backend/internal/service/chat_service.go

package service

import (
	"context"
	"errors"
	"fmt"
	"slices"
	"time"

	"with_you/internal/cache"
	"with_you/internal/dto"
	"with_you/internal/model"
	"with_you/internal/pkg/ws"
	"with_you/internal/repository"

	"github.com/redis/go-redis/v9"
	"go.uber.org/zap"
	"gorm.io/gorm"
)

// 撤回消息的时间限制（2分钟）
const RecallMessageTimeout = 2 * time.Minute

// 消息幂等性 TTL：24 小时内同一 client_msg_id 不会重复发送
const messageIdempotentTTL = 24 * time.Hour

// ChatService 聊天服务接口
type ChatService interface {
	// 会话管理
	GetOrCreateConversation(ctx context.Context, user1ID, user2ID string) (*model.Conversation, error)
	GetConversationList(ctx context.Context, userID string, page, pageSize int) ([]*model.Conversation, int64, error)
	GetConversationByID(ctx context.Context, conversationID string, userID string) (*model.Conversation, error)
	DeleteConversationForSelf(ctx context.Context, conversationID string, userID string) error
	SetConversationPinned(ctx context.Context, conversationID string, userID string, isPinned bool) error
	SetConversationNotificationMuted(ctx context.Context, conversationID string, userID string, notificationMuted bool) error

	// 消息操作
	SendMessage(ctx context.Context, senderID string, conversationID string, segments model.MessageSegments, replyToID *string, clientMsgID string) (*model.Message, error)
	GetMessages(ctx context.Context, conversationID string, userID string, page, pageSize int) ([]*model.Message, int64, error)
	GetMessagesAfterSeq(ctx context.Context, conversationID string, userID string, afterSeq int64, limit int) ([]*model.Message, error)
	GetMessagesBeforeSeq(ctx context.Context, conversationID string, userID string, beforeSeq int64, limit int) ([]*model.Message, error)

	// 已读管理
	MarkAsRead(ctx context.Context, conversationID string, userID string, seq int64) error
	MarkAsReadBatch(ctx context.Context, userID string, items []dto.BatchMarkReadItem) (int, error)
	GetUnreadCount(ctx context.Context, conversationID string, userID string) (int64, error)
	GetAllUnreadCount(ctx context.Context, userID string) (int64, error)

	// 消息同步
	GetSyncData(ctx context.Context, userID string) ([]dto.SyncDataItem, error)

	// 增量同步（版本日志）
	GetSyncByVersion(ctx context.Context, userID string, sinceVersion int64, limit int) (*dto.SyncVersionResponse, error)

	// 消息扩展功能
	RecallMessage(ctx context.Context, messageID string, userID string) error
	DeleteMessage(ctx context.Context, messageID string, userID string) error
	// GetReplyMessage 按 ID 获取被引用消息（鉴权：必须是该会话参与者）
	GetReplyMessage(ctx context.Context, messageID string, userID string) (*model.Message, error)

	// 实时事件相关
	SendTyping(ctx context.Context, senderID string, conversationID string)

	// 在线状态
	IsUserOnline(userID string) bool

	// 仅保存消息到数据库，不发送实时推送（供群聊等自行推送的场景使用）
	SaveMessage(ctx context.Context, senderID string, conversationID string, segments model.MessageSegments, replyToID *string) (*model.Message, error)

	// 批量查询（解决 N+1 问题）
	GetUnreadCountBatch(ctx context.Context, userID string, convIDs []string) (map[string]int64, error)
	GetLastMessagesBatch(ctx context.Context, convIDs []string) (map[string]*model.Message, error)

	// 已读位置（OpenIM 风格缓存）
	GetUserReadSeq(ctx context.Context, conversationID string, userID string) (int64, error)
}

// chatServiceImpl 聊天服务实现
type chatServiceImpl struct {
	repo      repository.MessageRepository
	userRepo  repository.UserRepository
	sensitive SensitiveService
	wsHub     ws.MessagePublisher
	pushSvc   PushService
	cache     cache.Cache

	conversationCache *cache.ConversationCache
	uploadService     UploadService
	versionLogRepo    repository.ConversationVersionLogRepository
	versionLogEnabled bool
	versionLogMaxGap  int64
	pushWorker        *PushWorker
	redisClient       *redis.Client

	// groupAbility 用于群消息发送前的群成员/禁言校验。
	// 可选依赖：为 nil 时跳过群能力校验（向后兼容旧测试构造），生产环境应注入。
	groupAbility GroupAbility
}

// NewChatService 创建聊天服务
//
// groupAbility 可选注入：群消息发送前的成员/禁言校验由此完成。
// 生产环境必须注入，否则群禁言规则无法生效。
func NewChatService(
	repo repository.MessageRepository,
	userRepo repository.UserRepository,
	sensitive SensitiveService,
	publisher ws.MessagePublisher,
	cacheBackend cache.Cache,
	uploadService UploadService,
	pushSvc PushService,
	seqBufferMgr *cache.SeqBufferManager,
	pushWorker *PushWorker,
	redisClient *redis.Client,
	groupAbility GroupAbility,
	versionLogRepo ...repository.ConversationVersionLogRepository,
) ChatService {
	// 创建适配器
	convRepoAdapter := cache.NewConversationRepositoryAdapter(repo)
	msgRepoAdapter := cache.NewMessageRepositoryAdapter(repo)

	// 创建会话缓存
	conversationCache := cache.NewConversationCache(
		cacheBackend,
		convRepoAdapter,
		msgRepoAdapter,
		cache.DefaultConversationCacheSettings(),
		seqBufferMgr,
	)

	impl := &chatServiceImpl{
		repo:              repo,
		userRepo:          userRepo,
		sensitive:         sensitive,
		wsHub:             publisher,
		pushSvc:           pushSvc,
		cache:             cacheBackend,
		conversationCache: conversationCache,
		uploadService:     uploadService,
		pushWorker:        pushWorker,
		redisClient:       redisClient,
		groupAbility:      groupAbility,
	}

	if len(versionLogRepo) > 0 && versionLogRepo[0] != nil {
		impl.versionLogRepo = versionLogRepo[0]
		impl.versionLogEnabled = true
		impl.versionLogMaxGap = 1000
	}

	return impl
}

func (s *chatServiceImpl) publishToUsers(userIDs []string, event string, payload any) {
	if s.wsHub == nil || len(userIDs) == 0 {
		return
	}
	s.wsHub.PublishToUsers(userIDs, event, payload)
}

// writeVersionLog 写入版本日志（异步，失败仅 warn）
func (s *chatServiceImpl) writeVersionLog(ctx context.Context, userID, conversationID, changeType string) {
	if !s.versionLogEnabled || s.versionLogRepo == nil {
		return
	}
	maxV, err := s.versionLogRepo.GetMaxVersion(ctx, userID)
	if err != nil {
		zap.L().Warn("writeVersionLog: get max version failed", zap.String("userID", userID), zap.Error(err))
		return
	}
	vlog := &model.ConversationVersionLog{
		UserID:         userID,
		ConversationID: conversationID,
		Version:        maxV + 1,
		ChangeType:     changeType,
	}
	if err := s.versionLogRepo.Create(ctx, vlog); err != nil {
		zap.L().Warn("writeVersionLog: create failed", zap.String("userID", userID), zap.Error(err))
	}
}

// writeVersionLogBatch 批量写入版本日志（异步，失败仅 warn）
func (s *chatServiceImpl) writeVersionLogBatch(ctx context.Context, userIDs []string, conversationID, changeType string) {
	if !s.versionLogEnabled || s.versionLogRepo == nil {
		return
	}
	logs := make([]*model.ConversationVersionLog, 0, len(userIDs))
	for _, uid := range userIDs {
		maxV, err := s.versionLogRepo.GetMaxVersion(ctx, uid)
		if err != nil {
			zap.L().Warn("writeVersionLogBatch: get max version failed", zap.String("userID", uid), zap.Error(err))
			continue
		}
		logs = append(logs, &model.ConversationVersionLog{
			UserID:         uid,
			ConversationID: conversationID,
			Version:        maxV + 1,
			ChangeType:     changeType,
		})
	}
	if len(logs) > 0 {
		if err := s.versionLogRepo.BatchCreate(ctx, logs); err != nil {
			zap.L().Warn("writeVersionLogBatch: batch create failed", zap.Error(err))
		}
	}
}

// GetSyncByVersion 增量同步：按版本号获取会话变更
func (s *chatServiceImpl) GetSyncByVersion(ctx context.Context, userID string, sinceVersion int64, limit int) (*dto.SyncVersionResponse, error) {
	if !s.versionLogEnabled || s.versionLogRepo == nil {
		return nil, errors.New("version log sync is not enabled")
	}

	if limit <= 0 {
		limit = 100
	}

	currentVersion, err := s.versionLogRepo.GetMaxVersion(ctx, userID)
	if err != nil {
		return nil, fmt.Errorf("failed to get current version: %w", err)
	}

	resp := &dto.SyncVersionResponse{
		CurrentVersion: currentVersion,
	}

	if currentVersion == 0 {
		resp.FullSync = true
		return resp, nil
	}

	gap := currentVersion - sinceVersion
	if gap > s.versionLogMaxGap {
		resp.FullSync = true
		return resp, nil
	}

	vlogs, err := s.versionLogRepo.GetByVersion(ctx, userID, sinceVersion, limit+1)
	if err != nil {
		return nil, fmt.Errorf("failed to get version logs: %w", err)
	}

	hasMore := len(vlogs) > limit
	if hasMore {
		vlogs = vlogs[:limit]
	}

	changes := make([]dto.SyncChangeItem, 0, len(vlogs))
	for _, vl := range vlogs {
		item := dto.SyncChangeItem{
			ConversationID: vl.ConversationID,
			ChangeType:     vl.ChangeType,
			Version:        vl.Version,
		}
		conv, cErr := s.repo.GetConversation(vl.ConversationID)
		if cErr == nil && conv != nil {
			item.LastMessageAt = conv.UpdatedAt.Unix()
			if maxSeq, sErr := s.conversationCache.GetConvMaxSeq(ctx, vl.ConversationID); sErr == nil {
				item.MaxSeq = maxSeq
			}
		}
		changes = append(changes, item)
	}

	resp.Changes = changes
	resp.HasMore = hasMore
	return resp, nil
}

// GetOrCreateConversation 获取或创建私聊会话
func (s *chatServiceImpl) GetOrCreateConversation(ctx context.Context, user1ID, user2ID string) (*model.Conversation, error) {
	conv, err := s.repo.GetOrCreatePrivateConversation(user1ID, user2ID)
	if err != nil {
		return nil, err
	}

	// 失效会话列表缓存
	if s.conversationCache != nil {
		s.conversationCache.InvalidateConversationList(user1ID)
		s.conversationCache.InvalidateConversationList(user2ID)
	}

	return conv, nil
}

// GetConversationList 获取用户的会话列表（带缓存）
func (s *chatServiceImpl) GetConversationList(ctx context.Context, userID string, page, pageSize int) ([]*model.Conversation, int64, error) {
	// 优先使用缓存
	if s.conversationCache != nil {
		return s.conversationCache.GetConversationList(ctx, userID, page, pageSize)
	}
	return s.repo.GetConversations(userID, page, pageSize)
}

// GetConversationByID 获取会话详情（带缓存）
func (s *chatServiceImpl) GetConversationByID(ctx context.Context, conversationID string, userID string) (*model.Conversation, error) {
	// 验证用户是否是会话参与者
	participant, err := s.getParticipant(ctx, conversationID, userID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, errors.New("conversation not found or no permission")
		}
		return nil, fmt.Errorf("failed to get participant: %w", err)
	}

	// 获取会话信息（优先使用缓存）
	var conv *model.Conversation
	if s.conversationCache != nil {
		conv, err = s.conversationCache.GetConversation(ctx, conversationID)
	} else {
		conv, err = s.repo.GetConversation(conversationID)
	}
	if err != nil {
		return nil, fmt.Errorf("failed to get conversation: %w", err)
	}

	_ = participant // 可以用于返回已读位置等信息

	return conv, nil
}

// getParticipant 获取参与者信息（优先使用缓存）
func (s *chatServiceImpl) getParticipant(ctx context.Context, conversationID, userID string) (*model.ConversationParticipant, error) {
	if s.conversationCache != nil {
		return s.conversationCache.GetParticipant(ctx, conversationID, userID)
	}
	return s.repo.GetParticipant(conversationID, userID)
}

// DeleteConversationForSelf 仅自己删除会话
func (s *chatServiceImpl) DeleteConversationForSelf(ctx context.Context, conversationID string, userID string) error {
	participant, err := s.getParticipant(ctx, conversationID, userID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return errors.New("conversation not found or no permission")
		}
		return fmt.Errorf("failed to get participant: %w", err)
	}
	if participant.ConversationID == "" {
		return errors.New("conversation not found or no permission")
	}

	if err := s.repo.HideConversationForUser(conversationID, userID); err != nil {
		return fmt.Errorf("failed to hide conversation: %w", err)
	}

	// 失效会话列表缓存
	if s.conversationCache != nil {
		s.conversationCache.InvalidateConversationList(userID)
	}

	go s.writeVersionLog(context.Background(), userID, conversationID, "hide")

	return nil
}

// SetConversationPinned 设置会话置顶（用户维度）
func (s *chatServiceImpl) SetConversationPinned(ctx context.Context, conversationID string, userID string, isPinned bool) error {
	participant, err := s.getParticipant(ctx, conversationID, userID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return errors.New("conversation not found or no permission")
		}
		return fmt.Errorf("failed to get participant: %w", err)
	}
	if participant.ConversationID == "" {
		return errors.New("conversation not found or no permission")
	}

	if err := s.repo.UpdatePinned(conversationID, userID, isPinned); err != nil {
		return fmt.Errorf("failed to update pinned status: %w", err)
	}

	// 失效缓存
	if s.conversationCache != nil {
		s.conversationCache.InvalidateParticipant(conversationID, userID)
		s.conversationCache.InvalidateConversationList(userID)
	}

	return nil
}

// SetConversationNotificationMuted 设置会话免打扰状态（用户维度）
func (s *chatServiceImpl) SetConversationNotificationMuted(ctx context.Context, conversationID string, userID string, notificationMuted bool) error {
	participant, err := s.getParticipant(ctx, conversationID, userID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return errors.New("conversation not found or no permission")
		}
		return fmt.Errorf("failed to get participant: %w", err)
	}
	if participant.ConversationID == "" {
		return errors.New("conversation not found or no permission")
	}

	if err := s.repo.UpdateNotificationMuted(conversationID, userID, notificationMuted); err != nil {
		return fmt.Errorf("failed to update notification_muted status: %w", err)
	}

	// 失效缓存
	if s.conversationCache != nil {
		s.conversationCache.InvalidateParticipant(conversationID, userID)
		s.conversationCache.InvalidateConversationList(userID)
	}

	return nil
}

func (s *chatServiceImpl) SendMessage(ctx context.Context, senderID string, conversationID string, segments model.MessageSegments, replyToID *string, clientMsgID string) (*model.Message, error) {
	if clientMsgID != "" && s.cache != nil {
		idemKey := cache.MessageIdempotentKey(senderID, clientMsgID)
		if cachedMsgID, ok := cache.GetTyped[string](s.cache, idemKey); ok && cachedMsgID != "" {
			if existing, err := s.repo.GetMessageByID(cachedMsgID); err == nil && existing != nil {
				return existing, nil
			}
		}
	}

	conv, err := s.getConversation(ctx, conversationID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, errors.New("会话不存在，请重新创建会话")
		}
		return nil, fmt.Errorf("failed to get conversation: %w", err)
	}

	// 拉黑限制：仅拦截"被拉黑方 -> 拉黑人"方向
	if conv.Type == model.ConversationTypePrivate && s.userRepo != nil {
		participants, pErr := s.getParticipants(ctx, conversationID)
		if pErr != nil {
			return nil, fmt.Errorf("failed to get participants: %w", pErr)
		}
		var sentCount *int64
		for _, p := range participants {
			if p.UserID == senderID {
				continue
			}
			blocked, bErr := s.userRepo.IsBlocked(p.UserID, senderID)
			if bErr != nil {
				return nil, fmt.Errorf("failed to check block status: %w", bErr)
			}
			if blocked {
				return nil, ErrUserBlocked
			}

			// 陌生人限制：对方未回关前，只允许发送一条文本消息，且禁止发送图片
			isFollowedBack, fErr := s.userRepo.IsFollowing(p.UserID, senderID)
			if fErr != nil {
				return nil, fmt.Errorf("failed to check follow status: %w", fErr)
			}
			if !isFollowedBack {
				if containsImageSegment(segments) {
					return nil, errors.New("对方未关注你，暂不支持发送图片")
				}
				if sentCount == nil {
					c, cErr := s.repo.CountMessagesBySenderInConversation(conversationID, senderID)
					if cErr != nil {
						return nil, fmt.Errorf("failed to count sender messages: %w", cErr)
					}
					sentCount = &c
				}
				if *sentCount >= 1 {
					return nil, errors.New("对方未关注你前，仅允许发送一条消息")
				}
			}
		}
	}

	// 验证用户是否是会话参与者
	_, err = s.getParticipant(ctx, conversationID, senderID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, errors.New("您不是该会话的参与者")
		}
		return nil, fmt.Errorf("failed to get participant: %w", err)
	}

	// 群消息发送：校验发送者是否仍是群成员、是否被禁言、群是否全员禁言。
	// 私聊会话不参与该校验。
	if conv.Type == model.ConversationTypeGroup && conv.GroupID != nil && *conv.GroupID != "" && s.groupAbility != nil {
		if err := s.groupAbility.CanSendGroupMessage(ctx, senderID, *conv.GroupID); err != nil {
			return nil, err
		}
	}

	if s.uploadService != nil {
		if err := s.uploadService.ValidateChatMessageImageSegments(segments); err != nil {
			return nil, err
		}
	}

	// 创建消息
	message := &model.Message{
		ConversationID: conversationID,
		SenderID:       senderID, // 直接使用string类型的UUID
		Segments:       segments,
		ReplyToID:      replyToID,
		Status:         model.MessageStatusNormal,
	}

	// seq 由 CreateMessageWithSeq 在事务内原子分配

	// 使用事务创建消息并更新seq
	if err := s.repo.CreateMessageWithSeq(message); err != nil {
		return nil, fmt.Errorf("failed to save message: %w", err)
	}

	// 写透 seq 到 Redis，保持缓存与 DB 一致
	if s.conversationCache != nil {
		s.conversationCache.SyncConvSeq(context.Background(), conversationID, message.Seq)
	}

	// 发送者自动已读：将发送者的 lastReadSeq 更新到消息 seq
	_ = s.repo.UpdateLastReadSeq(conversationID, senderID, message.Seq)
	if s.conversationCache != nil {
		_ = s.conversationCache.SetUserReadSeq(context.Background(), conversationID, senderID, message.Seq)
	}

	// 新消息会改变分页结果，先失效分页缓存，避免读到旧列表
	if s.conversationCache != nil {
		s.conversationCache.InvalidateMessagePages(conversationID)
	}

	go func() {
		if err := s.cacheMessage(context.Background(), conversationID, message); err != nil {
			zap.L().Warn("async cache message failed",
				zap.String("component", "ChatService"),
				zap.String("convID", conversationID),
				zap.String("msgID", message.ID),
				zap.Error(err),
			)
		}
	}()

	if clientMsgID != "" && s.cache != nil {
		s.cache.Set(cache.MessageIdempotentKey(senderID, clientMsgID), message.ID, messageIdempotentTTL)
	}

	// 获取会话中的参与者并发送消息
	participants, err := s.getParticipants(ctx, conversationID)
	if err == nil {
		// 版本日志：为所有参与者写入 new_msg
		pids := make([]string, 0, len(participants))
		for _, p := range participants {
			pids = append(pids, p.UserID)
		}
		go s.writeVersionLogBatch(context.Background(), pids, conversationID, "new_msg")

		// 先更新未读计数器，再推送 WS 事件，确保事件中的 total_unread 已包含新消息
		// 注意：已移除 IncrementUnread，未读数完全由 maxSeq - readSeq 算术计算
		if s.conversationCache != nil {
			keys := make([]string, 0, len(participants)*2)
			for _, p := range participants {
				keys = append(keys,
					cache.UnreadDetailKey(p.UserID, conversationID),
					cache.UnreadConversationKey(p.UserID),
				)
			}
			if len(keys) > 0 {
				s.cache.DeleteBatch(keys)
			}
			for _, p := range participants {
				s.conversationCache.InvalidateConversationList(p.UserID)
			}
		}

		// PushWorker 异步推送 or inline fallback
		if s.pushWorker != nil && s.pushWorker.IsEnabled() {
			streamMsg := &PushStreamMsg{
				ConversationID: conversationID,
				SenderID:       senderID,
				MessageID:      message.ID,
				ConvType:       string(conv.Type),
				Timestamp:      time.Now().UnixMilli(),
			}
			if pubErr := PublishToPush(context.Background(), s.redisClient, "msg_push", streamMsg); pubErr != nil {
				zap.L().Warn("push stream publish failed, falling back to inline push",
					zap.String("conversationID", conversationID),
					zap.Error(pubErr),
				)
				s.inlinePush(ctx, conv, participants, senderID, conversationID, message)
			}
		} else {
			s.inlinePush(ctx, conv, participants, senderID, conversationID, message)
		}
	}

	return message, nil
}

// inlinePush 内联推送（原有逻辑，PushWorker 失败时的 fallback）
func (s *chatServiceImpl) inlinePush(ctx context.Context, conv *model.Conversation, participants []*model.ConversationParticipant, senderID, conversationID string, message *model.Message) {
	targetIDs := make([]string, 0, len(participants))
	for _, p := range participants {
		if conv.Type == model.ConversationTypePrivate && p.UserID == senderID {
			continue
		}
		targetIDs = append(targetIDs, p.UserID)
	}
	detailType := "private"
	if conv.Type == model.ConversationTypeGroup {
		detailType = "group"
	}
	if len(targetIDs) > 20 && conv.Type == model.ConversationTypeGroup {
		s.wsHub.PublishToUsersConcurrent(targetIDs, "chat_message", map[string]any{
			"detail_type": detailType,
			"message":     dto.ConvertMessageToResponse(message),
		})
	} else {
		s.publishToUsers(targetIDs, "chat_message", map[string]any{
			"detail_type": detailType,
			"message":     dto.ConvertMessageToResponse(message),
		})
	}
	for _, p := range participants {
		if p.UserID == senderID {
			continue
		}
		if totalUnread, uErr := s.GetAllUnreadCount(ctx, p.UserID); uErr == nil {
			s.publishToUsers([]string{p.UserID}, "conversation_unread", map[string]any{
				"conversation_id": conversationID,
				"total_unread":    totalUnread,
			})
		}
	}

	if s.pushSvc != nil && len(participants) > 0 {
		sender := ChatMessageSender{ID: senderID}
		if senderUser, sErr := s.userRepo.GetByID(senderID); sErr == nil {
			sender.Name = senderUser.Nickname
			sender.Avatar = senderUser.Avatar
		}
		convType := conv.Type
		convName := ""
		groupID := ""
		groupAvatar := ""
		if conv.Type == model.ConversationTypeGroup && conv.Group != nil {
			convName = conv.Group.Name
			groupID = conv.Group.ID
			groupAvatar = conv.Group.Avatar
		}
		allTargetIDs := make([]string, 0, len(participants))
		for _, p := range participants {
			if p.UserID == senderID {
				continue
			}
			allTargetIDs = append(allTargetIDs, p.UserID)
		}
		// 直接对所有参与者推送（不按 WS 在线过滤）：
		// 多设备场景下某端在线不代表所有端在线，由 PushChatMessage 推送到用户所有移动设备
		if len(allTargetIDs) > 0 {
			go func(ids []string, sender ChatMessageSender, gid string, gavatar string) {
				for _, uid := range ids {
					if pushErr := s.pushSvc.PushChatMessage(context.Background(), uid, conversationID, &sender, convType, convName, message, gid, gavatar); pushErr != nil {
						zap.L().Debug("push chat message failed",
							zap.String("userID", uid),
							zap.String("conversationID", conversationID),
							zap.Error(pushErr),
						)
					}
				}
			}(allTargetIDs, sender, groupID, groupAvatar)
		}
	}
}

func (s *chatServiceImpl) getConversation(ctx context.Context, conversationID string) (*model.Conversation, error) {
	if s.conversationCache != nil {
		return s.conversationCache.GetConversation(ctx, conversationID)
	}
	return s.repo.GetConversation(conversationID)
}

// getParticipants 获取会话参与者（优先使用缓存）
func (s *chatServiceImpl) getParticipants(ctx context.Context, conversationID string) ([]*model.ConversationParticipant, error) {
	if s.conversationCache != nil {
		return s.conversationCache.GetParticipants(ctx, conversationID)
	}
	return s.repo.GetConversationParticipants(conversationID)
}

// cacheMessage 缓存消息（内部方法）
func (s *chatServiceImpl) cacheMessage(ctx context.Context, convID string, msg *model.Message) error {
	if s.conversationCache == nil {
		return nil
	}

	asyncCtx, cancel := context.WithTimeout(ctx, 5*time.Second)
	defer cancel()

	return s.conversationCache.CacheMessage(asyncCtx, convID, msg)
}

func containsImageSegment(segments model.MessageSegments) bool {
	return slices.ContainsFunc(segments, func(seg model.MessageSegment) bool {
		return seg.Type == string(model.ContentTypeImage) || seg.Type == "image"
	})
}

// GetMessages 获取消息历史（分页，带缓存）
func (s *chatServiceImpl) GetMessages(ctx context.Context, conversationID string, userID string, page, pageSize int) ([]*model.Message, int64, error) {
	// 验证用户是否是会话参与者
	_, err := s.getParticipant(ctx, conversationID, userID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, 0, errors.New("conversation not found or no permission")
		}
		return nil, 0, fmt.Errorf("failed to get participant: %w", err)
	}

	// 优先使用缓存
	if s.conversationCache != nil {
		return s.conversationCache.GetMessages(ctx, conversationID, page, pageSize)
	}

	return s.repo.GetMessages(conversationID, page, pageSize)
}

// GetMessagesAfterSeq 获取指定seq之后的消息（用于增量同步）
func (s *chatServiceImpl) GetMessagesAfterSeq(ctx context.Context, conversationID string, userID string, afterSeq int64, limit int) ([]*model.Message, error) {
	// 验证用户是否是会话参与者
	_, err := s.getParticipant(ctx, conversationID, userID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, errors.New("conversation not found or no permission")
		}
		return nil, fmt.Errorf("failed to get participant: %w", err)
	}

	if limit <= 0 {
		limit = 100
	}

	return s.repo.GetMessagesAfterSeq(conversationID, afterSeq, limit)
}

// GetMessagesBeforeSeq 获取指定seq之前的历史消息（用于下拉加载更多）
func (s *chatServiceImpl) GetMessagesBeforeSeq(ctx context.Context, conversationID string, userID string, beforeSeq int64, limit int) ([]*model.Message, error) {
	// 验证用户是否是会话参与者
	_, err := s.getParticipant(ctx, conversationID, userID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, errors.New("conversation not found or no permission")
		}
		return nil, fmt.Errorf("failed to get participant: %w", err)
	}

	if limit <= 0 {
		limit = 20
	}

	return s.repo.GetMessagesBeforeSeq(conversationID, beforeSeq, limit)
}

// MarkAsRead 标记已读
func (s *chatServiceImpl) MarkAsRead(ctx context.Context, conversationID string, userID string, seq int64) error {
	// 验证用户是否是会话参与者
	_, err := s.getParticipant(ctx, conversationID, userID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return errors.New("conversation not found or no permission")
		}
		return fmt.Errorf("failed to get participant: %w", err)
	}

	// 1. 先写入DB（保证数据一致性，DB是唯一数据源）
	err = s.repo.UpdateLastReadSeq(conversationID, userID, seq)
	if err != nil {
		return fmt.Errorf("failed to update last read seq: %w", err)
	}

	// 2. 更新 Redis hasReadSeq 缓存（防回退）
	if s.conversationCache != nil {
		_ = s.conversationCache.SetUserReadSeq(ctx, conversationID, userID, seq)
		// 清除旧// 失效参与者缓存
		s.conversationCache.InvalidateParticipant(conversationID, userID)
		// 失效未读数缓存（旧 cache-aside 键）
		s.conversationCache.InvalidateUnreadCount(userID, conversationID)
		// 失效会话列表缓存
		s.conversationCache.InvalidateConversationList(userID)
	}

	participants, pErr := s.getParticipants(ctx, conversationID)
	if pErr == nil {
		detailType := "private"
		groupID := ""
		conv, _ := s.getConversation(ctx, conversationID)
		if conv != nil && conv.Type == model.ConversationTypeGroup {
			detailType = "group"
			if conv.GroupID != nil {
				groupID = *conv.GroupID
			}
		}

		// 私聊：通知所有参与者（含对方）；群聊：只通知自己
		readTargets := []string{userID}
		if conv != nil && conv.Type == model.ConversationTypePrivate {
			readTargets = make([]string, 0, len(participants))
			for _, p := range participants {
				readTargets = append(readTargets, p.UserID)
			}
		}
		s.publishToUsers(readTargets, "message_read", map[string]any{
			"detail_type":     detailType,
			"conversation_id": conversationID,
			"group_id":        groupID,
			"user_id":         userID,
			"seq":             seq,
		})
	}
	if totalUnread, uErr := s.GetAllUnreadCount(ctx, userID); uErr == nil {
		s.publishToUsers([]string{userID}, "conversation_unread", map[string]any{
			"conversation_id": conversationID,
			"total_unread":    totalUnread,
		})
	}

	return nil
}

// MarkAsReadBatch 批量标记多个会话已读
func (s *chatServiceImpl) MarkAsReadBatch(ctx context.Context, userID string, items []dto.BatchMarkReadItem) (int, error) {
	successCount := 0

	for _, item := range items {
		_, err := s.getParticipant(ctx, item.ConversationID, userID)
		if err != nil {
			continue
		}

		if err := s.repo.UpdateLastReadSeq(item.ConversationID, userID, item.LastReadSeq); err != nil {
			continue
		}

		if s.conversationCache != nil {
			_ = s.conversationCache.SetUserReadSeq(ctx, item.ConversationID, userID, item.LastReadSeq)
			s.conversationCache.InvalidateParticipant(item.ConversationID, userID)
			s.conversationCache.InvalidateUnreadCount(userID, item.ConversationID)
		}

		successCount++
	}

	if s.conversationCache != nil {
		s.conversationCache.InvalidateConversationList(userID)
	}

	// 为每个成功的会话发送 read 通知
	for i := 0; i < successCount && i < len(items); i++ {
		item := items[i]
		participants, pErr := s.getParticipants(ctx, item.ConversationID)
		if pErr == nil {
			conv, _ := s.getConversation(ctx, item.ConversationID)
			readTargets := []string{userID}
			if conv != nil && conv.Type == model.ConversationTypePrivate {
				readTargets = make([]string, 0, len(participants))
				for _, p := range participants {
					readTargets = append(readTargets, p.UserID)
				}
			}
			s.publishToUsers(readTargets, "message_read", map[string]any{
				"conversation_id": item.ConversationID,
				"user_id":         userID,
				"seq":             item.LastReadSeq,
			})
		}
	}

	// 发送总未读数通知
	if totalUnread, uErr := s.GetAllUnreadCount(ctx, userID); uErr == nil {
		s.publishToUsers([]string{userID}, "conversation_unread", map[string]any{
			"total_unread": totalUnread,
		})
	}

	return successCount, nil
}

// GetUnreadCount 获取指定会话的未读消息数（纯算术：maxSeq - readSeq）
func (s *chatServiceImpl) GetUnreadCount(ctx context.Context, conversationID string, userID string) (int64, error) {
	_, err := s.getParticipant(ctx, conversationID, userID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return 0, errors.New("conversation not found or no permission")
		}
		return 0, fmt.Errorf("failed to get participant: %w", err)
	}

	if s.conversationCache != nil {
		if count, err := s.conversationCache.ComputeUnreadCount(ctx, conversationID, userID); err == nil {
			return count, nil
		}
	}
	return s.repo.GetUnreadCount(conversationID, userID)
}

// GetAllUnreadCount 获取所有会话的未读消息总数（批量 MGet maxSeq，纯算术）
func (s *chatServiceImpl) GetAllUnreadCount(ctx context.Context, userID string) (int64, error) {
	if s.conversationCache != nil {
		if convs, _, err := s.GetConversationList(ctx, userID, 1, 200); err == nil && len(convs) > 0 {
			convIDs := make([]string, len(convs))
			for i, conv := range convs {
				convIDs[i] = conv.ID
			}
			maxSeqs, err := s.conversationCache.GetConvMaxSeqBatch(ctx, convIDs)
			if err == nil && len(maxSeqs) == len(convIDs) {
				if total, err := s.conversationCache.ComputeAllUnreadCount(ctx, userID, convIDs, maxSeqs); err == nil {
					return total, nil
				}
			}
		}
	}
	return s.repo.GetAllUnreadCount(userID)
}

// RecallMessage 撤回消息（2分钟内）
func (s *chatServiceImpl) RecallMessage(ctx context.Context, messageID string, userID string) error {
	// 获取消息
	message, err := s.repo.GetMessageByID(messageID)
	if err != nil {
		return errors.New("message not found")
	}

	// 验证是否是消息发送者
	if message.SenderIDStr() != userID {
		return errors.New("can only recall your own messages")
	}

	// 验证消息是否已被撤回
	if message.Status == model.MessageStatusRecalled {
		return errors.New("message already recalled")
	}

	// 验证是否在2分钟内
	if time.Since(message.CreatedAt) > RecallMessageTimeout {
		return errors.New("message recall timeout (2 minutes)")
	}

	// 更新消息状态为已撤回，并清空原始消息内容，仅保留撤回占位
	err = s.repo.RecallMessage(messageID, userID)
	if err != nil {
		return fmt.Errorf("failed to recall message: %w", err)
	}

	// 失效消息缓存
	if s.conversationCache != nil {
		s.conversationCache.InvalidateConversation(message.ConversationID)
	}

	if participants, pErr := s.getParticipants(ctx, message.ConversationID); pErr == nil {
		detailType := "private"
		groupID := ""
		if conv, convErr := s.getConversation(ctx, message.ConversationID); convErr == nil && conv.Type == model.ConversationTypeGroup {
			detailType = "group"
			if conv.GroupID != nil {
				groupID = *conv.GroupID
			}
		}
		targetIDs := make([]string, 0, len(participants))
		for _, p := range participants {
			targetIDs = append(targetIDs, p.UserID)
		}
		s.publishToUsers(targetIDs, "message_recall", map[string]any{
			"detail_type":     detailType,
			"conversation_id": message.ConversationID,
			"group_id":        groupID,
			"message_id":      messageID,
			"sender_id":       userID,
		})
	}

	return nil
}

// DeleteMessage 删除消息（仅对自己可见）
func (s *chatServiceImpl) DeleteMessage(ctx context.Context, messageID string, userID string) error {
	// 获取消息
	message, err := s.repo.GetMessageByID(messageID)
	if err != nil {
		return errors.New("message not found")
	}

	// 验证用户是否是会话参与者
	_, err = s.getParticipant(ctx, message.ConversationID, userID)
	if err != nil {
		return errors.New("no permission to delete this message")
	}

	// 对于删除消息，我们使用软删除，但需要确保只对当前用户隐藏
	// 这里简化处理：只有发送者可以删除自己的消息
	if message.SenderIDStr() != userID {
		return errors.New("can only delete your own messages")
	}

	// 更新消息状态为已删除
	err = s.repo.UpdateMessageStatus(message.ID, model.MessageStatusDeleted)
	if err != nil {
		return fmt.Errorf("failed to delete message: %w", err)
	}

	// 失效消息缓存
	if s.conversationCache != nil {
		s.conversationCache.InvalidateConversation(message.ConversationID)
	}

	return nil
}

// GetReplyMessage 按消息 ID 获取被引用消息（用于引用预览/跳转的回填）
// 鉴权：调用者必须是该消息所属会话的参与者，否则拒绝（防止 IDOR）
func (s *chatServiceImpl) GetReplyMessage(ctx context.Context, messageID string, userID string) (*model.Message, error) {
	message, err := s.repo.GetMessageByID(messageID)
	if err != nil {
		return nil, errors.New("message not found")
	}

	// 验证用户是否是会话参与者
	_, err = s.getParticipant(ctx, message.ConversationID, userID)
	if err != nil {
		return nil, errors.New("no permission to view this message")
	}

	return message, nil
}

// SendTyping 发送正在输入状态
func (s *chatServiceImpl) SendTyping(ctx context.Context, senderID string, conversationID string) {
	if s.wsHub == nil {
		return
	}

	// 验证用户是否是会话参与者
	_, err := s.getParticipant(ctx, conversationID, senderID)
	if err != nil {
		return
	}

	// 获取会话中的其他参与者
	participants, err := s.getParticipants(ctx, conversationID)
	if err != nil {
		return
	}

	detailType := "private"
	if conv, convErr := s.getConversation(ctx, conversationID); convErr == nil && conv.Type == model.ConversationTypeGroup {
		detailType = "group"
	}
	for _, p := range participants {
		if p.UserID == senderID {
			continue
		}
		if s.wsHub != nil {
			s.wsHub.PublishToUser(p.UserID, "typing", map[string]any{
				"detail_type":     detailType,
				"conversation_id": conversationID,
				"user_id":         senderID,
				"is_typing":       true,
			})
		}
	}
}

// IsUserOnline 检查用户是否在线
func (s *chatServiceImpl) IsUserOnline(userID string) bool {
	if s.wsHub != nil {
		return s.wsHub.HasClients(userID)
	}
	return false
}

// SaveMessage 仅保存消息到数据库，不发送实时推送
// 适用于群聊等由调用方自行负责推送的场景
func (s *chatServiceImpl) SaveMessage(ctx context.Context, senderID string, conversationID string, segments model.MessageSegments, replyToID *string) (*model.Message, error) {
	// 验证会话是否存在（保留 conv 用于群消息能力校验）
	conv, err := s.getConversation(ctx, conversationID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, errors.New("会话不存在，请重新创建会话")
		}
		return nil, fmt.Errorf("failed to get conversation: %w", err)
	}

	// 验证用户是否是会话参与者
	_, err = s.getParticipant(ctx, conversationID, senderID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, errors.New("您不是该会话的参与者")
		}
		return nil, fmt.Errorf("failed to get participant: %w", err)
	}

	// 群消息发送：校验发送者是否仍是群成员、是否被禁言、群是否全员禁言。
	// 私聊会话不参与该校验。
	if conv.Type == model.ConversationTypeGroup && conv.GroupID != nil && *conv.GroupID != "" && s.groupAbility != nil {
		if err := s.groupAbility.CanSendGroupMessage(ctx, senderID, *conv.GroupID); err != nil {
			return nil, err
		}
	}

	if s.uploadService != nil {
		if err := s.uploadService.ValidateChatMessageImageSegments(segments); err != nil {
			return nil, err
		}
	}

	message := &model.Message{
		ConversationID: conversationID,
		SenderID:       senderID,
		Segments:       segments,
		ReplyToID:      replyToID,
		Status:         model.MessageStatusNormal,
	}

	// seq 由 CreateMessageWithSeq 在事务内原子分配

	if err := s.repo.CreateMessageWithSeq(message); err != nil {
		return nil, fmt.Errorf("failed to save message: %w", err)
	}

	// 写透 seq 到 Redis，保持缓存与 DB 一致
	if s.conversationCache != nil {
		s.conversationCache.SyncConvSeq(context.Background(), conversationID, message.Seq)
	}

	// 新消息会改变分页结果，先失效分页缓存，避免读到旧列表
	if s.conversationCache != nil {
		s.conversationCache.InvalidateMessagePages(conversationID)
	}

	// 异步写入缓存
	go func() {
		if err := s.cacheMessage(context.Background(), conversationID, message); err != nil {
			zap.L().Warn("async cache message failed",
				zap.String("component", "ChatService"),
				zap.String("convID", conversationID),
				zap.String("msgID", message.ID),
				zap.Error(err),
			)
		}
	}()

	return message, nil
}

// GetUnreadCountBatch 批量获取用户在多个会话中的未读数（批量 MGet）
func (s *chatServiceImpl) GetUnreadCountBatch(ctx context.Context, userID string, convIDs []string) (map[string]int64, error) {
	if s.conversationCache != nil && len(convIDs) > 0 {
		maxSeqs, err := s.conversationCache.GetConvMaxSeqBatch(ctx, convIDs)
		if err == nil && len(maxSeqs) > 0 {
			readSeqs, err := s.conversationCache.GetUserReadSeqs(ctx, userID, convIDs)
			if err == nil {
				result := make(map[string]int64, len(convIDs))
				for _, convID := range convIDs {
					maxSeq, ok := maxSeqs[convID]
					if !ok {
						result[convID] = 0
						continue
					}
					readSeq, hasRead := readSeqs[convID]
					if !hasRead {
						result[convID] = maxSeq
					} else {
						unread := maxSeq - readSeq
						if unread < 0 {
							unread = 0
						}
						result[convID] = unread
					}
				}
				if len(maxSeqs) == len(convIDs) {
					return result, nil
				}
			}
		}
	}
	return s.repo.GetUnreadCountBatch(ctx, userID, convIDs)
}

// GetLastMessagesBatch 批量获取每个会话的最后一条消息
func (s *chatServiceImpl) GetLastMessagesBatch(ctx context.Context, convIDs []string) (map[string]*model.Message, error) {
	return s.repo.GetLastMessagesBatch(ctx, convIDs)
}

// GetUserReadSeq 获取用户在某会话的已读位置（优先从 Redis 缓存读取）
func (s *chatServiceImpl) GetUserReadSeq(ctx context.Context, conversationID string, userID string) (int64, error) {
	if s.conversationCache != nil {
		if seq, err := s.conversationCache.GetUserReadSeq(ctx, conversationID, userID); err == nil {
			return seq, nil
		}
	}
	// 降级到 DB
	participant, err := s.getParticipant(ctx, conversationID, userID)
	if err != nil {
		return 0, err
	}
	return participant.LastReadSeq, nil
}

// GetSyncData 获取用户所有会话的同步元数据（seq + 时间，轻量级）
func (s *chatServiceImpl) GetSyncData(ctx context.Context, userID string) ([]dto.SyncDataItem, error) {
	convs, _, err := s.GetConversationList(ctx, userID, 1, 200)
	if err != nil {
		return nil, fmt.Errorf("failed to get conversation list: %w", err)
	}

	if len(convs) == 0 {
		return nil, nil
	}

	convIDs := make([]string, len(convs))
	for i, conv := range convs {
		convIDs[i] = conv.ID
	}

	maxSeqs, _ := s.conversationCache.GetConvMaxSeqBatch(ctx, convIDs)

	items := make([]dto.SyncDataItem, 0, len(convs))
	for _, conv := range convs {
		item := dto.SyncDataItem{
			ConversationID: conv.ID,
			MaxSeq:         maxSeqs[conv.ID],
			LastMessageAt:  conv.UpdatedAt.Format(time.RFC3339),
		}
		items = append(items, item)
	}
	return items, nil
}