backend/internal/repository/comment_repo.go

package repository

import (
	"carrot_bbs/internal/model"
	"carrot_bbs/internal/pkg/cursor"
	"context"

	"gorm.io/gorm"
)

// CommentRepository 评论仓储
type CommentRepository struct {
	db *gorm.DB
}

// NewCommentRepository 创建评论仓储
func NewCommentRepository(db *gorm.DB) *CommentRepository {
	return &CommentRepository{db: db}
}

// Create 创建评论
func (r *CommentRepository) Create(comment *model.Comment) error {
	return r.db.Create(comment).Error
}

// GetByID 根据ID获取评论
func (r *CommentRepository) GetByID(id string) (*model.Comment, error) {
	var comment model.Comment
	err := r.db.Preload("User").First(&comment, "id = ?", id).Error
	if err != nil {
		return nil, err
	}
	return &comment, nil
}

// Update 更新评论
func (r *CommentRepository) Update(comment *model.Comment) error {
	return r.db.Save(comment).Error
}

// UpdateModerationStatus 更新评论审核状态
func (r *CommentRepository) UpdateModerationStatus(commentID string, status model.CommentStatus) error {
	return r.db.Model(&model.Comment{}).
		Where("id = ?", commentID).
		Update("status", status).Error
}

// Delete 删除评论（软删除，同时清理关联数据）
func (r *CommentRepository) Delete(id string) error {
	return r.db.Transaction(func(tx *gorm.DB) error {
		// 先查询评论获取post_id和parent_id
		var comment model.Comment
		if err := tx.First(&comment, "id = ?", id).Error; err != nil {
			return err
		}

		// 删除评论点赞记录
		if err := tx.Where("comment_id = ?", id).Delete(&model.CommentLike{}).Error; err != nil {
			return err
		}

		// 删除评论（软删除）
		if err := tx.Delete(&model.Comment{}, "id = ?", id).Error; err != nil {
			return err
		}

		// 仅已发布评论才参与统计，避免 pending/rejected 影响计数
		if comment.Status == model.CommentStatusPublished {
			// 减少帖子的评论数并同步热度分
			if err := tx.Model(&model.Post{}).Where("id = ?", comment.PostID).
				Updates(map[string]interface{}{
					"comments_count": gorm.Expr("comments_count - 1"),
					"hot_score":      gorm.Expr("likes_count * 2 + (comments_count - 1) * 3 + views_count * 0.1"),
				}).Error; err != nil {
				return err
			}

			// 如果是回复，减少父评论的回复数
			if comment.ParentID != nil && *comment.ParentID != "" {
				if err := tx.Model(&model.Comment{}).Where("id = ?", *comment.ParentID).
					UpdateColumn("replies_count", gorm.Expr("replies_count - 1")).Error; err != nil {
					return err
				}
			}
		}

		return nil
	})
}

// ApplyPublishedStats 在评论审核通过后更新帖子评论数/回复数
func (r *CommentRepository) ApplyPublishedStats(comment *model.Comment) error {
	if comment == nil {
		return nil
	}
	return r.db.Transaction(func(tx *gorm.DB) error {
		// 增加帖子的评论数并同步热度分
		if err := tx.Model(&model.Post{}).Where("id = ?", comment.PostID).
			Updates(map[string]interface{}{
				"comments_count": gorm.Expr("comments_count + 1"),
				"hot_score":      gorm.Expr("likes_count * 2 + (comments_count + 1) * 3 + views_count * 0.1"),
			}).Error; err != nil {
			return err
		}

		// 如果是回复，增加父评论的回复数
		if comment.ParentID != nil && *comment.ParentID != "" {
			if err := tx.Model(&model.Comment{}).Where("id = ?", *comment.ParentID).
				UpdateColumn("replies_count", gorm.Expr("replies_count + 1")).Error; err != nil {
				return err
			}
		}
		return nil
	})
}

// GetByPostID 获取帖子评论
func (r *CommentRepository) GetByPostID(postID string, page, pageSize int) ([]*model.Comment, int64, error) {
	var comments []*model.Comment
	var total int64

	r.db.Model(&model.Comment{}).Where("post_id = ? AND parent_id IS NULL AND status = ?", postID, model.CommentStatusPublished).Count(&total)

	offset := (page - 1) * pageSize
	err := r.db.Where("post_id = ? AND parent_id IS NULL AND status = ?", postID, model.CommentStatusPublished).
		Preload("User").
		Offset(offset).Limit(pageSize).
		Order("created_at ASC").
		Find(&comments).Error

	return comments, total, err
}

// GetByPostIDWithReplies 获取帖子评论（包含回复，扁平化结构）
// 所有层级的回复都扁平化展示在顶级评论的 replies 中
func (r *CommentRepository) GetByPostIDWithReplies(postID string, page, pageSize, replyLimit int) ([]*model.Comment, int64, error) {
	var comments []*model.Comment
	var total int64

	r.db.Model(&model.Comment{}).Where("post_id = ? AND parent_id IS NULL AND status = ?", postID, model.CommentStatusPublished).Count(&total)

	offset := (page - 1) * pageSize
	err := r.db.Where("post_id = ? AND parent_id IS NULL AND status = ?", postID, model.CommentStatusPublished).
		Preload("User").
		Offset(offset).Limit(pageSize).
		Order("created_at ASC").
		Find(&comments).Error

	if err != nil {
		return nil, 0, err
	}

	if len(comments) == 0 {
		return comments, total, nil
	}

	rootIDs := make([]string, 0, len(comments))
	commentsByID := make(map[string]*model.Comment, len(comments))
	for _, comment := range comments {
		rootIDs = append(rootIDs, comment.ID)
		commentsByID[comment.ID] = comment
	}

	// 批量加载所有回复，内存中按 root_id 分组并裁剪每个根评论的返回条数
	var allReplies []*model.Comment
	if err := r.db.Where("root_id IN ? AND status = ?", rootIDs, model.CommentStatusPublished).
		Preload("User").
		Order("created_at ASC").
		Find(&allReplies).Error; err != nil {
		return nil, 0, err
	}

	repliesByRoot := make(map[string][]*model.Comment, len(rootIDs))
	for _, reply := range allReplies {
		if reply.RootID == nil {
			continue
		}
		rootID := *reply.RootID
		if replyLimit <= 0 || len(repliesByRoot[rootID]) < replyLimit {
			repliesByRoot[rootID] = append(repliesByRoot[rootID], reply)
		}
	}

	type replyCountRow struct {
		RootID string
		Total  int64
	}
	var replyCountRows []replyCountRow
	if err := r.db.Model(&model.Comment{}).
		Select("root_id, COUNT(*) AS total").
		Where("root_id IN ? AND status = ?", rootIDs, model.CommentStatusPublished).
		Group("root_id").
		Scan(&replyCountRows).Error; err != nil {
		return nil, 0, err
	}

	replyCountMap := make(map[string]int64, len(replyCountRows))
	for _, row := range replyCountRows {
		replyCountMap[row.RootID] = row.Total
	}

	for _, rootID := range rootIDs {
		comment := commentsByID[rootID]
		comment.Replies = repliesByRoot[rootID]
		comment.RepliesCount = int(replyCountMap[rootID])
	}

	return comments, total, nil
}

// loadFlatReplies 加载评论的所有回复（扁平化，所有层级都在同一层）
func (r *CommentRepository) loadFlatReplies(rootComment *model.Comment, limit int) {
	var allReplies []*model.Comment

	// 查询所有以该评论为根评论的回复（不包括顶级评论本身）
	r.db.Where("root_id = ? AND status = ?", rootComment.ID, model.CommentStatusPublished).
		Preload("User").
		Order("created_at ASC").
		Limit(limit).
		Find(&allReplies)

	rootComment.Replies = allReplies
}

// GetRepliesByRootID 根据根评论ID分页获取回复（扁平化）
func (r *CommentRepository) GetRepliesByRootID(rootID string, page, pageSize int) ([]*model.Comment, int64, error) {
	var replies []*model.Comment
	var total int64

	// 统计总数
	r.db.Model(&model.Comment{}).Where("root_id = ? AND status = ?", rootID, model.CommentStatusPublished).Count(&total)

	// 分页查询
	offset := (page - 1) * pageSize
	err := r.db.Where("root_id = ? AND status = ?", rootID, model.CommentStatusPublished).
		Preload("User").
		Order("created_at ASC").
		Offset(offset).
		Limit(pageSize).
		Find(&replies).Error

	return replies, total, err
}

// GetReplies 获取回复
func (r *CommentRepository) GetReplies(parentID string) ([]*model.Comment, error) {
	var comments []*model.Comment
	err := r.db.Where("parent_id = ? AND status = ?", parentID, model.CommentStatusPublished).
		Preload("User").
		Order("created_at ASC").
		Find(&comments).Error
	return comments, err
}

// Like 点赞评论
func (r *CommentRepository) Like(commentID, userID string) error {
	// 检查是否已经点赞
	var existing model.CommentLike
	err := r.db.Where("comment_id = ? AND user_id = ?", commentID, userID).First(&existing).Error
	if err == nil {
		// 已经点赞
		return nil
	}
	if err != gorm.ErrRecordNotFound {
		return err
	}

	// 创建点赞记录
	like := &model.CommentLike{
		CommentID: commentID,
		UserID:    userID,
	}
	err = r.db.Create(like).Error
	if err != nil {
		return err
	}

	// 增加评论点赞数
	return r.db.Model(&model.Comment{}).Where("id = ?", commentID).
		UpdateColumn("likes_count", gorm.Expr("likes_count + 1")).Error
}

// Unlike 取消点赞评论
func (r *CommentRepository) Unlike(commentID, userID string) error {
	result := r.db.Where("comment_id = ? AND user_id = ?", commentID, userID).Delete(&model.CommentLike{})
	if result.Error != nil {
		return result.Error
	}
	if result.RowsAffected > 0 {
		// 减少评论点赞数
		return r.db.Model(&model.Comment{}).Where("id = ?", commentID).
			UpdateColumn("likes_count", gorm.Expr("likes_count - 1")).Error
	}
	return nil
}

// IsLiked 检查是否已点赞
func (r *CommentRepository) IsLiked(commentID, userID string) bool {
	var count int64
	r.db.Model(&model.CommentLike{}).Where("comment_id = ? AND user_id = ?", commentID, userID).Count(&count)
	return count > 0
}

// AdminCommentListFilter 管理端评论列表筛选条件
type AdminCommentListFilter struct {
	Keyword   string
	PostID    string
	AuthorID  string
	Status    string
	StartDate string
	EndDate   string
	Page      int
	PageSize  int
}

// GetAdminCommentList 获取管理端评论列表
func (r *CommentRepository) GetAdminCommentList(filter AdminCommentListFilter) ([]*model.Comment, int64, error) {
	var comments []*model.Comment
	var total int64

	query := r.db.Model(&model.Comment{}).Preload("User")

	// 应用筛选条件
	if filter.Keyword != "" {
		query = query.Where("content LIKE ?", "%"+filter.Keyword+"%")
	}
	if filter.PostID != "" {
		query = query.Where("post_id = ?", filter.PostID)
	}
	if filter.AuthorID != "" {
		query = query.Where("user_id = ?", filter.AuthorID)
	}
	if filter.Status != "" {
		query = query.Where("status = ?", filter.Status)
	}
	if filter.StartDate != "" {
		query = query.Where("created_at >= ?", filter.StartDate)
	}
	if filter.EndDate != "" {
		query = query.Where("created_at <= ?", filter.EndDate+" 23:59:59")
	}

	// 统计总数
	if err := query.Count(&total).Error; err != nil {
		return nil, 0, err
	}

	// 分页查询
	offset := (filter.Page - 1) * filter.PageSize
	if err := query.Offset(offset).Limit(filter.PageSize).Order("created_at DESC").Find(&comments).Error; err != nil {
		return nil, 0, err
	}

	return comments, total, nil
}

// GetAdminCommentByID 获取管理端评论详情（包含关联信息）
func (r *CommentRepository) GetAdminCommentByID(id string) (*model.Comment, error) {
	var comment model.Comment
	err := r.db.Preload("User").First(&comment, "id = ?", id).Error
	if err != nil {
		return nil, err
	}
	return &comment, nil
}

// BatchDelete 批量删除评论
func (r *CommentRepository) BatchDelete(ids []string) ([]string, error) {
	var failedIDs []string

	for _, id := range ids {
		if err := r.Delete(id); err != nil {
			failedIDs = append(failedIDs, id)
		}
	}

	return failedIDs, nil
}

// GetCommentsByPostIDForAdmin 管理端获取帖子的评论列表（包含所有状态）
func (r *CommentRepository) GetCommentsByPostIDForAdmin(postID string, page, pageSize int) ([]*model.Comment, int64, error) {
	var comments []*model.Comment
	var total int64

	r.db.Model(&model.Comment{}).Where("post_id = ?", postID).Count(&total)

	offset := (page - 1) * pageSize
	err := r.db.Where("post_id = ?", postID).
		Preload("User").
		Offset(offset).Limit(pageSize).
		Order("created_at DESC").
		Find(&comments).Error

	return comments, total, err
}

// ========== Cursor Pagination Methods ==========

// GetCommentsByCursor 游标分页获取帖子评论（包含回复）
// 排序方式：created_at DESC
func (r *CommentRepository) GetCommentsByCursor(ctx context.Context, postID string, req *cursor.PageRequest) (*cursor.CursorPageResult[*model.Comment], error) {
	// 构建基础查询 - 只查询顶级评论
	query := r.db.WithContext(ctx).Model(&model.Comment{}).
		Where("post_id = ? AND parent_id IS NULL AND status = ?", postID, model.CommentStatusPublished)

	// 使用游标构建器
	builder := cursor.NewBuilder(query, cursor.SortByCreatedAtDesc).
		WithCursor(req.Cursor, req.Direction).
		WithPageSize(req.PageSize)

	if builder.Error() != nil {
		// 无效游标，返回空列表
		return cursor.NewCursorPageResult[*model.Comment]([]*model.Comment{}, "", "", false), nil
	}

	// 执行查询
	var comments []*model.Comment
	query = builder.Build().Preload("User")
	if err := query.Find(&comments).Error; err != nil {
		return nil, err
	}

	// 构建响应
	pageSize := builder.GetPageSize()
	hasMore := cursor.HasMore(len(comments), pageSize)
	if hasMore {
		comments = comments[:pageSize]
	}

	// 加载每个评论的回复（默认加载前3条）
	if len(comments) > 0 {
		r.loadRepliesForComments(comments, 3)
	}

	// 生成游标
	var nextCursor, prevCursor string
	if len(comments) > 0 {
		// 下一页游标
		if hasMore {
			lastComment := comments[len(comments)-1]
			nextCursor = cursor.NewCursor(
				cursor.FormatTime(lastComment.CreatedAt),
				lastComment.ID,
				cursor.SortByCreatedAtDesc,
			).Encode()
		}
		// 上一页游标
		firstComment := comments[0]
		prevCursor = cursor.NewCursor(
			cursor.FormatTime(firstComment.CreatedAt),
			firstComment.ID,
			cursor.SortByCreatedAtDesc,
		).Encode()
	}

	return cursor.NewCursorPageResult(comments, nextCursor, prevCursor, hasMore), nil
}

// loadRepliesForComments 为评论列表加载回复
func (r *CommentRepository) loadRepliesForComments(comments []*model.Comment, replyLimit int) {
	if len(comments) == 0 {
		return
	}

	rootIDs := make([]string, 0, len(comments))
	commentsByID := make(map[string]*model.Comment, len(comments))
	for _, comment := range comments {
		rootIDs = append(rootIDs, comment.ID)
		commentsByID[comment.ID] = comment
	}

	// 批量加载所有回复
	var allReplies []*model.Comment
	if err := r.db.Where("root_id IN ? AND status = ?", rootIDs, model.CommentStatusPublished).
		Preload("User").
		Order("created_at ASC").
		Find(&allReplies).Error; err != nil {
		return
	}

	// 按 root_id 分组并裁剪
	repliesByRoot := make(map[string][]*model.Comment, len(rootIDs))
	for _, reply := range allReplies {
		if reply.RootID == nil {
			continue
		}
		rootID := *reply.RootID
		if replyLimit <= 0 || len(repliesByRoot[rootID]) < replyLimit {
			repliesByRoot[rootID] = append(repliesByRoot[rootID], reply)
		}
	}

	// 查询每个根评论的回复总数
	type replyCountRow struct {
		RootID string
		Total  int64
	}
	var replyCountRows []replyCountRow
	if err := r.db.Model(&model.Comment{}).
		Select("root_id, COUNT(*) AS total").
		Where("root_id IN ? AND status = ?", rootIDs, model.CommentStatusPublished).
		Group("root_id").
		Scan(&replyCountRows).Error; err != nil {
		return
	}

	replyCountMap := make(map[string]int64, len(replyCountRows))
	for _, row := range replyCountRows {
		replyCountMap[row.RootID] = row.Total
	}

	// 设置回复和回复数
	for _, rootID := range rootIDs {
		comment := commentsByID[rootID]
		comment.Replies = repliesByRoot[rootID]
		comment.RepliesCount = int(replyCountMap[rootID])
	}
}

// GetRepliesByCursor 游标分页获取根评论的回复
// 排序方式：created_at ASC（回复按时间正序）
func (r *CommentRepository) GetRepliesByCursor(ctx context.Context, rootID string, req *cursor.PageRequest) (*cursor.CursorPageResult[*model.Comment], error) {
	// 构建基础查询
	query := r.db.WithContext(ctx).Model(&model.Comment{}).
		Where("root_id = ? AND status = ?", rootID, model.CommentStatusPublished)

	// 使用游标构建器（回复按时间升序）
	builder := cursor.NewBuilder(query, cursor.SortByCreatedAtAsc).
		WithCursor(req.Cursor, req.Direction).
		WithPageSize(req.PageSize)

	if builder.Error() != nil {
		// 无效游标，返回空列表
		return cursor.NewCursorPageResult[*model.Comment]([]*model.Comment{}, "", "", false), nil
	}

	// 执行查询
	var replies []*model.Comment
	query = builder.Build().Preload("User")
	if err := query.Find(&replies).Error; err != nil {
		return nil, err
	}

	// 构建响应
	pageSize := builder.GetPageSize()
	hasMore := cursor.HasMore(len(replies), pageSize)
	if hasMore {
		replies = replies[:pageSize]
	}

	// 生成游标
	var nextCursor, prevCursor string
	if len(replies) > 0 {
		// 下一页游标
		if hasMore {
			lastReply := replies[len(replies)-1]
			nextCursor = cursor.NewCursor(
				cursor.FormatTime(lastReply.CreatedAt),
				lastReply.ID,
				cursor.SortByCreatedAtAsc,
			).Encode()
		}
		// 上一页游标
		firstReply := replies[0]
		prevCursor = cursor.NewCursor(
			cursor.FormatTime(firstReply.CreatedAt),
			firstReply.ID,
			cursor.SortByCreatedAtAsc,
		).Encode()
	}

	return cursor.NewCursorPageResult(replies, nextCursor, prevCursor, hasMore), nil
}