import 'package:flutter/widgets.dart' show NetworkImage;
import 'package:flutter_riverpod/flutter_riverpod.dart';

import '../downloads/download_manager.dart';
import '../history/play_history.dart';
import '../library/browse_query.dart';
import '../library/library_index.dart';
import '../playback/playback_engine.dart';
import '../playlists/playlists.dart';
import '../settings/settings_store.dart';
import '../subsonic/credentials.dart';
import '../subsonic/models.dart';
import '../subsonic/subsonic_client.dart';
import '../theme/accent.dart';
import '../theme/accent_extract.dart';
import 'favorites.dart';
import 'remote_providers.dart';

// `BrowseMode`/`SearchMode` are defined in the settings store (so they can be
// persisted) but historically lived here — re-export so existing importers of
// this file keep resolving them.
export '../settings/settings_store.dart'
    show BrowseMode, SearchMode, AlbumSort, TrackSort;
export '../library/browse_query.dart' show BrowseFilter;

// ---- Connection ---------------------------------------------------------

enum ConnStatus { disconnected, connecting, online, error }

class ConnectionState {
  const ConnectionState({
    required this.status,
    this.client,
    this.credentials,
    this.error,
    this.servers = const [],
  });

  final ConnStatus status;
  final SubsonicClient? client;
  final SubsonicCredentials? credentials;
  final String? error;

  /// All saved servers (one may be the active [credentials]). Drives the
  /// server switcher and the Settings "Servers" section.
  final List<SubsonicCredentials> servers;

  bool get isOnline => status == ConnStatus.online;

  /// Id of the active server, or null when disconnected with none configured.
  String? get activeId => credentials?.id;

  /// Only the saved-servers list changes; connection fields are preserved.
  ConnectionState copyWith({List<SubsonicCredentials>? servers}) =>
      ConnectionState(
        status: status,
        client: client,
        credentials: credentials,
        error: error,
        servers: servers ?? this.servers,
      );
}

final credentialStoreProvider =
    Provider<CredentialStore>((_) => CredentialStore());

/// Owns the active server connection and the list of saved servers: builds the
/// client, pings, persists credentials, auto-restores on launch, and switches
/// between servers (one active at a time — TODO #2).
class ConnectionController extends StateNotifier<ConnectionState> {
  ConnectionController(this._store)
      : super(const ConnectionState(status: ConnStatus.disconnected)) {
    _restore();
  }

  final CredentialStore _store;
  List<SubsonicCredentials> _servers = const [];
  String? _activeId;

  Future<void> _restore() async {
    try {
      _servers = await _store.loadAll();
      _activeId = await _store.loadActiveId();
      state = state.copyWith(servers: _servers);
      if (_servers.isEmpty) return;
      final active = _servers.firstWhere(
        (s) => s.id == _activeId,
        orElse: () => _servers.first,
      );
      _activeId = active.id;
      await connect(active, persist: false);
    } catch (_) {
      // No secure-storage backend available (e.g. Linux without a running
      // keyring daemon) — start disconnected rather than crashing.
    }
  }

  Future<bool> connect(SubsonicCredentials creds, {bool persist = true}) async {
    state = ConnectionState(status: ConnStatus.connecting, servers: _servers);
    final client = SubsonicClient(
      baseUrl: creds.url,
      username: creds.username,
      password: creds.password,
    );
    try {
      final ok = await client.ping();
      if (!ok) {
        // Keep the credentials on a reachability failure so the app still knows
        // *which* server it is (offline downloads / playlists key off this) and
        // can retry — only auth failures below drop them.
        state = ConnectionState(
          status: ConnStatus.error,
          credentials: creds,
          error: 'Could not reach the server.',
          servers: _servers,
        );
        return false;
      }
      // Persistence is best-effort: a locked/absent secure-storage backend
      // (e.g. a locked Linux keyring) must not stop this session connecting.
      // A successful connect saves the server and makes it active.
      if (persist) {
        try {
          await _addOrUpdate(creds, makeActive: true);
        } catch (_) {}
      } else {
        _activeId = creds.id;
      }
      state = ConnectionState(
        status: ConnStatus.online,
        client: client,
        credentials: creds,
        servers: _servers,
      );
      return true;
    } on SubsonicError catch (e) {
      // Auth failures drop the credentials (they're wrong); any other server
      // error keeps them so offline features still resolve the server key.
      state = ConnectionState(
        status: ConnStatus.error,
        credentials: e.isAuthFailure ? null : creds,
        error: e.isAuthFailure ? 'Wrong username or password.' : e.message,
        servers: _servers,
      );
      return false;
    } catch (e) {
      state = ConnectionState(
        status: ConnStatus.error,
        credentials: creds,
        error: e.toString(),
        servers: _servers,
      );
      return false;
    }
  }

  /// Switch the active server to [id] and connect. No password re-entry — saved
  /// servers keep their credentials. Per-server downloads/playlists reload
  /// automatically via [serverKeyProvider] listeners.
  Future<bool> switchTo(String id) async {
    SubsonicCredentials? creds;
    for (final s in _servers) {
      if (s.id == id) {
        creds = s;
        break;
      }
    }
    if (creds == null) return false;
    _activeId = id;
    try {
      await _store.saveAll(_servers, _activeId);
    } catch (_) {}
    return connect(creds, persist: false);
  }

  /// Add or update a saved server *without* connecting (used by the add/edit
  /// form). Updating an entry with the same [SubsonicCredentials.id] overwrites
  /// its password/alias.
  Future<void> saveServer(SubsonicCredentials creds) async {
    await _addOrUpdate(creds, makeActive: false);
    state = state.copyWith(servers: _servers);
  }

  /// Remove a saved server. If it was the active one, switch to another saved
  /// server (or go disconnected when none remain).
  Future<void> removeServer(String id) async {
    _servers = _servers.where((s) => s.id != id).toList();
    final removedActive = id == _activeId;
    if (removedActive) {
      _activeId = _servers.isEmpty ? null : _servers.first.id;
    }
    try {
      await _store.saveAll(_servers, _activeId);
    } catch (_) {}
    if (removedActive) {
      if (_servers.isNotEmpty) {
        await connect(_servers.first, persist: false);
      } else {
        state = ConnectionState(
          status: ConnStatus.disconnected,
          servers: _servers,
        );
      }
    } else {
      state = state.copyWith(servers: _servers);
    }
  }

  Future<void> _addOrUpdate(SubsonicCredentials creds,
      {required bool makeActive}) async {
    final idx = _servers.indexWhere((s) => s.id == creds.id);
    final next = [..._servers];
    if (idx >= 0) {
      next[idx] = creds;
    } else {
      next.add(creds);
    }
    _servers = next;
    if (makeActive) _activeId = creds.id;
    await _store.saveAll(_servers, _activeId);
  }

  /// Forget every saved server and drop the connection.
  Future<void> disconnect() async {
    _servers = const [];
    _activeId = null;
    try {
      await _store.clear();
    } catch (_) {}
    state = const ConnectionState(status: ConnStatus.disconnected);
  }
}

final connectionProvider =
    StateNotifierProvider<ConnectionController, ConnectionState>(
  (ref) => ConnectionController(ref.watch(credentialStoreProvider)),
);

/// The active client, or null when not connected.
final subsonicClientProvider = Provider<SubsonicClient?>(
  (ref) => ref.watch(connectionProvider).client,
);

/// Stable per-server cache key (`md5(baseUrl|username)`), derived from the
/// current credentials so it also resolves while offline (the error state
/// retains credentials). Null when no server has ever been configured. Used to
/// scope on-disk downloads/playlists to the server they belong to.
final serverKeyProvider = Provider<String?>((ref) {
  return ref.watch(connectionProvider).credentials?.id;
});

// ---- Navigation / browse mode -------------------------------------------

/// The active bottom-tab index. Single source of truth shared by the tab bar
/// and the mini-player (which jumps to Now Playing on tap).
final selectedTabProvider = StateProvider<int>((_) => 0);

/// Index of the Now Playing tab in the shell's tab list.
const int nowPlayingTabIndex = 2;

/// Top-level Browse mode selector. Seeded once from the persisted
/// `AppSettings.defaultBrowseMode` by `AppShell`; manual selection then wins.
final browseModeProvider = StateProvider<BrowseMode>((_) => BrowseMode.artists);

// ---- Library ------------------------------------------------------------

final artistsProvider = FutureProvider<List<Artist>>((ref) async {
  final client = ref.watch(subsonicClientProvider);
  if (client == null) return const [];
  final result = await client.getArtists();
  return result.all;
});

/// All albums (alphabetical), paged through fully so nothing is silently
/// truncated. Backs the Albums cover-art grid.
final albumsProvider = FutureProvider<List<Album>>((ref) async {
  final client = ref.watch(subsonicClientProvider);
  if (client == null) return const [];
  const pageSize = 500;
  final all = <Album>[];
  var offset = 0;
  while (true) {
    final page = await client.getAlbumList2(size: pageSize, offset: offset);
    all.addAll(page);
    if (page.length < pageSize) break;
    offset += pageSize;
  }
  return all;
});

/// The crawled + cached flat song index that backs the Tracks view. Cleared
/// (and any in-flight build cancelled) whenever the server changes.
final libraryIndexProvider =
    StateNotifierProvider<LibraryIndexController, LibraryIndexState>((ref) {
  final controller =
      LibraryIndexController(() => ref.read(subsonicClientProvider));
  ref.listen<ConnectionState>(connectionProvider, (_, _) {
    controller.onConnectionChanged();
  });
  return controller;
});

// ---- Browse filtering / sorting -----------------------------------------

/// Session-only genre/year filter for the Albums grid (resets on restart).
final albumFilterProvider =
    StateProvider<BrowseFilter>((_) => const BrowseFilter());

/// Session-only genre/year filter for the Tracks list (resets on restart).
final trackFilterProvider =
    StateProvider<BrowseFilter>((_) => const BrowseFilter());

/// Distinct genres present across all albums, for the album genre picker.
final albumGenresProvider = Provider<List<String>>((ref) {
  final albums = ref.watch(albumsProvider).valueOrNull ?? const <Album>[];
  return distinctGenres(albums.map((a) => a.genre));
});

/// Distinct release years present across all albums, newest first.
final albumYearsProvider = Provider<List<int>>((ref) {
  final albums = ref.watch(albumsProvider).valueOrNull ?? const <Album>[];
  return distinctYears(albums.map((a) => a.year));
});

/// Albums after applying the session filter and the persisted sort. Async so
/// callers keep the underlying load/error states from [albumsProvider].
final visibleAlbumsProvider = Provider<AsyncValue<List<Album>>>((ref) {
  final filter = ref.watch(albumFilterProvider);
  final sort = ref.watch(settingsProvider.select((s) => s.albumSort));
  return ref
      .watch(albumsProvider)
      .whenData((albums) => applyAlbumQuery(albums, filter, sort));
});

/// Distinct genres present across all indexed tracks.
final trackGenresProvider = Provider<List<String>>((ref) {
  final songs = ref.watch(libraryIndexProvider).songs;
  return distinctGenres(songs.map((s) => s.genre));
});

/// Distinct release years present across all indexed tracks, newest first.
final trackYearsProvider = Provider<List<int>>((ref) {
  final songs = ref.watch(libraryIndexProvider).songs;
  return distinctYears(songs.map((s) => s.year));
});

/// Indexed tracks after applying the session filter and the persisted sort.
final visibleTracksProvider = Provider<List<Song>>((ref) {
  final filter = ref.watch(trackFilterProvider);
  final sort = ref.watch(settingsProvider.select((s) => s.trackSort));
  final songs = ref.watch(libraryIndexProvider).songs;
  return applyTrackQuery(songs, filter, sort);
});

/// Recently-added albums (`getAlbumList2` type `newest`) — a discovery shelf on
/// the Home tab. Small page; the Home shelf shows the first handful.
final newestAlbumsProvider = FutureProvider<List<Album>>((ref) async {
  final client = ref.watch(subsonicClientProvider);
  if (client == null) return const [];
  return client.getAlbumList2(type: 'newest', size: 20);
});

/// A random album shelf (`getAlbumList2` type `random`). Re-rolls when
/// [rediscoverSeedProvider] bumps so it shares the Home "shuffle" affordance.
final randomAlbumsProvider = FutureProvider<List<Album>>((ref) async {
  ref.watch(rediscoverSeedProvider);
  final client = ref.watch(subsonicClientProvider);
  if (client == null) return const [];
  return client.getAlbumList2(type: 'random', size: 20);
});

final artistProvider = FutureProvider.family<Artist, String>((ref, id) async {
  final client = ref.watch(subsonicClientProvider);
  if (client == null) throw StateError('Not connected');
  return client.getArtist(id);
});

final albumProvider = FutureProvider.family<Album, String>((ref, id) async {
  final client = ref.watch(subsonicClientProvider);
  if (client == null) throw StateError('Not connected');
  return client.getAlbum(id);
});

final searchProvider =
    FutureProvider.family<SearchResult3, String>((ref, query) async {
  final client = ref.watch(subsonicClientProvider);
  final q = query.trim();
  if (client == null || q.isEmpty) {
    return SearchResult3(artists: const [], albums: const [], songs: const []);
  }
  final result = await client.search3(q);
  // "Standard" trims the server's broad matches down to name/title hits;
  // "Discovery" (default) returns the server result unchanged.
  final mode = ref.watch(settingsProvider).searchMode;
  return mode == SearchMode.standard ? filterSearchToStandard(result, q) : result;
});

/// Narrows a [SearchResult3] to items whose *own* name/title contains [query]
/// (case-insensitive) — dropping songs that only matched via their artist or
/// album fields. Backs the "Standard" search mode (TODO #4).
SearchResult3 filterSearchToStandard(SearchResult3 r, String query) {
  final q = query.toLowerCase();
  bool has(String? s) => s != null && s.toLowerCase().contains(q);
  return SearchResult3(
    artists: r.artists.where((a) => has(a.name)).toList(),
    albums: r.albums.where((a) => has(a.name)).toList(),
    songs: r.songs.where((s) => has(s.title)).toList(),
  );
}

// ---- History (Home tab) -------------------------------------------------

final playHistoryProvider =
    StateNotifierProvider<HistoryController, List<PlayRecord>>(
  (ref) => HistoryController(),
);

final recentSongsProvider = Provider<List<PlayRecord>>(
  (ref) => recentSongs(ref.watch(playHistoryProvider)),
);

final recentAlbumsProvider = Provider<List<PlayRecord>>(
  (ref) => recentAlbums(ref.watch(playHistoryProvider)),
);

/// Bump to re-roll the rediscover suggestions.
final rediscoverSeedProvider = StateProvider<int>((_) => 0);

final rediscoverProvider = Provider<List<RediscoverArtist>>((ref) {
  final history = ref.watch(playHistoryProvider);
  final seed = ref.watch(rediscoverSeedProvider);
  return rediscover(history, seed: seed);
});

// ---- Favorites / ratings ------------------------------------------------

final favoritesProvider =
    StateNotifierProvider<FavoritesController, FavoritesState>((ref) {
  final controller =
      FavoritesController(() => ref.read(subsonicClientProvider));
  // Re-hydrate on connect, clear on disconnect.
  ref.listen<ConnectionState>(connectionProvider, (prev, next) {
    if (next.isOnline) {
      controller.hydrate();
    } else {
      controller.clear();
    }
  });
  return controller;
});

/// Full starred set for the Favorites screen.
final starredProvider = FutureProvider<Starred2>((ref) async {
  // Re-run when the local favorites set changes (e.g. after a toggle).
  ref.watch(favoritesProvider);
  final client = ref.watch(subsonicClientProvider);
  if (client == null) {
    return Starred2(artists: const [], albums: const [], songs: const []);
  }
  return client.getStarred2();
});

// ---- Downloads ----------------------------------------------------------

/// Offline download store: fetches tracks to disk (per-server) and exposes
/// their status. Reloads its manifest whenever the server key changes.
final downloadManagerProvider =
    StateNotifierProvider<DownloadController, DownloadState>((ref) {
  final controller = DownloadController(
    clientGetter: () => ref.read(subsonicClientProvider),
    settingsGetter: () => ref.read(settingsProvider),
    serverKeyGetter: () => ref.read(serverKeyProvider),
  );
  ref.listen<String?>(serverKeyProvider, (_, _) {
    controller.reloadForServer();
  });
  // Raising the concurrency cap should launch queued downloads right away.
  ref.listen<int>(
    settingsProvider.select((s) => s.maxConcurrentDownloads),
    (_, _) => controller.onConcurrencyChanged(),
  );
  return controller;
});

// ---- Playlists ----------------------------------------------------------

/// Server-backed playlists with an offline mirror. Reloads/refreshes whenever
/// the server key changes (connect / disconnect / server switch).
final playlistsProvider =
    StateNotifierProvider<PlaylistsController, PlaylistsState>((ref) {
  final controller = PlaylistsController(
    clientGetter: () => ref.read(subsonicClientProvider),
    serverKeyGetter: () => ref.read(serverKeyProvider),
  );
  ref.listen<String?>(serverKeyProvider, (_, _) {
    controller.reloadForServer();
  });
  return controller;
});

/// User-facing playlists — everything *not* marked as a Timbre tag. Backs the
/// Playlists screen and the "add to playlist" sheet.
final realPlaylistsProvider = Provider<List<Playlist>>((ref) => ref
    .watch(playlistsProvider)
    .playlists
    .where((p) => !isTagPlaylist(p))
    .toList());

/// Tags — playlists carrying the tag comment marker. Backs the Tags screen and
/// the "add tag" sheet. Same underlying store as [playlistsProvider]; only the
/// partition differs.
final tagsProvider = Provider<List<Playlist>>(
    (ref) => ref.watch(playlistsProvider).playlists.where(isTagPlaylist).toList());

/// The signed-in user's name on the active server, or null when disconnected.
/// Used to split owned playlists from ones shared by other users.
final currentUsernameProvider = Provider<String?>(
    (ref) => ref.watch(connectionProvider).credentials?.username);

/// The user's own playlists (owned, or owner unknown). Backs the main list and
/// the "add to playlist" sheet — you can only add tracks to your own playlists.
final myPlaylistsProvider = Provider<List<Playlist>>((ref) {
  final me = ref.watch(currentUsernameProvider);
  return ref
      .watch(realPlaylistsProvider)
      .where((p) => isOwnedBy(p, me))
      .toList();
});

/// Playlists shared by *other* users on the same server (public, owner != me).
final sharedPlaylistsProvider = Provider<List<Playlist>>((ref) {
  final me = ref.watch(currentUsernameProvider);
  return ref
      .watch(realPlaylistsProvider)
      .where((p) => !isOwnedBy(p, me))
      .toList();
});

// ---- Playback -----------------------------------------------------------

final playbackProvider =
    StateNotifierProvider<PlaybackController, PlaybackState>((ref) {
  // Prefer a local downloaded file when one exists (works offline / survives
  // service interruptions); otherwise stream at the configured bitrate.
  Uri? streamUriFor(Song s) {
    final local = ref.read(downloadManagerProvider.notifier).localPathFor(s.id);
    if (local != null) return Uri.file(local);
    final client = ref.read(subsonicClientProvider);
    if (client == null) return null;
    return client.streamUri(
      s.id,
      maxBitRate: ref.read(settingsProvider).streamMaxBitRate,
    );
  }

  Uri? coverArtUriFor(Song s) {
    final client = ref.read(subsonicClientProvider);
    if (client == null || s.coverArt == null) return null;
    return client.coverArtUri(s.coverArt!, size: 512);
  }

  final controller = PlaybackController(
    streamUriFor: streamUriFor,
    coverArtUriFor: coverArtUriFor,
    serverKeyGetter: () => ref.read(serverKeyProvider),
    onArt: (artUri) async {
      // Skip extraction entirely when the user has pinned a static accent.
      if (ref.read(settingsProvider).useStaticAccent) return;
      final color = await extractAccent(NetworkImage(artUri.toString()));
      if (color != null) ref.read(accentProvider.notifier).set(color);
    },
    onPlay: (song) {
      // Local history (drives the Home tab) + best-effort server scrobble.
      ref.read(playHistoryProvider.notifier).record(song);
      ref.read(subsonicClientProvider)?.scrobble(song.id).ignore();
    },
  );
  // Restore the persisted queue on connect / server switch, and catch the
  // already-connected case at creation (the listener only fires on changes).
  ref.listen<String?>(serverKeyProvider, (_, _) {
    controller.restoreForServer();
  });
  controller.restoreForServer();
  return controller;
});

/// The playback state the UI should render: the mirrored state of the device
/// we're controlling as a remote when attached (updates-features.md #3), else
/// the local engine's state. Widgets watch this (with `.select`) instead of
/// [playbackProvider] so the local/remote source is a single swappable seam.
final activePlaybackProvider = Provider<PlaybackState>((ref) {
  final remote = ref.watch(
    remoteControlProvider.select((s) => s.isAttached ? s.remoteState : null),
  );
  return remote ?? ref.watch(playbackProvider);
});

/// Keeps the theme accent in sync while acting as a remote (bug #6).
///
/// On the controlling device the local playback engine never loads the track,
/// so its `onArt` extraction (see [playbackControllerProvider]) never fires and
/// the accent would stay at the default. Here we re-extract the accent from the
/// mirrored remote track's cover art — the controlling device is connected to
/// the same server, so it can fetch the art itself. Selecting on `coverArt`
/// (a value-equal String) means this only fires on an actual art change, not on
/// the ~1/s snapshot churn. Watched in `main.dart` so it stays alive.
final remoteAccentSyncProvider = Provider<void>((ref) {
  ref.listen<String?>(
    remoteControlProvider.select(
      (s) => s.isAttached ? s.remoteState?.current?.coverArt : null,
    ),
    (prev, coverArt) async {
      if (ref.read(settingsProvider).useStaticAccent) return;
      if (coverArt == null) return;
      final client = ref.read(subsonicClientProvider);
      if (client == null) return;
      final uri = client.coverArtUri(coverArt, size: 512);
      final color = await extractAccent(NetworkImage(uri.toString()));
      if (color != null) ref.read(accentProvider.notifier).set(color);
    },
    fireImmediately: true,
  );
});

/// The command sink the UI should drive — a proxy that serializes commands over
/// the LAN to the attached device when acting as a remote, else the local
/// [PlaybackController]. Widgets read this instead of `playbackProvider.notifier`.
final playbackCommandsProvider = Provider<PlaybackCommands>((ref) {
  final attached = ref.watch(remoteControlProvider.select((s) => s.isAttached));
  if (attached) {
    final remote = ref.read(remoteControlProvider.notifier).remoteCommands;
    if (remote != null) return remote;
  }
  return ref.watch(playbackProvider.notifier);
});