import { unwrap, type Track } from '@pipu/core';
import { useRouter } from 'expo-router';
import { useInfiniteQuery } from '@tanstack/react-query';
import { useEffect, useState } from 'react';
import { useTranslation } from 'react-i18next';
import { FlatList, Text, View } from 'react-native';

import { useSession } from '../../lib/session';
import { downloads } from '../../offline/downloads';
import { player } from '../../player/controller';
import { usePlayerState } from '../../player/hooks';
import { useColors } from '../../theme';
import { DownloadButton, useDownloads } from '../../ui/downloads';
import { Button, H1, Muted, Screen, Segmented, TrackRow } from '../../ui/kit';

type Tab = 'history' | 'likes' | 'dislikes' | 'downloads';

export default function CollectionScreen() {
  const colors = useColors();
  const { t, i18n } = useTranslation();
  const session = useSession();
  const current = usePlayerState().track;
  const [tab, setTab] = useState<Tab>('likes');
  const router = useRouter();

  const list = useInfiniteQuery({
    queryKey: ['m-collection', tab],
    enabled: tab !== 'downloads',
    initialPageParam: undefined as string | undefined,
    queryFn: async ({ pageParam }) => {
      const query = { query: { cursor: pageParam, limit: 100 } };
      if (tab === 'history') {
        const page = unwrap(await session.client.GET('/api/v1/me/history', { params: query }));
        return { items: page.items.map((i) => ({ track: i.track, at: i.played_at })), next: page.next_cursor };
      }
      const path = tab === 'likes' ? '/api/v1/me/likes' : '/api/v1/me/dislikes';
      const page = unwrap(await session.client.GET(path, { params: query }));
      return { items: page.items.map((i) => ({ track: i.track, at: i.created_at })), next: page.next_cursor };
    },
    getNextPageParam: (p) => p.next ?? undefined,
  });
  const items = list.data?.pages.flatMap((p) => p.items) ?? [];

  /** Все лайки целиком, а не только загруженные страницы списка. */
  const downloadAllLikes = async () => {
    let cursor: string | undefined;
    do {
      const page = unwrap(await session.client.GET('/api/v1/me/likes', { params: { query: { cursor, limit: 100 } } }));
      await downloads.enqueue(page.items.map((i) => i.track));
      cursor = page.next_cursor ?? undefined;
    } while (cursor);
  };
  const tracks: Track[] = items.map((i) => i.track);
  const time = new Intl.DateTimeFormat(i18n.language, { day: 'numeric', month: 'short', hour: '2-digit', minute: '2-digit' });
  const context = tab === 'history' ? ({ type: 'history' } as const) : ({ type: 'collection', id: tab } as const);
  const empty = { history: 'collection.empty_history', likes: 'collection.empty_likes', dislikes: 'collection.empty_dislikes' } as const;

  const tabs = (
    <View style={{ gap: 12 }}>
    <Button title={t('playlists.title')} icon="queue-music" variant="secondary" onPress={() => router.push('/playlists')} />
    <Segmented<Tab>
      value={tab}
      onChange={setTab}
      options={[
        { value: 'likes', label: t('collection.likes') },
        { value: 'history', label: t('collection.history') },
        { value: 'downloads', label: t('mobile.dl_title') },
        { value: 'dislikes', label: t('collection.dislikes') },
      ]}
    />
    </View>
  );
  if (tab === 'downloads') return <DownloadsTab tabs={tabs} />;

  return (
    <Screen>
      <FlatList
        data={items}
        keyExtractor={(it, i) => `${it.track.id}-${i}`}
        onEndReached={() => list.hasNextPage && void list.fetchNextPage()}
        onRefresh={() => void list.refetch()}
        refreshing={list.isRefetching}
        ListHeaderComponent={
          <View style={{ padding: 16, gap: 14 }}>
            <H1>{t('collection.title')}</H1>
            {tabs}
            {tab === 'likes' && tracks.length > 0 && (
              <Button title={t('collection.play_all')} icon="play-arrow" onPress={() => void player.playList(tracks, 0, context)} />
            )}
            {tab === 'likes' && tracks.length > 0 && (
              <Button title={t('mobile.dl_all_likes')} variant="secondary" icon="download" onPress={() => void downloadAllLikes()} />
            )}
          </View>
        }
        ListEmptyComponent={list.isSuccess ? <Text style={{ color: colors.text3, textAlign: 'center', padding: 24 }}>{t(empty[tab])}</Text> : null}
        renderItem={({ item, index }) => (
          <TrackRow
            track={item.track}
            current={current?.id === item.track.id}
            meta={tab === 'history' ? time.format(new Date(item.at)) : undefined}
            onPress={() => void player.playList(tracks, index, context)}
            onLike={tab === 'dislikes' ? undefined : () => void player.react(item.track, item.track.reaction === 'like' ? null : 'like').then(() => list.refetch())}
          />
        )}
      />
    </Screen>
  );
}

const MB = 1024 * 1024;

/** Коллекция → Скачанное: работает без сети, данные — из SQLite. */
function DownloadsTab({ tabs }: { tabs: React.ReactNode }) {
  const colors = useColors();
  const { t } = useTranslation();
  const dl = useDownloads();
  const current = usePlayerState().track;
  const [usage, setUsage] = useState<{ used: number; free: number } | null>(null);
  const items = [...dl.items.values()];
  const done = items.filter((i) => i.status === 'done').map((i) => i.track);
  const pending = items.filter((i) => i.status === 'queued' || i.status === 'downloading').length;
  const failed = items.some((i) => i.status === 'error');
  const context = { type: 'collection', id: 'downloads' } as const;

  useEffect(() => {
    void downloads.usage().then(setUsage);
  }, [done.length]);

  return (
    <Screen>
      <FlatList
        data={items}
        keyExtractor={(it) => it.track.id}
        ListHeaderComponent={
          <View style={{ padding: 16, gap: 14 }}>
            <H1>{t('collection.title')}</H1>
            {tabs}
            {usage && <Muted>{t('mobile.dl_usage', { used: (usage.used / MB).toFixed(0), free: (usage.free / MB / 1024).toFixed(1) })}</Muted>}
            {pending > 0 && (
              <Muted>{t(dl.allowed ? 'mobile.dl_pending' : dl.wifiOnly ? 'mobile.dl_waiting_wifi' : 'mobile.dl_waiting_network', { count: pending })}</Muted>
            )}
            {failed && <Button title={t('mobile.dl_retry')} variant="secondary" icon="refresh" onPress={() => void downloads.retry()} />}
            {done.length > 0 && <Button title={t('collection.play_all')} icon="play-arrow" onPress={() => void player.playList(done, 0, context)} />}
          </View>
        }
        ListEmptyComponent={<Text style={{ color: colors.text3, textAlign: 'center', padding: 24 }}>{t('mobile.dl_empty')}</Text>}
        renderItem={({ item }) => (
          <TrackRow
            track={item.track}
            current={current?.id === item.track.id}
            meta={item.status === 'downloading' ? `${Math.round(item.progress * 100)}%` : undefined}
            onPress={() => {
              if (item.status === 'done') void player.playList(done, done.indexOf(item.track), context);
            }}
            trailing={<DownloadButton track={item.track} size={20} />}
          />
        )}
      />
    </Screen>
  );
}