import {
  View, Text, FlatList, TouchableOpacity, RefreshControl, ScrollView, StyleSheet, Animated,
} from 'react-native'
import { SafeAreaView } from 'react-native-safe-area-context'
import { useState, useEffect, useRef, useCallback } from 'react'
import { useRouter } from 'expo-router'
import { useFocusEffect } from 'expo-router'
import { useNewsList } from '@/hooks/useNews'
import { NewsCard } from '@/components/news/NewsCard'
import { EmptyState } from '@/components/ui/EmptyState'
import { LoadingSpinner } from '@/components/ui/LoadingSpinner'
import { useNewsReadStore } from '@/store/news.store'

function SkeletonCard() {
  const anim = useRef(new Animated.Value(0.4)).current
  useEffect(() => {
    Animated.loop(
      Animated.sequence([
        Animated.timing(anim, { toValue: 1, duration: 800, useNativeDriver: true }),
        Animated.timing(anim, { toValue: 0.4, duration: 800, useNativeDriver: true }),
      ])
    ).start()
  }, [])
  return (
    <Animated.View style={[skeletonStyles.card, { opacity: anim }]}>
      <View style={skeletonStyles.badge} />
      <View style={skeletonStyles.titleLine} />
      <View style={skeletonStyles.titleLineShort} />
      <View style={skeletonStyles.metaLine} />
    </Animated.View>
  )
}

const skeletonStyles = StyleSheet.create({
  card: { backgroundColor: '#FFFFFF', borderRadius: 12, padding: 16, marginBottom: 10, marginHorizontal: 16 },
  badge: { height: 20, width: 80, borderRadius: 10, backgroundColor: '#E2E8F0', marginBottom: 12 },
  titleLine: { height: 16, borderRadius: 8, backgroundColor: '#E2E8F0', width: '85%', marginBottom: 8 },
  titleLineShort: { height: 16, borderRadius: 8, backgroundColor: '#E2E8F0', width: '55%', marginBottom: 12 },
  metaLine: { height: 12, borderRadius: 6, backgroundColor: '#F1F5F9', width: '40%' },
})

const FILTERS = [
  { value: undefined, label: 'Alle' },
  { value: 'Wichtig', label: 'Wichtig' },
  { value: 'Pruefung', label: 'Pruefung' },
  { value: 'Foerderung', label: 'Foerderung' },
  { value: 'Veranstaltung', label: 'Veranstaltung' },
]

export default function NewsScreen() {
  const router = useRouter()
  const [kategorie, setKategorie] = useState<string | undefined>(undefined)
  const [showSkeleton, setShowSkeleton] = useState(true)
  // Fetch all news (without category filter) to compute per-category unread counts
  const { data: allData, refetch: refetchAll, isRefetching: isRefetchingAll } = useNewsList(undefined)
  const { data, isLoading, refetch, isRefetching } = useNewsList(kategorie)
  const localReadIds = useNewsReadStore((s) => s.readIds)

  useFocusEffect(
    useCallback(() => {
      setShowSkeleton(true)
      const t = setTimeout(() => setShowSkeleton(false), 800)
      return () => clearTimeout(t)
    }, [])
  )

  // Compute unread count per category (combining server isRead + local store)
  function getUnreadCount(filterValue: string | undefined) {
    const source = allData ?? []
    const filtered = filterValue === undefined
      ? source
      : source.filter((n) => n.kategorie === filterValue)
    return filtered.filter((n) => !n.isRead && !localReadIds.has(n.id)).length
  }

  return (
    <SafeAreaView style={styles.safeArea} edges={['top']}>
      <View style={styles.header}>
        <View style={styles.titleRow}>
          <Text style={styles.screenTitle}>Aktuelles</Text>
        </View>

        <ScrollView
          horizontal
          showsHorizontalScrollIndicator={false}
          contentContainerStyle={styles.filterScroll}
        >
          {FILTERS.map((opt) => {
            const active = kategorie === opt.value
            const count = getUnreadCount(opt.value)
            return (
              <TouchableOpacity
                key={String(opt.value)}
                onPress={() => setKategorie(opt.value)}
                style={[styles.chip, active && styles.chipActive]}
                activeOpacity={0.85}
              >
                <Text style={[styles.chipLabel, active && styles.chipLabelActive]}>
                  {opt.label}
                </Text>
                {count > 0 && (
                  <View style={[styles.chipBadge, active && styles.chipBadgeActive]}>
                    <Text style={[styles.chipBadgeText, active && styles.chipBadgeTextActive]}>
                      {count}
                    </Text>
                  </View>
                )}
              </TouchableOpacity>
            )
          })}
        </ScrollView>
      </View>

      <View style={styles.divider} />

      {showSkeleton ? (
        <View style={{ paddingTop: 16 }}>
          {[1,2,3,4].map((i) => <SkeletonCard key={i} />)}
        </View>
      ) : (
        <FlatList
          data={data ?? []}
          keyExtractor={(item) => item.id}
          contentContainerStyle={styles.list}
          initialNumToRender={10}
          maxToRenderPerBatch={10}
          windowSize={5}
          refreshControl={
            <RefreshControl refreshing={isRefetching} onRefresh={refetch} tintColor="#003B7E" progressViewOffset={50} />
          }
          renderItem={({ item }) => (
            <NewsCard
              news={item}
              onPress={() => router.push(`/(app)/news/${item.id}` as never)}
            />
          )}
          ListEmptyComponent={
            <EmptyState icon="newspaper-outline" title="Keine News" subtitle="Noch keine Beitraege veroeffentlicht." />
          }
        />
      )}
    </SafeAreaView>
  )
}

const styles = StyleSheet.create({
  safeArea: {
    flex: 1,
    backgroundColor: '#F8FAFC',
  },
  header: {
    backgroundColor: '#FFFFFF',
    paddingHorizontal: 20,
    paddingTop: 14,
    paddingBottom: 0,
  },
  titleRow: {
    flexDirection: 'row',
    alignItems: 'center',
    justifyContent: 'space-between',
    marginBottom: 14,
  },
  screenTitle: {
    fontSize: 28,
    fontWeight: '800',
    color: '#0F172A',
    letterSpacing: -0.5,
  },
  filterScroll: {
    paddingBottom: 14,
    gap: 8,
    paddingRight: 20,
  },
  chip: {
    flexDirection: 'row',
    alignItems: 'center',
    gap: 5,
    paddingHorizontal: 14,
    paddingVertical: 7,
    borderRadius: 99,
    borderWidth: 1,
    borderColor: '#E2E8F0',
    backgroundColor: '#FFFFFF',
  },
  chipActive: {
    backgroundColor: '#003B7E',
    borderColor: '#003B7E',
  },
  chipLabel: {
    fontSize: 13,
    fontWeight: '600',
    color: '#64748B',
  },
  chipLabelActive: {
    color: '#FFFFFF',
  },
  chipBadge: {
    backgroundColor: '#003B7E',
    borderRadius: 99,
    minWidth: 18,
    height: 18,
    paddingHorizontal: 5,
    alignItems: 'center',
    justifyContent: 'center',
  },
  chipBadgeActive: {
    backgroundColor: '#FFFFFF',
  },
  chipBadgeText: {
    fontSize: 10,
    fontWeight: '700',
    color: '#FFFFFF',
  },
  chipBadgeTextActive: {
    color: '#003B7E',
  },
  divider: {
    height: 1,
    backgroundColor: '#E2E8F0',
  },
  list: {
    padding: 16,
    gap: 10,
    paddingBottom: 30,
  },
})