package channel

import (
	"context"
	"fmt"
	"net/http"

	"github.com/smartwalle/alipay/v3"

	"github.com/wangjia/pay/internal/model"
)

type alipayChannel struct {
	client *alipay.Client
}

func newAlipay(m *model.Merchant) (Channel, error) {
	if m.AppID == "" || m.AppPrivateKey == "" || m.AlipayPublicKey == "" {
		return nil, fmt.Errorf("商户 %s 的支付宝凭证不完整（app_id/app_private_key/alipay_public_key）", m.Code)
	}
	client, err := alipay.New(m.AppID, m.AppPrivateKey, m.Production)
	if err != nil {
		return nil, fmt.Errorf("初始化支付宝客户端失败: %w", err)
	}
	// 公钥模式（沙箱常用）。若改用证书模式，这里换成 LoadAppCertPublicKey 等。
	if err := client.LoadAliPayPublicKey(m.AlipayPublicKey); err != nil {
		return nil, fmt.Errorf("加载支付宝公钥失败: %w", err)
	}
	return &alipayChannel{client: client}, nil
}

func (a *alipayChannel) Name() string { return "alipay" }

func (a *alipayChannel) PagePay(_ context.Context, req CreateReq) (string, error) {
	var p = alipay.TradePagePay{}
	p.OutTradeNo = req.OutTradeNo
	p.Subject = req.Subject
	p.TotalAmount = req.Amount
	p.ProductCode = "FAST_INSTANT_TRADE_PAY"
	p.NotifyURL = req.NotifyURL
	p.ReturnURL = req.ReturnURL
	u, err := a.client.TradePagePay(p)
	if err != nil {
		return "", fmt.Errorf("支付宝下单失败: %w", err)
	}
	return u.String(), nil
}

func (a *alipayChannel) PreCreate(ctx context.Context, req CreateReq) (string, error) {
	var p = alipay.TradePreCreate{}
	p.OutTradeNo = req.OutTradeNo
	p.Subject = req.Subject
	p.TotalAmount = req.Amount
	p.NotifyURL = req.NotifyURL
	rsp, err := a.client.TradePreCreate(ctx, p)
	if err != nil {
		return "", fmt.Errorf("支付宝预下单调用失败: %w", err)
	}
	if rsp.IsFailure() {
		return "", fmt.Errorf("支付宝预下单失败: %s / %s", rsp.Msg, rsp.SubMsg)
	}
	return rsp.QRCode, nil
}

func (a *alipayChannel) VerifyNotify(ctx context.Context, r *http.Request) (*NotifyResult, error) {
	if err := r.ParseForm(); err != nil {
		return nil, fmt.Errorf("解析回调表单失败: %w", err)
	}
	// DecodeNotification 内部用已加载的支付宝公钥验签，验签不过会返回错误。
	noti, err := a.client.DecodeNotification(ctx, r.Form)
	if err != nil {
		return nil, fmt.Errorf("回调验签失败: %w", err)
	}
	paid := noti.TradeStatus == alipay.TradeStatusSuccess || noti.TradeStatus == alipay.TradeStatusFinished
	return &NotifyResult{
		OutTradeNo:   noti.OutTradeNo,
		TradeNo:      noti.TradeNo,
		Amount:       noti.TotalAmount,
		BuyerLogonID: noti.BuyerLogonId,
		Paid:         paid,
		Raw:          r.Form.Encode(),
	}, nil
}

func (a *alipayChannel) Query(ctx context.Context, outTradeNo string) (*QueryResult, error) {
	var p = alipay.TradeQuery{OutTradeNo: outTradeNo}
	rsp, err := a.client.TradeQuery(ctx, p)
	if err != nil {
		return nil, fmt.Errorf("支付宝查单调用失败: %w", err)
	}
	if rsp.IsFailure() {
		// 交易不存在（TRADE_NOT_EXIST）等：视为未找到，不报错，交由上层决定。
		return &QueryResult{Found: false}, nil
	}
	paid := rsp.TradeStatus == alipay.TradeStatusSuccess || rsp.TradeStatus == alipay.TradeStatusFinished
	return &QueryResult{
		Found:      true,
		OutTradeNo: rsp.OutTradeNo,
		TradeNo:    rsp.TradeNo,
		Amount:     rsp.TotalAmount,
		Paid:       paid,
	}, nil
}