import { useLocalSearchParams, useRouter } from 'expo-router'
import { StatusBar } from 'expo-status-bar'
import React, { useEffect, useCallback, useState, useMemo } from 'react'
import {
    Platform,
    FlatList,
    StyleSheet,
    StatusBar as RNStatusBar,
    View,
    ActivityIndicator,
    RefreshControl,
    Dimensions,
} from 'react-native'
import { SafeAreaView, useSafeAreaInsets } from 'react-native-safe-area-context'

import { TitleBar, HeroSlider, TabNavigation, TemplateCard } from '@/components/blocks/home'
import ErrorState from '@/components/ErrorState'
import LoadingState from '@/components/LoadingState'
import { useActivates } from '@/hooks/use-activates'
import { useCategoriesWithTags } from '@/hooks/use-categories-with-tags'
import { useCategoryTemplates } from '@/hooks/use-category-templates'
import { useStickyTabs } from '@/hooks/use-sticky-tabs'
import { useTabNavigation } from '@/hooks/use-tab-navigation'
import { useTemplateFilter } from '@/hooks/use-template-filter'

const NUM_COLUMNS = 3
const HORIZONTAL_PADDING = 16
const CARD_GAP = 5
const SCREEN_WIDTH = Dimensions.get('window').width

// 计算卡片宽度
const calculateCardWidth = () => {
    return (SCREEN_WIDTH - HORIZONTAL_PADDING * 2 - CARD_GAP * (NUM_COLUMNS - 1)) / NUM_COLUMNS
}

const CARD_WIDTH = calculateCardWidth()

export default function HomeScreen() {
    const insets = useSafeAreaInsets()
    const router = useRouter()
    const params = useLocalSearchParams()

    // 分类数据加载
    const { load: loadCategories, data: categoriesData, loading: categoriesLoading, error: categoriesError } = useCategoriesWithTags()
    const { load: loadActivates, data: activatesData } = useActivates()

    // 模板数据加载（分页）
    const {
        templates,
        loading: templatesLoading,
        loadingMore,
        execute: loadTemplates,
        loadMore,
        hasMore,
    } = useCategoryTemplates()

    // 标签导航状态
    const {
        activeIndex,
        selectedCategoryId,
        tabs,
        selectTab,
        selectCategoryById,
    } = useTabNavigation({
        categories: categoriesData?.categories || [],
        initialCategoryId: params.categoryId as string | undefined,
    })

    // 吸顶状态
    const {
        isSticky,
        tabsHeight,
        titleBarHeightRef,
        handleScroll,
        handleTabsLayout,
        handleTitleBarLayout,
    } = useStickyTabs()

    // 模板过滤 - 使用 useMemo 缓存
    const { filteredTemplates } = useTemplateFilter({
        templates,
        excludeVideo: true,
    })

    // 初始化加载
    useEffect(() => {
        loadCategories()
        loadActivates()
    }, [])

    // 当分类变化时加载模板
    useEffect(() => {
        if (selectedCategoryId) {
            loadTemplates({ categoryId: selectedCategoryId })
        }
    }, [selectedCategoryId])

    // 路由参数同步
    useEffect(() => {
        if (params.categoryId) {
            selectCategoryById(params.categoryId as string)
        }
    }, [params.categoryId])

    // 状态判断 - 使用 useMemo 缓存
    const showLoading = categoriesLoading
    const showEmptyState = useMemo(() =>
        !categoriesLoading && categoriesData?.categories?.length === 0,
        [categoriesLoading, categoriesData?.categories?.length]
    )
    const showEmptyTemplates = useMemo(() =>
        !categoriesLoading && !templatesLoading && !showEmptyState && filteredTemplates.length === 0,
        [categoriesLoading, templatesLoading, showEmptyState, filteredTemplates.length]
    )

    const [refreshing, setRefreshing] = useState(false)

    // 下拉刷新处理 - 只刷新当前分类的模板
    const handleRefresh = useCallback(async () => {
        if (!selectedCategoryId) return
        setRefreshing(true)
        await loadTemplates({ categoryId: selectedCategoryId })
        setRefreshing(false)
    }, [selectedCategoryId, loadTemplates])

    // 加载更多处理
    const handleEndReached = useCallback(() => {
        if (!loadingMore && hasMore && !templatesLoading) {
            loadMore()
        }
    }, [loadingMore, hasMore, templatesLoading, loadMore])

    // 导航处理 - 使用 useCallback memoize
    const handlePointsPress = useCallback(() => router.push('/membership' as any), [router])
    const handleSearchPress = useCallback(() => router.push('/searchTemplate'), [router])
    const handleActivityPress = useCallback((link: string) => router.push(link as any), [router])
    const handleArrowPress = useCallback(() => router.push({
        pathname: '/channels' as any,
        params: selectedCategoryId ? { categoryId: selectedCategoryId } : undefined,
    }), [router, selectedCategoryId])
    const handleTemplatePress = useCallback((id: string) => router.push({
        pathname: '/templateDetail' as any,
        params: { id },
    }), [router])

    // 渲染模板卡片
    const renderTemplateItem = useCallback(({ item }: { item: typeof filteredTemplates[0] }) => {
        if (!item.id) return null
        return (
            <TemplateCard
                id={item.id}
                title={item.title}
                previewUrl={item.previewUrl}
                webpPreviewUrl={item.webpPreviewUrl}
                coverImageUrl={item.coverImageUrl}
                aspectRatio={item.aspectRatio}
                cardWidth={CARD_WIDTH}
                onPress={handleTemplatePress}
            />
        )
    }, [handleTemplatePress])

    // 提取 key
    const keyExtractor = useCallback((item: typeof filteredTemplates[0]) => item.id || '', [])

    // 列表头部组件
    const ListHeaderComponent = useMemo(() => (
        <>
            {/* 活动轮播图 */}
            <HeroSlider
                activities={activatesData?.activities || []}
                onActivityPress={handleActivityPress}
            />

            {/* 标签导航 */}
            {!showLoading && !showEmptyState && (
                <View
                    onLayout={(e) => handleTabsLayout(e.nativeEvent.layout.y, e.nativeEvent.layout.height)}
                    style={isSticky ? { opacity: 0, height: tabsHeight } : undefined}
                >
                    <TabNavigation
                        tabs={tabs}
                        activeIndex={activeIndex}
                        onTabPress={selectTab}
                        showArrow={true}
                        onArrowPress={handleArrowPress}
                    />
                </View>
            )}

            {/* 加载状态 */}
            {showLoading && <LoadingState />}

            {/* 错误状态 */}
            {categoriesError && (
                <ErrorState message="加载分类失败" onRetry={() => loadCategories()} variant="error" />
            )}

            {/* 空状态 - 分类数据为空 */}
            {showEmptyState && !categoriesError && (
                <ErrorState message="暂无分类数据" onRetry={() => loadCategories()} />
            )}

            {/* 空状态 - 当前分类下没有模板 */}
            {showEmptyTemplates && (
                <ErrorState message="该分类暂无模板" onRetry={() => loadTemplates({ categoryId: selectedCategoryId! })} />
            )}

            {/* 模板加载中 */}
            {templatesLoading && !showLoading && (
                <View style={styles.templatesLoadingContainer}>
                    <ActivityIndicator size="large" color="#FFFFFF" />
                </View>
            )}
        </>
    ), [
        activatesData?.activities,
        handleActivityPress,
        showLoading,
        showEmptyState,
        isSticky,
        tabsHeight,
        tabs,
        activeIndex,
        selectTab,
        handleArrowPress,
        categoriesError,
        showEmptyTemplates,
        templatesLoading,
        selectedCategoryId,
        handleTabsLayout,
        loadCategories,
        loadTemplates,
    ])

    // 列表底部组件
    const ListFooterComponent = useMemo(() => {
        if (loadingMore) {
            return (
                <View style={styles.loadingMoreContainer}>
                    <ActivityIndicator size="small" color="#FFFFFF" />
                </View>
            )
        }
        return null
    }, [loadingMore])

    // 获取有效的模板列表（过滤掉没有 id 的）
    const validTemplates = useMemo(() =>
        filteredTemplates.filter(t => !!t.id),
        [filteredTemplates]
    )

    // 只有在非加载状态且有数据时才显示列表
    const showTemplateList = !showLoading && !showEmptyState && !showEmptyTemplates && !templatesLoading

    return (
        <SafeAreaView style={styles.container} edges={['top']}>
            <StatusBar style="light" />
            <RNStatusBar barStyle="light-content" />

            {/* 标题栏 */}
            <TitleBar
                onPointsPress={handlePointsPress}
                onSearchPress={handleSearchPress}
                onLayout={handleTitleBarLayout}
            />

            {/* 吸顶标签导航 */}
            {isSticky && !showLoading && !showEmptyState && (
                <View style={[styles.stickyTabsWrapper, { top: titleBarHeightRef.current + insets.top }]}>
                    <TabNavigation
                        tabs={tabs}
                        activeIndex={activeIndex}
                        onTabPress={selectTab}
                        showArrow={true}
                        onArrowPress={handleArrowPress}
                        isSticky={true}
                    />
                </View>
            )}

            <FlatList
                data={showTemplateList ? validTemplates : []}
                keyExtractor={keyExtractor}
                renderItem={renderTemplateItem}
                numColumns={NUM_COLUMNS}
                columnWrapperStyle={styles.columnWrapper}
                style={styles.scrollView}
                contentContainerStyle={[styles.scrollContent, { paddingBottom: 60 + insets.bottom + 20 }]}
                showsVerticalScrollIndicator={false}
                onScroll={(e) => handleScroll(e.nativeEvent.contentOffset.y)}
                scrollEventThrottle={Platform.OS === 'ios' ? 16 : 50}
                onEndReached={handleEndReached}
                onEndReachedThreshold={0.5}
                ListHeaderComponent={ListHeaderComponent}
                ListFooterComponent={ListFooterComponent}
                removeClippedSubviews={Platform.OS === 'android'}
                maxToRenderPerBatch={12}
                windowSize={5}
                initialNumToRender={12}
                getItemLayout={(_, index) => ({
                    length: CARD_WIDTH * 1.5,
                    offset: CARD_WIDTH * 1.5 * Math.floor(index / NUM_COLUMNS),
                    index,
                })}
                refreshControl={
                    <RefreshControl
                        refreshing={refreshing}
                        onRefresh={handleRefresh}
                        tintColor="#9966FF"
                        colors={['#9966FF', '#FF6699', '#FF9966']}
                        progressBackgroundColor="#1C1E22"
                        progressViewOffset={10}
                    />
                }
            />
        </SafeAreaView>
    )
}

const styles = StyleSheet.create({
    container: {
        flex: 1,
        backgroundColor: '#090A0B',
    },
    scrollView: {
        flex: 1,
        backgroundColor: '#090A0B',
    },
    scrollContent: {
        paddingHorizontal: HORIZONTAL_PADDING,
        paddingBottom: 20,
        backgroundColor: '#090A0B',
    },
    columnWrapper: {
        gap: CARD_GAP,
        marginBottom: CARD_GAP,
    },
    stickyTabsWrapper: {
        position: 'absolute',
        top: 0,
        left: 0,
        right: 0,
        zIndex: 100,
        backgroundColor: '#090A0B',
    },
    templatesLoadingContainer: {
        paddingVertical: 40,
        alignItems: 'center',
        justifyContent: 'center',
    },
    loadingMoreContainer: {
        paddingVertical: 20,
        alignItems: 'center',
        justifyContent: 'center',
    },
})
