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

import { TitleBar, TemplateCard } from '@/components/blocks/home'
import ErrorState from '@/components/ErrorState'
import LoadingState from '@/components/LoadingState'
import { useUserFavorites } from '@/hooks/use-user-favorites'
import { useTemplateSocialStore } from '@/stores/templateSocialStore'

const NUM_COLUMNS = 2
const HORIZONTAL_PADDING = 16
const CARD_GAP = 8
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 FavoritesScreen() {
    const insets = useSafeAreaInsets()
    const router = useRouter()

    // 使用 Store 中的点赞/收藏状态
    const { setLiked, setFavorited } = useTemplateSocialStore()

    // 获取收藏列表
    const {
        favorites,
        loading,
        loadingMore,
        error,
        execute,
        refetch,
        loadMore,
        hasMore,
    } = useUserFavorites()

    // 页面聚焦时刷新数据
    useFocusEffect(
        useCallback(() => {
            refetch()
        }, [refetch])
    )

    // 初始加载
    useEffect(() => {
        execute()
    }, [])

    const [refreshing, setRefreshing] = useState(false)

    // 下拉刷新处理
    const handleRefresh = useCallback(async () => {
        setRefreshing(true)
        await refetch()
        setRefreshing(false)
    }, [refetch])

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

    // 导航处理
    const handleTemplatePress = useCallback((id: string) => {
        router.push({
            pathname: '/templateDetail' as any,
            params: { id },
        })
    }, [router])

    // 点赞/取消点赞处理
    const handleLike = useCallback((id: string) => {
        setLiked(id, true)
        console.log('Like template:', id)
    }, [setLiked])

    const handleUnlike = useCallback((id: string) => {
        setLiked(id, false)
        console.log('Unlike template:', id)
    }, [setLiked])

    // 收藏/取消收藏处理
    const handleFavorite = useCallback((id: string) => {
        setFavorited(id, true)
        console.log('Favorite template:', id)
    }, [setFavorited])

    const handleUnfavorite = useCallback((id: string) => {
        setFavorited(id, false)
        console.log('Unfavorite template:', id)
    }, [setFavorited])

    // 状态判断
    const isLoading = useMemo(() => loading, [loading])
    const showEmptyState = useMemo(() =>
        !isLoading && favorites.length === 0 && !error,
        [isLoading, favorites.length, error]
    )
    const showErrorState = useMemo(() =>
        !isLoading && error,
        [isLoading, error]
    )

    // 渲染模板卡片
    const renderTemplateItem = useCallback(({ item }: { item: typeof favorites[0] }) => {
        if (!item.template?.id) return null

        const template = item.template
        return (
            <TemplateCard
                id={template.id}
                title={template.title}
                titleEn={template.titleEn}
                previewUrl={template.previewUrl}
                webpPreviewUrl={template.webpPreviewUrl}
                coverImageUrl={template.coverImageUrl}
                aspectRatio={template.aspectRatio}
                cardWidth={CARD_WIDTH}
                onPress={handleTemplatePress}
                liked={template.isLiked}
                favorited={template.isFavorited}
                onLike={handleLike}
                onUnlike={handleUnlike}
                onFavorite={handleFavorite}
                onUnfavorite={handleUnfavorite}
            />
        )
    }, [handleTemplatePress, handleLike, handleUnlike, handleFavorite, handleUnfavorite])

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

    // 列表头部组件
    const ListHeaderComponent = useMemo(() => {
        if (isLoading) {
            return <LoadingState />
        }

        if (showErrorState) {
            return (
                <ErrorState
                    message="加载收藏失败"
                    onRetry={() => execute()}
                    variant="error"
                />
            )
        }

        if (showEmptyState) {
            return (
                <ErrorState
                    message="暂无收藏"
                    onRetry={() => execute()}
                    variant="empty"
                />
            )
        }

        return null
    }, [isLoading, showErrorState, showEmptyState, execute])

    // 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])

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

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

            {/* 标题栏 */}
            <TitleBar
                points={0}
                onPointsPress={() => {}}
                onSearchPress={() => {}}
            />

            <FlatList
                data={showTemplateList ? favorites : []}
                keyExtractor={keyExtractor}
                renderItem={renderTemplateItem}
                numColumns={NUM_COLUMNS}
                columnWrapperStyle={styles.columnWrapper}
                style={styles.scrollView}
                contentContainerStyle={[styles.scrollContent, { paddingBottom: 60 + insets.bottom + 20 }]}
                showsVerticalScrollIndicator={false}
                onEndReached={handleEndReached}
                onEndReachedThreshold={0.5}
                ListHeaderComponent={ListHeaderComponent}
                ListFooterComponent={ListFooterComponent}
                refreshControl={
                    <RefreshControl
                        refreshing={refreshing}
                        onRefresh={handleRefresh}
                        tintColor="#9966FF"
                        colors={['#9966FF', '#FF6699', '#FF9966']}
                        progressBackgroundColor="#1C1E22"
                    />
                }
            />
        </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,
    },
    loadingMoreContainer: {
        paddingVertical: 20,
        alignItems: 'center',
        justifyContent: 'center',
    },
})