package service

import (
	"errors"

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

// FavoriteService 收藏服务：收藏公开可见，公开列表只出 published 帖
type FavoriteService struct {
	db    *gorm.DB
	posts *PostService
}

func NewFavoriteService(db *gorm.DB) *FavoriteService {
	return &FavoriteService{db: db}
}

// WithPosts 注入帖子服务（列表复用 PostListItem 组装与最后回复填充）
func (s *FavoriteService) WithPosts(p *PostService) *FavoriteService {
	s.posts = p
	return s
}

// Toggle 切换收藏状态：已收藏则取消，未收藏则收藏。返回 (favorited, error)
func (s *FavoriteService) Toggle(postID, userID uint) (bool, error) {
	var post model.Post
	if err := s.db.First(&post, postID).Error; err != nil {
		return false, errors.New("帖子不存在")
	}

	var fav model.Favorite
	err := s.db.Where("post_id = ? AND user_id = ?", postID, userID).First(&fav).Error
	if err == nil {
		if err := s.db.Delete(&fav).Error; err != nil {
			return true, err
		}
		return false, nil
	}
	if !errors.Is(err, gorm.ErrRecordNotFound) {
		return false, err
	}
	if err := s.db.Create(&model.Favorite{PostID: postID, UserID: userID}).Error; err != nil {
		return false, err
	}
	return true, nil
}

// HasFavorited 判断用户是否已收藏某帖子
func (s *FavoriteService) HasFavorited(postID, userID uint) bool {
	var count int64
	s.db.Model(&model.Favorite{}).Where("post_id = ? AND user_id = ?", postID, userID).Count(&count)
	return count > 0
}

// BatchHasFavorited 批量查询用户对多个帖子的收藏状态，返回 postID -> bool
func (s *FavoriteService) BatchHasFavorited(postIDs []uint, userID uint) map[uint]bool {
	result := make(map[uint]bool)
	if len(postIDs) == 0 || userID == 0 {
		return result
	}
	var favs []model.Favorite
	s.db.Where("post_id IN ? AND user_id = ?", postIDs, userID).Find(&favs)
	for _, f := range favs {
		result[f.PostID] = true
	}
	return result
}

// List 用户收藏的帖子列表（公开可见，仅 published；按收藏时间倒序）
func (s *FavoriteService) List(userID uint, page, size int) ([]PostListItem, int64, error) {
	if page < 1 {
		page = 1
	}
	if size < 1 || size > 50 {
		size = 20
	}
	query := s.db.Model(&model.Post{}).
		Joins("JOIN favorites ON favorites.post_id = posts.id").
		Where("favorites.user_id = ? AND posts.status = ?", userID, model.ContentStatusPublished)
	var total int64
	if err := query.Count(&total).Error; err != nil {
		return nil, 0, err
	}
	var posts []model.Post
	offset := (page - 1) * size
	if err := query.Select("posts.*").Order("favorites.created_at DESC").Offset(offset).Limit(size).
		Preload("Board").Preload("User").Preload("User.Badges.Badge").Find(&posts).Error; err != nil {
		return nil, 0, err
	}
	items := toPostListItems(posts)
	if s.posts != nil {
		s.posts.fillLastReply(items)
	}
	return items, total, nil
}

// CountByUser 用户收藏数量
func (s *FavoriteService) CountByUser(userID uint) int64 {
	var count int64
	s.db.Model(&model.Favorite{}).Where("user_id = ?", userID).Count(&count)
	return count
}