package repository

import (
	"dianshang/internal/model"
	"time"

	"gorm.io/gorm"
)

// CouponRepository 优惠券仓储
type CouponRepository struct {
	db *gorm.DB
}

// NewCouponRepository 创建优惠券仓储
func NewCouponRepository(db *gorm.DB) *CouponRepository {
	return &CouponRepository{db: db}
}

// GetAvailableCoupons 获取可用优惠券列表
func (r *CouponRepository) GetAvailableCoupons() ([]model.Coupon, error) {
	var coupons []model.Coupon
	now := time.Now()
	err := r.db.Where("status = ? AND start_time <= ? AND end_time >= ?", 1, now, now).
		Where("total_count = 0 OR used_count < total_count").
		Order("created_at DESC").
		Find(&coupons).Error
	return coupons, err
}

// GetUserCoupons 获取用户优惠券
func (r *CouponRepository) GetUserCoupons(userID uint, status int) ([]model.UserCoupon, error) {
	var userCoupons []model.UserCoupon
	query := r.db.Preload("Coupon").Where("user_id = ?", userID)
	
	if status > 0 {
		// API状态值到数据库状态值的映射
		// API: 1=未使用,2=已使用,3=已过期
		// DB:  0=未使用,1=已使用,2=已过期
		dbStatus := status - 1
		query = query.Where("status = ?", dbStatus)
	}
	
	err := query.Order("created_at DESC").Find(&userCoupons).Error
	return userCoupons, err
}

// GetByID 根据ID获取优惠券
func (r *CouponRepository) GetByID(id uint) (*model.Coupon, error) {
	var coupon model.Coupon
	err := r.db.First(&coupon, id).Error
	return &coupon, err
}

// CheckUserCouponExists 检查用户是否已领取优惠券
func (r *CouponRepository) CheckUserCouponExists(userID, couponID uint) (bool, error) {
	var count int64
	err := r.db.Model(&model.UserCoupon{}).
		Where("user_id = ? AND coupon_id = ?", userID, couponID).
		Count(&count).Error
	return count > 0, err
}

// GetUserCouponCount 获取用户领取某优惠券的数量
func (r *CouponRepository) GetUserCouponCount(userID, couponID uint) (int, error) {
	var count int64
	err := r.db.Model(&model.UserCoupon{}).
		Where("user_id = ? AND coupon_id = ?", userID, couponID).
		Count(&count).Error
	return int(count), err
}

// CreateUserCoupon 创建用户优惠券记录
func (r *CouponRepository) CreateUserCoupon(userCoupon *model.UserCoupon) error {
	return r.db.Transaction(func(tx *gorm.DB) error {
		// 创建用户优惠券记录
		if err := tx.Create(userCoupon).Error; err != nil {
			return err
		}
		
		// 更新优惠券使用数量
		return tx.Model(&model.Coupon{}).
			Where("id = ?", userCoupon.CouponID).
			UpdateColumn("used_count", gorm.Expr("used_count + ?", 1)).Error
	})
}

// GetUserCouponByID 根据ID获取用户优惠券
func (r *CouponRepository) GetUserCouponByID(id uint) (*model.UserCoupon, error) {
	var userCoupon model.UserCoupon
	err := r.db.Preload("Coupon").First(&userCoupon, id).Error
	return &userCoupon, err
}

// GetUserCouponByOrderID 根据订单ID获取用户优惠券
func (r *CouponRepository) GetUserCouponByOrderID(orderID uint) (*model.UserCoupon, error) {
	var userCoupon model.UserCoupon
	err := r.db.Preload("Coupon").Where("order_id = ?", orderID).First(&userCoupon).Error
	return &userCoupon, err
}

// UseCoupon 使用优惠券
func (r *CouponRepository) UseCoupon(userCouponID, orderID uint) error {
	now := time.Now()
	return r.db.Model(&model.UserCoupon{}).
		Where("id = ?", userCouponID).
		Updates(map[string]interface{}{
			"status":    1, // 已使用
			"order_id":  orderID,
			"used_time": &now,
		}).Error
}

// RestoreCoupon 恢复优惠券（取消订单时使用）
func (r *CouponRepository) RestoreCoupon(userCouponID uint) error {
	return r.db.Model(&model.UserCoupon{}).
		Where("id = ?", userCouponID).
		Updates(map[string]interface{}{
			"status":    0,   // 恢复为未使用
			"order_id":  nil, // 清除订单关联
			"used_time": nil, // 清除使用时间
		}).Error
}