import 'dart:async';
import 'dart:developer' as developer;
import 'dart:ui' as ui;

import 'package:audio_service/audio_service.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'app.dart';
import 'servicios/arranque_audio.dart';
import 'servicios/musica_local_auto.dart';
import 'servicios/navegacion_auto.dart';
import 'servicios/servicio_audio.dart';
import 'servicios/servicio_audio_session.dart';
import 'servicios/servicio_presets_personalizados.dart';
import 'tema/pluriwave_tokens.dart';

const _anchoMinimoLandscape = 600.0;

/// Branded monochrome status-bar icon, replacing the default full-color
/// launcher silhouette fallback.
const androidNotificationIconResource = 'drawable/ic_stat_pluriwave';

/// S5-R8: media notification accent uses the brand color, not the M3
/// default purple. Top-level const so tests can assert it.
const configuracionAudioService = AudioServiceConfig(
  androidNotificationChannelId: 'es.freetimelab.pluriwave.audio',
  androidNotificationChannelName: 'PluriWave Radio',
  androidNotificationOngoing: true,
  androidStopForegroundOnPause: true,
  notificationColor: PluriWaveTokens.brand,
  androidNotificationIcon: androidNotificationIconResource,
);

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();

  // Android Auto browse source: registered FIRST, before any await at all.
  // It depends on nothing, and everything below it is a potential place to
  // get stuck — so nothing may sit between engine start and this line.
  //
  // Reported: with Android Auto connected, the car screen sometimes came up
  // black and the app then opened WHITE on the phone until it was
  // force-killed. `AudioServiceActivity.provideFlutterEngine` returns the
  // engine from `AudioServicePlugin.getFlutterEngine`, which CREATES the
  // engine and runs `main()` headlessly the first time — with no Activity —
  // when the car binds the MediaBrowserService before the app is opened.
  // `_aplicarPoliticaOrientacion` used to be the first `await` here, and
  // `SystemChrome.setPreferredOrientations` travels the `flutter/platform`
  // channel, whose handler (`PlatformPlugin`) is installed by the Activity.
  // Headless there is nobody to answer it, so `main()` died or hung on line
  // one: the browse source below was never registered (`getChildren` had no
  // source -> black car screen) and `runApp` was never reached. Opening the
  // app then REUSED that same cached, already-dead engine -> white screen,
  // and only a force-kill (which disposes the engine) recovered it.
  final fuenteAuto = FuenteEmisorasAutoLocal();
  registrarFuenteNavegacion(fuenteAuto);

  // Cosmetic, and deliberately NOT awaited: a display preference must never
  // gate `runApp`. `_OrientacionResponsiveApp.didChangeDependencies` applies
  // it again as soon as a real view exists, which is the only moment it can
  // actually take effect anyway.
  unawaited(aplicarPoliticaOrientacion());

  // S3-R4: single SharedPreferences instance resolved once at startup and
  // injected into every state/service below.
  final prefs = await SharedPreferences.getInstance();

  // Local-music browse source (Design "getChildren data source
  // registration"), same injectable-prefs DI convention as every other
  // startup service — required so `_fuenteMusicaLocalGlobal` is ever
  // non-null; without this registration the local-music root would stay
  // permanently hidden (`hayCarpetaConfigurada()` has no fuente to ask).
  registrarFuenteMusicaLocal(FuenteMusicaLocalAutoImpl(prefs: prefs));

  // User-saved EQ presets for the car's Ecualizador folder, same
  // injectable-prefs DI convention and same pre-init placement as the two
  // registrations above (neither depends on the AudioHandler). Passed as a
  // read function, not the service, so the folder re-reads on every browse:
  // a preset saved on the phone appears in the car without an app restart.
  final presetsPersonalizados = ServicioPresetsPersonalizados(prefs: prefs);
  registrarFuentePresetsPersonalizados(presetsPersonalizados.listar);

  // Silent-error channel (fix/notificacion-media): `AudioService.asyncError`
  // had ZERO subscribers app-wide, and a `PublishSubject` with no listeners
  // drops what it is given — so every exception `audio_service` catches
  // internally was discarded without a trace, which is exactly why the
  // "media notification disappeared" report came with no evidence attached.
  // Subscribed BEFORE `AudioService.init` below (the getter only touches a
  // static subject, so it needs no initialisation) so nothing reported
  // during the MediaBrowser handshake is missed, and placed here rather than
  // in `conectarHandler` so ONE subscription covers both the on-time and the
  // degraded/timeout startup paths.
  final subErroresAudio = observarErroresAudio(
    AudioService.asyncError,
    registrar: registrarErrorAudioService,
  );

  // Design "Timeout without re-init": AudioService.init is started exactly
  // ONCE here and `handlerFuturo` is the only future ever awaited for it —
  // the plugin caches state internally, so a double-configure call is
  // unsafe and must never happen, even on the degraded/timeout path below.
  final handlerFuturo = AudioService.init(
    builder: () => PluriWaveAudioHandler(),
    config: configuracionAudioService,
  );

  // S3-R1: audio focus — phone calls / transient losses pause or duck the
  // radio; headphones unplugged pauses it. Shared by both the on-time and
  // degraded/late-completion paths below.
  void conectarHandler(PluriWaveAudioHandler handler) {
    registrarHandler(handler);
    // The handler is the only thing this app ever tears down
    // (`onTaskRemoved`), so the asyncError subscription's `cancel` travels
    // with it and can never leak — same "register from main.dart" convention
    // as `registrarHandler` itself.
    registrarLimpiezaArranque(subErroresAudio.cancel);
    final sesionAudio = ServicioAudioSession(objetivo: handler);
    unawaited(sesionAudio.configurar());
  }

  Widget construirApp() => _OrientacionResponsiveApp(
    child: PluriWaveApp(prefs: prefs, fuenteAuto: fuenteAuto),
  );

  final resultado = await esperarArranqueAudio(handlerFuturo);
  switch (resultado) {
    case ArranqueAudioListo<PluriWaveAudioHandler>(:final handler):
      // Handshake finished in time — exactly today's startup path.
      conectarHandler(handler);
      runApp(construirApp());
    case ArranqueAudioPendiente<PluriWaveAudioHandler>(
      handlerFuturo: final futuroPendiente,
    ):
      // Handshake still hung after the timeout: run the app anyway with a
      // minimal loading bootstrap that keeps awaiting the SAME
      // `futuroPendiente` — identical to the outer `handlerFuturo`, per
      // esperarArranqueAudio's contract (never a second AudioService.init
      // call) — and wires the handler + swaps to the real app once it
      // eventually resolves.
      runApp(
        ArranqueAudioApp<PluriWaveAudioHandler>(
          handlerFuturo: futuroPendiente,
          alListo: conectarHandler,
          construirApp: (_) => construirApp(),
        ),
      );
  }
}

/// Which orientations a display [anchoLogico] dp wide may use: phones stay
/// portrait, tablets get everything. Pure, so the policy is testable without
/// a platform channel.
@visibleForTesting
List<DeviceOrientation> orientacionesPara(double anchoLogico) =>
    anchoLogico < _anchoMinimoLandscape
        ? const [DeviceOrientation.portraitUp]
        : DeviceOrientation.values;

/// Applies [orientacionesPara] to the active display.
///
/// NEVER throws and never blocks a caller that matters. This runs on the
/// headless engine Android Auto starts (see `main`), where the
/// `flutter/platform` channel has no handler because there is no Activity to
/// install `PlatformPlugin` — so the call can fail with a
/// `MissingPluginException` or simply never be answered. Before this guard
/// that outcome killed `main()` outright, taking the Android Auto browse
/// registration and `runApp` with it.
///
/// [aplicar] is injectable so the swallow-everything contract is testable
/// without a real platform channel.
@visibleForTesting
Future<void> aplicarPoliticaOrientacion({
  ui.Display? display,
  Future<void> Function(List<DeviceOrientation>)? aplicar,
}) async {
  try {
    final vista =
        WidgetsBinding.instance.platformDispatcher.views.isNotEmpty
            ? WidgetsBinding.instance.platformDispatcher.views.first
            : null;
    final displayActivo = display ?? vista?.display;
    if (displayActivo == null) return;

    final anchoLogico =
        displayActivo.size.width / displayActivo.devicePixelRatio;
    await (aplicar ?? SystemChrome.setPreferredOrientations)(
      orientacionesPara(anchoLogico),
    );
  } catch (e) {
    // Deliberately broad: a cosmetic preference is never worth a failed
    // startup, and headless is exactly where this fails.
    developer.log(
      '[PluriWave] no se pudo aplicar la política de orientación: $e',
      name: 'Arranque',
      level: 900,
    );
  }
}

class _OrientacionResponsiveApp extends StatefulWidget {
  const _OrientacionResponsiveApp({required this.child});

  final Widget child;

  @override
  State<_OrientacionResponsiveApp> createState() =>
      _OrientacionResponsiveAppState();
}

class _OrientacionResponsiveAppState extends State<_OrientacionResponsiveApp>
    with WidgetsBindingObserver {
  ui.Display? _display;

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addObserver(this);
  }

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    _display = View.maybeOf(context)?.display;
    unawaited(aplicarPoliticaOrientacion(display: _display));
  }

  @override
  void didChangeMetrics() {
    unawaited(aplicarPoliticaOrientacion(display: _display));
  }

  @override
  void dispose() {
    WidgetsBinding.instance.removeObserver(this);
    super.dispose();
  }

  @override
  Widget build(BuildContext context) => widget.child;
}