// Package alipay adapts Alipay web payment (page/wap) to provider.Provider,
// porting v1 internal/channel/alipay.go's verify/query logic. The *alipay.Client
// (with app private key + Alipay public key) is built from env credentials at
// assembly time and injected, so verify_callback/query hold their own credentials.
package alipay

import (
	"context"
	"fmt"
	"net/url"
	"time"

	sw "github.com/smartwalle/alipay/v3"

	"github.com/wangjia/pay/internal/money"
	"github.com/wangjia/pay/internal/provider"
)

// gmtPaymentLayout 支付宝 gmt_payment/gmt_create 等时间字段格式,固定北京时间(无时区位),
// 用 FixedZone 而非 LoadLocation("Asia/Shanghai") 避免依赖运行环境是否内置 tzdata。
const gmtPaymentLayout = "2006-01-02 15:04:05"

var cst = time.FixedZone("CST", 8*3600)

type Provider struct{ client *sw.Client }

func New(client *sw.Client) *Provider { return &Provider{client: client} }

func (p *Provider) Method() string { return "alipay" }

func (p *Provider) Capabilities() provider.Capabilities {
	return provider.Capabilities{
		RenderTypes:      []provider.RenderType{provider.RenderRedirect},
		SupportsRefund:   false, // 退款 P4
		SettleCurrencies: []string{"CNY"},
		Regions:          []string{"cn"},
	}
}

func (p *Provider) Create(_ context.Context, req provider.CreateRequest) (*provider.Session, error) {
	if req.Currency != "CNY" {
		return nil, fmt.Errorf("alipay: 仅支持 CNY, got %s", req.Currency)
	}
	amount, err := money.Format(req.AmountMinor, "CNY")
	if err != nil {
		return nil, err
	}
	var payURL *url.URL
	if req.Metadata["is_mobile"] == "1" {
		wp := sw.TradeWapPay{}
		wp.OutTradeNo = req.OutTradeNo
		wp.Subject = req.Subject
		wp.TotalAmount = amount
		wp.ProductCode = "QUICK_WAP_WAY"
		wp.ReturnURL = req.ReturnURL
		payURL, err = p.client.TradeWapPay(wp)
	} else {
		pp := sw.TradePagePay{}
		pp.OutTradeNo = req.OutTradeNo
		pp.Subject = req.Subject
		pp.TotalAmount = amount
		pp.ProductCode = "FAST_INSTANT_TRADE_PAY"
		pp.ReturnURL = req.ReturnURL
		pp.QRPayMode = "2" // 跳转到完整扫码收银台(迁移 v1 语义)
		payURL, err = p.client.TradePagePay(pp)
	}
	if err != nil {
		return nil, fmt.Errorf("alipay: 下单失败: %w", err)
	}
	return &provider.Session{
		ProviderRef: req.OutTradeNo, // 支付宝以 out_trade_no 归位
		RenderType:  provider.RenderRedirect,
		Payload:     map[string]any{"url": payURL.String()},
	}, nil
}

func (p *Provider) VerifyCallback(ctx context.Context, in provider.CallbackInput) (*provider.PaidEvent, error) {
	form, err := url.ParseQuery(string(in.Raw))
	if err != nil {
		return nil, fmt.Errorf("alipay: 解析回调表单失败: %w", err)
	}
	// smartwalle/alipay v3.2.29 的 DecodeNotification 签名是 (ctx, values),
	// 内部用已加载支付宝公钥验签(见 v1 internal/channel/alipay.go 同用法)。
	noti, err := p.client.DecodeNotification(ctx, form)
	if err != nil {
		return nil, fmt.Errorf("alipay: 回调验签失败: %w", err)
	}
	paidAt := parseGmtPayment(noti.GmtPayment)
	return notifyToEvent(noti.OutTradeNo, string(noti.TradeStatus), noti.TotalAmount, paidAt, in.Raw)
}

func (p *Provider) Query(ctx context.Context, req provider.QueryRequest) (*provider.PaidEvent, error) {
	rsp, err := p.client.TradeQuery(ctx, sw.TradeQuery{OutTradeNo: req.OutTradeNo})
	if err != nil {
		return nil, fmt.Errorf("alipay: 查单失败: %w", err)
	}
	if rsp.IsFailure() {
		// 交易不存在等:视为未命中(pending),交管线继续轮询。
		return &provider.PaidEvent{ProviderRef: req.ProviderRef, Status: provider.PaidPending}, nil
	}
	// TradeQueryRsp 不带 gmt_payment(只有异步通知才有);查单场景 PaidAt 留 nil,
	// 由 settle 按 D4-A3 兜底用收到时间——不用 SendPayDate("打款给卖家时间"),
	// 那是结算时点,不是买家付款时点,拿来充 PaidAt 会误导对账。
	ev, err := notifyToEvent(rsp.OutTradeNo, string(rsp.TradeStatus), rsp.TotalAmount, nil, nil)
	if err != nil {
		return nil, err
	}
	ev.ProviderRef = req.ProviderRef
	return ev, nil
}

// parseGmtPayment 解析支付宝 "2006-01-02 15:04:05" 格式的付款时间(固定北京时间,无时区位)。
// 为空或解析失败均返回 nil——交 settle 按 D4-A3 兜底用收到时间,不因此让 VerifyCallback 报错。
func parseGmtPayment(s string) *time.Time {
	if s == "" {
		return nil
	}
	t, err := time.ParseInLocation(gmtPaymentLayout, s, cst)
	if err != nil {
		return nil
	}
	return &t
}

func notifyToEvent(outTradeNo, tradeStatus, totalAmount string, paidAt *time.Time, raw []byte) (*provider.PaidEvent, error) {
	// 支付宝交易状态四态(sw.TradeStatus* 全集)归一化:
	//   WAIT_BUYER_PAY(等待付款)→ pending;TRADE_SUCCESS/TRADE_FINISHED → succeeded;
	//   TRADE_CLOSED(超时未付关闭 / 全额退款后关闭)→ failed,不留在 pending 让轮询空转到天荒地老。
	status := provider.PaidPending
	switch sw.TradeStatus(tradeStatus) {
	case sw.TradeStatusSuccess, sw.TradeStatusFinished:
		status = provider.PaidSucceeded
	case sw.TradeStatusClosed:
		status = provider.PaidFailed
	}
	var minor int64
	if totalAmount != "" {
		m, err := money.Parse(totalAmount, "CNY")
		if err != nil {
			return nil, fmt.Errorf("alipay: 金额解析失败 %q: %w", totalAmount, err)
		}
		minor = m
	}
	return &provider.PaidEvent{
		ProviderRef:     outTradeNo,
		Status:          status,
		PaidAmountMinor: minor,
		PaidCurrency:    "CNY",
		Raw:             string(raw),
		PaidAt:          paidAt,
	}, nil
}