backend/internal/repository/system_notification_repo.go

package repository

import (
	"carrot_bbs/internal/model"

	"gorm.io/gorm"
)

// SystemNotificationRepository 系统通知仓储
type SystemNotificationRepository struct {
	db *gorm.DB
}

// NewSystemNotificationRepository 创建系统通知仓储
func NewSystemNotificationRepository(db *gorm.DB) *SystemNotificationRepository {
	return &SystemNotificationRepository{db: db}
}

// Create 创建系统通知
func (r *SystemNotificationRepository) Create(notification *model.SystemNotification) error {
	return r.db.Create(notification).Error
}

// GetByID 根据ID获取通知
func (r *SystemNotificationRepository) GetByID(id int64) (*model.SystemNotification, error) {
	var notification model.SystemNotification
	err := r.db.First(&notification, "id = ?", id).Error
	if err != nil {
		return nil, err
	}
	return &notification, nil
}

// GetByReceiverID 获取用户的通知列表
func (r *SystemNotificationRepository) GetByReceiverID(receiverID string, page, pageSize int) ([]*model.SystemNotification, int64, error) {
	var notifications []*model.SystemNotification
	var total int64

	query := r.db.Model(&model.SystemNotification{}).Where("receiver_id = ?", receiverID)
	query.Count(&total)

	offset := (page - 1) * pageSize
	err := query.Offset(offset).
		Limit(pageSize).
		Order("created_at DESC").
		Find(&notifications).Error

	return notifications, total, err
}

// GetUnreadByReceiverID 获取用户的未读通知列表
func (r *SystemNotificationRepository) GetUnreadByReceiverID(receiverID string, limit int) ([]*model.SystemNotification, error) {
	var notifications []*model.SystemNotification
	err := r.db.Where("receiver_id = ? AND is_read = ?", receiverID, false).
		Order("created_at DESC").
		Limit(limit).
		Find(&notifications).Error
	return notifications, err
}

// GetUnreadCount 获取用户未读通知数量
func (r *SystemNotificationRepository) GetUnreadCount(receiverID string) (int64, error) {
	var count int64
	err := r.db.Model(&model.SystemNotification{}).
		Where("receiver_id = ? AND is_read = ?", receiverID, false).
		Count(&count).Error
	return count, err
}

// MarkAsRead 标记单条通知为已读
func (r *SystemNotificationRepository) MarkAsRead(id int64, receiverID string) error {
	now := model.SystemNotification{}.UpdatedAt
	return r.db.Model(&model.SystemNotification{}).
		Where("id = ? AND receiver_id = ?", id, receiverID).
		Updates(map[string]interface{}{
			"is_read": true,
			"read_at": now,
		}).Error
}

// MarkAllAsRead 标记用户所有通知为已读
func (r *SystemNotificationRepository) MarkAllAsRead(receiverID string) error {
	now := model.SystemNotification{}.UpdatedAt
	return r.db.Model(&model.SystemNotification{}).
		Where("receiver_id = ? AND is_read = ?", receiverID, false).
		Updates(map[string]interface{}{
			"is_read": true,
			"read_at": now,
		}).Error
}

// Delete 删除通知（软删除）
func (r *SystemNotificationRepository) Delete(id int64, receiverID string) error {
	return r.db.Where("id = ? AND receiver_id = ?", id, receiverID).
		Delete(&model.SystemNotification{}).Error
}

// GetByType 获取用户指定类型的通知
func (r *SystemNotificationRepository) GetByType(receiverID string, notifyType model.SystemNotificationType, page, pageSize int) ([]*model.SystemNotification, int64, error) {
	var notifications []*model.SystemNotification
	var total int64

	query := r.db.Model(&model.SystemNotification{}).
		Where("receiver_id = ? AND type = ?", receiverID, notifyType)
	query.Count(&total)

	offset := (page - 1) * pageSize
	err := query.Offset(offset).
		Limit(pageSize).
		Order("created_at DESC").
		Find(&notifications).Error

	return notifications, total, err
}

// GetByReceiverIDCursor 游标分页获取用户的通知列表
func (r *SystemNotificationRepository) GetByReceiverIDCursor(receiverID string, cursor string, pageSize int) ([]*model.SystemNotification, string, bool, error) {
	query := r.db.Model(&model.SystemNotification{}).Where("receiver_id = ?", receiverID)

	// 如果有游标，解析游标并添加条件
	if cursor != "" {
		// 游标格式：createdAt_id
		query = query.Where("created_at < ? OR (created_at = ? AND id < ?)", cursor, cursor, cursor)
	}

	// 多取一条用于判断是否还有下一页
	var notifications []*model.SystemNotification
	err := query.Order("created_at DESC, id DESC").
		Limit(pageSize + 1).
		Find(&notifications).Error

	if err != nil {
		return nil, "", false, err
	}

	hasMore := len(notifications) > pageSize
	if hasMore {
		notifications = notifications[:pageSize]
	}

	// 生成下一页游标
	var nextCursor string
	if hasMore && len(notifications) > 0 {
		lastNotification := notifications[len(notifications)-1]
		nextCursor = lastNotification.CreatedAt.Format("2006-01-02 15:04:05.999999999")
	}

	return notifications, nextCursor, hasMore, nil
}