package service

import (
	"dianshang/internal/model"
	"dianshang/internal/repository"
	"errors"
	"fmt"
	"time"
	"gorm.io/gorm"
)

// PointsService 积分服务
type PointsService struct {
	pointsRepo *repository.PointsRepository
	db         *gorm.DB
}

// NewPointsService 创建积分服务
func NewPointsService(pointsRepo *repository.PointsRepository, db *gorm.DB) *PointsService {
	return &PointsService{
		pointsRepo: pointsRepo,
		db:         db,
	}
}

// GetUserPoints 获取用户积分
func (s *PointsService) GetUserPoints(userID uint) (int, error) {
	return s.pointsRepo.GetUserPoints(userID)
}

// AddPoints 增加用户积分
func (s *PointsService) AddPoints(userID uint, amount int, description string, orderID *uint, orderNo, productName string) error {
	if amount <= 0 {
		return errors.New("积分数量必须大于0")
	}
	
	// 开启事务
	tx := s.db.Begin()
	defer func() {
		if r := recover(); r != nil {
			tx.Rollback()
		}
	}()
	
	// 获取当前积分
	currentPoints, err := s.pointsRepo.GetUserPoints(userID)
	if err != nil {
		tx.Rollback()
		return err
	}
	
	// 更新用户积分
	newPoints := currentPoints + amount
	err = s.pointsRepo.UpdateUserPoints(userID, newPoints)
	if err != nil {
		tx.Rollback()
		return err
	}
	
	// 创建积分历史记录
	history := &model.PointsHistory{
		UserID:      userID,
		Type:        1, // 获得
		Points:      amount,
		Description: description,
		OrderID:     orderID,
		OrderNo:     orderNo,
		ProductName: productName,
	}
	
	err = s.pointsRepo.CreatePointsHistory(history)
	if err != nil {
		tx.Rollback()
		return err
	}
	
	return tx.Commit().Error
}

// DeductPoints 扣减用户积分
func (s *PointsService) DeductPoints(userID uint, amount int, description string, orderID *uint, orderNo, productName string) error {
	if amount <= 0 {
		return errors.New("积分数量必须大于0")
	}
	
	// 开启事务
	tx := s.db.Begin()
	defer func() {
		if r := recover(); r != nil {
			tx.Rollback()
		}
	}()
	
	// 获取当前积分
	currentPoints, err := s.pointsRepo.GetUserPoints(userID)
	if err != nil {
		tx.Rollback()
		return err
	}
	
	// 检查积分是否足够
	if currentPoints < amount {
		tx.Rollback()
		return errors.New("积分不足")
	}
	
	// 更新用户积分
	newPoints := currentPoints - amount
	err = s.pointsRepo.UpdateUserPoints(userID, newPoints)
	if err != nil {
		tx.Rollback()
		return err
	}
	
	// 创建积分历史记录
	history := &model.PointsHistory{
		UserID:      userID,
		Type:        2, // 消费
		Points:      amount,
		Description: description,
		OrderID:     orderID,
		OrderNo:     orderNo,
		ProductName: productName,
	}
	
	err = s.pointsRepo.CreatePointsHistory(history)
	if err != nil {
		tx.Rollback()
		return err
	}
	
	return tx.Commit().Error
}

// GetPointsHistory 获取积分历史记录
func (s *PointsService) GetPointsHistory(userID uint, page, pageSize int) ([]model.PointsHistory, map[string]interface{}, error) {
	if page <= 0 {
		page = 1
	}
	if pageSize <= 0 || pageSize > 100 {
		pageSize = 20
	}
	
	histories, total, err := s.pointsRepo.GetPointsHistory(userID, page, pageSize)
	if err != nil {
		return nil, nil, err
	}
	
	// 构建分页信息
	totalPages := (int(total) + pageSize - 1) / pageSize
	pagination := map[string]interface{}{
		"total":       total,
		"page":        page,
		"page_size":   pageSize,
		"total_pages": totalPages,
	}
	
	return histories, pagination, nil
}

// GetPointsRules 获取积分规则列表
func (s *PointsService) GetPointsRules() ([]model.PointsRule, error) {
	return s.pointsRepo.GetPointsRules()
}

// GetPointsExchangeList 获取积分兑换商品列表
func (s *PointsService) GetPointsExchangeList() ([]model.PointsExchange, error) {
	return s.pointsRepo.GetPointsExchangeList()
}

// ExchangePoints 积分兑换
func (s *PointsService) ExchangePoints(userID, exchangeID uint) error {
	// 开启事务
	tx := s.db.Begin()
	defer func() {
		if r := recover(); r != nil {
			tx.Rollback()
		}
	}()
	
	// 获取兑换商品信息
	exchange, err := s.pointsRepo.GetPointsExchangeByID(exchangeID)
	if err != nil {
		tx.Rollback()
		return errors.New("兑换商品不存在")
	}
	
	// 检查库存
	if exchange.Stock > 0 && exchange.ExchangeCount >= exchange.Stock {
		tx.Rollback()
		return errors.New("商品库存不足")
	}
	
	// 获取用户当前积分
	currentPoints, err := s.pointsRepo.GetUserPoints(userID)
	if err != nil {
		tx.Rollback()
		return err
	}
	
	// 检查积分是否足够
	if currentPoints < exchange.Points {
		tx.Rollback()
		return errors.New("积分不足")
	}
	
	// 扣减积分
	description := fmt.Sprintf("兑换商品：%s", exchange.Name)
	err = s.DeductPoints(userID, exchange.Points, description, nil, "", exchange.Name)
	if err != nil {
		tx.Rollback()
		return err
	}
	
	// 创建兑换记录
	record := &model.PointsExchangeRecord{
		UserID:           userID,
		PointsExchangeID: exchangeID,
		Points:           exchange.Points,
		Status:           1, // 已兑换
	}
	
	err = s.pointsRepo.CreatePointsExchangeRecord(record)
	if err != nil {
		tx.Rollback()
		return err
	}
	
	// 更新兑换次数
	err = s.pointsRepo.UpdatePointsExchangeCount(exchangeID)
	if err != nil {
		tx.Rollback()
		return err
	}
	
	return tx.Commit().Error
}

// GetUserExchangeRecords 获取用户兑换记录
func (s *PointsService) GetUserExchangeRecords(userID uint, page, pageSize int) ([]model.PointsExchangeRecord, map[string]interface{}, error) {
	if page <= 0 {
		page = 1
	}
	if pageSize <= 0 || pageSize > 100 {
		pageSize = 20
	}
	
	records, total, err := s.pointsRepo.GetUserExchangeRecords(userID, page, pageSize)
	if err != nil {
		return nil, nil, err
	}
	
	// 构建分页信息
	totalPages := (int(total) + pageSize - 1) / pageSize
	pagination := map[string]interface{}{
		"total":       total,
		"page":        page,
		"page_size":   pageSize,
		"total_pages": totalPages,
	}
	
	return records, pagination, nil
}

// GetPointsOverview 获取积分概览
func (s *PointsService) GetPointsOverview(userID uint) (map[string]interface{}, error) {
	// 获取用户当前积分
	currentPoints, err := s.pointsRepo.GetUserPoints(userID)
	if err != nil {
		return nil, err
	}
	
	// 获取积分历史统计
	var totalEarned, totalSpent, thisMonthEarned, thisMonthSpent int64
	
	// 统计总获得积分
	s.db.Model(&model.PointsHistory{}).
		Where("user_id = ? AND type = ?", userID, 1).
		Select("COALESCE(SUM(points), 0)").
		Scan(&totalEarned)
	
	// 统计总消费积分
	s.db.Model(&model.PointsHistory{}).
		Where("user_id = ? AND type = ?", userID, 2).
		Select("COALESCE(SUM(points), 0)").
		Scan(&totalSpent)
	
	// 获取本月的开始时间和结束时间
	now := time.Now()
	firstDayOfMonth := time.Date(now.Year(), now.Month(), 1, 0, 0, 0, 0, now.Location())
	firstDayOfNextMonth := firstDayOfMonth.AddDate(0, 1, 0)
	
	// 统计本月获得积分
	s.db.Model(&model.PointsHistory{}).
		Where("user_id = ? AND type = ? AND created_at >= ? AND created_at < ?", 
			userID, 1, firstDayOfMonth, firstDayOfNextMonth).
		Select("COALESCE(SUM(points), 0)").
		Scan(&thisMonthEarned)
	
	// 统计本月消费积分
	s.db.Model(&model.PointsHistory{}).
		Where("user_id = ? AND type = ? AND created_at >= ? AND created_at < ?", 
			userID, 2, firstDayOfMonth, firstDayOfNextMonth).
		Select("COALESCE(SUM(points), 0)").
		Scan(&thisMonthSpent)
	
	overview := map[string]interface{}{
		"total_points":       currentPoints,
		"available_points":   currentPoints,
		"frozen_points":      0,
		"total_earned":       totalEarned,
		"total_spent":        totalSpent,
		"this_month_earned":  thisMonthEarned,
		"this_month_spent":   thisMonthSpent,
	}
	
	return overview, nil
}

// CheckAndGiveDailyLoginPoints 检查并给予每日首次登录积分
func (s *PointsService) CheckAndGiveDailyLoginPoints(userID uint) (bool, error) {
	// 获取今天的开始时间（00:00:00）
	now := time.Now()
	today := time.Date(now.Year(), now.Month(), now.Day(), 0, 0, 0, 0, now.Location())
	tomorrow := today.Add(24 * time.Hour)
	
	// 检查今天是否已经有登录积分记录
	var count int64
	err := s.db.Model(&model.PointsHistory{}).
		Where("user_id = ? AND description = ? AND created_at >= ? AND created_at < ?", 
			userID, "每日首次登录", today, tomorrow).
		Count(&count).Error
	
	if err != nil {
		return false, fmt.Errorf("检查每日登录记录失败: %v", err)
	}
	
	// 如果今天已经有登录积分记录，则不再给予
	if count > 0 {
		return false, nil
	}
	
	// 给予每日登录积分（1积分）
	err = s.AddPoints(userID, 1, "每日首次登录", nil, "", "")
	if err != nil {
		return false, fmt.Errorf("给予每日登录积分失败: %v", err)
	}
	
	return true, nil
}