package service

import (
	"context"
	"errors"
	"fmt"
	"math/rand"
	"time"

	"order/consts"
	"order/dao"
	"order/model/dto"
	"order/model/entity"

	"go.mongodb.org/mongo-driver/v2/bson"
)

type payment struct{}

// Payment 支付服务
var Payment = new(payment)

// PayOrder 支付订单
func (s *payment) PayOrder(ctx context.Context, req *dto.PayOrderReq) (*dto.PayOrderResp, error) {
	// 1. 参数验证
	if req.TenantID == "" || req.OrderNo == "" || req.PayMethod == "" || req.PayType == "" {
		return nil, errors.New("必填参数不能为空")
	}

	// 2. 查询订单
	order, status, err := dao.Order.GetOrderByNo(ctx, req.OrderNo)
	if err != nil {
		return nil, fmt.Errorf("获取订单失败: %w", err)
	}

	if order == nil {
		return nil, errors.New("订单不存在")
	}

	// 3. 验证订单状态（只有待支付订单可以支付）
	if status != consts.OrderStatusPending {
		return nil, fmt.Errorf("订单状态不正确，当前状态: %s", status)
	}

	pendingOrder, ok := order.(*entity.OrderPending)
	if !ok {
		return nil, errors.New("订单类型错误")
	}

	// 4. 获取支付配置
	paymentConfig, err := dao.PaymentConfig.GetByTenantAndMethod(ctx, req.TenantID, req.PayMethod)
	if err != nil {
		return nil, fmt.Errorf("获取支付配置失败: %w", err)
	}

	if paymentConfig == nil {
		return nil, errors.New("支付配置不存在")
	}

	// 5. 调用第三方支付接口
	payResp, err := s.callThirdPartyPayment(ctx, paymentConfig, req, pendingOrder)
	if err != nil {
		return nil, fmt.Errorf("调用支付接口失败: %w", err)
	}

	// 6. 创建支付记录
	paymentRecord := &entity.PaymentRecord{
		OrderID:    pendingOrder.Id,
		OrderNo:    req.OrderNo,
		PayMethod:  req.PayMethod,
		PayType:    req.PayType,
		Amount:     pendingOrder.PayAmount,
		OutTradeNo: payResp.OutTradeNo,
		Status:     "pending",
	}

	if err := dao.PaymentRecord.Create(ctx, paymentRecord); err != nil {
		return nil, fmt.Errorf("创建支付记录失败: %w", err)
	}

	// 7. 更新订单支付信息
	payInfo := entity.PayInfo{
		OutTradeNo:  payResp.OutTradeNo,
		QRCode:      payResp.QRCode,
		PayURL:      payResp.PayURL,
		PrepayID:    payResp.PrepayID,
		JSAPIParams: payResp.JSAPIParams,
		APPParams:   payResp.APPParams,
	}

	if err := dao.Order.UpdatePayInfo(ctx, req.OrderNo, payInfo); err != nil {
		return nil, fmt.Errorf("更新订单支付信息失败: %w", err)
	}

	// 8. 返回支付信息
	resp := &dto.PayOrderResp{
		OrderNo:     req.OrderNo,
		QRCode:      payResp.QRCode,
		PayURL:      payResp.PayURL,
		PrepayID:    payResp.PrepayID,
		JSAPIParams: payResp.JSAPIParams,
		APPParams:   payResp.APPParams,
	}

	return resp, nil
}

// callThirdPartyPayment 调用第三方支付接口
func (s *payment) callThirdPartyPayment(ctx context.Context, config *entity.PaymentConfig, req *dto.PayOrderReq, order *entity.OrderPending) (*PaymentResponse, error) {
	// 这里应该是实际的第三方支付接口调用
	// 为了演示，我们返回模拟数据

	outTradeNo := s.generateOutTradeNo(req.TenantID)

	payResp := &PaymentResponse{
		OutTradeNo: outTradeNo,
	}

	// 根据支付类型返回不同的支付参数
	switch req.PayType {
	case "native":
		// 扫码支付
		payResp.QRCode = fmt.Sprintf("https://api.example.com/qrcode/%s", outTradeNo)
	case "jsapi":
		// JSAPI支付
		payResp.PrepayID = fmt.Sprintf("wxprepay_%s", outTradeNo)
		payResp.JSAPIParams = fmt.Sprintf(`{"appId":"%s","timeStamp":"%d","nonceStr":"%s","package":"prepay_id=%s","signType":"MD5","paySign":"signature"}`,
			config.AppID, time.Now().Unix(), s.generateNonceStr(), payResp.PrepayID)
	case "app":
		// APP支付
		payResp.APPParams = fmt.Sprintf(`{"appid":"%s","partnerid":"%s","prepayid":"%s","package":"Sign=WXPay","noncestr":"%s","timestamp":"%d","sign":"signature"}`,
			config.AppID, config.MchID, payResp.PrepayID, s.generateNonceStr(), time.Now().Unix())
	case "h5":
		// H5支付
		payResp.PayURL = fmt.Sprintf("https://api.example.com/h5pay/%s", outTradeNo)
	}

	return payResp, nil
}

// PaymentResponse 支付响应

type PaymentResponse struct {
	OutTradeNo  string `json:"out_trade_no"` // 商户订单号
	QRCode      string `json:"qrcode"`       // 支付二维码
	PayURL      string `json:"pay_url"`      // 支付链接
	PrepayID    string `json:"prepay_id"`    // 预支付ID
	JSAPIParams string `json:"jsapi_params"` // JSAPI参数
	APPParams   string `json:"app_params"`   // APP参数
}

// generateOutTradeNo 生成商户订单号
func (s *payment) generateOutTradeNo(tenantID string) string {
	timestamp := time.Now().Format("20060102150405")
	random := rand.Intn(10000)
	return fmt.Sprintf("%s%s%04d", tenantID, timestamp, random)
}

// generateNonceStr 生成随机字符串
func (s *payment) generateNonceStr() string {
	const charset = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
	b := make([]byte, 16)
	for i := range b {
		b[i] = charset[rand.Intn(len(charset))]
	}
	return string(b)
}

// HandlePaymentNotify 处理支付回调
func (s *payment) HandlePaymentNotify(ctx context.Context, req *dto.PaymentNotifyReq) error {
	// 1. 验证回调签名
	if !s.verifyNotifySignature(req) {
		return errors.New("签名验证失败")
	}

	// 2. 查询支付记录
	paymentRecord, err := dao.PaymentRecord.GetByOrderNo(ctx, req.TenantID, req.OrderNo)
	if err != nil {
		return fmt.Errorf("查询支付记录失败: %w", err)
	}

	if paymentRecord == nil {
		return errors.New("支付记录不存在")
	}

	// 3. 更新支付记录状态
	if err := dao.PaymentRecord.UpdateStatus(ctx, paymentRecord.Id.Hex(), req.Status, req.TransactionID, req.TradeNo); err != nil {
		return fmt.Errorf("更新支付记录失败: %w", err)
	}

	// 4. 如果支付成功，更新订单状态
	if req.Status == "success" {
		updateData := bson.M{
			"paid_at":         time.Now(),
			"transaction_id":  req.TransactionID,
			"trade_no":        req.TradeNo,
			"payment_channel": req.PayMethod,
		}

		if err := dao.Order.MoveOrderToStatus(ctx, consts.OrderStatusPending, consts.OrderStatusPaid, req.OrderNo, updateData); err != nil {
			return fmt.Errorf("更新订单状态失败: %w", err)
		}
	}

	return nil
}

// verifyNotifySignature 验证回调签名
func (s *payment) verifyNotifySignature(req *dto.PaymentNotifyReq) bool {
	// 这里应该是实际的签名验证逻辑
	// 为了演示，我们总是返回true
	return true
}

// RefundOrder 退款
func (s *payment) RefundOrder(ctx context.Context, req *dto.RefundOrderReq) (*dto.RefundOrderResp, error) {
	// 1. 参数验证
	if req.TenantID == "" || req.OrderNo == "" || req.RefundAmount <= 0 {
		return nil, errors.New("必填参数不能为空")
	}

	// 2. 查询订单
	order, status, err := dao.Order.GetOrderByNo(ctx, req.OrderNo)
	if err != nil {
		return nil, fmt.Errorf("获取订单失败: %w", err)
	}

	if order == nil {
		return nil, errors.New("订单不存在")
	}

	// 3. 验证订单状态（只有已支付订单可以退款）
	if status != consts.OrderStatusPaid {
		return nil, fmt.Errorf("订单状态不正确，当前状态: %s", status)
	}

	paidOrder, ok := order.(*entity.OrderPaid)
	if !ok {
		return nil, errors.New("订单类型错误")
	}

	// 4. 验证退款金额
	if req.RefundAmount > paidOrder.PayAmount {
		return nil, errors.New("退款金额不能超过支付金额")
	}

	// 5. 调用第三方退款接口
	refundResp, err := s.callThirdPartyRefund(ctx, req, paidOrder)
	if err != nil {
		return nil, fmt.Errorf("调用退款接口失败: %w", err)
	}

	// 6. 创建退款记录
	refundRecord := &entity.RefundRecord{
		OrderID:      paidOrder.Id,
		OrderNo:      req.OrderNo,
		RefundNo:     refundResp.RefundNo,
		RefundAmount: req.RefundAmount,
		Reason:       req.Reason,
		Status:       "pending",
	}

	if err := dao.RefundRecord.Create(ctx, refundRecord); err != nil {
		return nil, fmt.Errorf("创建退款记录失败: %w", err)
	}

	// 7. 如果是全额退款，更新订单状态
	if req.RefundAmount == paidOrder.PayAmount {
		updateData := bson.M{
			"refund_reason": req.Reason,
		}

		if err := dao.Order.MoveOrderToStatus(ctx, consts.OrderStatusPaid, consts.OrderStatusRefunded, req.OrderNo, updateData); err != nil {
			return nil, fmt.Errorf("更新订单状态失败: %w", err)
		}
	}

	// 8. 返回退款结果
	resp := &dto.RefundOrderResp{
		RefundNo:     refundResp.RefundNo,
		RefundID:     refundResp.RefundID,
		RefundAmount: req.RefundAmount,
	}

	return resp, nil
}

// callThirdPartyRefund 调用第三方退款接口
func (s *payment) callThirdPartyRefund(ctx context.Context, req *dto.RefundOrderReq, order *entity.OrderPaid) (*RefundResponse, error) {
	// 这里应该是实际的第三方退款接口调用
	// 为了演示，我们返回模拟数据

	refundNo := s.generateRefundNo(req.TenantID)
	refundID := fmt.Sprintf("refund_%s", refundNo)

	return &RefundResponse{
		RefundNo: refundNo,
		RefundID: refundID,
	}, nil
}

// RefundResponse 退款响应

type RefundResponse struct {
	RefundNo string `json:"refund_no"` // 退款单号
	RefundID string `json:"refund_id"` // 退款ID
}

// generateRefundNo 生成退款单号
func (s *payment) generateRefundNo(tenantID string) string {
	timestamp := time.Now().Format("20060102150405")
	random := rand.Intn(10000)
	return fmt.Sprintf("R%s%s%04d", tenantID, timestamp, random)
}

// HandleRefundNotify 处理退款回调
func (s *payment) HandleRefundNotify(ctx context.Context, req *dto.RefundNotifyReq) error {
	// 1. 验证回调签名
	if !s.verifyRefundNotifySignature(req) {
		return errors.New("签名验证失败")
	}

	// 2. 查询退款记录
	refundRecord, err := dao.RefundRecord.GetByRefundNo(ctx, req.TenantID, req.RefundNo)
	if err != nil {
		return fmt.Errorf("查询退款记录失败: %w", err)
	}

	if refundRecord == nil {
		return errors.New("退款记录不存在")
	}

	// 3. 更新退款记录状态
	if err := dao.RefundRecord.UpdateRefundStatus(ctx, refundRecord.Id.Hex(), req.Status, req.RefundID); err != nil {
		return fmt.Errorf("更新退款记录失败: %w", err)
	}

	return nil
}

// verifyRefundNotifySignature 验证退款回调签名
func (s *payment) verifyRefundNotifySignature(req *dto.RefundNotifyReq) bool {
	// 这里应该是实际的签名验证逻辑
	// 为了演示，我们总是返回true
	return true
}