jiang13-bbs/backend/service/notification.go

package service

import (
	"log"
	"time"

	"github.com/freefire/jiang13-bbs/model"
	"gorm.io/gorm"
)

// LikeNotifyDelay 点赞通知冷却：未满该时长即取消点赞则不通知作者
const LikeNotifyDelay = time.Minute

// NotificationService 通知服务
type NotificationService struct {
	db *gorm.DB
	// OnNotifyNew 落库成功后回调（用于 WS 推送红点）；可为 nil
	OnNotifyNew func(userID uint)
}

func NewNotificationService(db *gorm.DB) *NotificationService {
	return &NotificationService{db: db}
}

// FlushPendingLikeNotifications 将已冷却且仍有效的点赞落为通知（误赞撤回不会进入此处）。
func (s *NotificationService) FlushPendingLikeNotifications(limit int) {
	if limit < 1 {
		limit = 50
	}
	cutoff := time.Now().Add(-LikeNotifyDelay)
	type pendingLike struct {
		PostID   uint
		UserID   uint
		AuthorID uint
	}
	var rows []pendingLike
	err := s.db.Raw(`
		SELECT l.post_id AS post_id, l.user_id AS user_id, p.user_id AS author_id
		FROM likes l
		INNER JOIN posts p ON p.id = l.post_id
		WHERE l.created_at <= ?
		  AND p.deleted_at IS NULL
		  AND p.status = ?
		  AND l.user_id <> p.user_id
		  AND NOT EXISTS (
			SELECT 1 FROM notifications n
			WHERE n.type = ?
			  AND n.actor_id = l.user_id
			  AND n.post_id = l.post_id
			  AND n.user_id = p.user_id
			  AND n.created_at >= l.created_at
		  )
		ORDER BY l.created_at ASC
		LIMIT ?
	`, cutoff, model.ContentStatusPublished, model.NotificationTypeLike, limit).Scan(&rows).Error
	if err != nil {
		log.Printf("[notif] 扫描待发点赞通知失败: %v", err)
		return
	}
	for _, row := range rows {
		s.Create(row.AuthorID, row.UserID, model.NotificationTypeLike, row.PostID, 0, "")
	}
}

// StartLikeNotifyFlusher 周期落库冷却后的点赞通知
func StartLikeNotifyFlusher(s *NotificationService) {
	go func() {
		t := time.NewTicker(20 * time.Second)
		defer t.Stop()
		for range t.C {
			s.FlushPendingLikeNotifications(50)
		}
	}()
}

// Create 创建通知（actorID == userID 时跳过，不通知自己）
func (s *NotificationService) Create(userID, actorID uint, notifType string, postID, commentID uint, content string) {
	if userID == 0 || actorID == 0 || userID == actorID {
		return
	}
	// 截断内容预览
	if len(content) > 200 {
		content = content[:200]
	}
	n := &model.Notification{
		UserID:    userID,
		ActorID:   actorID,
		Type:      notifType,
		PostID:    postID,
		CommentID: commentID,
		Content:   content,
		IsRead:    false,
	}
	// 通知创建失败不影响主流程，忽略错误
	if err := s.db.Create(n).Error; err != nil {
		return
	}
	if s.OnNotifyNew != nil {
		s.OnNotifyNew(userID)
	}
}

// CreateSystem 系统通知（ActorID=0，提醒对象即本人，绕过自我通知检查；失败静默）
func (s *NotificationService) CreateSystem(userID uint, notifType string, postID, commentID uint, content string) {
	if userID == 0 {
		return
	}
	if len(content) > 200 {
		content = content[:200]
	}
	n := &model.Notification{
		UserID:    userID,
		ActorID:   0,
		Type:      notifType,
		PostID:    postID,
		CommentID: commentID,
		Content:   content,
		IsRead:    false,
	}
	if err := s.db.Create(n).Error; err != nil {
		return
	}
	if s.OnNotifyNew != nil {
		s.OnNotifyNew(userID)
	}
}

// CreateMention 创建群聊 @ 提醒（PostID=0，用 RoomID/MessageID 关联）。
// 返回创建出的通知 ID（0 表示未创建），供 handler 实时推送。
func (s *NotificationService) CreateMention(userID, actorID, roomID, messageID uint, content string) uint {
	if userID == 0 || actorID == 0 || userID == actorID || roomID == 0 {
		return 0
	}
	if runes := []rune(content); len(runes) > 100 {
		content = string(runes[:100])
	}
	n := &model.Notification{
		UserID:    userID,
		ActorID:   actorID,
		Type:      model.NotificationTypeMention,
		RoomID:    roomID,
		MessageID: messageID,
		Content:   content,
	}
	if err := s.db.Create(n).Error; err != nil {
		return 0
	}
	if s.OnNotifyNew != nil {
		s.OnNotifyNew(userID)
	}
	return n.ID
}

// List 获取用户通知列表（分页，按时间倒序）
func (s *NotificationService) List(userID uint, page, size int) ([]model.Notification, int64, error) {
	if page < 1 {
		page = 1
	}
	if size < 1 || size > 50 {
		size = 20
	}
	query := s.db.Model(&model.Notification{}).Where("user_id = ?", userID)
	var total int64
	if err := query.Count(&total).Error; err != nil {
		return nil, 0, err
	}
	var list []model.Notification
	offset := (page - 1) * size
	if err := query.Order("created_at DESC").Offset(offset).Limit(size).
		Preload("Actor").Preload("Post").Preload("Room").Find(&list).Error; err != nil {
		return nil, 0, err
	}
	return list, total, nil
}

// UnreadCount 获取未读通知数
func (s *NotificationService) UnreadCount(userID uint) (int64, error) {
	var total int64
	err := s.db.Model(&model.Notification{}).Where("user_id = ? AND is_read = ?", userID, false).Count(&total).Error
	return total, err
}

// MarkRead 标记单条通知为已读（校验归属）
func (s *NotificationService) MarkRead(id, userID uint) error {
	result := s.db.Model(&model.Notification{}).
		Where("id = ? AND user_id = ?", id, userID).
		Update("is_read", true)
	return result.Error
}

// MarkAllRead 标记用户所有通知为已读
func (s *NotificationService) MarkAllRead(userID uint) error {
	result := s.db.Model(&model.Notification{}).
		Where("user_id = ? AND is_read = ?", userID, false).
		Update("is_read", true)
	return result.Error
}