import { useState, useCallback } from 'react';
import { View, Text } from '@tarojs/components';
import Taro from '@tarojs/taro';
import { usePageData } from '@/hooks/usePageData';
import {
  getProduct,
  listProducts,
  exchangeProduct,
} from '../../../services/points';
import type { PointsProduct } from '../../../services/points';
import { usePointsStore } from '../../../stores/points';
import { useAuthStore } from '../../../stores/auth';
import Loading from '../../../components/Loading';
import { useElderClass } from '../../../hooks/useElderClass';
import { useSafeTimeout } from '@/hooks/useSafeTimeout';
import PageShell from '@/components/ui/PageShell';
import './index.scss';

const TYPE_CHAR: Record<string, string> = {
  physical: '物',
  service: '券',
  privilege: '权',
};

const TYPE_CLASS: Record<string, string> = {
  physical: 'physical',
  service: 'service',
  privilege: 'privilege',
};

export default function ExchangeConfirm() {
  const modeClass = useElderClass();
  const [product, setProduct] = useState<PointsProduct | null>(null);
  const account = usePointsStore((s) => s.account);
  const refreshPoints = usePointsStore((s) => s.refresh);
  const currentPatient = useAuthStore((s) => s.currentPatient);
  const [loading, setLoading] = useState(true);
  const [submitting, setSubmitting] = useState(false);
  const { safeSetTimeout } = useSafeTimeout();

  const loadData = useCallback(async () => {
    const instance = Taro.getCurrentInstance();
    const productId = instance.router?.params?.product_id;
    if (!productId) {
      Taro.showToast({ title: '参数错误', icon: 'none' });
      safeSetTimeout(() => Taro.navigateBack(), 1500);
      return;
    }

    setLoading(true);
    try {
      // 先尝试单商品接口，降级到列表查找
      let found: PointsProduct | null = null;
      try {
        found = await getProduct(productId);
      } catch (err) {
        console.warn('[exchange] 单商品接口失败，降级列表查找:', err);
        const productRes = await listProducts({ page: 1, page_size: 100 });
        found = productRes.data.find((p) => p.id === productId) || null;
      }
      if (!found) {
        Taro.showToast({ title: '商品不存在', icon: 'none' });
        safeSetTimeout(() => Taro.navigateBack(), 1500);
        return;
      }
      setProduct(found);
      await refreshPoints();
    } catch (err) {
      console.warn('[exchange] 加载兑换页面失败:', err);
      Taro.showToast({ title: '加载失败', icon: 'none' });
      safeSetTimeout(() => Taro.navigateBack(), 1500);
    } finally {
      setLoading(false);
    }
  }, [refreshPoints]);

  usePageData(
    useCallback(async () => {
      Taro.setNavigationBarTitle({ title: '确认兑换' });
      await loadData();
    }, [loadData]),
    { throttleMs: 10000, enablePullDown: false },
  );

  const balance = account?.balance ?? 0;
  const cost = product?.points_cost ?? 0;
  const insufficient = balance < cost;
  const remaining = balance - cost;
  const productType = product?.product_type || 'physical';
  const isService = productType === 'service';
  const typeChar = TYPE_CHAR[productType] || '礼';
  const typeCls = TYPE_CLASS[productType] || 'physical';

  const handleConfirm = useCallback(async () => {
    if (!product || submitting) return;

    if (insufficient) {
      Taro.showToast({ title: '积分不足', icon: 'none' });
      return;
    }

    const modalRes = await Taro.showModal({
      title: '确认兑换',
      content: `确定花费 ${cost} 积分兑换「${product.name}」吗？`,
    });
    if (!modalRes.confirm) return;

    setSubmitting(true);
    try {
      const order = await exchangeProduct(product.id);
      Taro.showToast({ title: '兑换成功', icon: 'success', duration: 2000 });

      safeSetTimeout(() => {
        if (isService && order.qr_code) {
          Taro.showModal({
            title: '兑换成功',
            content: `核销码: ${order.qr_code}\n请凭此码到前台核销`,
            showCancel: false,
            confirmText: '查看订单',
            success: () => {
              Taro.redirectTo({ url: '/pages/pkg-mall/orders/index' });
            },
          });
        } else {
          Taro.redirectTo({ url: '/pages/pkg-mall/orders/index' });
        }
      }, 2000);
    } catch (err) {
      const msg = err instanceof Error ? err.message : '兑换失败';
      if (msg.includes('余额不足') || msg.includes('insufficient')) {
        Taro.showToast({ title: '积分不足', icon: 'none' });
      } else {
        Taro.showToast({ title: msg, icon: 'none' });
      }
    } finally {
      setSubmitting(false);
    }
  }, [product, submitting, insufficient, cost, isService]);

  if (loading) {
    return (
      <PageShell className={modeClass}>
        <Loading />
      </PageShell>
    );
  }

  return (
    <PageShell padding="md" safeBottom={false} scroll={false} className={`exchange-page ${modeClass}`}>
      {/* 商品预览卡片 */}
      <View className='exchange-product-card'>
        <View className={`exchange-product-icon exchange-product-icon--${typeCls}`}>
          <Text className='exchange-product-icon-char'>{typeChar}</Text>
        </View>
        <View className='exchange-product-meta'>
          <Text className='exchange-product-name'>{product?.name || ''}</Text>
          <Text className='exchange-product-points'>{cost.toLocaleString()} 积分</Text>
          <Text className='exchange-product-qty'>×1</Text>
        </View>
      </View>

      {/* 收货信息（实体商品） */}
      {!isService && currentPatient && (
        <View className='exchange-address-card'>
          <View className='exchange-address-header'>
            <Text className='exchange-address-title'>收货信息</Text>
            <Text className='exchange-address-edit'>修改地址 ›</Text>
          </View>
          <Text className='exchange-address-name'>
            {currentPatient.name}
          </Text>
          <Text className='exchange-address-detail'>请前往个人中心完善收货地址</Text>
        </View>
      )}

      {/* 兑换明细 */}
      <View className='exchange-detail-card'>
        <Text className='exchange-detail-title'>兑换明细</Text>
        <View className='exchange-detail-row'>
          <Text className='exchange-detail-label'>商品积分</Text>
          <Text className='exchange-detail-value'>{cost.toLocaleString()}</Text>
        </View>
        <View className='exchange-detail-row'>
          <Text className='exchange-detail-label'>{isService ? '核销方式' : '运费'}</Text>
          <Text className='exchange-detail-value'>{isService ? '到院核销' : '¥0.00'}</Text>
        </View>
        <View className='exchange-detail-row'>
          <Text className='exchange-detail-label'>应扣积分</Text>
          <Text className='exchange-detail-value exchange-detail-cost'>{cost.toLocaleString()}</Text>
        </View>
        <View className='exchange-detail-row last'>
          <Text className='exchange-detail-label'>剩余积分</Text>
          <Text className={`exchange-detail-value ${remaining >= 0 ? 'sufficient' : 'insufficient'}`}>
            {remaining.toLocaleString()}
          </Text>
        </View>
      </View>

      {/* 确认兑换按钮 */}
      <View
        className={`exchange-confirm-btn ${insufficient || (product?.stock ?? 0) <= 0 || submitting ? 'disabled' : ''}`}
        onClick={insufficient || (product?.stock ?? 0) <= 0 || submitting ? undefined : handleConfirm}
      >
        <Text className='exchange-confirm-text'>
          {submitting
            ? '兑换中...'
            : insufficient
              ? '积分不足'
              : (product?.stock ?? 0) <= 0
                ? '已兑完'
                : '确认兑换'}
        </Text>
      </View>
    </PageShell>
  );
}