import { useRouter } from 'expo-router';
import React, { useCallback, useEffect, useMemo, useState } from 'react';
import {
    ActivityIndicator,
    FlatList,
    ImageBackground,
    RefreshControl,
    StatusBar,
    StyleSheet,
    Text,
    View,
} from 'react-native';
import { useSafeAreaInsets } from 'react-native-safe-area-context';

import { Banner } from '@/components/home/Banner';
import { GoodsCard } from '@/components/home/GoodsCard';
import { IPFilter } from '@/components/home/IPFilter';
import { QuickEntry } from '@/components/home/QuickEntry';
import { SearchBar } from '@/components/home/SearchBar';
import { Images } from '@/constants/images';

// API 服务
import { getIPList, IPItem } from '@/services/award';
import { BannerItem, getPageConfig, TabItem } from '@/services/base';
import { getGoodsList, GoodsItem, GoodsListParams } from '@/services/mall';

export default function HomeScreen() {
  const insets = useSafeAreaInsets();
  const router = useRouter();
  const [refreshing, setRefreshing] = useState(false);
  const [loading, setLoading] = useState(true);
  const [listLoading, setListLoading] = useState(false);

  // 数据状态
  const [goods, setGoods] = useState<GoodsItem[]>([]);
  const [banners, setBanners] = useState<BannerItem[]>([]);
  const [tabs, setTabs] = useState<TabItem[]>([]);
  const [ipList, setIpList] = useState<IPItem[]>([]);
  const [ipIndex, setIpIndex] = useState(0);

  // 搜索参数
  const [searchParams, setSearchParams] = useState<GoodsListParams>({
    current: 1,
    size: 15,
    keyword: '',
    worksId: '',
  });

  // 加载商品列表
  const loadGoods = useCallback(async (params: GoodsListParams, append = false) => {
    try {
      if (!append) setListLoading(true);
      const data = await getGoodsList(params);
      if (append) {
        setGoods((prev) => [...prev, ...data]);
      } else {
        setGoods(data);
      }
    } catch (error) {
      console.error('加载商品失败:', error);
    } finally {
      if (!append) setListLoading(false);
    }
  }, []);

  // 加载 IP 列表
  const loadIPList = useCallback(async () => {
    try {
      const data = await getIPList();
      const allIP: IPItem = { id: '', name: '所有IP' };
      setIpList([allIP, ...data.filter((item) => item !== null)]);
    } catch (error) {
      console.error('加载IP列表失败:', error);
    }
  }, []);

  // 加载页面配置
  const loadPageConfig = useCallback(async () => {
    try {
      const bannerConfig = await getPageConfig('index_banner');
      if (bannerConfig?.components?.[0]?.elements) {
        setBanners(bannerConfig.components[0].elements);
      }

      const iconConfig = await getPageConfig('index_icon');
      if (iconConfig?.components?.[0]?.elements) {
        setTabs(iconConfig.components[0].elements);
      }
    } catch (error) {
      console.error('加载页面配置失败:', error);
    }
  }, []);

  // 初始化数据
  const initData = useCallback(async () => {
    setLoading(true);
    await Promise.all([loadGoods(searchParams), loadIPList(), loadPageConfig()]);
    setLoading(false);
  }, []);

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

  // 下拉刷新
  const onRefresh = async () => {
    setRefreshing(true);
    const newParams = { ...searchParams, current: 1 };
    setSearchParams(newParams);
    await Promise.all([loadGoods(newParams), loadIPList(), loadPageConfig()]);
    setRefreshing(false);
  };

  // 搜索
  const handleSearch = async (keyword: string) => {
    const newParams = { ...searchParams, keyword, current: 1 };
    setSearchParams(newParams);
    await loadGoods(newParams);
  };

  // Banner 点击
  const handleBannerPress = (item: BannerItem) => {
    console.log('Banner pressed:', item);
  };

  // 功能入口点击
  const handleQuickEntryPress = (item: TabItem) => {
    console.log('Quick entry pressed:', item);
  };

  // IP 筛选
  const handleIPSelect = (item: IPItem, index: number) => {
    // 立即更新 UI，不等待网络请求
    setIpIndex(index);
    setGoods([]); // 清空列表，给予用户切换反馈 (或者可以保留旧数据直到新数据到来，取决于需求，清空通常感觉更"快"因为有反馈)
    
    // 异步加载数据
    requestAnimationFrame(async () => {
        const newParams = { ...searchParams, worksId: item.id, current: 1 };
        setSearchParams(newParams);
        await loadGoods(newParams);
    });
  };

  // 商品点击
  const handleGoodsPress = (item: GoodsItem) => {
    router.push(`/product/${item.id}` as any);
  };

  // 列表头部组件
  const ListHeader = useMemo(() => {
    return (
      <>
        {/* 搜索栏 */}
        <SearchBar onSearch={handleSearch} />

        {/* Banner 轮播 */}
        {banners.length > 0 && <Banner data={banners} onPress={handleBannerPress} />}

        {/* 功能入口 */}
        <View style={styles.section}>
          {tabs.length > 0 && <QuickEntry data={tabs} onPress={handleQuickEntryPress} />}

          {/* IP 分类筛选 */}
          {ipList.length > 0 && (
            <IPFilter data={ipList} activeIndex={ipIndex} onSelect={handleIPSelect} />
          )}
        </View>
      </>
    );
  }, [banners, tabs, ipList, ipIndex]); // 依赖项

  const renderItem = useCallback(({ item }: { item: GoodsItem }) => {
    return <GoodsCard data={item} onPress={handleGoodsPress} />;
  }, []);

  const ListEmptyComponent = useMemo(() => {
    if (listLoading) {
      return (
        <View style={styles.loadingListContainer}>
          <ActivityIndicator size="small" color="#aaa" />
          <Text style={styles.loadingText}>加载商品中...</Text>
        </View>
      );
    }
    if (!loading && goods.length === 0) {
        return (
            <View style={styles.emptyContainer}>
                <Text style={styles.emptyText}>暂无商品</Text>
            </View>
        )
    }
    return null;
  }, [listLoading, loading, goods.length]);

  if (loading) {
    return (
      <View style={styles.loadingContainer}>
        <ActivityIndicator size="large" color="#fff" />
        <Text style={styles.loadingText}>加载中...</Text>
      </View>
    );
  }

  return (
    <View style={styles.container}>
      <StatusBar barStyle="light-content" />
      <ImageBackground
        source={{ uri: Images.common.indexBg }}
        style={styles.background}
        resizeMode="cover"
      >
        <FlatList
          data={goods}
          renderItem={renderItem}
          keyExtractor={(item) => item.id}
          ListHeaderComponent={ListHeader}
          numColumns={2}
          columnWrapperStyle={styles.columnWrapper}
          contentContainerStyle={{ paddingTop: insets.top + 10, paddingBottom: 20 }}
          showsVerticalScrollIndicator={false}
          refreshControl={
            <RefreshControl refreshing={refreshing} onRefresh={onRefresh} tintColor="#fff" />
          }
          ListEmptyComponent={ListEmptyComponent}
          onEndReachedThreshold={0.5}
          // onEndReached={() => { /* Implement pagination if needed */ }}
        />
      </ImageBackground>
    </View>
  );
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: '#000',
  },
  background: {
    flex: 1,
  },
  section: {
    paddingHorizontal: 10,
  },
  loadingContainer: {
    flex: 1,
    backgroundColor: '#1a1a2e',
    justifyContent: 'center',
    alignItems: 'center',
  },
  loadingListContainer: {
    padding: 20,
    alignItems: 'center',
  },
  loadingText: {
    color: '#fff',
    marginTop: 10,
    fontSize: 14,
  },
  columnWrapper: {
    justifyContent: 'space-between',
    paddingHorizontal: 10,
  },
  emptyContainer: {
    padding: 50,
    alignItems: 'center',
  },
  emptyText: {
    color: '#999',
    fontSize: 14,
  },
});