backend/internal/repository/sticker_repo.go

package repository

import (
	"with_you/internal/model"
	"strings"

	"gorm.io/gorm"
)

// StickerRepository 自定义表情仓库接口
type StickerRepository interface {
	// 获取用户的所有表情
	GetByUserID(userID string) ([]model.UserSticker, error)
	// 根据ID获取表情
	GetByID(id string) (*model.UserSticker, error)
	// 创建表情
	Create(sticker *model.UserSticker) error
	// 删除表情
	Delete(id string) error
	// 删除用户的所有表情
	DeleteByUserID(userID string) error
	// 检查表情是否存在
	Exists(userID string, url string) (bool, error)
	// 更新排序
	UpdateSortOrder(id string, sortOrder int) error
	// 批量更新排序
	BatchUpdateSortOrder(userID string, orders map[string]int) error
	// 获取用户表情数量
	CountByUserID(userID string) (int64, error)
}

// stickerRepository 自定义表情仓库实现
type stickerRepository struct {
	db *gorm.DB
}

// NewStickerRepository 创建自定义表情仓库
func NewStickerRepository(db *gorm.DB) StickerRepository {
	return &stickerRepository{db: db}
}

// GetByUserID 获取用户的所有表情
func (r *stickerRepository) GetByUserID(userID string) ([]model.UserSticker, error) {
	var stickers []model.UserSticker
	err := r.db.Where("user_id = ?", userID).
		Order("sort_order ASC, created_at DESC").
		Find(&stickers).Error
	return stickers, err
}

// GetByID 根据ID获取表情
func (r *stickerRepository) GetByID(id string) (*model.UserSticker, error) {
	var sticker model.UserSticker
	err := r.db.Where("id = ?", id).First(&sticker).Error
	if err != nil {
		return nil, err
	}
	return &sticker, nil
}

// Create 创建表情
func (r *stickerRepository) Create(sticker *model.UserSticker) error {
	return r.db.Create(sticker).Error
}

// Delete 删除表情
func (r *stickerRepository) Delete(id string) error {
	return r.db.Where("id = ?", id).Delete(&model.UserSticker{}).Error
}

// DeleteByUserID 删除用户的所有表情
func (r *stickerRepository) DeleteByUserID(userID string) error {
	return r.db.Where("user_id = ?", userID).Delete(&model.UserSticker{}).Error
}

// Exists 检查表情是否存在
func (r *stickerRepository) Exists(userID string, url string) (bool, error) {
	var count int64
	err := r.db.Model(&model.UserSticker{}).
		Where("user_id = ? AND url = ?", userID, url).
		Count(&count).Error
	return count > 0, err
}

// UpdateSortOrder 更新排序
func (r *stickerRepository) UpdateSortOrder(id string, sortOrder int) error {
	return r.db.Model(&model.UserSticker{}).
		Where("id = ?", id).
		Update("sort_order", sortOrder).Error
}

// BatchUpdateSortOrder 批量更新排序（使用 CASE WHEN 批量更新，避免 N+1 问题）
func (r *stickerRepository) BatchUpdateSortOrder(userID string, orders map[string]int) error {
	if len(orders) == 0 {
		return nil
	}

	// 构建 CASE WHEN 批量更新 SQL
	var cases []string
	var args []any

	for id, sortOrder := range orders {
		cases = append(cases, "WHEN id = ? THEN ?")
		args = append(args, id, sortOrder)
	}

	ids := make([]string, 0, len(orders))
	for id := range orders {
		ids = append(ids, id)
	}

	sql := `UPDATE user_stickers SET sort_order = CASE ` + 
		strings.Join(cases, " ") + ` END WHERE id IN ? AND user_id = ?`
	args = append(args, ids, userID)

	return r.db.Exec(sql, args...).Error
}

// CountByUserID 获取用户表情数量
func (r *stickerRepository) CountByUserID(userID string) (int64, error) {
	var count int64
	err := r.db.Model(&model.UserSticker{}).
		Where("user_id = ?", userID).
		Count(&count).Error
	return count, err
}