import { useState, type ReactNode } from 'react';
import { Link, useNavigate } from 'react-router';
import { useClient } from 'hooks/useClient';
import { usePanelChannel } from 'hooks/usePanelChannel';
import { Heart, User, Disc3, Music, ChevronRight, X } from 'lucide-react';
import { useMusicPlayer, type PlayerTrack } from './useMusicPlayer';
import { MusicHeart } from './MusicHeart';
import { useMusicFavorites } from './useMusicFavorites';
import {
  MUSIC_FAV_CHANNEL,
  coverUrl,
  musicPath,
  parseAlbumName,
  sortTracks,
  toRel,
  type AlbumMeta,
  type FavoriteKind,
} from './shared';

// The user's favorited artists / albums / tracks, grouped — shown in the right panel. Keys follow the
// favorites convention: album/artist are music-relative ("Albums/…"), tracks are home paths
// ("Music/…/file"). An album/artist row is a link into the library; a track row plays, so it stays a
// button — it mutates rather than navigates, even though it also moves the library to the album.
export const FavoritesView = () => {
  const { get, token } = useClient();
  const navigate = useNavigate();
  const player = useMusicPlayer();
  const { favorites } = useMusicFavorites();
  const [, setFavOpen] = usePanelChannel<boolean>(MUSIC_FAV_CHANNEL, false);

  const playTrack = async (homePath: string) => {
    const cut = homePath.lastIndexOf('/');
    const albumHome = homePath.slice(0, cut);
    const file = homePath.slice(cut + 1);
    const albumRel = toRel(albumHome);
    try {
      const meta = await get<AlbumMeta>(`/music/meta?path=${encodeURIComponent(albumRel)}`);
      const q: PlayerTrack[] = sortTracks(meta.tracks).map((t) => ({
        albumRel,
        file: t.file,
        title: t.title,
        artist: t.artist,
      }));
      player.playQueue(
        q,
        Math.max(
          0,
          q.findIndex((t) => t.file === file),
        ),
      );
    } catch {
      player.playQueue([{ albumRel, file }], 0);
    }
    navigate(musicPath(albumRel));
    setFavOpen(false);
  };

  const empty = !favorites.artists.length && !favorites.albums.length && !favorites.tracks.length;

  return (
    <div className="h-full overflow-y-auto p-4 md:p-6">
      <div className="mb-4 flex items-center gap-2">
        <Heart size={20} className="fill-red-500 text-red-500" />
        <h1 className="flex-1 text-2xl font-bold text-foreground">Favorites</h1>
        <button
          type="button"
          onClick={() => setFavOpen(false)}
          className="cursor-pointer rounded p-1.5 text-muted-foreground hover:bg-muted hover:text-foreground"
        >
          <X size={18} />
        </button>
      </div>

      {empty ? (
        <div className="flex flex-col items-center justify-center gap-3 py-24 text-center">
          <Heart size={44} className="text-muted-foreground/30" />
          <p className="text-sm text-muted-foreground">
            No favorites yet. Click the heart on any artist, album or track.
          </p>
        </div>
      ) : (
        <div className="flex flex-col gap-6">
          <Section title="Artists" count={favorites.artists.length}>
            {favorites.artists.map((key) => {
              const segs = key.split('/');
              return (
                <FavRow
                  key={key}
                  kind="artist"
                  favKey={key}
                  cover={coverUrl(key, token)}
                  fallback={<User size={18} className="text-muted-foreground" />}
                  title={segs[segs.length - 1] ?? key}
                  to={musicPath(key)}
                  onClick={() => setFavOpen(false)}
                  chevron
                />
              );
            })}
          </Section>

          <Section title="Albums" count={favorites.albums.length}>
            {favorites.albums.map((key) => {
              const segs = key.split('/');
              const { title, year } = parseAlbumName(segs[segs.length - 1] ?? key);
              const artist = segs.length >= 3 ? segs[1] : '';
              return (
                <FavRow
                  key={key}
                  kind="album"
                  favKey={key}
                  cover={coverUrl(key, token)}
                  fallback={<Disc3 size={18} className="text-muted-foreground" />}
                  title={title}
                  subtitle={[artist, year].filter(Boolean).join(' · ')}
                  to={musicPath(key)}
                  onClick={() => setFavOpen(false)}
                  chevron
                />
              );
            })}
          </Section>

          <Section title="Tracks" count={favorites.tracks.length}>
            {favorites.tracks.map((key) => {
              const segs = key.split('/');
              const base = segs[segs.length - 1] ?? key;
              const albumRel = toRel(key.slice(0, Math.max(0, key.lastIndexOf('/'))));
              const album = segs.length >= 2 ? parseAlbumName(segs[segs.length - 2]!).title : '';
              return (
                <FavRow
                  key={key}
                  kind="track"
                  favKey={key}
                  cover={coverUrl(albumRel, token)}
                  fallback={<Music size={18} className="text-muted-foreground" />}
                  title={base.replace(/\.[^/.]+$/, '')}
                  subtitle={album}
                  onClick={() => playTrack(key)}
                />
              );
            })}
          </Section>
        </div>
      )}
    </div>
  );
};

const Section = ({ title, count, children }: { title: string; count: number; children: ReactNode }) =>
  count ? (
    <div>
      <h2 className="mb-1 px-2 text-xs font-semibold uppercase tracking-wide text-muted-foreground">
        {title} <span className="text-muted-foreground/60">{count}</span>
      </h2>
      <div className="flex flex-col">{children}</div>
    </div>
  ) : null;

// `to` makes the row an anchor (an album or artist, which is a place); without it the row is a button
// (a track, which plays). The heart stays a sibling either way — it must not be inside either one.
const FavRow = ({
  kind,
  favKey,
  cover,
  fallback,
  title,
  subtitle,
  to,
  onClick,
  chevron,
}: {
  kind: FavoriteKind;
  favKey: string;
  cover: string;
  fallback: ReactNode;
  title: string;
  subtitle?: string;
  to?: string;
  onClick: () => void;
  chevron?: boolean;
}) => {
  const [failed, setFailed] = useState(false);
  const inner = (
    <>
      <div className="flex h-11 w-11 shrink-0 items-center justify-center overflow-hidden rounded bg-muted">
        {cover && !failed ? (
          <img src={cover} alt="" className="h-full w-full object-cover" onError={() => setFailed(true)} />
        ) : (
          fallback
        )}
      </div>
      <div className="min-w-0 flex-1">
        <span className="block truncate text-sm text-foreground">{title}</span>
        {subtitle ? <span className="block truncate text-xs text-muted-foreground">{subtitle}</span> : null}
      </div>
    </>
  );
  const cls = 'flex min-w-0 flex-1 cursor-pointer items-center gap-3 text-left';
  return (
    <div className="group flex items-center gap-3 rounded-md px-2 py-1.5 hover:bg-muted">
      {to ? (
        <Link to={to} onClick={onClick} className={cls}>
          {inner}
        </Link>
      ) : (
        <button type="button" onClick={onClick} className={cls}>
          {inner}
        </button>
      )}
      <MusicHeart kind={kind} favKey={favKey} size={16} className="shrink-0" />
      {chevron ? <ChevronRight size={16} className="shrink-0 text-muted-foreground" /> : null}
    </div>
  );
};