import { useCallback, useEffect, useState } from 'react';
import { View, Text } from '@tarojs/components';
import '../../styles/order.css';
import Taro, { useDidShow, useRouter } from '@tarojs/taro';
import PageShell from '../../components/PageShell';
import SubPageHeader from '../../components/SubPageHeader';
import WechatLoginButton from '../../components/WechatLoginButton';
import { ensurePayReady } from '../../lib/pay-ready';
import {
  authorizeWechatForPay,
  fetchClientConfig,
  fetchUserProfile,
  isWechatAuthRequiredError,
  needsWechatAuthForPay,
  payOrder,
  saveWechatLoginResult,
} from '../../lib/pay-wechat';
import { applyWechatLoginResult } from '../../lib/wechat-auth';
import { isWechatEnv } from '../../lib/weixin';
import { goLogin } from '../../lib/auth-nav';
import { request, toast } from '../../lib/api';

export default function PayPage() {
  const router = useRouter();
  const orderId = router.params.orderId ?? '';
  const [loading, setLoading] = useState(false);
  const [authLoading, setAuthLoading] = useState(false);
  const [mockMode, setMockMode] = useState(true);
  const [needsWechatAuth, setNeedsWechatAuth] = useState(false);
  const [msg, setMsg] = useState('');
  const [orderNo, setOrderNo] = useState('');
  const [payAmount, setPayAmount] = useState('—');
  const [deliveryType, setDeliveryType] = useState('');

  const returnPath = orderId
    ? `/pages/pay/index?orderId=${orderId}`
    : '/pages/pay/index';

  const refreshPayReadiness = useCallback(async () => {
    try {
      const [config, profile] = await Promise.all([fetchClientConfig(), fetchUserProfile()]);
      setMockMode(config.mockPay);
      setNeedsWechatAuth(needsWechatAuthForPay(config, profile));
      return profile;
    } catch {
      return null;
    }
  }, []);

  useDidShow(() => {
    void refreshPayReadiness();
  });

  useEffect(() => {
    if (!orderId) return;
    if (process.env.TARO_ENV === 'weapp') {
      void ensurePayReady(returnPath);
    }
  }, [orderId, returnPath]);

  useEffect(() => {
    if (!orderId) {
      setOrderNo('');
      setPayAmount('—');
      return;
    }
    request<{
      orderNo?: string;
      payAmount?: number | string;
      totalAmount?: number | string;
      deliveryType?: string;
    }>(`/trade/orders/${orderId}`)
      .then((order) => {
        setOrderNo(order.orderNo || '');
        setDeliveryType(order.deliveryType || '');
        const amount = Number(order.payAmount ?? order.totalAmount ?? 0);
        if (Number.isFinite(amount) && amount > 0) {
          setPayAmount(amount.toFixed(2));
        }
      })
      .catch((e) => {
        setOrderNo('');
        setDeliveryType('');
        toast(e instanceof Error ? e.message : '加载订单失败');
      });
  }, [orderId]);

  async function wechatAuthorize() {
    setAuthLoading(true);
    setMsg('');
    try {
      if (!isWechatEnv()) {
        setMsg('请在微信内打开以授权微信支付');
        return;
      }
      if (process.env.TARO_ENV === 'weapp') {
        const ready = await ensurePayReady(returnPath);
        if (ready) await refreshPayReadiness();
        return;
      }
      const result = await authorizeWechatForPay();
      if (result) {
        if (result.needBindPhone && result.wxSessionKey) {
          goLogin(returnPath, { bindMode: '1', wxSessionKey: result.wxSessionKey });
          return;
        }
        if (saveWechatLoginResult(result) || applyWechatLoginResult(result)) {
          setMsg('');
          await refreshPayReadiness();
          toast('微信授权成功', 'success');
        }
      }
    } catch (e) {
      setMsg(e instanceof Error ? e.message : '微信授权失败');
    } finally {
      setAuthLoading(false);
    }
  }

  async function pay() {
    if (!orderId) {
      toast('订单不存在');
      return;
    }
    if (needsWechatAuth) {
      setMsg('请先完成微信授权后再支付');
      if (process.env.TARO_ENV === 'h5') {
        await wechatAuthorize();
      } else {
        await ensurePayReady(returnPath);
      }
      return;
    }

    const ready = await ensurePayReady(returnPath);
    if (!ready) return;

    setLoading(true);
    setMsg('');
    try {
      const status = await payOrder(orderId);
      if (status === 'pending') {
        toast('支付结果确认中，请稍后在订单列表查看');
      } else {
        toast('支付成功', 'success');
      }
      if (deliveryType === 'ON_SITE_PICKUP') {
        // 现场提货支付即完成 → 订单详情；from=pay 返回强制回首页，避免 navigateBack 退出小程序
        Taro.reLaunch({ url: `/pages/order-detail/index?id=${orderId}&from=pay` });
      } else {
        Taro.reLaunch({ url: '/pages/orders/index?tab=paid&from=pay' });
      }
    } catch (e) {
      if (isWechatAuthRequiredError(e)) {
        setNeedsWechatAuth(true);
        setMsg('微信支付需要先完成微信授权');
        return;
      }
      const message = e instanceof Error ? e.message : '支付失败';
      if (message.includes('取消')) {
        setMsg('已取消支付');
        return;
      }
      setMsg(message);
      toast(message);
    } finally {
      setLoading(false);
    }
  }

  return (
    <PageShell variant="sub" className="pay-page" hasFixedFooter>
      <SubPageHeader title="收银台" />
      <View className="sub-page-body">
        <View className="pay-status">
          <View className="pay-status-icon">
            <Text>¥</Text>
          </View>
          <Text className="pay-status-title">
            {needsWechatAuth ? '需完成微信授权' : '待支付'}
          </Text>
          <Text className="pay-status-amount">¥{payAmount}</Text>
        </View>

        {needsWechatAuth ? (
          <View className="pay-wechat-auth-card">
            <Text className="pay-wechat-auth-title">尚未授权微信</Text>
            <Text className="pay-wechat-auth-desc">
              授权后可安全调起微信支付，不会重复扣款
            </Text>
            <WechatLoginButton
              loading={authLoading}
              onClick={() => void wechatAuthorize()}
            />
          </View>
        ) : null}

        <View className="order-card">
          <View className="order-row">
            <Text className="order-row-label">订单号</Text>
            <Text className="order-row-value">{orderNo || '—'}</Text>
          </View>
          <View className="order-row">
            <Text className="order-row-label">支付方式</Text>
            <Text className="order-row-value">微信支付</Text>
          </View>
          <View className="order-row">
            <Text className="order-row-label">说明</Text>
            <Text className="order-row-value">
              {mockMode ? 'Mock 模式由服务端直接标记已付款' : '将调起微信收银台'}
            </Text>
          </View>
        </View>
        {msg ? (
          <Text className="pay-wechat-auth-msg" style={{ marginTop: 12 }}>
            {msg}
          </Text>
        ) : null}
      </View>
      <View className="pay-bar">
        <View
          className="order-confirm-submit"
          style={{ flex: 1, opacity: loading || needsWechatAuth ? 0.7 : 1 }}
          onClick={() => {
            if (loading) return;
            if (needsWechatAuth) {
              void wechatAuthorize();
              return;
            }
            void pay();
          }}
        >
          <Text>
            {loading
              ? '支付中…'
              : needsWechatAuth
                ? authLoading
                  ? '授权中…'
                  : '微信一键授权'
                : '立即支付'}
          </Text>
        </View>
      </View>
    </PageShell>
  );
}