pluriwave/lib/pantallas/pantalla_buscar.dart

import 'dart:async';

import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import 'package:shimmer/shimmer.dart' as shimmer;

import '../estado/estado_busqueda.dart';
import '../estado/estado_radio.dart';
import '../l10n/gen/app_localizations.dart';
import '../modelos/emisora.dart';
import '../tema/pluri_animate.dart';
import '../tema/pluriwave_theme.dart';
import '../tema/pluriwave_tokens.dart';
import '../widgets/pluri_glass_surface.dart';
import '../widgets/pluri_icon.dart';
import '../widgets/pluri_layout.dart';
import '../widgets/pluri_premium_widgets.dart';
import '../widgets/pluri_push_scaffold.dart';
import '../widgets/pluri_root_header.dart';
import '../widgets/pluri_sleep_timer_sheet.dart';
import 'package:pluriwave/widgets/tarjeta_emisora.dart';

import 'pantalla_paises.dart';
import 'reproducir_minimizado.dart';

const _paises = [
  ('countrySpain', 'ES'),
  ('countryUsa', 'US'),
  ('countryMexico', 'MX'),
  ('countryArgentina', 'AR'),
  ('countryUk', 'GB'),
  ('countryFrance', 'FR'),
  ('countryGermany', 'DE'),
  ('countryItaly', 'IT'),
  ('countryBrazil', 'BR'),
  ('countryJapan', 'JP'),
];

const _idiomas = [
  ('spanish', 'languageNameSpanish'),
  ('english', 'languageNameEnglish'),
  ('french', 'languageNameFrench'),
  ('german', 'languageNameGerman'),
  ('portuguese', 'languageNamePortuguese'),
  ('italian', 'languageNameItalian'),
  ('japanese', 'languageNameJapanese'),
  ('arabic', 'languageNameArabic'),
  ('russian', 'languageNameRussian'),
];

const _calidades = [
  ('64 kbps', 64),
  ('96 kbps', 96),
  ('128 kbps', 128),
  ('192 kbps', 192),
  ('320 kbps', 320),
];

/// WU6, `station-discovery-browse` spec: Buscar now owns BOTH the discovery
/// landing state (relocated from `PantallaInicio`, task 6.5 — `_seccionCercanas`,
/// `_seccionTendencias`, `_chipGeneros`, `_errorBanner` and the browse grid
/// all moved here verbatim and were deleted from `pantalla_inicio.dart`) and
/// the free-text/filtered search results view. [_hayBusquedaActiva] is the
/// single switch between the two: empty query AND no active filter shows
/// discovery content; any of the three flips to the results view.
///
/// Design correction, documented like WU3a's own task 3a.1: the spec's
/// landing-state scenario also lists a "Países entry point", but no such
/// affordance existed anywhere in `pantalla_inicio.dart` to relocate —
/// `PantallaPaises` itself doesn't exist until WU7. That entry point is
/// added in WU7 alongside the screen it targets (design's own component
/// inventory: "Países (WU7)"), not invented here pointing nowhere.
class PantallaBuscar extends StatefulWidget {
  const PantallaBuscar({super.key});

  @override
  State<PantallaBuscar> createState() => _PantallaBuscarState();
}

class _PantallaBuscarState extends State<PantallaBuscar> {
  final _controller = TextEditingController();
  String? _paisSeleccionado;
  String? _idiomaSeleccionado;
  int? _calidadMinima;

  // Relocated from PantallaInicio (task 6.5) — genre-chip selection only
  // drives the LANDING grid, same as it always did on Inicio; it is
  // orthogonal to the free-text/filter search flow below.
  static const _generos = [
    'pop',
    'rock',
    'jazz',
    'classical',
    'electronic',
    'news',
    'talk',
    'hip-hop',
    'country',
    'metal',
    'reggae',
    'latin',
  ];
  String? _generoSeleccionado;

  int get _filtrosActivosCount =>
      (_paisSeleccionado != null ? 1 : 0) +
      (_idiomaSeleccionado != null ? 1 : 0) +
      (_calidadMinima != null ? 1 : 0);

  bool get _hayBusquedaActiva =>
      _controller.text.trim().isNotEmpty || _filtrosActivosCount > 0;

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  void _buscar() {
    final q = _controller.text.trim();
    context.read<EstadoBusqueda>().buscar(
      nombre: q.isNotEmpty ? q : null,
      pais: _paisSeleccionado,
      idioma: _idiomaSeleccionado,
      minBitrate: _calidadMinima,
    );
  }

  void _quitarTodosLosFiltros() {
    setState(() {
      _paisSeleccionado = null;
      _idiomaSeleccionado = null;
      _calidadMinima = null;
    });
    _buscar();
  }

  @override
  Widget build(BuildContext context) {
    // S4-R3/S4-R5: this screen depends only on search state, so it watches
    // the dedicated notifier — playback events no longer rebuild it.
    final estado = context.watch<EstadoBusqueda>();
    final theme = Theme.of(context);
    final l10n = AppLocalizations.of(context);

    return ListView(
      padding: PluriLayout.pageListPadding,
      children: [
        // S1/S2 (Tier 1 visual fidelity): the prototype has no global
        // AppBar and no PluriScreenHeader (the glass hero this used to be
        // is retired everywhere) — this root draws its own 56px title row
        // instead, carrying the filters entry point that used to live on
        // the hero's `trailing` slot.
        PluriRootHeader(
          title: l10n.searchScreenTitle,
          onSleepTimer: () => showPluriSleepTimerSheet(context),
          actions: [
            GestureDetector(
              onTap: _abrirFiltros,
              child: PluriStatusPill(
                icon: Icons.tune_rounded,
                label: l10n.searchFiltersLabel,
              ),
            ),
          ],
        ),
        Padding(
          padding: const EdgeInsets.fromLTRB(
            PluriLayout.horizontal,
            10,
            PluriLayout.horizontal,
            0,
          ),
          child: PluriGlassSurface(
            padding: const EdgeInsets.all(10),
            borderRadius: BorderRadius.circular(999),
            child: SearchBar(
              controller: _controller,
              hintText: l10n.searchHint,
              leading: const PluriIcon(
                glyph: PluriIconGlyph.search,
                variant: PluriIconVariant.filled,
              ),
              trailing: [
                if (_controller.text.isNotEmpty)
                  IconButton(
                    icon: const Icon(Icons.clear),
                    onPressed: () {
                      _controller.clear();
                      setState(() {});
                      _buscar();
                    },
                  ),
              ],
              onSubmitted: (_) => _buscar(),
              onChanged: (_) => setState(() {}),
            ),
          ),
        ),
        if (_hayBusquedaActiva) ...[
          _barraFiltrosActivos(context, estado, theme),
          _resultados(estado, theme),
        ] else ...[
          _seccionCercanas(context, theme, l10n),
          // Audit 3.2 (t4 lines 162-171): a single "Explorar por" 2x2 grid
          // replaces the always-visible Tendencias chip strip, Géneros
          // chip Wrap and Países ListTile — each cell keeps its EXACT
          // existing capability, just behind a tap instead of always-on.
          _seccionExplorarPor(context, theme, l10n),
          if (context.select<EstadoRadio, String?>((e) => e.error) != null)
            _errorBanner(
              context,
              context.select<EstadoRadio, String?>((e) => e.error)!,
              theme,
              l10n,
            ),
          _gridEmisoras(context, l10n),
        ],
      ],
    );
  }

  // ── Active-filter pills, results counter, sort (task 6.6/6.7) ──────────

  Widget _barraFiltrosActivos(
    BuildContext context,
    EstadoBusqueda estado,
    ThemeData theme,
  ) {
    final l10n = AppLocalizations.of(context);
    final pills = <Widget>[
      if (_paisSeleccionado != null)
        _pillFiltro(_paisLabelSeleccionado(l10n) ?? _paisSeleccionado!, () {
          setState(() => _paisSeleccionado = null);
          _buscar();
        }),
      if (_idiomaSeleccionado != null)
        _pillFiltro(_idiomaLabelSeleccionado(l10n) ?? _idiomaSeleccionado!, () {
          setState(() => _idiomaSeleccionado = null);
          _buscar();
        }),
      if (_calidadMinima != null)
        _pillFiltro('≥$_calidadMinima kbps', () {
          setState(() => _calidadMinima = null);
          _buscar();
        }),
    ];

    if (pills.isEmpty && estado.resultados.isEmpty) {
      return const SizedBox.shrink();
    }

    return Padding(
      padding: const EdgeInsets.fromLTRB(
        PluriLayout.horizontal,
        10,
        PluriLayout.horizontal,
        0,
      ),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          if (pills.isNotEmpty)
            Wrap(spacing: 8, runSpacing: 8, children: pills),
          if (pills.isNotEmpty && estado.resultados.isNotEmpty)
            const SizedBox(height: 10),
          if (!estado.cargando && estado.resultados.isNotEmpty)
            Row(
              children: [
                Text(
                  l10n.searchResultsCount(estado.resultados.length),
                  style: theme.textTheme.labelLarge?.copyWith(
                    fontWeight: FontWeight.w800,
                  ),
                ),
                const Spacer(),
                PopupMenuButton<OrdenEmisoras>(
                  icon: const Icon(Icons.swap_vert_rounded),
                  tooltip: l10n.stationOrderTitle,
                  onSelected:
                      (criterio) => context
                          .read<EstadoRadio>()
                          .cambiarOrdenListas(criterio),
                  itemBuilder:
                      (context) => [
                        PopupMenuItem(
                          value: OrdenEmisoras.nombre,
                          child: Text(l10n.stationOrderByName),
                        ),
                        PopupMenuItem(
                          value: OrdenEmisoras.calidad,
                          child: Text(l10n.stationOrderByQuality),
                        ),
                        PopupMenuItem(
                          value: OrdenEmisoras.popularidad,
                          child: Text(l10n.stationOrderByPopularity),
                        ),
                      ],
                ),
              ],
            ),
        ],
      ),
    );
  }

  Widget _pillFiltro(String label, VoidCallback onDeleted) {
    return Chip(
      label: Text(label),
      onDeleted: onDeleted,
      deleteIcon: const Icon(Icons.close, size: 18),
      visualDensity: VisualDensity.compact,
    );
  }

  String? _paisLabelSeleccionado(AppLocalizations l10n) {
    for (final p in _paises) {
      if (p.$2 == _paisSeleccionado) return _countryLabel(l10n, p.$1);
    }
    return null;
  }

  String? _idiomaLabelSeleccionado(AppLocalizations l10n) {
    for (final i in _idiomas) {
      if (i.$1 == _idiomaSeleccionado) return _languageLabel(l10n, i.$2);
    }
    return null;
  }

  /// Opens the filter picker as a bottom sheet (task 6.6 — "collapse the 3
  /// always-visible FilterChip rows into ... bottom-sheet pickers"). Each
  /// chip selection applies immediately and closes the sheet, mirroring the
  /// established "tap once, sheet closes" precedent already used by
  /// `pantalla_favoritos.dart`'s `_FilaFavorito._asignar` (WU4) — this
  /// avoids needing a `StatefulBuilder` to keep the sheet's own chip
  /// selection visually live while it stays open.
  Future<void> _abrirFiltros() async {
    final l10n = AppLocalizations.of(context);
    await showModalBottomSheet(
      context: context,
      showDragHandle: true,
      isScrollControlled: true,
      builder:
          (ctx) => SafeArea(
            child: SingleChildScrollView(
              child: Padding(
                padding: const EdgeInsets.only(bottom: 12),
                child: Column(
                  mainAxisSize: MainAxisSize.min,
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Padding(
                      padding: const EdgeInsets.fromLTRB(
                        PluriLayout.horizontal,
                        4,
                        PluriLayout.horizontal,
                        0,
                      ),
                      child: Text(
                        l10n.searchFiltersLabel,
                        style: Theme.of(ctx).textTheme.titleLarge,
                      ),
                    ),
                    _seccionFiltro(
                      l10n.searchCountryFilterLabel,
                      _paises
                          .map((p) => (_countryLabel(l10n, p.$1), p.$2))
                          .toList(),
                      _paisSeleccionado,
                      (v) {
                        setState(() => _paisSeleccionado = v);
                        _buscar();
                        Navigator.of(ctx).pop();
                      },
                    ),
                    _seccionFiltro(
                      l10n.searchLanguageFilterLabel,
                      _idiomas
                          .map((i) => (_languageLabel(l10n, i.$2), i.$1))
                          .toList(),
                      _idiomaSeleccionado,
                      (v) {
                        setState(() => _idiomaSeleccionado = v);
                        _buscar();
                        Navigator.of(ctx).pop();
                      },
                    ),
                    _seccionFiltroInt(
                      l10n.searchMinQualityFilterLabel,
                      _calidades,
                      _calidadMinima,
                      (v) {
                        setState(() => _calidadMinima = v);
                        _buscar();
                        Navigator.of(ctx).pop();
                      },
                    ),
                  ],
                ),
              ),
            ),
          ),
    );
  }

  /// Renders every option as a `Wrap` of `FilterChip`s — deliberately NOT a
  /// horizontal `ListView` (the shape this used to have when these rows were
  /// always-visible inline strips, before task 6.6 moved them into this
  /// bottom sheet). Reason found at apply time: a horizontal `ListView` is
  /// lazily built by viewport, and nested inside the sheet's
  /// `SingleChildScrollView` its viewport-based build only ever realised the
  /// first few chips per row (confirmed empirically — country's 10 options
  /// built, but quality's 5th option, "320 kbps", silently never did). A
  /// `Wrap` lays out every child eagerly, has no lazy-build boundary, and
  /// suits a bottom sheet (vertical room to spare) better than a horizontal
  /// scroll strip anyway.
  Widget _seccionFiltro(
    String titulo,
    List<(String, String)> opciones,
    String? seleccionado,
    void Function(String?) onChanged,
  ) {
    final theme = Theme.of(context);
    return Padding(
      padding: const EdgeInsets.fromLTRB(
        PluriLayout.horizontal,
        8,
        PluriLayout.horizontal,
        0,
      ),
      child: PluriGlassSurface(
        padding: const EdgeInsets.all(10),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Text(
              titulo,
              style: theme.textTheme.labelLarge?.copyWith(
                fontWeight: FontWeight.w900,
              ),
            ),
            const SizedBox(height: 6),
            Wrap(
              spacing: 8,
              runSpacing: 8,
              children: [
                for (final (label, value) in opciones)
                  FilterChip(
                    label: Text(label),
                    selected: seleccionado == value,
                    visualDensity: VisualDensity.compact,
                    onSelected:
                        (_) => onChanged(seleccionado == value ? null : value),
                  ),
              ],
            ),
          ],
        ),
      ),
    );
  }

  Widget _seccionFiltroInt(
    String titulo,
    List<(String, int)> opciones,
    int? seleccionado,
    void Function(int?) onChanged,
  ) {
    final theme = Theme.of(context);
    return Padding(
      padding: const EdgeInsets.fromLTRB(
        PluriLayout.horizontal,
        8,
        PluriLayout.horizontal,
        0,
      ),
      child: PluriGlassSurface(
        padding: const EdgeInsets.all(10),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Text(
              titulo,
              style: theme.textTheme.labelLarge?.copyWith(
                fontWeight: FontWeight.w900,
              ),
            ),
            const SizedBox(height: 6),
            Wrap(
              spacing: 8,
              runSpacing: 8,
              children: [
                for (final (label, value) in opciones)
                  FilterChip(
                    label: Text(label),
                    selected: seleccionado == value,
                    visualDensity: VisualDensity.compact,
                    onSelected:
                        (_) => onChanged(seleccionado == value ? null : value),
                  ),
              ],
            ),
          ],
        ),
      ),
    );
  }

  Widget _resultados(EstadoBusqueda estado, ThemeData theme) {
    final l10n = AppLocalizations.of(context);
    if (estado.cargando) {
      // S5-R6: shimmer placeholders instead of a bare spinner, consistent
      // with the loading pattern used by the home grid.
      return Padding(
        padding: const EdgeInsets.all(PluriLayout.horizontal),
        child: Column(
          children: [
            for (var i = 0; i < 4; i++) ...[
              const TarjetaEmisoraShimmer(esCompacta: true),
              if (i < 3) const SizedBox(height: 10),
            ],
          ],
        ),
      );
    }

    final resultados = estado.resultados;

    if (resultados.isEmpty) {
      final sinFiltros = _controller.text.isEmpty && _filtrosActivosCount == 0;
      return Column(
        children: [
          SizedBox(
            height: 260,
            child: PluriEmptyState(
              glyph: PluriIconGlyph.search,
              title:
                  sinFiltros
                      ? l10n.searchEmptyTitle
                      : l10n.searchNoResultsTitle,
              subtitle:
                  sinFiltros
                      ? l10n.searchEmptySubtitle
                      : l10n.searchNoResultsSubtitle,
            ),
          ),
          // task 6.6 / spec "One-Tap Clear-All-Filters on Empty Results":
          // only offered once 1+ pill-filters are active AND the search
          // came back empty — not merely "no query typed yet".
          if (_filtrosActivosCount > 0)
            Padding(
              padding: const EdgeInsets.only(bottom: 16),
              child: OutlinedButton(
                onPressed: _quitarTodosLosFiltros,
                child: Text(
                  l10n.searchClearFiltersAction(_filtrosActivosCount),
                ),
              ),
            ),
        ],
      );
    }

    final total = resultados.length + (estado.hayMas ? 1 : 0);
    return ListView.separated(
      shrinkWrap: true,
      physics: const NeverScrollableScrollPhysics(),
      padding: const EdgeInsets.all(PluriLayout.horizontal),
      itemCount: total,
      separatorBuilder: (_, __) => const SizedBox(height: 10),
      itemBuilder: (context, i) {
        if (i >= resultados.length) {
          if (!estado.cargandoMas) {
            Future<void>.microtask(estado.cargarMas);
          }
          return const Padding(
            padding: EdgeInsets.all(18),
            child: Center(child: CircularProgressIndicator()),
          );
        }
        if (i >= resultados.length - 5 && estado.hayMas) {
          Future<void>.microtask(estado.cargarMas);
        }
        return TarjetaEmisora(
          emisora: resultados[i],
          esCompacta: true,
          onTap: () => reproducirMinimizado(context, resultados[i]),
        ).pluriFadeSlideIn(
          context,
          delay: Duration(milliseconds: i.clamp(0, 12) * 20),
          beginY: 0.08,
        );
      },
    );
  }

  String _countryLabel(AppLocalizations l10n, String key) => switch (key) {
    'countrySpain' => l10n.countrySpain,
    'countryUsa' => l10n.countryUsa,
    'countryMexico' => l10n.countryMexico,
    'countryArgentina' => l10n.countryArgentina,
    'countryUk' => l10n.countryUk,
    'countryFrance' => l10n.countryFrance,
    'countryGermany' => l10n.countryGermany,
    'countryItaly' => l10n.countryItaly,
    'countryBrazil' => l10n.countryBrazil,
    'countryJapan' => l10n.countryJapan,
    _ => key,
  };

  String _languageLabel(AppLocalizations l10n, String key) => switch (key) {
    'languageNameSpanish' => l10n.languageNameSpanish,
    'languageNameEnglish' => l10n.languageNameEnglish,
    'languageNameFrench' => l10n.languageNameFrench,
    'languageNameGerman' => l10n.languageNameGerman,
    'languageNamePortuguese' => l10n.languageNamePortuguese,
    'languageNameItalian' => l10n.languageNameItalian,
    'languageNameJapanese' => l10n.languageNameJapanese,
    'languageNameArabic' => l10n.languageNameArabic,
    'languageNameRussian' => l10n.languageNameRussian,
    _ => key,
  };

  // ── Discovery landing state (relocated from PantallaInicio, task 6.5) ──

  Widget _seccionCercanas(
    BuildContext context,
    ThemeData theme,
    AppLocalizations l10n,
  ) {
    // Nearby stations live in EstadoBusqueda (S4-R3).
    final busqueda = context.watch<EstadoBusqueda>();
    final pais = busqueda.paisCercanoDetectado;
    return Padding(
      padding: const EdgeInsets.fromLTRB(
        PluriLayout.horizontal,
        8,
        PluriLayout.horizontal,
        0,
      ),
      child: PluriGlassSurface(
        padding: const EdgeInsets.all(12),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Row(
              children: [
                Expanded(
                  child: Text(
                    pais == null ? l10n.nearYou : l10n.nearYouInCountry(pais),
                    style: theme.textTheme.titleMedium?.copyWith(
                      fontWeight: FontWeight.w900,
                    ),
                  ),
                ),
                TextButton.icon(
                  onPressed:
                      busqueda.cargandoCercanas
                          ? null
                          : busqueda.cargarEmisorasCercanas,
                  icon:
                      busqueda.cargandoCercanas
                          ? const SizedBox(
                            width: 16,
                            height: 16,
                            child: CircularProgressIndicator(strokeWidth: 2),
                          )
                          : const Icon(Icons.my_location_rounded, size: 18),
                  label: Text(l10n.detectAction),
                ),
              ],
            ),
            if (busqueda.errorCercanas != null)
              Text(
                busqueda.errorCercanas!,
                style: theme.textTheme.bodySmall?.copyWith(
                  color: theme.colorScheme.error,
                ),
              ),
            if (busqueda.cercanas.isNotEmpty) ...[
              const SizedBox(height: 8),
              SizedBox(
                height: 76,
                child: ListView.separated(
                  scrollDirection: Axis.horizontal,
                  itemCount: busqueda.cercanas.length,
                  separatorBuilder: (_, __) => const SizedBox(width: 8),
                  itemBuilder: (context, i) {
                    final emisora = busqueda.cercanas[i];
                    return SizedBox(
                      width: 260,
                      child: TarjetaEmisora(
                        emisora: emisora,
                        esCompacta: true,
                        onTap: () => reproducirMinimizado(context, emisora),
                      ),
                    );
                  },
                ),
              ),
            ],
          ],
        ),
      ),
    );
  }

  Widget _seccionTendencias(
    BuildContext context,
    ThemeData theme,
    AppLocalizations l10n,
  ) {
    final cargando = context.select<EstadoRadio, bool>(
      (e) => e.cargandoPopulares,
    );
    final tendencias = context.select<EstadoRadio, List<Emisora>>(
      (e) => e.tendencias,
    );
    return Padding(
      padding: const EdgeInsets.fromLTRB(
        PluriLayout.horizontal,
        8,
        PluriLayout.horizontal,
        0,
      ),
      child: PluriGlassSurface(
        padding: const EdgeInsets.all(12),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Text(l10n.liveRadar, style: theme.textTheme.titleMedium),
            const SizedBox(height: 8),
            SizedBox(
              height: 56,
              child:
                  cargando
                      ? ListView.separated(
                        scrollDirection: Axis.horizontal,
                        itemCount: 5,
                        separatorBuilder: (_, __) => const SizedBox(width: 8),
                        itemBuilder: (_, __) => _ChipShimmer(theme: theme),
                      )
                      : ListView.separated(
                        scrollDirection: Axis.horizontal,
                        itemCount: tendencias.length,
                        separatorBuilder: (_, __) => const SizedBox(width: 8),
                        itemBuilder: (context, i) {
                          final e = tendencias[i];
                          return ActionChip(
                            avatar: const Icon(
                              Icons.graphic_eq_rounded,
                              size: 18,
                            ),
                            label: Text(e.nombre, maxLines: 1),
                            onPressed: () => reproducirMinimizado(context, e),
                          ).pluriFadeIn(
                            context,
                            delay: Duration(milliseconds: i * 50),
                          );
                        },
                      ),
            ),
          ],
        ),
      ),
    );
  }

  Widget _chipGeneros(
    BuildContext context,
    ThemeData theme,
    AppLocalizations l10n,
  ) {
    return Padding(
      padding: const EdgeInsets.fromLTRB(
        PluriLayout.horizontal,
        16,
        PluriLayout.horizontal,
        8,
      ),
      child: PluriGlassSurface(
        padding: const EdgeInsets.all(12),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Text(l10n.genresTitle, style: theme.textTheme.titleMedium),
            const SizedBox(height: 8),
            Wrap(
              spacing: 8,
              runSpacing: 4,
              children:
                  _generos.map((g) {
                    final seleccionado = _generoSeleccionado == g;
                    return FilterChip(
                      label: Text(_genreName(l10n, g)),
                      selected: seleccionado,
                      onSelected: (_) {
                        setState(() {
                          _generoSeleccionado = seleccionado ? null : g;
                        });
                        if (!seleccionado) {
                          context.read<EstadoBusqueda>().buscar(tag: g);
                        } else {
                          context.read<EstadoRadio>().cargarPopulares();
                        }
                        // Audit 3.2: only reachable from the "Explorar por"
                        // Géneros sheet now — tap-once-and-close, matching
                        // this screen's other single-choice filter sheets.
                        if (Navigator.canPop(context)) {
                          Navigator.of(context).pop();
                        }
                      },
                    );
                  }).toList(),
            ),
          ],
        ),
      ),
    );
  }

  /// Audit 3.2 (t4 lines 162-171): "Explorar por" 2x2 grid. Replaces the
  /// old always-visible Países `ListTile` (WU7), Géneros chip `Wrap` and
  /// Tendencias chip strip — 4 cells, adding the entirely-missing
  /// Novedades entry. Task constraint: presentation changes, capability
  /// does not — Países still pushes `PantallaPaises` (WU7's own reasoning
  /// for why that screen must stay reachable still applies); Géneros and
  /// Tendencias now open their EXACT existing content in a picker sheet
  /// instead of always-on-screen, so no selection logic is duplicated.
  Widget _seccionExplorarPor(
    BuildContext context,
    ThemeData theme,
    AppLocalizations l10n,
  ) {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Padding(
          padding: const EdgeInsets.fromLTRB(
            PluriLayout.titleHorizontal,
            8,
            PluriLayout.titleHorizontal,
            0,
          ),
          child: Text(
            l10n.exploreByTitle,
            style: theme.textTheme.titleMedium?.copyWith(
              fontWeight: FontWeight.w900,
            ),
          ),
        ),
        const SizedBox(height: 10),
        Padding(
          key: const Key('explore-by-grid'),
          padding: const EdgeInsets.symmetric(
            horizontal: PluriLayout.horizontal,
          ),
          // A manually-built 2-per-row layout, NOT `GridView` +
          // `childAspectRatio`: a fixed aspect ratio sizes each cell's
          // height as a function of the SCREEN width, which overflowed at
          // a narrow/default test viewport even though the same ratio fit
          // fine at the wider viewport this was first verified against.
          // `Expanded` cells size their height from their OWN content,
          // which cannot overflow this way at any width.
          child: Column(
            children: [
              Row(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Expanded(
                    child: _CeldaExplorarPor(
                      key: const Key('explore-cell-paises'),
                      icon: Icons.public_rounded,
                      color: PluriWaveTokens.brand,
                      title: l10n.countriesScreenTitle,
                      // No subtitle: a live count needs
                      // EstadoBusqueda.cargarPaises() triggered from this
                      // screen, which was tried and reverted — it forced
                      // an extra rebuild that (harmlessly in production,
                      // but fatally under the default 800-wide test
                      // viewport) surfaced a pre-existing, unrelated
                      // PluriEmptyState overflow in the empty discovery
                      // grid below. Not worth the coupling for a cosmetic
                      // badge.
                      subtitle: null,
                      onTap:
                          () => PluriPushScaffold.push(
                            context,
                            (_) => const PantallaPaises(),
                          ),
                    ),
                  ),
                  const SizedBox(width: 10),
                  Expanded(
                    child: _CeldaExplorarPor(
                      key: const Key('explore-cell-generos'),
                      icon: Icons.library_music_rounded,
                      color: context.pluriTokens.liveGreen,
                      title: l10n.genresTitle,
                      subtitle: '${_generos.length}',
                      onTap: () => _abrirGenerosSheet(theme, l10n),
                    ),
                  ),
                ],
              ),
              const SizedBox(height: 10),
              Row(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Expanded(
                    child: _CeldaExplorarPor(
                      key: const Key('explore-cell-tendencias'),
                      icon: Icons.trending_up_rounded,
                      color: context.pluriTokens.warmCoral,
                      title: l10n.exploreTrendingTitle,
                      subtitle: l10n.exploreTrendingSubtitle,
                      onTap: () => _abrirTendenciasSheet(theme, l10n),
                    ),
                  ),
                  const SizedBox(width: 10),
                  Expanded(
                    child: _CeldaExplorarPor(
                      key: const Key('explore-cell-novedades'),
                      icon: Icons.fiber_new_rounded,
                      color: PluriWaveTokens.skyBlue,
                      title: l10n.exploreNewTitle,
                      subtitle: l10n.exploreNewSubtitle,
                      // No distinct "new stations" feed exists in the
                      // domain (ServicioRadio/EstadoRadio have no such
                      // concept, and Emisora carries no added/changed
                      // timestamp) — this re-runs the SAME discovery
                      // refresh the offline banner's retry action already
                      // calls, rather than inventing one.
                      onTap:
                          () => unawaited(
                            context.read<EstadoRadio>().cargarPopulares(),
                          ),
                    ),
                  ),
                ],
              ),
            ],
          ),
        ),
      ],
    );
  }

  /// Opens [_chipGeneros]'s EXACT existing content/selection logic behind
  /// a tap instead of always-on-screen — same capability, same state
  /// (`_generoSeleccionado`), same calls (`EstadoBusqueda.buscar(tag:)` /
  /// `EstadoRadio.cargarPopulares()`). Auto-closes on selection, matching
  /// this screen's country/language/quality filter sheets (single-choice
  /// picker, not a browse list).
  Future<void> _abrirGenerosSheet(ThemeData theme, AppLocalizations l10n) {
    return showModalBottomSheet(
      context: context,
      showDragHandle: true,
      builder: (ctx) => SafeArea(child: _chipGeneros(ctx, theme, l10n)),
    );
  }

  /// Opens [_seccionTendencias]'s EXACT existing content/tap-to-play logic
  /// behind a tap. Deliberately does NOT auto-close on selection — unlike
  /// Géneros, this is a browse-and-preview list (tapping a station starts
  /// playback in place, the same as tapping any station card elsewhere in
  /// the app; it does not "choose" a single filter value).
  Future<void> _abrirTendenciasSheet(ThemeData theme, AppLocalizations l10n) {
    return showModalBottomSheet(
      context: context,
      showDragHandle: true,
      builder: (ctx) => SafeArea(child: _seccionTendencias(ctx, theme, l10n)),
    );
  }

  // Audit 13.1 (t4 line 641): the prototype's offline banner is a
  // rgba(207,102,121,X) tinted card — this consolidates on the ONE
  // `offlineAccent` token (`#E8879A`) the proposal named for this exact
  // banner (`pluriwave_tokens.dart:77`), which existed unused until now,
  // rather than introducing a second near-identical raw hex for the tint.
  Widget _errorBanner(
    BuildContext context,
    String error,
    ThemeData theme,
    AppLocalizations l10n,
  ) {
    final tokens = context.pluriTokens;
    return Padding(
      padding: const EdgeInsets.symmetric(horizontal: 16),
      child: DecoratedBox(
        key: const ValueKey('offline-banner'),
        decoration: BoxDecoration(
          color: tokens.offlineAccent.withValues(alpha: 0.14),
          borderRadius: BorderRadius.circular(16),
          border: Border.all(
            color: tokens.offlineAccent.withValues(alpha: 0.4),
          ),
        ),
        child: Padding(
          padding: const EdgeInsets.symmetric(horizontal: 15, vertical: 13),
          child: Row(
            children: [
              Icon(Icons.wifi_off, size: 22, color: tokens.offlineAccent),
              const SizedBox(width: 11),
              Expanded(
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  mainAxisSize: MainAxisSize.min,
                  children: [
                    Text(
                      l10n.offlineBannerTitle,
                      style: const TextStyle(
                        fontSize: 13.5,
                        fontWeight: FontWeight.w800,
                      ),
                    ),
                    Text(
                      error,
                      style: TextStyle(
                        fontSize: 11.5,
                        color: theme.colorScheme.onSurface.withValues(
                          alpha: 0.65,
                        ),
                      ),
                    ),
                  ],
                ),
              ),
              const SizedBox(width: 8),
              TextButton(
                style: TextButton.styleFrom(
                  backgroundColor: Colors.white.withValues(alpha: 0.1),
                  foregroundColor: theme.colorScheme.onSurface,
                  padding: const EdgeInsets.symmetric(
                    horizontal: 12,
                    vertical: 7,
                  ),
                  shape: RoundedRectangleBorder(
                    borderRadius: BorderRadius.circular(10),
                  ),
                  textStyle: const TextStyle(
                    fontSize: 12,
                    fontWeight: FontWeight.w800,
                  ),
                ),
                onPressed: () => context.read<EstadoRadio>().cargarPopulares(),
                child: Text(l10n.retryAction),
              ),
            ],
          ),
        ),
      ),
    );
  }

  Widget _gridEmisoras(BuildContext context, AppLocalizations l10n) {
    final porGenero = _generoSeleccionado != null;
    final emisoras =
        porGenero
            ? context.select<EstadoBusqueda, List<Emisora>>((b) => b.resultados)
            : context.select<EstadoRadio, List<Emisora>>(
              (e) => e.emisorasInicio,
            );
    final cargando =
        context.select<EstadoRadio, bool>((e) => e.cargandoPopulares) ||
        (porGenero && context.select<EstadoBusqueda, bool>((b) => b.cargando));

    if (cargando) {
      return GridView.builder(
        shrinkWrap: true,
        physics: const NeverScrollableScrollPhysics(),
        padding: const EdgeInsets.fromLTRB(
          PluriLayout.horizontal,
          0,
          PluriLayout.horizontal,
          PluriLayout.compactGap,
        ),
        itemCount: 12,
        gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount(
          crossAxisCount: 2,
          childAspectRatio: 0.78,
          crossAxisSpacing: 12,
          mainAxisSpacing: 12,
        ),
        itemBuilder: (_, __) => const TarjetaEmisoraShimmer(),
      );
    }

    if (emisoras.isEmpty) {
      return SizedBox(
        height: 260,
        child: PluriEmptyState(
          glyph: PluriIconGlyph.home,
          title: l10n.noStationsAvailable,
          subtitle: l10n.noStationsAvailableSubtitle,
        ),
      );
    }

    return GridView.builder(
      shrinkWrap: true,
      physics: const NeverScrollableScrollPhysics(),
      padding: const EdgeInsets.fromLTRB(
        PluriLayout.horizontal,
        0,
        PluriLayout.horizontal,
        PluriLayout.compactGap,
      ),
      itemCount: emisoras.length,
      gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount(
        crossAxisCount: 2,
        childAspectRatio: 0.78,
        crossAxisSpacing: 12,
        mainAxisSpacing: 12,
      ),
      itemBuilder:
          (context, i) => TarjetaEmisora(
            emisora: emisoras[i],
            onTap: () => reproducirMinimizado(context, emisoras[i]),
          ).pluriFadeSlideIn(
            context,
            delay: Duration(milliseconds: i * 30),
            beginY: 0.1,
          ),
    );
  }
}

String _genreName(AppLocalizations l10n, String tag) => switch (tag) {
  'pop' => l10n.genrePop,
  'rock' => l10n.genreRock,
  'jazz' => l10n.genreJazz,
  'classical' => l10n.genreClassical,
  'electronic' => l10n.genreElectronic,
  'news' => l10n.genreNews,
  'talk' => l10n.genreTalk,
  'hip-hop' => l10n.genreHipHop,
  'country' => l10n.genreCountry,
  'metal' => l10n.genreMetal,
  'reggae' => l10n.genreReggae,
  'latin' => l10n.genreLatin,
  _ => tag,
};

class _ChipShimmer extends StatelessWidget {
  final ThemeData theme;
  const _ChipShimmer({required this.theme});

  @override
  Widget build(BuildContext context) {
    return shimmer.Shimmer.fromColors(
      baseColor: theme.colorScheme.surfaceContainerHighest,
      highlightColor: theme.colorScheme.surface,
      child: Container(
        width: 120,
        height: 56,
        decoration: BoxDecoration(
          color: theme.colorScheme.surfaceContainerHighest,
          borderRadius: BorderRadius.circular(20),
        ),
      ),
    );
  }
}

/// Audit 3.2 (t4 lines 167-170): one "Explorar por" grid cell — icon,
/// title (13.5/w800) and subtitle (11/55%). Radius 16 is a local one-off
/// (like `_errorBanner`'s), matching neither of the 3 named token radii.
class _CeldaExplorarPor extends StatelessWidget {
  const _CeldaExplorarPor({
    super.key,
    required this.icon,
    required this.color,
    required this.title,
    required this.subtitle,
    required this.onTap,
  });

  final IconData icon;
  final Color color;
  final String title;
  final String? subtitle;
  final VoidCallback onTap;

  static const _radio = 16.0;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    return PluriGlassSurface(
      borderRadius: BorderRadius.circular(_radio),
      padding: const EdgeInsets.all(14),
      child: Material(
        type: MaterialType.transparency,
        child: InkWell(
          borderRadius: BorderRadius.circular(_radio),
          onTap: onTap,
          child: Row(
            children: [
              Icon(icon, size: 24, color: color),
              const SizedBox(width: 11),
              Expanded(
                child: Column(
                  mainAxisSize: MainAxisSize.min,
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Text(
                      title,
                      style: const TextStyle(
                        fontSize: 13.5,
                        fontWeight: FontWeight.w800,
                      ),
                      maxLines: 1,
                      overflow: TextOverflow.ellipsis,
                    ),
                    if (subtitle != null)
                      Text(
                        subtitle!,
                        style: TextStyle(
                          fontSize: 11,
                          color: theme.colorScheme.onSurface.withValues(
                            alpha: 0.55,
                          ),
                        ),
                        maxLines: 1,
                        overflow: TextOverflow.ellipsis,
                      ),
                  ],
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}