import { useCallback, useMemo, useRef, useState } from 'react';
import { View, Text, Image, Swiper, SwiperItem } from '@tarojs/components';
import Taro, {
  useDidShow,
  usePageScroll,
  usePullDownRefresh,
  useShareAppMessage,
  useShareTimeline,
} from '@tarojs/taro';
import PageShell from '../../components/PageShell';
import TabMainHeader from '../../components/TabMainHeader';
import CouponBadge from '../../components/CouponBadge';
import WechatShareReady from '../../components/WechatShareReady';
import UserTabBar, { shouldRenderPageTabBar, syncTabBarSelected } from '../../components/UserTabBar';
import { goLogin } from '../../lib/auth-nav';
import { getToken, isLoggedIn, request, toast } from '../../lib/api';
import {
  getHomeCatalogCache,
  isHomeCatalogBootstrapped,
  setHomeCatalogCache,
} from '../../lib/home-catalog-session';
import { ensurePayReady } from '../../lib/pay-ready';
import { capturePromoSceneAndTouchScan } from '../../lib/promo';
import { getProductMainImage } from '../../lib/product-images';
import {
  canBuyOnline,
  canCrossCity,
  canPickupOnSite,
  normalizeFulfillmentFlags,
} from '../../lib/product-fulfillment';
import { getCityCodeForCatalog, resolveUserCity } from '../../lib/user-location';
import {
  DEFAULT_SHARE_DESC,
  DEFAULT_SHARE_TITLE,
  toWeappShareMessage,
} from '../../lib/wechat-share';
type Product = {
  id: string;
  name: string;
  subtitle?: string;
  spec?: string;
  price: number;
  benefitDisplay?: number;
  mainImageUrl?: string | null;
  carouselUrls?: string[] | null;
  aromaType: string;
  allowOnSitePickup?: boolean;
  allowOnlinePurchase?: boolean;
  allowCrossCityDelivery?: boolean;
};

type FulfillmentFilter = 'ALL' | 'ONLINE' | 'CROSS_CITY' | 'ON_SITE';

const FULFILLMENT_FILTERS: Array<{ key: FulfillmentFilter; label: string }> = [
  { key: 'ALL', label: '全部' },
  { key: 'ONLINE', label: '线上' },
  { key: 'CROSS_CITY', label: '跨城' },
  { key: 'ON_SITE', label: '现场' },
];

function matchFulfillmentFilter(p: Product, filter: FulfillmentFilter): boolean {
  if (filter === 'ALL') return true;
  if (filter === 'ONLINE') return canBuyOnline(p);
  if (filter === 'CROSS_CITY') return canCrossCity(p);
  return canPickupOnSite(p);
}

type MiniHomeConfig = {
  banners: string[];
  footerUrl: string | null;
};

const AROMA_TABS = [
  { key: 'QINGXIANG', label: '清香型' },
  { key: 'JIANGXIANG', label: '酱香型' },
  { key: 'NONGXIANG', label: '浓香型' },
] as const;

type AromaKey = (typeof AROMA_TABS)[number]['key'];

/** sticky 香型导航高度（与 CSS 大致一致），锚点滚动时预留 */
const AROMA_NAV_OFFSET_PX = 44;

function aromaSectionId(key: AromaKey) {
  return `aroma-section-${key}`;
}

export default function HomePage() {
  const [activeAroma, setActiveAroma] = useState<AromaKey>('QINGXIANG');
  const [fulfillmentFilter, setFulfillmentFilter] = useState<FulfillmentFilter>('ALL');
  const [products, setProducts] = useState<Product[]>([]);
  const [loading, setLoading] = useState(true);
  const [displayCity, setDisplayCity] = useState('郑州市');
  const [cityCode, setCityCode] = useState('410100');
  const [miniHome, setMiniHome] = useState<MiniHomeConfig>({ banners: [], footerUrl: null });
  const scrollingToRef = useRef<AromaKey | null>(null);
  const scrollLockTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null);
  const lastScrollSyncAtRef = useRef(0);

  const loadMiniHome = useCallback(() => {
    return request<{ miniHome?: MiniHomeConfig }>('/common/client-config')
      .then((cfg) => {
        const banners = Array.isArray(cfg.miniHome?.banners)
          ? cfg.miniHome!.banners.filter((u) => typeof u === 'string' && !!u.trim())
          : [];
        const footerUrl =
          typeof cfg.miniHome?.footerUrl === 'string' && cfg.miniHome.footerUrl.trim()
            ? cfg.miniHome.footerUrl.trim()
            : null;
        setMiniHome({ banners, footerUrl });
      })
      .catch(() => {
        /* 首页装饰图失败不阻断商品列表 */
      });
  }, []);

  const applyProductList = useCallback((list: Product[], nextCode: string, authKey: string) => {
    const normalized = Array.isArray(list) ? list.map((p) => normalizeFulfillmentFlags(p)) : [];
    setProducts(normalized);
    setHomeCatalogCache({ cityCode: nextCode, authKey, products: normalized });
  }, []);

  const fetchProducts = useCallback(
    (nextCode: string, authKey: string) => {
      setLoading(true);
      return request<Product[]>(`/catalog/products?cityCode=${encodeURIComponent(nextCode)}`)
        .then((list) => applyProductList(list, nextCode, authKey))
        .catch((e) => toast(e instanceof Error ? e.message : '加载失败'))
        .finally(() => setLoading(false));
    },
    [applyProductList],
  );

  /**
   * 首次进入 / 城市或登录态变化：拉商品。
   * 同次再切 tab：只同步选中态，不重复请求（对齐门店页）。
   */
  useDidShow(() => {
    syncTabBarSelected(0);
    void capturePromoSceneAndTouchScan();
    void loadMiniHome();

    const authKey = getToken() || '';
    void (async () => {
      const resolved = await resolveUserCity();
      const nextCode = getCityCodeForCatalog(resolved);
      setDisplayCity(resolved.displayCity);
      setCityCode(nextCode);

      const cache = getHomeCatalogCache();
      if (
        isHomeCatalogBootstrapped() &&
        cache &&
        cache.cityCode === nextCode &&
        cache.authKey === authKey &&
        Array.isArray(cache.products)
      ) {
        setProducts(cache.products as Product[]);
        setLoading(false);
        return;
      }

      await fetchProducts(nextCode, authKey);
    })();
  });

  usePullDownRefresh(() => {
    void (async () => {
      try {
        const authKey = getToken() || '';
        const resolved = await resolveUserCity();
        setDisplayCity(resolved.displayCity);
        const nextCode = getCityCodeForCatalog(resolved);
        setCityCode(nextCode);
        setLoading(true);
        const [list] = await Promise.all([
          request<Product[]>(`/catalog/products?cityCode=${encodeURIComponent(nextCode)}`),
          loadMiniHome(),
        ]);
        applyProductList(
          Array.isArray(list) ? list : [],
          nextCode,
          authKey,
        );
      } catch (e) {
        toast(e instanceof Error ? e.message : '加载失败');
      } finally {
        setLoading(false);
        Taro.stopPullDownRefresh();
      }
    })();
  });
  function openProductDetail(id: string) {
    Taro.navigateTo({ url: `/pages/product-detail/index?id=${id}` });
  }

  async function goOnSitePickup(productId: string) {
    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 });
  }

  const filteredProducts = useMemo(
    () => products.filter((p) => matchFulfillmentFilter(p, fulfillmentFilter)),
    [products, fulfillmentFilter],
  );

  const productsByAroma = useMemo(() => {
    const map: Record<AromaKey, Product[]> = {
      QINGXIANG: [],
      JIANGXIANG: [],
      NONGXIANG: [],
    };
    for (const p of filteredProducts) {
      const key = p.aromaType as AromaKey;
      if (key in map) map[key].push(p);
    }
    return map;
  }, [filteredProducts]);

  const banners = miniHome.banners;
  const footerUrl = miniHome.footerUrl;

  const sharePayload = useMemo(
    () => ({
      title: DEFAULT_SHARE_TITLE,
      desc: DEFAULT_SHARE_DESC,
      path: '/pages/home/index',
      imgUrl: banners[0] || undefined,
    }),
    [banners],
  );

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

  function scrollToAroma(key: AromaKey) {
    setActiveAroma(key);
    scrollingToRef.current = key;
    if (scrollLockTimerRef.current) clearTimeout(scrollLockTimerRef.current);
    scrollLockTimerRef.current = setTimeout(() => {
      scrollingToRef.current = null;
    }, 450);

    const query = Taro.createSelectorQuery();
    query.select(`#${aromaSectionId(key)}`).boundingClientRect();
    query.selectViewport().scrollOffset();
    query.exec((res) => {
      const rect = res?.[0] as { top?: number } | undefined;
      const viewport = res?.[1] as { scrollTop?: number } | undefined;
      if (rect?.top == null || viewport?.scrollTop == null) return;
      const scrollTop = Math.max(0, viewport.scrollTop + rect.top - AROMA_NAV_OFFSET_PX);
      void Taro.pageScrollTo({ scrollTop, duration: 280 });
    });
  }

  usePageScroll(() => {
    if (scrollingToRef.current) return;
    const now = Date.now();
    if (now - lastScrollSyncAtRef.current < 80) return;
    lastScrollSyncAtRef.current = now;
    const query = Taro.createSelectorQuery();
    AROMA_TABS.forEach((t) => {
      query.select(`#${aromaSectionId(t.key)}`).boundingClientRect();
    });
    query.exec((rects) => {
      if (!Array.isArray(rects) || rects.length === 0) return;
      let next: AromaKey = AROMA_TABS[0].key;
      for (let i = 0; i < AROMA_TABS.length; i++) {
        const rect = rects[i] as { top?: number } | null;
        if (!rect || rect.top == null) continue;
        // 区块顶进入导航下方一带时视为当前香型
        if (rect.top <= AROMA_NAV_OFFSET_PX + 24) {
          next = AROMA_TABS[i].key;
        }
      }
      setActiveAroma((prev) => (prev === next ? prev : next));
    });
  });

  function renderProductCard(p: Product) {
    const thumb = getProductMainImage(p);
    const spec = p.subtitle || p.spec || '';
    return (
      <View key={p.id} className="home-product-card">
        <View className="home-product-card-inner" onClick={() => openProductDetail(p.id)}>
          <View className="home-product-thumb-wrap">
            {thumb ? (
              <Image className="home-product-thumb" src={thumb} mode="aspectFill" />
            ) : (
              <View className="home-product-thumb home-product-thumb--empty" />
            )}
          </View>
          <View className="home-product-main">
            <View className="home-product-row">
              <Text className="home-product-name">{p.name}</Text>
              <Text className="home-product-price">¥{Number(p.price).toFixed(0)}</Text>
            </View>
            {spec ? <Text className="home-product-sub">{spec}</Text> : null}
            <View className="home-product-footer">
              <CouponBadge amount={p.benefitDisplay ?? p.price} label="好客权益" />
            </View>
            <View className="home-product-actions">
              {canPickupOnSite(p) ? (
                <Text
                  className="home-pickup-btn"
                  onClick={(e) => {
                    e.stopPropagation?.();
                    void goOnSitePickup(p.id);
                  }}
                >
                  现场取货
                </Text>
              ) : null}
              {canBuyOnline(p) ? (
                <Text
                  className="home-buy-btn"
                  onClick={(e) => {
                    e.stopPropagation?.();
                    openProductDetail(p.id);
                  }}
                >
                  立即购买
                </Text>
              ) : null}
            </View>
          </View>
        </View>
      </View>
    );
  }

  return (
    <PageShell variant="tab" className="home-page no-tab-header">
      <WechatShareReady payload={sharePayload} />
      <TabMainHeader title="杜康好客" />

      {banners.length > 0 ? (
        <View className="home-promo-banner">
          <Swiper
            className="home-promo-banner-swiper"
            indicatorDots={banners.length > 1}
            autoplay={banners.length > 1}
            circular={banners.length > 1}
            interval={2500}
          >
            {banners.map((url) => (
              <SwiperItem key={url}>
                <Image className="home-promo-banner-img" src={url} mode="aspectFill" />
              </SwiperItem>
            ))}
          </Swiper>
        </View>
      ) : null}

      <View className="home-aroma-nav">
        <View className="home-aroma-tabs">
          {AROMA_TABS.map((t) => (
            <Text
              key={t.key}
              className={`home-aroma-tab${activeAroma === t.key ? ' home-aroma-tab--active' : ''}`}
              onClick={() => scrollToAroma(t.key)}
            >
              {t.label}
            </Text>
          ))}
        </View>
        <Text className="home-aroma-city">{displayCity}</Text>
      </View>

      <View className="home-fulfillment-filters">
        {FULFILLMENT_FILTERS.map((f) => (
          <Text
            key={f.key}
            className={`home-fulfillment-chip${fulfillmentFilter === f.key ? ' home-fulfillment-chip--active' : ''}`}
            onClick={() => setFulfillmentFilter(f.key)}
          >
            {f.label}
          </Text>
        ))}
      </View>

      <View className="home-product-list">
        {loading ? <View className="home-empty">加载中…</View> : null}
        {!loading && products.length === 0 ? (
          <View className="home-empty">当前城市暂无在售商品</View>
        ) : null}
        {!loading && products.length > 0 && filteredProducts.length === 0 ? (
          <View className="home-empty">暂无符合履约方式的商品</View>
        ) : null}
        {!loading &&
          filteredProducts.length > 0 &&
          AROMA_TABS.map((t) => {
            const list = productsByAroma[t.key];
            return (
              <View key={t.key} id={aromaSectionId(t.key)} className="home-aroma-section">
                <Text className="home-aroma-section-title">{t.label}</Text>
                {list.length === 0 ? (
                  <View className="home-empty home-empty--section">该香型暂未上线</View>
                ) : (
                  list.map((p) => renderProductCard(p))
                )}
              </View>
            );
          })}
      </View>

      {footerUrl ? (
        <View className="home-promo-footer">
          <Image className="home-promo-footer-img" src={footerUrl} mode="aspectFill" />
        </View>
      ) : null}

      {shouldRenderPageTabBar() ? <UserTabBar selected={0} /> : null}
    </PageShell>
  );
}