package repository

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

	"gorm.io/gorm"
	"gorm.io/gorm/clause"
)

// UserRepository 用户仓储接口
type UserRepository interface {
	Create(user *model.User) error
	GetByID(id string) (*model.User, error)
	GetByUsername(username string) (*model.User, error)
	GetByEmail(email string) (*model.User, error)
	GetByPhone(phone string) (*model.User, error)
	Update(user *model.User) error
	Delete(id string) error
	List(page, pageSize int) ([]*model.User, int64, error)
	GetFollowers(userID string, page, pageSize int) ([]*model.User, int64, error)
	GetFollowing(userID string, page, pageSize int) ([]*model.User, int64, error)
	CreateFollow(follow *model.Follow) error
	DeleteFollow(followerID, followingID string) error
	IsFollowing(followerID, followingID string) (bool, error)
	IsFollowingBatch(followerID string, targetUserIDs []string) (map[string]bool, error)
	IncrementFollowersCount(userID string) error
	DecrementFollowersCount(userID string) error
	IncrementFollowingCount(userID string) error
	DecrementFollowingCount(userID string) error
	RefreshFollowersCount(userID string) error
	GetPostsCount(userID string) (int64, error)
	GetPostsCountBatch(userIDs []string) (map[string]int64, error)
	RefreshFollowingCount(userID string) error
	IsBlocked(blockerID, blockedID string) (bool, error)
	IsBlockedBatch(blockerID string, blockedIDs []string) (map[string]bool, error)
	IsBlockedEitherDirection(userA, userB string) (bool, error)
	BlockUserAndCleanupRelations(blockerID, blockedID string) error
	UnblockUser(blockerID, blockedID string) error
	GetBlockedUsers(blockerID string, page, pageSize int) ([]*model.User, int64, error)
	Search(keyword string, page, pageSize int) ([]*model.User, int64, error)
	GetMutualFollowStatus(currentUserID string, targetUserIDs []string) (map[string][2]bool, error)
	AdminList(page, pageSize int, keyword, status string) ([]*model.User, int64, error)
	GetCommentsCount(userID string) (int64, error)
	UpdateStatus(userID string, status model.UserStatus) error

	// 隐私设置
	UpdatePrivacySettings(userID string, settings *model.PrivacySettings) error
	GetPrivacySettings(userID string) (*model.PrivacySettings, error)

	// 账号注销
	RequestDeletion(userID string) error
	CancelDeletion(userID string) error
	GetPendingDeletionUsers(beforeTime time.Time) ([]*model.User, error)
	HardDeleteUser(userID string) error
}

// userRepository 用户仓储实现
type userRepository struct {
	db *gorm.DB
}

// NewUserRepository 创建用户仓储
func NewUserRepository(db *gorm.DB) UserRepository {
	return &userRepository{db: db}
}

// Create 创建用户
func (r *userRepository) Create(user *model.User) error {
	return r.db.Create(user).Error
}

// GetByID 根据ID获取用户
func (r *userRepository) GetByID(id string) (*model.User, error) {
	var user model.User
	err := r.db.First(&user, "id = ?", id).Error
	if err != nil {
		return nil, err
	}
	return &user, nil
}

// GetByUsername 根据用户名获取用户
func (r *userRepository) GetByUsername(username string) (*model.User, error) {
	var user model.User
	err := r.db.First(&user, "username = ?", username).Error
	if err != nil {
		return nil, err
	}
	return &user, nil
}

// GetByEmail 根据邮箱获取用户
func (r *userRepository) GetByEmail(email string) (*model.User, error) {
	var user model.User
	err := r.db.First(&user, "email = ?", email).Error
	if err != nil {
		return nil, err
	}
	return &user, nil
}

// GetByPhone 根据手机号获取用户
func (r *userRepository) GetByPhone(phone string) (*model.User, error) {
	var user model.User
	err := r.db.First(&user, "phone = ?", phone).Error
	if err != nil {
		return nil, err
	}
	return &user, nil
}

// Update 更新用户
func (r *userRepository) Update(user *model.User) error {
	return r.db.Save(user).Error
}

// Delete 删除用户
func (r *userRepository) Delete(id string) error {
	return r.db.Delete(&model.User{}, "id = ?", id).Error
}

// List 分页获取用户列表
func (r *userRepository) List(page, pageSize int) ([]*model.User, int64, error) {
	var users []*model.User
	var total int64

	r.db.Model(&model.User{}).Count(&total)

	offset := (page - 1) * pageSize
	err := r.db.Order("created_at DESC, id DESC").Offset(offset).Limit(pageSize).Find(&users).Error

	return users, total, err
}

// GetFollowers 获取用户粉丝
func (r *userRepository) GetFollowers(userID string, page, pageSize int) ([]*model.User, int64, error) {
	var users []*model.User
	var total int64

	subQuery := r.db.Model(&model.Follow{}).Where("following_id = ?", userID).Select("follower_id")
	r.db.Model(&model.User{}).Where("id IN (?)", subQuery).Count(&total)

	offset := (page - 1) * pageSize
	err := r.db.Where("id IN (?)", subQuery).
		Order("created_at DESC, id DESC").
		Offset(offset).Limit(pageSize).
		Find(&users).Error

	return users, total, err
}

// GetFollowing 获取用户关注
func (r *userRepository) GetFollowing(userID string, page, pageSize int) ([]*model.User, int64, error) {
	var users []*model.User
	var total int64

	subQuery := r.db.Model(&model.Follow{}).Where("follower_id = ?", userID).Select("following_id")
	r.db.Model(&model.User{}).Where("id IN (?)", subQuery).Count(&total)

	offset := (page - 1) * pageSize
	err := r.db.Where("id IN (?)", subQuery).
		Order("created_at DESC, id DESC").
		Offset(offset).Limit(pageSize).
		Find(&users).Error

	return users, total, err
}

// CreateFollow 创建关注关系
func (r *userRepository) CreateFollow(follow *model.Follow) error {
	return r.db.Create(follow).Error
}

// DeleteFollow 删除关注关系
func (r *userRepository) DeleteFollow(followerID, followingID string) error {
	return r.db.Where("follower_id = ? AND following_id = ?", followerID, followingID).Delete(&model.Follow{}).Error
}

// IsFollowing 检查是否关注了某用户
func (r *userRepository) IsFollowing(followerID, followingID string) (bool, error) {
	var count int64
	err := r.db.Model(&model.Follow{}).Where("follower_id = ? AND following_id = ?", followerID, followingID).Count(&count).Error
	if err != nil {
		return false, err
	}
	return count > 0, nil
}

// IsFollowingBatch 批量检查当前用户是否关注了目标用户（解决 N+1 问题）
// 返回 map[targetUserID]bool
func (r *userRepository) IsFollowingBatch(followerID string, targetUserIDs []string) (map[string]bool, error) {
	result := make(map[string]bool)
	if len(targetUserIDs) == 0 || followerID == "" {
		return result, nil
	}

	// 初始化所有目标用户为 false
	for _, id := range targetUserIDs {
		result[id] = false
	}

	// 一次性查询所有关注记录
	var followingIDs []string
	err := r.db.Model(&model.Follow{}).
		Where("follower_id = ? AND following_id IN ?", followerID, targetUserIDs).
		Pluck("following_id", &followingIDs).Error
	if err != nil {
		return nil, err
	}

	// 更新已关注的用户
	for _, id := range followingIDs {
		result[id] = true
	}

	return result, nil
}

// IncrementFollowersCount 增加用户粉丝数
func (r *userRepository) IncrementFollowersCount(userID string) error {
	return r.db.Model(&model.User{}).Where("id = ?", userID).
		UpdateColumn("followers_count", gorm.Expr("followers_count + 1")).Error
}

// DecrementFollowersCount 减少用户粉丝数
func (r *userRepository) DecrementFollowersCount(userID string) error {
	return r.db.Model(&model.User{}).Where("id = ? AND followers_count > 0", userID).
		UpdateColumn("followers_count", gorm.Expr("followers_count - 1")).Error
}

// IncrementFollowingCount 增加用户关注数
func (r *userRepository) IncrementFollowingCount(userID string) error {
	return r.db.Model(&model.User{}).Where("id = ?", userID).
		UpdateColumn("following_count", gorm.Expr("following_count + 1")).Error
}

// DecrementFollowingCount 减少用户关注数
func (r *userRepository) DecrementFollowingCount(userID string) error {
	return r.db.Model(&model.User{}).Where("id = ? AND following_count > 0", userID).
		UpdateColumn("following_count", gorm.Expr("following_count - 1")).Error
}

// RefreshFollowersCount 刷新用户粉丝数（通过实际计数）
func (r *userRepository) RefreshFollowersCount(userID string) error {
	var count int64
	err := r.db.Model(&model.Follow{}).Where("following_id = ?", userID).Count(&count).Error
	if err != nil {
		return err
	}
	return r.db.Model(&model.User{}).Where("id = ?", userID).
		UpdateColumn("followers_count", count).Error
}

// GetPostsCount 获取用户帖子数（实时计算）
func (r *userRepository) GetPostsCount(userID string) (int64, error) {
	var count int64
	err := r.db.Model(&model.Post{}).
		Where("user_id = ? AND status = ?", userID, model.PostStatusPublished).
		Count(&count).Error
	return count, err
}

// GetPostsCountBatch 批量获取用户帖子数（实时计算）
// 返回 map[userID]postsCount
func (r *userRepository) GetPostsCountBatch(userIDs []string) (map[string]int64, error) {
	result := make(map[string]int64)
	if len(userIDs) == 0 {
		return result, nil
	}

	// 初始化所有用户ID的计数为0
	for _, userID := range userIDs {
		result[userID] = 0
	}

	// 使用 GROUP BY 一次性查询所有用户的帖子数
	type CountResult struct {
		UserID string
		Count  int64
	}
	var counts []CountResult
	err := r.db.Model(&model.Post{}).
		Select("user_id, count(*) as count").
		Where("user_id IN ? AND status = ?", userIDs, model.PostStatusPublished).
		Group("user_id").
		Scan(&counts).Error
	if err != nil {
		return nil, err
	}

	// 更新查询结果
	for _, c := range counts {
		result[c.UserID] = c.Count
	}

	return result, nil
}

// RefreshFollowingCount 刷新用户关注数（通过实际计数）
func (r *userRepository) RefreshFollowingCount(userID string) error {
	var count int64
	err := r.db.Model(&model.Follow{}).Where("follower_id = ?", userID).Count(&count).Error
	if err != nil {
		return err
	}
	return r.db.Model(&model.User{}).Where("id = ?", userID).
		UpdateColumn("following_count", count).Error
}

// IsBlocked 检查拉黑关系是否存在（blocker -> blocked）
func (r *userRepository) IsBlocked(blockerID, blockedID string) (bool, error) {
	var count int64
	err := r.db.Model(&model.UserBlock{}).
		Where("blocker_id = ? AND blocked_id = ?", blockerID, blockedID).
		Count(&count).Error
	if err != nil {
		return false, err
	}
	return count > 0, nil
}

// IsBlockedBatch 批量检查拉黑关系（解决 N+1 问题）
// 返回 map[blockedUserID]bool
func (r *userRepository) IsBlockedBatch(blockerID string, blockedIDs []string) (map[string]bool, error) {
	result := make(map[string]bool)
	if len(blockedIDs) == 0 || blockerID == "" {
		return result, nil
	}

	// 初始化所有目标用户为 false
	for _, id := range blockedIDs {
		result[id] = false
	}

	// 一次性查询所有拉黑记录
	var blockedUserIDs []string
	err := r.db.Model(&model.UserBlock{}).
		Where("blocker_id = ? AND blocked_id IN ?", blockerID, blockedIDs).
		Pluck("blocked_id", &blockedUserIDs).Error
	if err != nil {
		return nil, err
	}

	// 更新已拉黑的用户
	for _, id := range blockedUserIDs {
		result[id] = true
	}

	return result, nil
}

// IsBlockedEitherDirection 检查是否任一方向存在拉黑
func (r *userRepository) IsBlockedEitherDirection(userA, userB string) (bool, error) {
	var count int64
	err := r.db.Model(&model.UserBlock{}).
		Where("(blocker_id = ? AND blocked_id = ?) OR (blocker_id = ? AND blocked_id = ?)",
			userA, userB, userB, userA).
		Count(&count).Error
	if err != nil {
		return false, err
	}
	return count > 0, nil
}

// BlockUserAndCleanupRelations 拉黑用户并清理双向关注关系（事务）
func (r *userRepository) BlockUserAndCleanupRelations(blockerID, blockedID string) error {
	return r.db.Transaction(func(tx *gorm.DB) error {
		block := &model.UserBlock{
			BlockerID: blockerID,
			BlockedID: blockedID,
		}
		if err := tx.Clauses(clause.OnConflict{
			Columns:   []clause.Column{{Name: "blocker_id"}, {Name: "blocked_id"}},
			DoNothing: true,
		}).Create(block).Error; err != nil {
			return err
		}

		if err := tx.Where("follower_id = ? AND following_id = ?", blockerID, blockedID).
			Delete(&model.Follow{}).Error; err != nil {
			return err
		}
		if err := tx.Where("follower_id = ? AND following_id = ?", blockedID, blockerID).
			Delete(&model.Follow{}).Error; err != nil {
			return err
		}

		for _, uid := range []string{blockerID, blockedID} {
			if err := tx.Model(&model.User{}).Where("id = ?", uid).
				UpdateColumn("followers_count", tx.Model(&model.Follow{}).
					Select("COUNT(*)").Where("following_id = ?", uid)).Error; err != nil {
				return err
			}

			if err := tx.Model(&model.User{}).Where("id = ?", uid).
				UpdateColumn("following_count", tx.Model(&model.Follow{}).
					Select("COUNT(*)").Where("follower_id = ?", uid)).Error; err != nil {
				return err
			}
		}

		return nil
	})
}

// UnblockUser 取消拉黑
func (r *userRepository) UnblockUser(blockerID, blockedID string) error {
	return r.db.Where("blocker_id = ? AND blocked_id = ?", blockerID, blockedID).
		Delete(&model.UserBlock{}).Error
}

// GetBlockedUsers 获取用户黑名单列表
func (r *userRepository) GetBlockedUsers(blockerID string, page, pageSize int) ([]*model.User, int64, error) {
	var users []*model.User
	var total int64

	subQuery := r.db.Model(&model.UserBlock{}).Where("blocker_id = ?", blockerID).Select("blocked_id")
	r.db.Model(&model.User{}).Where("id IN (?)", subQuery).Count(&total)

	offset := (page - 1) * pageSize
	err := r.db.Where("id IN (?)", subQuery).
		Order("created_at DESC, id DESC").
		Offset(offset).
		Limit(pageSize).
		Find(&users).Error

	return users, total, err
}

// Search 搜索用户
func (r *userRepository) Search(keyword string, page, pageSize int) ([]*model.User, int64, error) {
	var users []*model.User
	var total int64

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

	// 搜索用户名、昵称、简介
	if keyword != "" {
		if r.db.Dialector.Name() == "postgres" {
			query = query.Where(
				"to_tsvector('simple', COALESCE(username, '') || ' ' || COALESCE(nickname, '') || ' ' || COALESCE(bio, '')) @@ plainto_tsquery('simple', ?)",
				keyword,
			)
		} else {
			// SQLite: 使用 LOWER() 实现大小写不敏感的模糊搜索
			lowerSearchPattern := "%" + strings.ToLower(keyword) + "%"
			query = query.Where(
				"LOWER(username) LIKE ? OR LOWER(nickname) LIKE ? OR LOWER(bio) LIKE ?",
				lowerSearchPattern, lowerSearchPattern, lowerSearchPattern,
			)
		}
	}

	query.Count(&total)

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

	return users, total, err
}

// GetMutualFollowStatus 批量获取双向关注状态
// 返回 map[userID][isFollowing, isFollowingMe]
func (r *userRepository) GetMutualFollowStatus(currentUserID string, targetUserIDs []string) (map[string][2]bool, error) {
	result := make(map[string][2]bool)

	if len(targetUserIDs) == 0 {
		return result, nil
	}

	// 初始化所有目标用户为未关注状态
	for _, userID := range targetUserIDs {
		result[userID] = [2]bool{false, false}
	}

	// 查询当前用户关注了哪些目标用户 (isFollowing)
	var followingIDs []string
	err := r.db.Model(&model.Follow{}).
		Where("follower_id = ? AND following_id IN ?", currentUserID, targetUserIDs).
		Pluck("following_id", &followingIDs).Error
	if err != nil {
		return nil, err
	}
	for _, id := range followingIDs {
		status := result[id]
		status[0] = true
		result[id] = status
	}

	// 查询哪些目标用户关注了当前用户 (isFollowingMe)
	var followerIDs []string
	err = r.db.Model(&model.Follow{}).
		Where("follower_id IN ? AND following_id = ?", targetUserIDs, currentUserID).
		Pluck("follower_id", &followerIDs).Error
	if err != nil {
		return nil, err
	}
	for _, id := range followerIDs {
		status := result[id]
		status[1] = true
		result[id] = status
	}

	return result, nil
}

// AdminList 管理端分页获取用户列表（支持关键词和状态筛选）
func (r *userRepository) AdminList(page, pageSize int, keyword, status string) ([]*model.User, int64, error) {
	var users []*model.User
	var total int64

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

	// 关键词搜索（用户名、昵称、邮箱）
	if keyword != "" {
		if r.db.Dialector.Name() == "postgres" {
			query = query.Where(
				"username ILIKE ? OR nickname ILIKE ? OR email ILIKE ?",
				"%"+keyword+"%", "%"+keyword+"%", "%"+keyword+"%",
			)
		} else {
			lowerSearchPattern := "%" + strings.ToLower(keyword) + "%"
			query = query.Where(
				"LOWER(username) LIKE ? OR LOWER(nickname) LIKE ? OR LOWER(email) LIKE ?",
				lowerSearchPattern, lowerSearchPattern, lowerSearchPattern,
			)
		}
	}

	// 状态筛选
	if status != "" {
		query = query.Where("status = ?", status)
	}

	query.Count(&total)

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

	return users, total, err
}

// GetCommentsCount 获取用户评论数
func (r *userRepository) GetCommentsCount(userID string) (int64, error) {
	var count int64
	err := r.db.Model(&model.Comment{}).
		Where("user_id = ?", userID).
		Count(&count).Error
	return count, err
}

// UpdateStatus 更新用户状态
func (r *userRepository) UpdateStatus(userID string, status model.UserStatus) error {
	return r.db.Model(&model.User{}).Where("id = ?", userID).Update("status", status).Error
}

// UpdatePrivacySettings 更新隐私设置
func (r *userRepository) UpdatePrivacySettings(userID string, settings *model.PrivacySettings) error {
	return r.db.Model(&model.User{}).Where("id = ?", userID).Updates(map[string]interface{}{
		"privacy_followers_visibility": settings.FollowersVisibility,
		"privacy_following_visibility": settings.FollowingVisibility,
		"privacy_posts_visibility":     settings.PostsVisibility,
		"privacy_favorites_visibility": settings.FavoritesVisibility,
	}).Error
}

// GetPrivacySettings 获取隐私设置
func (r *userRepository) GetPrivacySettings(userID string) (*model.PrivacySettings, error) {
	var user model.User
	err := r.db.Select("privacy_followers_visibility, privacy_following_visibility, privacy_posts_visibility, privacy_favorites_visibility").
		First(&user, "id = ?", userID).Error
	if err != nil {
		return nil, err
	}
	return &user.PrivacySettings, nil
}

// RequestDeletion 申请注销账号
func (r *userRepository) RequestDeletion(userID string) error {
	now := time.Now()
	return r.db.Model(&model.User{}).Where("id = ?", userID).Updates(map[string]interface{}{
		"deletion_requested_at": &now,
		"status":                model.UserStatusPendingDeletion,
	}).Error
}

// CancelDeletion 取消注销
func (r *userRepository) CancelDeletion(userID string) error {
	return r.db.Model(&model.User{}).Where("id = ?", userID).Updates(map[string]interface{}{
		"deletion_requested_at": nil,
		"status":                model.UserStatusActive,
	}).Error
}

// GetPendingDeletionUsers 获取待删除的用户列表（注销申请时间早于指定时间）
func (r *userRepository) GetPendingDeletionUsers(beforeTime time.Time) ([]*model.User, error) {
	var users []*model.User
	err := r.db.Where("deletion_requested_at IS NOT NULL AND deletion_requested_at < ?", beforeTime).
		Find(&users).Error
	return users, err
}

// HardDeleteUser 硬删除用户（永久删除）
func (r *userRepository) HardDeleteUser(userID string) error {
	return r.db.Unscoped().Delete(&model.User{}, "id = ?", userID).Error
}