := m.sessions[sessionID]
	if !ok {
		m.mu.RUnlock()
		return nil, false
	}
	m.mu.RUnlock()

	m.mu.Lock()
	item.LastValue = time.Now()
	m.sessions[sessionID] = item
	m.mu.Unlock()

	return item.Instance, true
}

func (m *SessionManager) Del(sessionID string) {
	m.mu.Lock()
	defer m.mu.Unlock()

	if item, ok := m.sessions[sessionID]; ok {
		m.removeSession(sessionID, item)
	}
}

func (m *SessionManager) KeepAlive(ctx context.Context, id string) {
	ticker := time.NewTicker(2 * time.Minute)
	defer ticker.Stop()

	log.Info("启动 KeepAlive", zap.String("id", id))

	for {
		select {
		case <-ctx.Done():
			log.Info("KeepAlive 已停止", zap.String("id", id))
			return
		case <-ticker.C:
			m.mu.RLock()
			item, ok := m.sessions[id]
			m.mu.RUnlock()
			if !ok || item.Instance == nil {
				log.Info("Session 已不存在，停止 KeepAlive", zap.String("id", id))
				return
			}

			_, err := item.Instance.Online()
			if err != nil {
				log.Error("自动保活请求失败", zap.Error(err))
			}
		}
	}
}

func (m *SessionManager) ClearAll() {
	m.mu.Lock()
	defer m.mu.Unlock()

	for sessionID, item := range m.sessions {
		m.removeSession(sessionID, item)
	}

	log.Info("所有 Session 已清空")
}

func (m *SessionManager) ClearExpired(d time.Duration) {
	m.mu.Lock()
	defer m.mu.Unlock()

	now := time.Now()

	for sessionID, item := range m.sessions {
		if now.Sub(item.LastValue) > d {
			m.removeSession(sessionID, item)
		}
	}
}