package service

import (
	"errors"

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

// LikeService 点赞服务
type LikeService struct {
	db *gorm.DB
}

func NewLikeService(db *gorm.DB) *LikeService {
	return &LikeService{db: db}
}

// Toggle 切换点赞状态：已点赞则取消，未点赞则点赞
// 返回 (liked, likeCount, error)
func (s *LikeService) Toggle(postID, userID uint) (bool, int, error) {
	// 检查帖子是否存在
	var post model.Post
	if err := s.db.First(&post, postID).Error; err != nil {
		return false, 0, errors.New("帖子不存在")
	}

	var like model.Like
	err := s.db.Where("post_id = ? AND user_id = ?", postID, userID).First(&like).Error

	if err == nil {
		// 已点赞 → 取消点赞
		if err := s.db.Delete(&like).Error; err != nil {
			return false, post.LikeCount, err
		}
		newCount := post.LikeCount - 1
		if newCount < 0 {
			newCount = 0
		}
		s.db.Model(&post).UpdateColumn("like_count", newCount)
		return false, newCount, nil
	}

	if !errors.Is(err, gorm.ErrRecordNotFound) {
		return false, post.LikeCount, err
	}

	// 未点赞 → 点赞
	newLike := model.Like{PostID: postID, UserID: userID}
	if err := s.db.Create(&newLike).Error; err != nil {
		return false, post.LikeCount, err
	}
	newCount := post.LikeCount + 1
	s.db.Model(&post).UpdateColumn("like_count", newCount)
	return true, newCount, nil
}

// HasLiked 判断用户是否已点赞某帖子
func (s *LikeService) HasLiked(postID, userID uint) bool {
	var count int64
	s.db.Model(&model.Like{}).Where("post_id = ? AND user_id = ?", postID, userID).Count(&count)
	return count > 0
}

// BatchHasLiked 批量查询用户对多个帖子的点赞状态，返回 postID -> bool
func (s *LikeService) BatchHasLiked(postIDs []uint, userID uint) map[uint]bool {
	result := make(map[uint]bool)
	if len(postIDs) == 0 || userID == 0 {
		return result
	}
	var likes []model.Like
	s.db.Where("post_id IN ? AND user_id = ?", postIDs, userID).Find(&likes)
	for _, l := range likes {
		result[l.PostID] = true
	}
	return result
}