package service

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

	"gorm.io/gorm"
)

// AfterSaleService 售后服务
type AfterSaleService struct {
	db *gorm.DB
}

// NewAfterSaleService 创建售后服务
func NewAfterSaleService(db *gorm.DB) *AfterSaleService {
	return &AfterSaleService{
		db: db,
	}
}

// GetUserAfterSales 获取用户售后列表
func (s *AfterSaleService) GetUserAfterSales(userID uint, page, pageSize int, status int) ([]model.AfterSale, int64, error) {
	var afterSales []model.AfterSale
	var total int64

	query := s.db.Model(&model.AfterSale{}).Where("user_id = ?", userID)
	
	// 如果指定了状态，添加状态过滤
	if status > 0 {
		query = query.Where("status = ?", status)
	}

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

	// 分页查询，预加载关联数据
	offset := (page - 1) * pageSize
	if err := query.Preload("Order").Preload("OrderItem").Preload("User").
		Order("created_at DESC").
		Offset(offset).Limit(pageSize).
		Find(&afterSales).Error; err != nil {
		return nil, 0, err
	}

	return afterSales, total, nil
}

// GetAfterSaleDetail 获取售后详情
func (s *AfterSaleService) GetAfterSaleDetail(userID, afterSaleID uint) (*model.AfterSale, error) {
	var afterSale model.AfterSale
	
	if err := s.db.Where("id = ? AND user_id = ?", afterSaleID, userID).
		Preload("Order").Preload("OrderItem").Preload("User").
		First(&afterSale).Error; err != nil {
		return nil, err
	}

	return &afterSale, nil
}

// CreateAfterSale 创建售后申请
func (s *AfterSaleService) CreateAfterSale(userID uint, req *CreateAfterSaleRequest) (*model.AfterSale, error) {
	// 验证订单是否存在且属于该用户
	var order model.Order
	if err := s.db.Where("id = ? AND user_id = ?", req.OrderID, userID).First(&order).Error; err != nil {
		return nil, fmt.Errorf("订单不存在或无权限")
	}

	// 验证订单项是否存在
	var orderItem model.OrderItem
	if err := s.db.Where("id = ? AND order_id = ?", req.OrderItemID, req.OrderID).First(&orderItem).Error; err != nil {
		return nil, fmt.Errorf("订单项不存在")
	}

	// 创建售后记录
	afterSale := &model.AfterSale{
		OrderID:     req.OrderID,
		OrderItemID: req.OrderItemID,
		UserID:      userID,
		Type:        req.Type,
		Reason:      req.Reason,
		Description: req.Description,
		Images:      req.Images,
		Status:      1, // 1待审核
		CreatedAt:   time.Now(),
		UpdatedAt:   time.Now(),
	}

	if err := s.db.Create(afterSale).Error; err != nil {
		return nil, err
	}

	// 预加载关联数据
	if err := s.db.Preload("Order").Preload("OrderItem").Preload("User").
		First(afterSale, afterSale.ID).Error; err != nil {
		return nil, err
	}

	return afterSale, nil
}

// CreateAfterSaleRequest 创建售后申请请求
type CreateAfterSaleRequest struct {
	OrderID     uint      `json:"order_id" binding:"required"`
	OrderItemID uint      `json:"order_item_id" binding:"required"`
	Type        int       `json:"type" binding:"required"` // 1退货，2换货，3维修
	Reason      string    `json:"reason" binding:"required"`
	Description string    `json:"description"`
	Images      model.JSONSlice `json:"images"`
}

// UpdateAfterSaleStatus 更新售后状态
func (s *AfterSaleService) UpdateAfterSaleStatus(afterSaleID uint, status int, adminRemark string) error {
	return s.db.Model(&model.AfterSale{}).
		Where("id = ?", afterSaleID).
		Updates(map[string]interface{}{
			"status":       status,
			"admin_remark": adminRemark,
			"updated_at":   time.Now(),
		}).Error
}