package handler

import (
	"context"
	"strconv"

	"github.com/gin-gonic/gin"

	"with_you/internal/dto"
	"with_you/internal/model"
	"with_you/internal/pkg/cursor"
	"with_you/internal/pkg/response"
	"with_you/internal/pkg/ws"
	"with_you/internal/service"
)

// enrichConversations 批量填充会话列表响应数据（解决 N+1 问题）
func (h *MessageHandler) enrichConversations(ctx context.Context, convs []*model.Conversation, userID string) []*dto.ConversationResponse {
	if len(convs) == 0 {
		return nil
	}

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

	// 批量查询：4-5 次查询替代 N*5 次
	unreadCounts, _ := h.chatService.GetUnreadCountBatch(ctx, userID, convIDs)
	lastMessages, _ := h.chatService.GetLastMessagesBatch(ctx, convIDs)
	myParticipants, _ := h.messageService.GetMyParticipantsBatch(ctx, convIDs, userID)
	allParticipants, _ := h.messageService.GetParticipantsBatch(ctx, convIDs)

	// 收集需要额外查询的 ID
	var groupIDs []string
	var userIDs []string
	for _, conv := range convs {
		if conv.Type == model.ConversationTypeGroup && conv.GroupID != nil && *conv.GroupID != "" {
			groupIDs = append(groupIDs, *conv.GroupID)
		}
	}
	for _, participants := range allParticipants {
		for _, p := range participants {
			if p.UserID != userID {
				userIDs = append(userIDs, p.UserID)
			}
		}
	}

	memberCounts, _ := h.groupService.GetMemberCountBatch(ctx, groupIDs)
	usersMap, _ := h.userService.GetUsersByIDs(ctx, userIDs)

	// 组装响应
	result := make([]*dto.ConversationResponse, len(convs))
	for i, conv := range convs {
		unreadCount := unreadCounts[conv.ID]
		lastMessage := lastMessages[conv.ID]

		myP := myParticipants[conv.ID]
		isPinned := myP != nil && myP.IsPinned
		notificationMuted := myP != nil && myP.NotificationMuted

		var resp *dto.ConversationResponse
		if conv.Type == model.ConversationTypeGroup && conv.GroupID != nil && *conv.GroupID != "" {
			resp = dto.ConvertConversationToResponse(conv, nil, int(unreadCount), lastMessage, isPinned, notificationMuted)
			if mc, ok := memberCounts[*conv.GroupID]; ok {
				resp.MemberCount = int(mc)
			}
		} else {
			participants := allParticipants[conv.ID]
			var users []*model.User
			for _, p := range participants {
				if p.UserID == userID {
					continue
				}
				if u, ok := usersMap[p.UserID]; ok {
					users = append(users, u)
				}
			}
			resp = dto.ConvertConversationToResponse(conv, users, int(unreadCount), lastMessage, isPinned, notificationMuted)
		}
		result[i] = resp
	}
	return result
}

// MessageHandler 消息处理器
type MessageHandler struct {
	chatService    service.ChatService
	messageService *service.MessageService
	userService    service.UserService
	groupService   service.GroupService
	wsPublisher    ws.MessagePublisher
}

// NewMessageHandler 创建消息处理器
func NewMessageHandler(chatService service.ChatService, messageService *service.MessageService, userService service.UserService, groupService service.GroupService, wsPublisher ws.MessagePublisher) *MessageHandler {
	return &MessageHandler{
		chatService:    chatService,
		messageService: messageService,
		userService:    userService,
		groupService:   groupService,
		wsPublisher:    wsPublisher,
	}
}

// HandleTyping 输入状态上报
// POST /api/v1/conversations/typing
func (h *MessageHandler) HandleTyping(c *gin.Context) {
	userID := c.GetString("user_id")
	if userID == "" {
		response.Unauthorized(c, "")
		return
	}

	conversationID := getIDParam(c, "id")
	if conversationID == "" {
		response.BadRequest(c, "conversation id is required")
		return
	}

	h.chatService.SendTyping(c.Request.Context(), userID, conversationID)
	response.SuccessWithMessage(c, "typing sent", nil)
}

// GetConversations 获取会话列表
// GET /api/conversations
func (h *MessageHandler) GetConversations(c *gin.Context) {
	userID := c.GetString("user_id")
	// 添加调试日志
	if userID == "" {
		response.Unauthorized(c, "")
		return
	}

	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
	pageSize, _ := strconv.Atoi(c.DefaultQuery("page_size", "20"))

	convs, _, err := h.chatService.GetConversationList(c.Request.Context(), userID, page, pageSize)
	if err != nil {
		response.InternalServerError(c, "failed to get conversations")
		return
	}

	// 过滤掉系统会话（系统通知现在使用独立的表）
	filteredConvs := make([]*model.Conversation, 0)
	for _, conv := range convs {
		if conv.ID != model.SystemConversationID {
			filteredConvs = append(filteredConvs, conv)
		}
	}

	// 批量填充会话数据（解决 N+1 问题）
	result := h.enrichConversations(c.Request.Context(), filteredConvs, userID)

	// 更新 total 为过滤后的数量
	response.Paginated(c, result, int64(len(filteredConvs)), page, pageSize)
}

// CreateConversation 创建私聊会话
// POST /api/conversations
func (h *MessageHandler) CreateConversation(c *gin.Context) {
	userID := c.GetString("user_id")
	if userID == "" {
		response.Unauthorized(c, "")
		return
	}

	var req dto.CreateConversationRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		response.BadRequest(c, err.Error())
		return
	}

	// 验证目标用户是否存在
	targetUser, err := h.userService.GetUserByID(c.Request.Context(), req.UserID)
	if err != nil {
		response.BadRequest(c, "target user not found")
		return
	}

	// 不能和自己创建会话
	if userID == req.UserID {
		response.BadRequest(c, "cannot create conversation with yourself")
		return
	}

	conv, err := h.chatService.GetOrCreateConversation(c.Request.Context(), userID, req.UserID)
	if err != nil {
		response.InternalServerError(c, "failed to create conversation")
		return
	}

	// 获取参与者信息
	participants := []*model.User{targetUser}
	myParticipant, _ := h.getMyConversationParticipant(conv.ID, userID)
	isPinned := myParticipant != nil && myParticipant.IsPinned
	notificationMuted := myParticipant != nil && myParticipant.NotificationMuted

	response.Success(c, dto.ConvertConversationToResponse(conv, participants, 0, nil, isPinned, notificationMuted))
}

// GetConversationByID 获取会话详情
// GET /api/conversations/:id
func (h *MessageHandler) GetConversationByID(c *gin.Context) {
	userID := c.GetString("user_id")
	if userID == "" {
		response.Unauthorized(c, "")
		return
	}

	conversationIDStr := c.Param("id")
	conversationID, err := service.ParseConversationID(conversationIDStr)
	if err != nil {
		response.BadRequest(c, "invalid conversation id")
		return
	}

	conv, err := h.chatService.GetConversationByID(c.Request.Context(), conversationID, userID)
	if err != nil {
		response.BadRequest(c, err.Error())
		return
	}

	// 获取未读数
	unreadCount, _ := h.chatService.GetUnreadCount(c.Request.Context(), conversationID, userID)

	// 获取参与者信息
	participants, _ := h.getConversationParticipants(c.Request.Context(), conversationID, userID)

	// 获取当前用户的已读位置
	myLastReadSeq := int64(0)
	isPinned := false
	notificationMuted := false
	allParticipants, _ := h.messageService.GetConversationParticipants(conversationID)
	for _, p := range allParticipants {
		if p.UserID == userID {
			myLastReadSeq = p.LastReadSeq
			isPinned = p.IsPinned
			notificationMuted = p.NotificationMuted
			break
		}
	}

	// 获取对方用户的已读位置
	otherLastReadSeq := int64(0)
	for _, p := range allParticipants {
		if p.UserID != userID {
			otherLastReadSeq = p.LastReadSeq
			break
		}
	}
	response.Success(c, dto.ConvertConversationToDetailResponse(conv, participants, unreadCount, nil, myLastReadSeq, otherLastReadSeq, isPinned, notificationMuted))
}

// GetMessages 获取消息列表
// GET /api/conversations/:id/messages
func (h *MessageHandler) GetMessages(c *gin.Context) {
	userID := c.GetString("user_id")
	if userID == "" {
		response.Unauthorized(c, "")
		return
	}

	conversationIDStr := c.Param("id")
	conversationID, err := service.ParseConversationID(conversationIDStr)
	if err != nil {
		response.BadRequest(c, "invalid conversation id")
		return
	}

	// 检查是否使用增量同步（after_seq参数）
	afterSeqStr := c.Query("after_seq")
	if afterSeqStr != "" {
		// 增量同步模式
		afterSeq, err := strconv.ParseInt(afterSeqStr, 10, 64)
		if err != nil {
			response.BadRequest(c, "invalid after_seq")
			return
		}

		limit, _ := strconv.Atoi(c.DefaultQuery("limit", "20"))

		messages, err := h.chatService.GetMessagesAfterSeq(c.Request.Context(), conversationID, userID, afterSeq, limit)
		if err != nil {
			response.BadRequest(c, err.Error())
			return
		}

		// 转换为响应格式
		result := dto.ConvertMessagesToResponse(messages)

		response.Success(c, &dto.MessageSyncResponse{
			Messages: result,
			HasMore:  len(messages) == limit,
		})
		return
	}

	// 检查是否使用历史消息加载（before_seq参数）
	beforeSeqStr := c.Query("before_seq")
	if beforeSeqStr != "" {
		// 加载更早的消息（下拉加载更多）
		beforeSeq, err := strconv.ParseInt(beforeSeqStr, 10, 64)
		if err != nil {
			response.BadRequest(c, "invalid before_seq")
			return
		}

		limit, _ := strconv.Atoi(c.DefaultQuery("limit", "20"))

		messages, err := h.chatService.GetMessagesBeforeSeq(c.Request.Context(), conversationID, userID, beforeSeq, limit)
		if err != nil {
			response.BadRequest(c, err.Error())
			return
		}

		// 转换为响应格式
		result := dto.ConvertMessagesToResponse(messages)

		response.Success(c, &dto.MessageSyncResponse{
			Messages: result,
			HasMore:  len(messages) == limit,
		})
		return
	}

	// 分页模式
	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
	pageSize, _ := strconv.Atoi(c.DefaultQuery("page_size", "20"))

	messages, total, err := h.chatService.GetMessages(c.Request.Context(), conversationID, userID, page, pageSize)
	if err != nil {
		response.BadRequest(c, err.Error())
		return
	}

	// 转换为响应格式
	result := dto.ConvertMessagesToResponse(messages)

	response.Paginated(c, result, total, page, pageSize)
}

// SendMessage 发送消息
// POST /api/conversations/:id/messages
func (h *MessageHandler) SendMessage(c *gin.Context) {
	userID := c.GetString("user_id")
	if userID == "" {
		response.Unauthorized(c, "")
		return
	}

	conversationIDStr := c.Param("id")
	conversationID, err := service.ParseConversationID(conversationIDStr)
	if err != nil {
		response.BadRequest(c, "invalid conversation id")
		return
	}

	var req dto.SendMessageRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		response.BadRequest(c, err.Error())
		return
	}

	msg, err := h.chatService.SendMessage(c.Request.Context(), userID, conversationID, req.Segments, req.ReplyToID, req.ClientMsgID)
	if err != nil {
		response.BadRequest(c, err.Error())
		return
	}

	response.Success(c, dto.ConvertMessageToResponse(msg))
}

// HandleSendMessage RESTful 风格的发送消息端点
// POST /api/v1/conversations/:id/messages
// 请求体格式: {"detail_type": "private", "segments": [{"type": "text", "data": {"text": "嗨～"}}]}
func (h *MessageHandler) HandleSendMessage(c *gin.Context) {
	userID := c.GetString("user_id")
	if userID == "" {
		response.Unauthorized(c, "")
		return
	}

	conversationID := getIDParam(c, "id")
	if conversationID == "" {
		response.BadRequest(c, "conversation id is required")
		return
	}

	var params dto.SendMessageParams
	if err := c.ShouldBindJSON(&params); err != nil {
		response.BadRequest(c, err.Error())
		return
	}

	// 验证参数
	if params.DetailType == "" {
		response.BadRequest(c, "detail_type is required")
		return
	}
	if len(params.Segments) == 0 {
		response.BadRequest(c, "segments is required")
		return
	}

	// 发送消息
	msg, err := h.chatService.SendMessage(c.Request.Context(), userID, conversationID, params.Segments, params.ReplyToID, params.ClientMsgID)
	if err != nil {
		response.BadRequest(c, err.Error())
		return
	}

	// 构建 WSEventResponse 格式响应
	wsResponse := dto.WSEventResponse{
		ID:             msg.ID,
		Time:           msg.CreatedAt.UnixMilli(),
		Type:           "message",
		DetailType:     params.DetailType,
		ConversationID: conversationID,
		Seq:            strconv.FormatInt(msg.Seq, 10),
		Segments:       params.Segments,
		SenderID:       userID,
	}

	response.Success(c, wsResponse)
}

// HandleDeleteMsg 撤回消息
// POST /api/v1/messages/delete_msg
// 请求体格式: {"message_id": "xxx"}
func (h *MessageHandler) HandleDeleteMsg(c *gin.Context) {
	userID := c.GetString("user_id")
	if userID == "" {
		response.Unauthorized(c, "")
		return
	}

	var params dto.DeleteMsgParams
	if err := c.ShouldBindJSON(&params); err != nil {
		response.BadRequest(c, err.Error())
		return
	}

	// 验证参数
	if params.MessageID == "" {
		response.BadRequest(c, "message_id is required")
		return
	}

	// 撤回消息
	err := h.chatService.RecallMessage(c.Request.Context(), params.MessageID, userID)
	if err != nil {
		response.BadRequest(c, err.Error())
		return
	}

	response.SuccessWithMessage(c, "消息已撤回", nil)
}

// HandleGetConversationList 获取会话列表
// GET /api/v1/conversations
func (h *MessageHandler) HandleGetConversationList(c *gin.Context) {
	userID := c.GetString("user_id")
	if userID == "" {
		response.Unauthorized(c, "")
		return
	}

	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
	pageSize, _ := strconv.Atoi(c.DefaultQuery("page_size", "20"))

	convs, _, err := h.chatService.GetConversationList(c.Request.Context(), userID, page, pageSize)
	if err != nil {
		response.InternalServerError(c, "failed to get conversations")
		return
	}

	// 过滤掉系统会话（系统通知现在使用独立的表）
	filteredConvs := make([]*model.Conversation, 0)
	for _, conv := range convs {
		if conv.ID != model.SystemConversationID {
			filteredConvs = append(filteredConvs, conv)
		}
	}

	// 批量填充会话数据（解决 N+1 问题）
	result := h.enrichConversations(c.Request.Context(), filteredConvs, userID)

	response.Paginated(c, result, int64(len(filteredConvs)), page, pageSize)
}

// HandleDeleteConversationForSelf 仅自己删除会话
// DELETE /api/v1/conversations/:id/self
func (h *MessageHandler) HandleDeleteConversationForSelf(c *gin.Context) {
	userID := c.GetString("user_id")
	if userID == "" {
		response.Unauthorized(c, "")
		return
	}

	conversationID := getIDParam(c, "id")
	if conversationID == "" {
		response.BadRequest(c, "conversation id is required")
		return
	}

	if err := h.chatService.DeleteConversationForSelf(c.Request.Context(), conversationID, userID); err != nil {
		response.BadRequest(c, err.Error())
		return
	}

	response.SuccessWithMessage(c, "conversation deleted for self", nil)
}

// MarkAsRead 标记为已读
// POST /api/conversations/:id/read
func (h *MessageHandler) MarkAsRead(c *gin.Context) {
	userID := c.GetString("user_id")
	if userID == "" {
		response.Unauthorized(c, "")
		return
	}

	conversationIDStr := c.Param("id")
	conversationID, err := service.ParseConversationID(conversationIDStr)
	if err != nil {
		response.BadRequest(c, "invalid conversation id")
		return
	}

	var req dto.MarkReadRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		response.BadRequest(c, "last_read_seq is required")
		return
	}

	err = h.chatService.MarkAsRead(c.Request.Context(), conversationID, userID, req.LastReadSeq)
	if err != nil {
		response.BadRequest(c, err.Error())
		return
	}

	response.SuccessWithMessage(c, "marked as read", nil)
}

// GetUnreadCount 获取未读消息总数
// GET /api/conversations/unread/count
func (h *MessageHandler) GetUnreadCount(c *gin.Context) {
	userID := c.GetString("user_id")

	if userID == "" {
		response.Unauthorized(c, "")
		return
	}

	count, err := h.chatService.GetAllUnreadCount(c.Request.Context(), userID)
	if err != nil {
		response.InternalServerError(c, "failed to get unread count")
		return
	}

	response.Success(c, &dto.UnreadCountResponse{
		TotalUnreadCount: count,
	})
}

// HandleGetSyncData 获取同步元数据（轻量级 seq + 时间）
// GET /api/v1/conversations/sync-data
func (h *MessageHandler) HandleGetSyncData(c *gin.Context) {
	userID := c.GetString("user_id")
	if userID == "" {
		response.Unauthorized(c, "")
		return
	}

	items, err := h.chatService.GetSyncData(c.Request.Context(), userID)
	if err != nil {
		response.InternalServerError(c, "failed to get sync data")
		return
	}

	response.Success(c, &dto.SyncDataResponse{
		Conversations: items,
	})
}

// GetConversationUnreadCount 获取单个会话的未读数
// GET /api/conversations/:id/unread/count
func (h *MessageHandler) GetConversationUnreadCount(c *gin.Context) {
	userID := c.GetString("user_id")
	if userID == "" {
		response.Unauthorized(c, "")
		return
	}

	conversationIDStr := c.Param("id")
	conversationID, err := service.ParseConversationID(conversationIDStr)
	if err != nil {
		response.BadRequest(c, "invalid conversation id")
		return
	}

	count, err := h.chatService.GetUnreadCount(c.Request.Context(), conversationID, userID)
	if err != nil {
		response.BadRequest(c, err.Error())
		return
	}

	response.Success(c, &dto.ConversationUnreadCountResponse{
		ConversationID: conversationID,
		UnreadCount:    count,
	})
}

// RecallMessage 撤回消息
// POST /api/messages/:id/recall
func (h *MessageHandler) RecallMessage(c *gin.Context) {
	userID := c.GetString("user_id")
	if userID == "" {
		response.Unauthorized(c, "")
		return
	}

	messageIDStr := c.Param("id")
	// 直接使用 string 类型的 messageID
	err := h.chatService.RecallMessage(c.Request.Context(), messageIDStr, userID)
	if err != nil {
		response.BadRequest(c, err.Error())
		return
	}

	response.SuccessWithMessage(c, "message recalled", nil)
}

// DeleteMessage 删除消息
// DELETE /api/messages/:id
func (h *MessageHandler) DeleteMessage(c *gin.Context) {
	userID := c.GetString("user_id")
	if userID == "" {
		response.Unauthorized(c, "")
		return
	}

	messageIDStr := c.Param("id")
	// 直接使用 string 类型的 messageID
	err := h.chatService.DeleteMessage(c.Request.Context(), messageIDStr, userID)
	if err != nil {
		response.BadRequest(c, err.Error())
		return
	}

	response.SuccessWithMessage(c, "message deleted", nil)
}

// 辅助函数：验证内容类型
func isValidContentType(contentType model.ContentType) bool {
	switch contentType {
	case model.ContentTypeText, model.ContentTypeImage, model.ContentTypeVideo, model.ContentTypeAudio, model.ContentTypeFile:
		return true
	default:
		return false
	}
}

// 辅助函数：获取会话参与者信息
func (h *MessageHandler) getConversationParticipants(ctx context.Context, conversationID string, currentUserID string) ([]*model.User, error) {
	// 从repository获取参与者列表
	participants, err := h.messageService.GetConversationParticipants(conversationID)
	if err != nil {
		return nil, err
	}

	// 获取参与者用户信息
	var users []*model.User
	for _, p := range participants {
		// 跳过当前用户
		if p.UserID == currentUserID {
			continue
		}
		user, err := h.userService.GetUserByID(ctx, p.UserID)
		if err != nil {
			continue
		}
		users = append(users, user)
	}
	return users, nil
}

// 获取当前用户在会话中的参与者信息
func (h *MessageHandler) getMyConversationParticipant(conversationID string, userID string) (*model.ConversationParticipant, error) {
	participants, err := h.messageService.GetConversationParticipants(conversationID)
	if err != nil {
		return nil, err
	}
	for _, p := range participants {
		if p.UserID == userID {
			return p, nil
		}
	}
	return nil, nil
}

// getIDParam 从路径参数获取 ID
func getIDParam(c *gin.Context, paramName string) string {
	return c.Param(paramName)
}

// ==================== RESTful Action 端点 ====================

// HandleCreateConversation 创建会话
// POST /api/v1/conversations/create
func (h *MessageHandler) HandleCreateConversation(c *gin.Context) {
	userID := c.GetString("user_id")
	if userID == "" {
		response.Unauthorized(c, "")
		return
	}

	var params dto.CreateConversationParams
	if err := c.ShouldBindJSON(&params); err != nil {
		response.BadRequest(c, err.Error())
		return
	}

	// 验证目标用户是否存在
	targetUser, err := h.userService.GetUserByID(c.Request.Context(), params.UserID)
	if err != nil {
		response.BadRequest(c, "target user not found")
		return
	}

	// 不能和自己创建会话
	if userID == params.UserID {
		response.BadRequest(c, "cannot create conversation with yourself")
		return
	}

	conv, err := h.chatService.GetOrCreateConversation(c.Request.Context(), userID, params.UserID)
	if err != nil {
		response.InternalServerError(c, "failed to create conversation")
		return
	}

	// 获取参与者信息
	participants := []*model.User{targetUser}
	myParticipant, _ := h.getMyConversationParticipant(conv.ID, userID)
	isPinned := myParticipant != nil && myParticipant.IsPinned
	notificationMuted := myParticipant != nil && myParticipant.NotificationMuted

	response.Success(c, dto.ConvertConversationToResponse(conv, participants, 0, nil, isPinned, notificationMuted))
}

// HandleGetConversation 获取会话详情
// GET /api/v1/conversations/:id
func (h *MessageHandler) HandleGetConversation(c *gin.Context) {
	userID := c.GetString("user_id")
	if userID == "" {
		response.Unauthorized(c, "")
		return
	}

	conversationID := getIDParam(c, "id")
	if conversationID == "" {
		response.BadRequest(c, "conversation_id is required")
		return
	}

	conv, err := h.chatService.GetConversationByID(c.Request.Context(), conversationID, userID)
	if err != nil {
		response.BadRequest(c, err.Error())
		return
	}

	// 获取未读数
	unreadCount, _ := h.chatService.GetUnreadCount(c.Request.Context(), conversationID, userID)

	// 获取参与者信息
	participants, _ := h.getConversationParticipants(c.Request.Context(), conversationID, userID)

	// 获取当前用户的已读位置（优先从 Redis 缓存读取）
	myLastReadSeq := int64(0)
	isPinned := false
	notificationMuted := false
	allParticipants, _ := h.messageService.GetConversationParticipants(conversationID)
	for _, p := range allParticipants {
		if p.UserID == userID {
			myLastReadSeq = p.LastReadSeq
			isPinned = p.IsPinned
			notificationMuted = p.NotificationMuted
			break
		}
	}

	// 获取对方用户的已读位置（优先从 Redis 缓存读取）
	otherLastReadSeq := int64(0)
	for _, p := range allParticipants {
		if p.UserID != userID {
			otherLastReadSeq = p.LastReadSeq
			break
		}
	}
	response.Success(c, dto.ConvertConversationToDetailResponse(conv, participants, unreadCount, nil, myLastReadSeq, otherLastReadSeq, isPinned, notificationMuted))
}

// HandleGetMessages 获取会话消息
// GET /api/v1/conversations/:id/messages
func (h *MessageHandler) HandleGetMessages(c *gin.Context) {
	userID := c.GetString("user_id")
	if userID == "" {
		response.Unauthorized(c, "")
		return
	}

	conversationID := getIDParam(c, "id")
	if conversationID == "" {
		response.BadRequest(c, "conversation_id is required")
		return
	}

	// 检查是否使用增量同步（after_seq参数）
	afterSeqStr := c.Query("after_seq")
	if afterSeqStr != "" {
		// 增量同步模式
		afterSeq, err := strconv.ParseInt(afterSeqStr, 10, 64)
		if err != nil {
			response.BadRequest(c, "invalid after_seq")
			return
		}

		limit, _ := strconv.Atoi(c.DefaultQuery("limit", "100"))

		messages, err := h.chatService.GetMessagesAfterSeq(c.Request.Context(), conversationID, userID, afterSeq, limit)
		if err != nil {
			response.BadRequest(c, err.Error())
			return
		}

		// 转换为响应格式
		result := dto.ConvertMessagesToResponse(messages)

		response.Success(c, &dto.MessageSyncResponse{
			Messages: result,
			HasMore:  len(messages) == limit,
		})
		return
	}

	// 检查是否使用历史消息加载（before_seq参数）
	beforeSeqStr := c.Query("before_seq")
	if beforeSeqStr != "" {
		// 加载更早的消息（下拉加载更多）
		beforeSeq, err := strconv.ParseInt(beforeSeqStr, 10, 64)
		if err != nil {
			response.BadRequest(c, "invalid before_seq")
			return
		}

		limit, _ := strconv.Atoi(c.DefaultQuery("limit", "20"))

		messages, err := h.chatService.GetMessagesBeforeSeq(c.Request.Context(), conversationID, userID, beforeSeq, limit)
		if err != nil {
			response.BadRequest(c, err.Error())
			return
		}

		// 转换为响应格式
		result := dto.ConvertMessagesToResponse(messages)

		response.Success(c, &dto.MessageSyncResponse{
			Messages: result,
			HasMore:  len(messages) == limit,
		})
		return
	}

	// 分页模式
	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
	pageSize, _ := strconv.Atoi(c.DefaultQuery("page_size", "20"))

	messages, total, err := h.chatService.GetMessages(c.Request.Context(), conversationID, userID, page, pageSize)
	if err != nil {
		response.BadRequest(c, err.Error())
		return
	}

	// 转换为响应格式
	result := dto.ConvertMessagesToResponse(messages)

	response.Paginated(c, result, total, page, pageSize)
}

// HandleMarkRead 标记已读
// POST /api/v1/conversations/:id/read
func (h *MessageHandler) HandleMarkRead(c *gin.Context) {
	userID := c.GetString("user_id")
	if userID == "" {
		response.Unauthorized(c, "")
		return
	}

	conversationID := getIDParam(c, "id")
	if conversationID == "" {
		response.BadRequest(c, "conversation id is required")
		return
	}

	var req dto.MarkReadRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		response.BadRequest(c, err.Error())
		return
	}

	err := h.chatService.MarkAsRead(c.Request.Context(), conversationID, userID, req.LastReadSeq)
	if err != nil {
		response.BadRequest(c, err.Error())
		return
	}

	response.SuccessWithMessage(c, "marked as read", nil)
}

// HandleMarkReadAll 批量标记所有会话已读
// POST /api/v1/conversations/read-all
func (h *MessageHandler) HandleMarkReadAll(c *gin.Context) {
	userID := c.GetString("user_id")
	if userID == "" {
		response.Unauthorized(c, "")
		return
	}

	var req dto.BatchMarkReadRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		response.BadRequest(c, err.Error())
		return
	}

	successCount, err := h.chatService.MarkAsReadBatch(c.Request.Context(), userID, req.Conversations)
	if err != nil {
		response.InternalServerError(c, "failed to mark all as read")
		return
	}

	response.Success(c, &dto.BatchMarkReadResponse{
		SuccessCount: successCount,
		TotalCount:   len(req.Conversations),
	})
}

// HandleSetConversationPinned 设置会话置顶
// PUT /api/v1/conversations/:id/pinned
func (h *MessageHandler) HandleSetConversationPinned(c *gin.Context) {
	userID := c.GetString("user_id")
	if userID == "" {
		response.Unauthorized(c, "")
		return
	}

	conversationID := getIDParam(c, "id")
	if conversationID == "" {
		response.BadRequest(c, "conversation id is required")
		return
	}

	var req struct {
		IsPinned bool `json:"is_pinned"`
	}
	if err := c.ShouldBindJSON(&req); err != nil {
		response.BadRequest(c, err.Error())
		return
	}

	if err := h.chatService.SetConversationPinned(c.Request.Context(), conversationID, userID, req.IsPinned); err != nil {
		response.BadRequest(c, err.Error())
		return
	}

	response.SuccessWithMessage(c, "conversation pinned status updated", gin.H{
		"conversation_id": conversationID,
		"is_pinned":       req.IsPinned,
	})
}

// HandleSetConversationNotificationMuted 设置会话免打扰状态
// PUT /api/v1/conversations/:id/notification_muted
func (h *MessageHandler) HandleSetConversationNotificationMuted(c *gin.Context) {
	userID := c.GetString("user_id")
	if userID == "" {
		response.Unauthorized(c, "")
		return
	}

	conversationID := getIDParam(c, "id")
	if conversationID == "" {
		response.BadRequest(c, "conversation id is required")
		return
	}

	var req struct {
		NotificationMuted bool `json:"notification_muted"`
	}
	if err := c.ShouldBindJSON(&req); err != nil {
		response.BadRequest(c, err.Error())
		return
	}

	if err := h.chatService.SetConversationNotificationMuted(c.Request.Context(), conversationID, userID, req.NotificationMuted); err != nil {
		response.BadRequest(c, err.Error())
		return
	}

	response.SuccessWithMessage(c, "conversation notification_muted status updated", gin.H{
		"conversation_id":    conversationID,
		"notification_muted": req.NotificationMuted,
	})
}

// ==================== Cursor Pagination Handlers ====================

// GetMessagesByCursor 游标分页获取会话消息
// GET /api/v1/conversations/:id/messages/cursor
// 请求参数：
//   - cursor: 游标字符串（可选）
//   - direction: 分页方向 forward 或 backward（默认 forward）
//   - page_size: 每页数量（默认 20，最大 100）
func (h *MessageHandler) GetMessagesByCursor(c *gin.Context) {
	userID := c.GetString("user_id")
	if userID == "" {
		response.Unauthorized(c, "")
		return
	}

	conversationID := getIDParam(c, "id")
	if conversationID == "" {
		response.BadRequest(c, "conversation_id is required")
		return
	}

	// 解析游标分页参数
	pageReq := parseCursorPageRequest(c)

	// 调用服务层
	result, err := h.messageService.GetMessagesByCursor(c.Request.Context(), conversationID, pageReq)
	if err != nil {
		response.InternalServerError(c, "failed to get messages")
		return
	}

	// 转换为响应格式
	items := dto.ConvertMessagesToResponse(result.Items)

	response.Success(c, &dto.MessageCursorPageResponse{
		Items:      items,
		NextCursor: result.NextCursor,
		PrevCursor: result.PrevCursor,
		HasMore:    result.HasMore,
	})
}

// GetConversationsByCursor 游标分页获取会话列表
// GET /api/v1/conversations/cursor
// 请求参数：
//   - cursor: 游标字符串（可选）
//   - direction: 分页方向 forward 或 backward（默认 forward）
//   - page_size: 每页数量（默认 20，最大 100）
func (h *MessageHandler) GetConversationsByCursor(c *gin.Context) {
	userID := c.GetString("user_id")
	if userID == "" {
		response.Unauthorized(c, "")
		return
	}

	// 解析游标分页参数
	pageReq := parseCursorPageRequest(c)

	// 调用服务层
	result, err := h.messageService.GetConversationsByCursor(c.Request.Context(), userID, pageReq)
	if err != nil {
		response.InternalServerError(c, "failed to get conversations")
		return
	}

	// 过滤掉系统会话
	filteredItems := make([]*model.Conversation, 0)
	for _, conv := range result.Items {
		if conv.ID != model.SystemConversationID {
			filteredItems = append(filteredItems, conv)
		}
	}

	// 批量填充会话数据（解决 N+1 问题）
	items := h.enrichConversations(c.Request.Context(), filteredItems, userID)
	response.Success(c, &dto.ConversationCursorPageResponse{
		Items:      items,
		NextCursor: result.NextCursor,
		PrevCursor: result.PrevCursor,
		HasMore:    result.HasMore,
	})
}

// parseCursorPageRequest 解析游标分页请求参数
func parseCursorPageRequest(c *gin.Context) *cursor.PageRequest {
	cursorStr := c.Query("cursor")
	direction := cursor.Direction(c.DefaultQuery("direction", "forward"))
	pageSize, _ := strconv.Atoi(c.DefaultQuery("page_size", "20"))

	return cursor.NewPageRequest(cursorStr, direction, pageSize)
}