package service

import (
	"errors"
	"fmt"
	"time"
	"wails-app/internal/dao"
	"wails-app/internal/global"
	"wails-app/internal/modules/monthly/repository"
	paymentSvc "wails-app/internal/modules/payment/service"

	"gorm.io/gorm"
)

type MonthlyCardService struct {
	repo *repository.MonthlyCardRepository
}

func NewMonthlyCardService() *MonthlyCardService {
	return &MonthlyCardService{repo: &repository.MonthlyCardRepository{}}
}

func cardDays(cardType string) int {
	switch cardType {
	case "month":
		return 30
	case "quarter":
		return 90
	case "year":
		return 365
	default:
		return 30
	}
}

// Create 办理月卡：月卡、白名单、支付流水在同一事务中，任一步失败整体回滚。
func (s *MonthlyCardService) Create(vehicleID uint, cardType string, fee float64, operatorID uint, remark string) (*dao.MonthlyCard, error) {
	existing, err := s.repo.GetByVehicleID(vehicleID)
	if err != nil && !errors.Is(err, gorm.ErrRecordNotFound) {
		return nil, fmt.Errorf("查询有效月卡失败: %w", err)
	}
	if existing != nil {
		return nil, errors.New("该车辆已有有效月卡，请先退卡或等过期后续费")
	}

	var vehicle dao.Vehicle
	if err := global.GVA_DB.First(&vehicle, vehicleID).Error; err != nil {
		return nil, errors.New("车辆不存在")
	}

	now := time.Now()
	endDate := now.AddDate(0, 0, cardDays(cardType))

	card := &dao.MonthlyCard{
		VehicleID: vehicleID, CardType: cardType,
		StartDate: now, EndDate: endDate,
		Fee: fee, PaymentStatus: "paid", OperatorID: operatorID, Remark: remark,
	}

	err = global.GVA_DB.Transaction(func(tx *gorm.DB) error {
		if err := tx.Create(card).Error; err != nil {
			return fmt.Errorf("创建月卡失败: %w", err)
		}

		shortlist := dao.Shortlist{
			VehicleId:      int(vehicleID),
			ListType:       "白名单",
			ExpirationTime: &endDate,
		}
		if err := tx.Create(&shortlist).Error; err != nil {
			return fmt.Errorf("写入白名单失败: %w", err)
		}

		payRecord := dao.PaymentRecord{
			RecordID: 0, PaymentEntry: paymentSvc.EntryCounter, PaymentMethod: paymentSvc.PaymentCash,
			Amount: fee, PaidAmount: fee, ChangeAmount: 0,
			OperatorID: operatorID, PaidAt: now,
			Remark: fmt.Sprintf("包月卡办理(%s)", cardType),
		}
		if err := tx.Create(&payRecord).Error; err != nil {
			return fmt.Errorf("创建支付流水失败: %w", err)
		}
		return nil
	})
	if err != nil {
		return nil, err
	}
	return card, nil
}

// Renew 续费：未过期卡从原到期日顺延，已过期卡从今天起算；
// 月卡、白名单、支付流水在同一事务中，任一步失败整体回滚。
func (s *MonthlyCardService) Renew(cardID uint, cardType string, fee float64, operatorID uint) error {
	return global.GVA_DB.Transaction(func(tx *gorm.DB) error {
		var card dao.MonthlyCard
		if err := tx.First(&card, cardID).Error; err != nil {
			return errors.New("月卡记录不存在")
		}
		if card.PaymentStatus != "paid" {
			return errors.New("月卡已退卡，无法续费")
		}

		now := time.Now()
		// 过期卡从今天起算，避免"续费后仍处于过期状态"
		base := card.EndDate
		if base.Before(now) {
			base = now
		}
		newEnd := base.AddDate(0, 0, cardDays(cardType))

		card.EndDate = newEnd
		card.Fee += fee
		if err := tx.Save(&card).Error; err != nil {
			return fmt.Errorf("更新月卡失败: %w", err)
		}

		if err := tx.Model(&dao.Shortlist{}).
			Where("vehicle_id = ? AND list_type = ?", card.VehicleID, "白名单").
			Update("expiration_time", newEnd).Error; err != nil {
			return fmt.Errorf("更新白名单失败: %w", err)
		}

		payRecord := dao.PaymentRecord{
			RecordID: 0, PaymentEntry: paymentSvc.EntryCounter, PaymentMethod: paymentSvc.PaymentCash,
			Amount: fee, PaidAmount: fee, ChangeAmount: 0,
			OperatorID: operatorID, PaidAt: now,
			Remark: fmt.Sprintf("包月卡续费(%s)", cardType),
		}
		if err := tx.Create(&payRecord).Error; err != nil {
			return fmt.Errorf("创建支付流水失败: %w", err)
		}
		return nil
	})
}

// Refund 退卡：标记退款状态与移除白名单在同一事务中，任一步失败整体回滚。
func (s *MonthlyCardService) Refund(cardID uint) error {
	return global.GVA_DB.Transaction(func(tx *gorm.DB) error {
		var card dao.MonthlyCard
		if err := tx.First(&card, cardID).Error; err != nil {
			return errors.New("月卡记录不存在")
		}

		card.PaymentStatus = "refunded"
		if err := tx.Save(&card).Error; err != nil {
			return fmt.Errorf("更新月卡状态失败: %w", err)
		}

		if err := tx.Where("vehicle_id = ? AND list_type = ?", card.VehicleID, "白名单").
			Unscoped().Delete(&dao.Shortlist{}).Error; err != nil {
			return fmt.Errorf("移除白名单失败: %w", err)
		}
		return nil
	})
}

func (s *MonthlyCardService) List(q repository.MonthlyCardQuery) ([]repository.MonthlyCardResult, int64, error) {
	return s.repo.List(q)
}