import { useCallback, useEffect, useMemo, useState } from 'react';
import { View, Text, Image } from '@tarojs/components';
import Taro, {
  useDidShow,
  usePageScroll,
  useRouter,
  useShareAppMessage,
  useShareTimeline,
} from '@tarojs/taro';
import type { ProductDetailContentDto } from '@dukang/shared-types';
import PageShell from '../../components/PageShell';
import PageNavBar from '../../components/PageNavBar';
import ProductCarousel from '../../components/ProductCarousel';
import ShareNavButton from '../../components/ShareNavButton';
import WechatShareReady from '../../components/WechatShareReady';
import { goLogin } from '../../lib/auth-nav';
import { ensurePayReady } from '../../lib/pay-ready';
import { isLoggedIn, request, toast } from '../../lib/api';
import {
  getProductCarouselImages,
  getProductDetailImages,
  getProductMainImage,
  type ProductImageSource,
} from '../../lib/product-images';
import {
  canBuyOnline,
  canPickupOnSite,
  normalizeFulfillmentFlags,
} from '../../lib/product-fulfillment';
import {
  DEFAULT_SHARE_DESC,
  DEFAULT_SHARE_TITLE,
  toWeappShareMessage,
} from '../../lib/wechat-share';
import iconHome from '../../assets/tabbar/home.png';
import { usePageView } from '../../lib/usePageView';

type Product = ProductImageSource & {
  id: string;
  name: string;
  subtitle?: string | null;
  price: number;
  benefitAmount?: number;
  benefitDisplay?: number;
  detailContent?: ProductDetailContentDto | null;
  allowOnSitePickup?: boolean;
  allowOnlinePurchase?: boolean;
  allowCrossCityDelivery?: boolean;
};

export default function ProductDetailPage() {
  const router = useRouter();
  const productId = router.params.id ?? '';
  usePageView(
    'product_detail_view',
    productId ? { refType: 'PRODUCT', refId: productId, productId } : undefined,
  );
  const [product, setProduct] = useState<Product | null>(null);
  const [headerSolid, setHeaderSolid] = useState(false);

  usePageScroll(({ scrollTop }) => {
    setHeaderSolid(scrollTop > 100);
  });

  const loadProduct = useCallback(() => {
    if (!productId) return;
    request<Product | null>(`/catalog/products/${productId}`)
      .then((p) => {
        if (!p) {
          setProduct(null);
          toast('商品不存在或暂未开放');
          return;
        }
        setProduct(normalizeFulfillmentFlags(p));
      })
      .catch((e) => {
        setProduct(null);
        toast(e instanceof Error ? e.message : '加载失败');
      });
  }, [productId]);

  useEffect(() => {
    loadProduct();
  }, [loadProduct]);

  // 登录后返回详情须带 token 重拉，否则白名单商品会一直空白
  useDidShow(() => {
    loadProduct();
  });

  const sharePayload = useMemo(
    () => ({
      title: product?.name || DEFAULT_SHARE_TITLE,
      desc: product?.subtitle || DEFAULT_SHARE_DESC,
      path: `/pages/product-detail/index?id=${productId}`,
      imgUrl: (product ? getProductMainImage(product) : '') || undefined,
    }),
    [product, productId],
  );

  useShareAppMessage(() => toWeappShareMessage(sharePayload));
  useShareTimeline(() => ({
    title: sharePayload.title || DEFAULT_SHARE_TITLE,
    query: productId ? `id=${productId}` : '',
    imageUrl: sharePayload.imgUrl,
  }));

  function goBack() {
    const pages = Taro.getCurrentPages();
    if (pages.length > 1) {
      Taro.navigateBack();
      return;
    }
    Taro.switchTab({ url: '/pages/home/index' });
  }

  function goHome() {
    Taro.switchTab({ url: '/pages/home/index' });
  }

  async function goBuy() {
    if (!productId) return;
    const returnPath = `/pages/order-confirm/index?productId=${productId}&qty=2`;
    if (!isLoggedIn()) {
      goLogin(returnPath);
      return;
    }
    const ready = await ensurePayReady(returnPath);
    if (!ready) return;
    Taro.navigateTo({ url: returnPath });
  }

  async function goOnSitePickup() {
    if (!productId) return;
    const returnPath = `/pages/order-confirm-pickup/index?productId=${productId}&qty=1`;
    if (!isLoggedIn()) {
      goLogin(returnPath);
      return;
    }
    const ready = await ensurePayReady(returnPath);
    if (!ready) return;
    Taro.navigateTo({ url: returnPath });
  }

  if (!product) {
    return (
      <PageShell variant="scroll" className="product-detail-page">
        <PageNavBar title="商品详情" solid onBack={goBack} />
        <View className="page-with-nav-bar u-empty">加载中…</View>
      </PageShell>
    );
  }

  const allowOnline = canBuyOnline(product);
  const allowOnSite = canPickupOnSite(product);
  const benefit = Number(product.benefitDisplay ?? product.benefitAmount ?? product.price);
  const carouselImages = getProductCarouselImages(product);
  const detailImages = getProductDetailImages(product);
  const detail = product.detailContent ?? {};
  const features = detail.features ?? [];

  return (
    <PageShell variant="scroll" className="product-detail-page" hasFixedFooter>
      <WechatShareReady payload={sharePayload} />
      <PageNavBar
        title={product.name}
        solid={headerSolid}
        titleVisible={headerSolid}
        onBack={goBack}
        right={<ShareNavButton payload={sharePayload} />}
      />

      <View className="product-detail-main">
        <View className="product-detail-hero full-bleed">
          <ProductCarousel images={carouselImages} alt={product.name} variant="detail" />
        </View>

        <View className="product-detail-info">
          <View className="product-detail-price">
            <Text className="product-detail-price-symbol">¥</Text>
            <Text className="product-detail-price-value">{Number(product.price).toFixed(2)}</Text>
          </View>
          <Text className="product-detail-name">{product.name}</Text>
          {product.subtitle ? (
            <Text className="product-detail-subtitle">{product.subtitle}</Text>
          ) : null}

          <View className="product-detail-promo">
            <View className="product-detail-promo-glow" />
            <View className="product-detail-promo-head">
              <View className="product-detail-promo-icon">
                <Text className="product-detail-promo-icon-text">惠</Text>
              </View>
              <Text className="product-detail-promo-title">
                买杜康美酒 · 享全城好客礼遇
                <Text className="product-detail-promo-amount"> ¥{benefit}</Text>
              </Text>
            </View>
            <Text className="product-detail-promo-desc">
              购酒即享本城专属好客权益，为您安排一场地道饭局。权益金可直接用于本地签约门店消费，到店享用，醇香美酒配佳肴。
            </Text>
          </View>
        </View>

        <View className="product-detail-content">
          <View className="product-detail-section-head">
            <View className="product-detail-section-bar" />
            <Text className="product-detail-section-title">商品详情</Text>
          </View>

          {detailImages.map((src, index) => (
            <Image
              key={`${src}-${index}`}
              className="product-detail-banner full-bleed"
              src={src}
              mode="widthFix"
            />
          ))}

          {(detail.storyTitle || detail.storyText || features.length > 0) ? (
            <View className="product-detail-copy">
              {(detail.storyTitle || detail.storyText) ? (
                <View className="product-detail-story">
                  {detail.storyTitle ? (
                    <Text className="product-detail-story-title">{detail.storyTitle}</Text>
                  ) : null}
                  {detail.storyText ? (
                    <Text className="product-detail-story-text">{detail.storyText}</Text>
                  ) : null}
                </View>
              ) : null}

              {features.length > 0 ? (
                <View className="product-detail-features">
                  {features.map((f) => (
                    <View key={`${f.title}-${f.icon}`} className="product-detail-feature">
                      <Text className="product-detail-feature-icon">★</Text>
                      <Text className="product-detail-feature-title">{f.title}</Text>
                      <Text className="product-detail-feature-desc">{f.desc}</Text>
                    </View>
                  ))}
                </View>
              ) : null}
            </View>
          ) : null}
        </View>
      </View>

      <View className="product-detail-bar">
        <View className="product-detail-bar-home" onClick={goHome}>
          <Image className="product-detail-bar-home-icon" src={iconHome} mode="aspectFit" />
          <Text className="product-detail-bar-home-label">首页</Text>
        </View>
        {allowOnSite ? (
          <View className="product-detail-pickup-btn" onClick={() => void goOnSitePickup()}>
            <Text className="product-detail-pickup-btn-text">现场取货</Text>
          </View>
        ) : null}
        {allowOnline ? (
          <View className="product-detail-buy-btn" onClick={() => void goBuy()}>
            <Text className="product-detail-buy-btn-text">立即购买</Text>
          </View>
        ) : null}
        {!allowOnline && !allowOnSite ? (
          <View className="product-detail-buy-btn product-detail-buy-btn--disabled">
            <Text className="product-detail-buy-btn-text">暂不可购</Text>
          </View>
        ) : null}
      </View>
    </PageShell>
  );
}