package service

import (
	"context"
	"errors"
	"log/slog"

	"time"

	"pay-bridge/internal/channel"
	"pay-bridge/internal/errcode"
	"pay-bridge/internal/model"
	"pay-bridge/internal/repository"
	"pay-bridge/pkg/sequence"
)

// CreateRefundReq 退款请求
type CreateRefundReq struct {
	AppID        string
	TradeNo      string
	RefundAmount int64
	Reason       string
	NotifyURL    string
}

// RefundService 退款服务
type RefundService struct {
	refundRepo *repository.RefundOrderRepository
	tradeRepo  *repository.TradeOrderRepository
	channelSvc *ChannelService
	seqSvc     *sequence.Service
	notifySvc  *NotifyService
}

func NewRefundService(
	refundRepo *repository.RefundOrderRepository,
	tradeRepo *repository.TradeOrderRepository,
	channelSvc *ChannelService,
	seqSvc *sequence.Service,
	notifySvc *NotifyService,
) *RefundService {
	return &RefundService{
		refundRepo: refundRepo,
		tradeRepo:  tradeRepo,
		channelSvc: channelSvc,
		seqSvc:     seqSvc,
		notifySvc:  notifySvc,
	}
}

// CreateRefund 发起退款
func (s *RefundService) CreateRefund(ctx context.Context, req *CreateRefundReq) (*model.RefundOrder, error) {
	// 查询原交易
	order, err := s.tradeRepo.GetByTradeNo(ctx, req.TradeNo)
	if err != nil {
		return nil, err
	}
	if order == nil || order.AppID != req.AppID {
		return nil, errors.New(errcode.ErrOrderNotFound)
	}
	if order.Status != model.TradeStatusPaid && order.Status != model.TradeStatusRefunded {
		return nil, errors.New(errcode.ErrOrderNotPaid)
	}

	// 校验可退金额
	refunded, err := s.refundRepo.SumRefundedAmount(ctx, req.TradeNo)
	if err != nil {
		return nil, err
	}
	if refunded+req.RefundAmount > order.Amount {
		return nil, errors.New(errcode.ErrRefundAmountExceed)
	}

	// 生成退款单号
	refundNo, err := s.seqSvc.NextRefundNo(ctx, req.AppID)
	if err != nil {
		return nil, err
	}

	// 创建退款记录
	refund := &model.RefundOrder{
		RefundNo:     refundNo,
		TradeNo:      req.TradeNo,
		AppID:        req.AppID,
		ChannelCode:  order.ChannelCode,
		RefundAmount: req.RefundAmount,
		Reason:       req.Reason,
		Status:       model.RefundStatusPending,
		NotifyURL:    req.NotifyURL,
	}
	if err := s.refundRepo.Create(ctx, refund); err != nil {
		return nil, err
	}

	// 调用渠道退款
	ch, err := s.channelSvc.GetChannel(ctx, req.AppID, order.ChannelCode)
	if err != nil {
		return nil, err
	}

	channelResp, err := ch.Refund(ctx, &channel.RefundReq{
		TradeNo:        req.TradeNo,
		ChannelTradeNo: order.ChannelTradeNo,
		RefundNo:       refundNo,
		RefundAmount:   req.RefundAmount,
		TotalAmount:    order.Amount,
		Reason:         req.Reason,
		NotifyURL:      req.NotifyURL,
	})
	if err != nil {
		s.refundRepo.UpdateStatus(ctx, refundNo, model.RefundStatusPending, model.RefundStatusFailed, nil)
		return nil, errors.New(errcode.ErrChannelRefundFail)
	}

	// 更新渠道退款单号
	updates := map[string]any{
		"channel_refund_no": channelResp.ChannelRefundNo,
		"status":            model.RefundStatusProcessing,
	}
	s.refundRepo.UpdateStatus(ctx, refundNo, model.RefundStatusPending, model.RefundStatusProcessing, updates)

	refund.ChannelRefundNo = channelResp.ChannelRefundNo
	refund.Status = model.RefundStatusProcessing
	return refund, nil
}

// QueryRefund 查询退款状态
func (s *RefundService) QueryRefund(ctx context.Context, appID, refundNo string) (*model.RefundOrder, error) {
	refund, err := s.refundRepo.GetByRefundNo(ctx, refundNo)
	if err != nil {
		return nil, err
	}
	if refund == nil || refund.AppID != appID {
		return nil, errors.New(errcode.ErrRefundNotFound)
	}

	// 如果处于处理中，主动查询渠道
	if refund.Status == model.RefundStatusProcessing {
		s.syncRefundStatus(ctx, refund)
		// 重新查询最新状态
		refund, _ = s.refundRepo.GetByRefundNo(ctx, refundNo)
	}

	return refund, nil
}

// HandleRefundNotify 处理退款回调
func (s *RefundService) HandleRefundNotify(ctx context.Context, refundNo string, channelRefundNo string, status model.RefundStatus) error {
	refund, err := s.refundRepo.GetByRefundNo(ctx, refundNo)
	if err != nil || refund == nil {
		return errors.New(errcode.ErrRefundNotFound)
	}

	if refund.Status == model.RefundStatusSuccess {
		return nil // 幂等
	}

	updates := map[string]any{
		"channel_refund_no": channelRefundNo,
	}
	if status == model.RefundStatusSuccess {
		now := time.Now()
		updates["refund_time"] = now
	}

	ok, err := s.refundRepo.UpdateStatus(ctx, refundNo, model.RefundStatusProcessing, status, updates)
	if err != nil {
		return err
	}
	if !ok {
		return nil // 幂等
	}

	// 退款成功后通知下游
	if status == model.RefundStatusSuccess && refund.NotifyURL != "" && s.notifySvc != nil {
		go func() {
			bgCtx := context.Background()
			if err := s.notifySvc.SendNotify(bgCtx, refund.TradeNo, model.NotifyTypeRefund, refund.NotifyURL); err != nil {
				slog.Error("send refund notify failed", "refund_no", refundNo, "err", err)
			}
		}()
	}

	return nil
}

func (s *RefundService) syncRefundStatus(ctx context.Context, refund *model.RefundOrder) {
	order, err := s.tradeRepo.GetByTradeNo(ctx, refund.TradeNo)
	if err != nil || order == nil {
		return
	}
	ch, err := s.channelSvc.GetChannel(ctx, refund.AppID, refund.ChannelCode)
	if err != nil {
		return
	}
	resp, err := ch.QueryRefund(ctx, &channel.QueryRefundReq{
		RefundNo:        refund.RefundNo,
		ChannelRefundNo: refund.ChannelRefundNo,
	})
	if err != nil {
		return
	}
	if resp.Status != refund.Status {
		updates := map[string]any{
			"channel_refund_no": resp.ChannelRefundNo,
		}
		if resp.RefundTime != nil {
			updates["refund_time"] = resp.RefundTime
		}
		s.refundRepo.UpdateStatus(ctx, refund.RefundNo, refund.Status, resp.Status, updates)
	}
}