import React, { useState, useCallback } from 'react';
import { View, Text } from '@tarojs/components';
import Taro, { useDidShow } from '@tarojs/taro';
import {
  listProducts,
  exchangeProduct,
} from '../../../services/points';
import type { PointsProduct } from '../../../services/points';
import { usePointsStore } from '../../../stores/points';
import Loading from '../../../components/Loading';
import { useElderClass } from '../../../hooks/useElderClass';
import './index.scss';

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

const TYPE_LABEL: Record<string, string> = {
  physical: '实物商品',
  service: '服务券',
  privilege: '权益卡',
};

const TYPE_COLOR: Record<string, string> = {
  physical: '#5B7A5E',
  service: '#C4623A',
  privilege: '#8B3E1F',
};

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

  useDidShow(() => {
    Taro.setNavigationBarTitle({ title: '确认兑换' });
    loadData();
  });

  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' });
      setTimeout(() => Taro.navigateBack(), 1500);
      return;
    }

    setLoading(true);
    try {
      const [productRes] = await Promise.all([
        listProducts({ page: 1, page_size: 100 }),
        refreshPoints(),
      ]);
      const found = productRes.data.find((p) => p.id === productId);
      if (!found) {
        Taro.showToast({ title: '商品不存在', icon: 'none' });
        setTimeout(() => Taro.navigateBack(), 1500);
        return;
      }
      setProduct(found);
    } catch {
      Taro.showToast({ title: '加载失败', icon: 'none' });
      setTimeout(() => Taro.navigateBack(), 1500);
    } finally {
      setLoading(false);
    }
  }, [refreshPoints]);

  const balance = account?.balance ?? 0;
  const cost = product?.points_cost ?? 0;
  const insufficient = balance < cost;

  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 });

      setTimeout(() => {
        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.navigateTo({
              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]);

  if (loading) {
    return (
      <View className={`exchange-page ${modeClass}`}>
        <Loading />
      </View>
    );
  }

  const productType = product?.product_type || 'physical';
  const initial = TYPE_INITIAL[productType] || '礼';
  const typeLabel = TYPE_LABEL[productType] || '商品';
  const typeColor = TYPE_COLOR[productType] || '#C4623A';

  return (
    <View className={`exchange-page ${modeClass}`}>
      {/* 商品预览卡片 */}
      <View className='product-card'>
        <View
          className='product-icon-wrap'
          style={{ backgroundColor: typeColor }}
        >
          <Text className='product-icon-char'>{initial}</Text>
        </View>
        <View className='product-meta'>
          <Text className='product-name'>{product?.name || ''}</Text>
          <Text className='product-type-tag'>{typeLabel}</Text>
        </View>
      </View>

      {/* 兑换明细 */}
      <View className='detail-section'>
        <Text className='detail-section-title'>兑换明细</Text>
        <View className='detail-card'>
          <View className='detail-row'>
            <Text className='detail-label'>所需积分</Text>
            <Text className='detail-value detail-cost'>{cost.toLocaleString()}</Text>
          </View>
          <View className='detail-row'>
            <Text className='detail-label'>当前余额</Text>
            <Text
              className={`detail-value ${insufficient ? 'detail-insufficient' : 'detail-sufficient'}`}
            >
              {balance.toLocaleString()}
            </Text>
          </View>
          {insufficient && (
            <View className='detail-row'>
              <Text className='detail-label'>差额</Text>
              <Text className='detail-value detail-insufficient'>
                -{(cost - balance).toLocaleString()}
              </Text>
            </View>
          )}
          <View className='detail-row last'>
            <Text className='detail-label'>库存</Text>
            <Text className='detail-value'>
              {product && product.stock > 0 ? `剩余 ${product.stock} 件` : '已兑完'}
            </Text>
          </View>
        </View>
      </View>

      {/* 温馨提示 */}
      <View className='notice-section'>
        <Text className='notice-title'>温馨提示</Text>
        <Text className='notice-text'>
          兑换成功后将生成核销码，请凭核销码到前台核销领取。
        </Text>
        <Text className='notice-text'>积分一经兑换不可退回。</Text>
      </View>

      {/* 底部操作 */}
      <View className='exchange-footer'>
        <View className='footer-cost'>
          <Text className='footer-cost-label'>合计</Text>
          <Text className='footer-cost-num'>{cost.toLocaleString()}</Text>
          <Text className='footer-cost-unit'>积分</Text>
        </View>
        <View
          className={`confirm-btn ${insufficient || (product?.stock ?? 0) <= 0 || submitting ? 'disabled' : ''}`}
          onClick={insufficient || (product?.stock ?? 0) <= 0 || submitting ? undefined : handleConfirm}
        >
          <Text className='confirm-btn-text'>
            {submitting
              ? '兑换中...'
              : insufficient
                ? '积分不足'
                : (product?.stock ?? 0) <= 0
                  ? '已兑完'
                  : '确认兑换'}
          </Text>
        </View>
      </View>
    </View>
  );
}