backend/internal/handler/system_message_handler.go

package handler

import (
	"strconv"

	"github.com/gin-gonic/gin"

	"carrot_bbs/internal/dto"
	"carrot_bbs/internal/pkg/response"
	"carrot_bbs/internal/service"
)

// SystemMessageHandler 系统消息处理器
type SystemMessageHandler struct {
	systemMsgService service.SystemMessageService
}

// NewSystemMessageHandler 创建系统消息处理器
func NewSystemMessageHandler(
	systemMsgService service.SystemMessageService,
) *SystemMessageHandler {
	return &SystemMessageHandler{
		systemMsgService: systemMsgService,
	}
}

// GetSystemMessages 获取系统消息列表
// GET /api/v1/messages/system
func (h *SystemMessageHandler) GetSystemMessages(c *gin.Context) {
	userID := c.GetString("user_id")
	if userID == "" {
		response.Unauthorized(c, "")
		return
	}

	// 检查是否使用游标分页
	_, cursorExists := c.GetQuery("cursor")
	if cursorExists {
		h.GetSystemMessagesByCursor(c)
		return
	}

	// 偏移分页（向后兼容）
	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
	pageSize, _ := strconv.Atoi(c.DefaultQuery("page_size", "20"))

	// 获取当前用户的系统通知
	notifications, total, err := h.systemMsgService.GetNotifications(userID, page, pageSize)
	if err != nil {
		response.InternalServerError(c, "failed to get system messages")
		return
	}

	// 转换为响应格式
	result := make([]*dto.SystemMessageResponse, 0)
	for _, n := range notifications {
		resp := dto.SystemNotificationToResponse(n)
		result = append(result, resp)
	}

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

// GetSystemMessagesByCursor 游标分页获取系统消息列表
func (h *SystemMessageHandler) GetSystemMessagesByCursor(c *gin.Context) {
	userID := c.GetString("user_id")
	if userID == "" {
		response.Unauthorized(c, "")
		return
	}

	// 解析游标分页请求
	cursorStr := c.Query("cursor")
	pageSize, _ := strconv.Atoi(c.DefaultQuery("page_size", "20"))

	// 获取当前用户的系统通知（使用兼容旧版接口）
	notifications, nextCursor, hasMore, err := h.systemMsgService.GetNotificationsByCursor(userID, cursorStr, pageSize)
	if err != nil {
		response.InternalServerError(c, "failed to get system messages")
		return
	}

	// 转换为响应格式
	items := make([]*dto.SystemMessageResponse, 0)
	for _, n := range notifications {
		resp := dto.SystemNotificationToResponse(n)
		items = append(items, resp)
	}

	// 构建游标分页响应
	cursorResp := &dto.SystemMessageCursorPageResponse{
		Items:      items,
		NextCursor: nextCursor,
		PrevCursor: "",
		HasMore:    hasMore,
	}

	response.Success(c, cursorResp)
}

// GetUnreadCount 获取系统消息未读数
// GET /api/v1/messages/system/unread-count
func (h *SystemMessageHandler) GetUnreadCount(c *gin.Context) {
	userID := c.GetString("user_id")
	if userID == "" {
		response.Unauthorized(c, "")
		return
	}

	// 获取当前用户的未读通知数
	unreadCount, err := h.systemMsgService.GetUnreadCount(userID)
	if err != nil {
		response.InternalServerError(c, "failed to get unread count")
		return
	}

	response.Success(c, &dto.SystemUnreadCountResponse{
		UnreadCount: unreadCount,
	})
}

// MarkAsRead 标记系统消息为已读
// PUT /api/v1/messages/system/:id/read
func (h *SystemMessageHandler) MarkAsRead(c *gin.Context) {
	userID := c.GetString("user_id")
	if userID == "" {
		response.Unauthorized(c, "")
		return
	}

	notificationIDStr := c.Param("id")
	notificationID, err := strconv.ParseInt(notificationIDStr, 10, 64)
	if err != nil {
		response.BadRequest(c, "invalid notification id")
		return
	}

	// 标记为已读
	err = h.systemMsgService.MarkAsRead(notificationID, userID)
	if err != nil {
		response.InternalServerError(c, "failed to mark as read")
		return
	}

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

// MarkAllAsRead 标记所有系统消息为已读
// PUT /api/v1/messages/system/read-all
func (h *SystemMessageHandler) MarkAllAsRead(c *gin.Context) {
	userID := c.GetString("user_id")
	if userID == "" {
		response.Unauthorized(c, "")
		return
	}

	// 标记当前用户所有通知为已读
	err := h.systemMsgService.MarkAllAsRead(userID)
	if err != nil {
		response.InternalServerError(c, "failed to mark all as read")
		return
	}

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

// DeleteSystemMessage 删除系统消息
// DELETE /api/v1/messages/system/:id
func (h *SystemMessageHandler) DeleteSystemMessage(c *gin.Context) {
	userID := c.GetString("user_id")
	if userID == "" {
		response.Unauthorized(c, "")
		return
	}

	notificationIDStr := c.Param("id")
	notificationID, err := strconv.ParseInt(notificationIDStr, 10, 64)
	if err != nil {
		response.BadRequest(c, "invalid notification id")
		return
	}

	// 删除通知
	err = h.systemMsgService.DeleteNotification(notificationID, userID)
	if err != nil {
		response.InternalServerError(c, "failed to delete notification")
		return
	}

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