package payment

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

	"server/models"

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

// AlipayChannel 支付宝（电脑网站支付 / 手机网站支付，RSA2）
//
// 渠道参数（config_json）：
//
//	appid             开放平台应用 APPID
//	app_private_key   应用私钥（RSA2，PKCS8）
//	alipay_public_key 支付宝公钥（回显公钥，用于验签）
//	is_production     "1" 正式环境 / 其他为沙箱
type AlipayChannel struct{}

func (c *AlipayChannel) Code() string { return ChannelAlipay }
func (c *AlipayChannel) Name() string { return "支付宝" }

func (c *AlipayChannel) buildClient(cfg *ChannelConfig) (*alipay.Client, error) {
	appID := cfg.Get("appid")
	priv := cfg.Get("app_private_key")
	pub := cfg.Get("alipay_public_key")
	if appID == "" || priv == "" || pub == "" {
		return nil, fmt.Errorf("支付宝参数不完整：需要 appid / app_private_key / alipay_public_key")
	}
	client, err := alipay.New(appID, priv, cfg.Get("is_production") == "1")
	if err != nil {
		return nil, fmt.Errorf("创建支付宝客户端失败: %w", err)
	}
	if err := client.LoadAliPayPublicKey(pub); err != nil {
		return nil, fmt.Errorf("加载支付宝公钥失败: %w", err)
	}
	return client, nil
}

func (c *AlipayChannel) Prepay(ctx context.Context, order *models.PlatformPaymentOrder, cfg *ChannelConfig, opt PrepayOption) (*PayParams, error) {
	client, err := c.buildClient(cfg)
	if err != nil {
		return nil, err
	}

	trade := alipay.Trade{
		NotifyURL:   cfg.CallbackURL,
		ReturnURL:   order.ReturnURL,
		Subject:     order.Subject,
		OutTradeNo:  order.PayNo,
		TotalAmount: FenToYuan(order.Amount),
	}
	if order.ExpireAt != nil {
		mins := int(time.Until(*order.ExpireAt).Minutes())
		if mins < 1 {
			mins = 1
		}
		trade.TimeoutExpress = fmt.Sprintf("%dm", mins)
	}

	if strings.EqualFold(opt.PayType, PayTypeH5) {
		// 手机网站支付
		trade.ProductCode = "QUICK_WAP_WAY"
		u, err := client.TradeWapPay(alipay.TradeWapPay{Trade: trade})
		if err != nil {
			return nil, fmt.Errorf("支付宝手机网站下单失败: %w", err)
		}
		return &PayParams{Channel: ChannelAlipay, PayType: PayTypeH5, RedirectURL: u.String()}, nil
	}

	// 默认：电脑网站支付（PC 收银台）
	trade.ProductCode = "FAST_INSTANT_TRADE_PAY"
	u, err := client.TradePagePay(alipay.TradePagePay{Trade: trade})
	if err != nil {
		return nil, fmt.Errorf("支付宝电脑网站下单失败: %w", err)
	}
	return &PayParams{Channel: ChannelAlipay, PayType: PayTypeWeb, RedirectURL: u.String()}, nil
}

// normalizeAlipayStatus 支付宝交易状态 -> 归一化状态
func normalizeAlipayStatus(status alipay.TradeStatus) string {
	switch status {
	case alipay.TradeStatusSuccess, alipay.TradeStatusFinished:
		return StateSuccess
	case alipay.TradeStatusClosed:
		return StateClosed
	case alipay.TradeStatusWaitBuyerPay:
		return StatePending
	default:
		return StatePending
	}
}

func (c *AlipayChannel) Query(ctx context.Context, order *models.PlatformPaymentOrder, cfg *ChannelConfig) (*ChannelState, error) {
	client, err := c.buildClient(cfg)
	if err != nil {
		return nil, err
	}
	rsp, err := client.TradeQuery(ctx, alipay.TradeQuery{OutTradeNo: order.PayNo})
	if err != nil {
		return nil, fmt.Errorf("支付宝查询订单失败: %w", err)
	}
	// 交易不存在（如超时未付被渠道关闭）：不视为失败，返回待支付以便走关闭逻辑
	if rsp.Code != "10000" {
		if rsp.SubCode == "ACQ.TRADE_NOT_EXIST" {
			return &ChannelState{TradeState: StatePending, Raw: rsp.SubMsg}, nil
		}
		return nil, fmt.Errorf("支付宝查询失败: %s %s %s", rsp.Code, rsp.SubCode, rsp.SubMsg)
	}

	state := &ChannelState{
		ChannelTradeNo: rsp.TradeNo,
		TradeState:     normalizeAlipayStatus(rsp.TradeStatus),
		Raw:            fmt.Sprintf("trade_no=%s status=%s total=%s", rsp.TradeNo, rsp.TradeStatus, rsp.TotalAmount),
	}
	if fen, err := YuanToFen(rsp.TotalAmount); err == nil {
		state.Amount = fen
	}
	if state.TradeState == StateSuccess {
		now := time.Now()
		state.PaidAt = &now
	}
	return state, nil
}

func (c *AlipayChannel) ParseNotify(ctx context.Context, r *http.Request, cfg *ChannelConfig) (*NotifyResult, error) {
	client, err := c.buildClient(cfg)
	if err != nil {
		return nil, err
	}
	if err := r.ParseForm(); err != nil {
		return nil, fmt.Errorf("解析支付宝通知参数失败: %w", err)
	}
	notification, err := client.DecodeNotification(ctx, r.Form)
	if err != nil {
		return nil, fmt.Errorf("支付宝通知验签失败: %w", err)
	}

	result := &NotifyResult{
		EventType:      notification.NotifyType,
		EventID:        notification.NotifyId,
		OutTradeNo:     notification.OutTradeNo,
		PayNo:          notification.OutTradeNo,
		ChannelTradeNo: notification.TradeNo,
		AckBody:        "success",
	}
	if fen, err := YuanToFen(notification.TotalAmount); err == nil {
		result.Amount = fen
	}
	result.TradeState = normalizeAlipayStatus(notification.TradeStatus)
	result.Paid = result.TradeState == StateSuccess
	return result, nil
}

func (c *AlipayChannel) Refund(ctx context.Context, order *models.PlatformPaymentOrder, refundNo string, amount int64, reason string, cfg *ChannelConfig) (string, error) {
	client, err := c.buildClient(cfg)
	if err != nil {
		return "", err
	}
	rsp, err := client.TradeRefund(ctx, alipay.TradeRefund{
		OutTradeNo:   order.PayNo,
		RefundAmount: FenToYuan(amount),
		RefundReason: reason,
		OutRequestNo: refundNo,
	})
	if err != nil {
		return "", fmt.Errorf("支付宝退回请求失败: %w", err)
	}
	if rsp.Code != "10000" {
		return "", fmt.Errorf("支付宝退回失败: %s %s %s", rsp.Code, rsp.SubCode, rsp.SubMsg)
	}
	return rsp.TradeNo, nil
}

func (c *AlipayChannel) TestConnect(ctx context.Context, cfg *ChannelConfig) (string, error) {
	client, err := c.buildClient(cfg)
	if err != nil {
		return "", err
	}
	// 查询一笔必然不存在的交易：能返回「交易不存在」即说明 APPID 与签名配置正确
	rsp, err := client.TradeQuery(ctx, alipay.TradeQuery{OutTradeNo: "__connect_test__"})
	if err != nil {
		return "", fmt.Errorf("支付宝凭证校验失败: %w", err)
	}
	if rsp.Code == "10000" || rsp.SubCode == "ACQ.TRADE_NOT_EXIST" {
		return "连接成功：APPID 与 RSA2 签名校验通过", nil
	}
	return "", fmt.Errorf("支付宝凭证校验未通过: %s %s %s", rsp.Code, rsp.SubCode, rsp.SubMsg)
}