import 'dart:convert';

import 'package:shared_preferences/shared_preferences.dart';

import '../modelos/preset_ecualizador.dart';
import 'persistencia_tolerante.dart';
import 'servicio_dispositivo_audio.dart'
    show idAltavozInterno, prefijoDispositivoOtro;

class ConfiguracionEcualizador {
  const ConfiguracionEcualizador({
    required this.principal,
    required this.porEmisora,
    this.activo = true,
    this.eqMultiDeviceEnabled = false,
    this.presetsDispositivo = const {},
    this.presetsMatriz = const {},
    this.nombresDispositivos = const {},
  });

  final PresetEcualizador principal;
  final Map<String, PresetEcualizador> porEmisora;
  final bool activo;

  /// Feature toggle: when false all multi-device logic is bypassed.
  final bool eqMultiDeviceEnabled;

  /// Per-device presets: deviceId → PresetEcualizador.
  final Map<String, PresetEcualizador> presetsDispositivo;

  /// Matrix presets: "stationUuid:deviceId" → PresetEcualizador.
  final Map<String, PresetEcualizador> presetsMatriz;

  /// Custom display names for devices: deviceId → custom name.
  final Map<String, String> nombresDispositivos;
}

class ServicioEcualizador {
  ServicioEcualizador({SharedPreferences? prefs}) : _prefs = prefs;

  static const _keyPresetPrincipal = 'eq_preset_principal_v1';
  static const _keyPresetsPorEmisora = 'eq_presets_por_emisora_v1';
  static const _keyActivo = 'eq_activo_v1';
  static const _keyMultiDeviceEnabled = 'eq_multi_device_enabled_v1';
  static const _keyPresetsPorDispositivo = 'eq_preset_por_dispositivo_v1';
  static const _keyPresetsMatriz = 'eq_presets_matriz_v1';
  static const _keyNombresDispositivos = 'eq_nombres_dispositivos_v1';

  /// bt-device-identity ADR-5: guard flag for the one-time placeholder purge.
  static const _keyPlaceholderPurgaHecha = 'eq_placeholder_purge_done_v1';

  /// bt-device-identity ADR-3: the exact OS placeholder MAC, in the
  /// `bt_a2dp:`-prefixed id shape used across all device-keyed SP maps.
  static const _placeholderMacLiteral = 'bt_a2dp:02:00:00:00:00:00';

  /// Guard flag for the one-time `builtin_speaker` collision purge.
  static const _keyColisionBasePurgaHecha = 'eq_builtin_speaker_purge_done_v1';

  final SharedPreferences? _prefs;

  /// Injected startup instance (S3-R4); getInstance() is only a fallback.
  Future<SharedPreferences> _resolverPrefs() async =>
      _prefs ?? SharedPreferences.getInstance();

  Future<ConfiguracionEcualizador> cargar() async {
    await migrarClavesPlaceholder();
    await migrarColisionAltavozInterno();
    final prefs = await _resolverPrefs();
    final principal = _leerPresetPrincipal(prefs);
    final porEmisora = _leerPresetsPorEmisora(prefs);
    final presetsDispositivo = _leerMapa(prefs, _keyPresetsPorDispositivo);
    final presetsMatriz = _leerMapa(prefs, _keyPresetsMatriz);
    final nombresDispositivos = _leerMapaStrings(
      prefs,
      _keyNombresDispositivos,
    );
    return ConfiguracionEcualizador(
      principal: principal,
      porEmisora: porEmisora,
      activo: prefs.getBool(_keyActivo) ?? true,
      eqMultiDeviceEnabled: prefs.getBool(_keyMultiDeviceEnabled) ?? false,
      presetsDispositivo: presetsDispositivo,
      presetsMatriz: presetsMatriz,
      nombresDispositivos: nombresDispositivos,
    );
  }

  /// One-time guarded migration (bt-device-identity ADR-5): purges entries
  /// keyed by the exact OS placeholder MAC ([_placeholderMacLiteral]) from
  /// all three device-keyed SP maps. Idempotent — short-circuits via
  /// [_keyPlaceholderPurgaHecha] after the first successful run. Every other
  /// entry (including near-miss keys) is preserved byte-for-byte.
  Future<void> migrarClavesPlaceholder() async {
    final prefs = await _resolverPrefs();
    if (prefs.getBool(_keyPlaceholderPurgaHecha) ?? false) return;
    await _purgarDeviceId(prefs, _placeholderMacLiteral);
    await prefs.setBool(_keyPlaceholderPurgaHecha, true);
  }

  /// One-time guarded migration: purges entries keyed by [idAltavozInterno].
  ///
  /// `MainActivity.deviceToMap` used to hand the phone-speaker id to ANY output
  /// type it could not name (LE Audio, car bus, dock). Dart then created a
  /// device entry under that id, and from then on every playback through the
  /// phone's own speaker matched it — permanently flagging whatever the user
  /// had renamed it to as the active device. The native id is fixed; this
  /// clears what the collision already persisted. Idempotent via
  /// [_keyColisionBasePurgaHecha]; every other entry survives byte-for-byte.
  Future<void> migrarColisionAltavozInterno() async {
    final prefs = await _resolverPrefs();
    if (prefs.getBool(_keyColisionBasePurgaHecha) ?? false) return;
    await _purgarDeviceId(prefs, idAltavozInterno);
    await _purgarPrefijoDispositivo(prefs, prefijoDispositivoOtro);
    await prefs.setBool(_keyColisionBasePurgaHecha, true);
  }

  /// Removes every device-keyed entry whose id starts with [prefijo].
  ///
  /// Used for the `other:` namespace: a build that ranked every unlisted
  /// `AudioDeviceInfo` type above the phone speaker selected permanent internal
  /// sinks (TYPE_FM on Xiaomi, TYPE_BUILTIN_SPEAKER_SAFE elsewhere) as the
  /// active output and persisted rows for them. Genuine external outputs in
  /// this namespace are re-registered on their next connection, so clearing the
  /// whole prefix costs nothing and needs no per-type knowledge here.
  Future<void> _purgarPrefijoDispositivo(
    SharedPreferences prefs,
    String prefijo,
  ) async {
    final presetsPorDispositivo = _leerMapa(prefs, _keyPresetsPorDispositivo);
    final dispositivos =
        presetsPorDispositivo.keys
            .where((clave) => clave.startsWith(prefijo))
            .toList();

    final nombres = _leerMapaStrings(prefs, _keyNombresDispositivos);
    final nombresAPurgar =
        nombres.keys.where((clave) => clave.startsWith(prefijo)).toList();

    final matriz = _leerMapa(prefs, _keyPresetsMatriz);
    final matrizAPurgar =
        matriz.keys.where((clave) {
          final separador = clave.indexOf(':');
          if (separador == -1) return false;
          return clave.substring(separador + 1).startsWith(prefijo);
        }).toList();

    for (final clave in dispositivos) {
      presetsPorDispositivo.remove(clave);
    }
    for (final clave in nombresAPurgar) {
      nombres.remove(clave);
    }
    for (final clave in matrizAPurgar) {
      matriz.remove(clave);
    }

    if (dispositivos.isNotEmpty) {
      await _guardarMapa(
        prefs,
        _keyPresetsPorDispositivo,
        presetsPorDispositivo,
      );
    }
    if (nombresAPurgar.isNotEmpty) {
      await _guardarMapaStrings(prefs, _keyNombresDispositivos, nombres);
    }
    if (matrizAPurgar.isNotEmpty) {
      await _guardarMapa(prefs, _keyPresetsMatriz, matriz);
    }
  }

  /// Removes every trace of [deviceId] from the three device-keyed SP maps.
  ///
  /// Shared by the guarded migrations and by [eliminarDispositivo]; each map is
  /// only rewritten when the key was actually present.
  Future<void> _purgarDeviceId(SharedPreferences prefs, String deviceId) async {
    final presetsPorDispositivo = _leerMapa(prefs, _keyPresetsPorDispositivo);
    if (presetsPorDispositivo.remove(deviceId) != null) {
      await _guardarMapa(
        prefs,
        _keyPresetsPorDispositivo,
        presetsPorDispositivo,
      );
    }

    // Matrix keys are "stationUuid:deviceId"; split on the FIRST colon only
    // (station UUIDs are RFC4122 and contain no colons — multi-device-eq
    // ADR-3), since deviceId itself may contain colons (e.g. a MAC-based id).
    final presetsMatriz = _leerMapa(prefs, _keyPresetsMatriz);
    final clavesMatrizAPurgar =
        presetsMatriz.keys.where((clave) {
          final separador = clave.indexOf(':');
          if (separador == -1) return false;
          return clave.substring(separador + 1) == deviceId;
        }).toList();
    if (clavesMatrizAPurgar.isNotEmpty) {
      for (final clave in clavesMatrizAPurgar) {
        presetsMatriz.remove(clave);
      }
      await _guardarMapa(prefs, _keyPresetsMatriz, presetsMatriz);
    }

    final nombresDispositivos = _leerMapaStrings(
      prefs,
      _keyNombresDispositivos,
    );
    if (nombresDispositivos.remove(deviceId) != null) {
      await _guardarMapaStrings(
        prefs,
        _keyNombresDispositivos,
        nombresDispositivos,
      );
    }
  }

  /// Forgets a device completely: its preset, its custom name and every matrix
  /// entry that targets it. Used by the "remove device" action so the user can
  /// clear stale or duplicate entries from the known-devices list.
  Future<void> eliminarDispositivo(String deviceId) async {
    final prefs = await _resolverPrefs();
    await _purgarDeviceId(prefs, deviceId);
  }

  Future<void> guardarPrincipal(PresetEcualizador preset) async {
    final prefs = await _resolverPrefs();
    await prefs.setString(_keyPresetPrincipal, jsonEncode(preset.toJson()));
  }

  Future<void> guardarPorEmisora(String uuid, PresetEcualizador preset) async {
    final prefs = await _resolverPrefs();
    final mapa = _leerPresetsPorEmisora(prefs);
    mapa[uuid] = preset;
    await _guardarPresetsPorEmisora(prefs, mapa);
  }

  Future<void> guardarActivo(bool activo) async {
    final prefs = await _resolverPrefs();
    await prefs.setBool(_keyActivo, activo);
  }

  Future<void> eliminarPorEmisora(String uuid) async {
    final prefs = await _resolverPrefs();
    final mapa = _leerPresetsPorEmisora(prefs);
    mapa.remove(uuid);
    await _guardarPresetsPorEmisora(prefs, mapa);
  }

  Future<void> guardarConfiguracion(ConfiguracionEcualizador config) async {
    final prefs = await _resolverPrefs();
    await prefs.setString(
      _keyPresetPrincipal,
      jsonEncode(config.principal.toJson()),
    );
    await _guardarPresetsPorEmisora(prefs, config.porEmisora);
    await prefs.setBool(_keyActivo, config.activo);
    await prefs.setBool(_keyMultiDeviceEnabled, config.eqMultiDeviceEnabled);
    await _guardarMapa(
      prefs,
      _keyPresetsPorDispositivo,
      config.presetsDispositivo,
    );
    await _guardarMapa(prefs, _keyPresetsMatriz, config.presetsMatriz);
    await _guardarMapaStrings(
      prefs,
      _keyNombresDispositivos,
      config.nombresDispositivos,
    );
  }

  /// Persists the multi-device feature toggle.
  Future<void> guardarToggleMultiDispositivo(bool habilitado) async {
    final prefs = await _resolverPrefs();
    await prefs.setBool(_keyMultiDeviceEnabled, habilitado);
  }

  /// Saves a per-device preset.
  Future<void> guardarPresetDispositivo(
    String deviceId,
    PresetEcualizador preset,
  ) async {
    final prefs = await _resolverPrefs();
    final mapa = _leerMapa(prefs, _keyPresetsPorDispositivo);
    mapa[deviceId] = preset;
    await _guardarMapa(prefs, _keyPresetsPorDispositivo, mapa);
  }

  /// Saves a matrix (stationUuid:deviceId) preset entry.
  Future<void> guardarPresetMatriz(
    String clave,
    PresetEcualizador preset,
  ) async {
    final prefs = await _resolverPrefs();
    final mapa = _leerMapa(prefs, _keyPresetsMatriz);
    mapa[clave] = preset;
    await _guardarMapa(prefs, _keyPresetsMatriz, mapa);
  }

  /// Removes a per-device preset entry.
  Future<void> eliminarPresetDispositivo(String deviceId) async {
    final prefs = await _resolverPrefs();
    final mapa = _leerMapa(prefs, _keyPresetsPorDispositivo);
    mapa.remove(deviceId);
    await _guardarMapa(prefs, _keyPresetsPorDispositivo, mapa);
  }

  /// Removes a matrix preset entry.
  Future<void> eliminarPresetMatriz(String clave) async {
    final prefs = await _resolverPrefs();
    final mapa = _leerMapa(prefs, _keyPresetsMatriz);
    mapa.remove(clave);
    await _guardarMapa(prefs, _keyPresetsMatriz, mapa);
  }

  /// Returns the persisted device custom names map.
  Future<Map<String, String>> cargarNombresDispositivos() async {
    final prefs = await _resolverPrefs();
    return _leerMapaStrings(prefs, _keyNombresDispositivos);
  }

  /// Persists the device custom names map.
  Future<void> guardarNombresDispositivos(Map<String, String> nombres) async {
    final prefs = await _resolverPrefs();
    await _guardarMapaStrings(prefs, _keyNombresDispositivos, nombres);
  }

  /// Reads a `Map<String, PresetEcualizador>` from a SharedPreferences JSON
  /// key with per-entry tolerance (persistence-resilience D6): a value that
  /// fails to parse is skipped and logged, its sibling entries survive and
  /// every surviving key (including the matrix's colon-delimited
  /// `stationUuid:deviceId` keys) is preserved byte-for-byte. A top-level
  /// decode failure still degrades the whole map to empty (now logged too);
  /// no flag/quarantine here — EQ presets are explicit-only writes and
  /// trivially re-creatable (D6, intentional asymmetry vs. Alarms/Stations).
  Map<String, PresetEcualizador> _leerMapa(
    SharedPreferences prefs,
    String key,
  ) {
    final raw = prefs.getString(key);
    if (raw == null || raw.isEmpty) return {};
    try {
      final data = Map<String, dynamic>.from(jsonDecode(raw) as Map);
      final resultado = parseMapaTolerante<PresetEcualizador>(
        data,
        (valor) => PresetEcualizador.desdeJson(
          Map<String, dynamic>.from(valor as Map),
        ),
        subsistema: 'ecualizador',
        coleccion: key,
      );
      return resultado.validas;
    } catch (e) {
      registrarSaltoPersistencia(
        subsistema: 'ecualizador',
        detalle: key,
        razon: e.toString(),
      );
      return {};
    }
  }

  Future<void> _guardarMapa(
    SharedPreferences prefs,
    String key,
    Map<String, PresetEcualizador> mapa,
  ) async {
    final serializado = mapa.map((k, v) => MapEntry(k, v.toJson()));
    await prefs.setString(key, jsonEncode(serializado));
  }

  /// Reads a `Map<String, String>` from a SharedPreferences JSON key with
  /// per-entry tolerance (persistence-resilience D6): a value that is not a
  /// String is skipped and logged, sibling entries and keys survive
  /// untouched. A top-level decode failure still degrades the whole map to
  /// empty (now logged too); no flag/quarantine here (D6).
  Map<String, String> _leerMapaStrings(SharedPreferences prefs, String key) {
    final raw = prefs.getString(key);
    if (raw == null || raw.isEmpty) return {};
    try {
      final data = Map<String, dynamic>.from(jsonDecode(raw) as Map);
      final resultado = parseMapaTolerante<String>(
        data,
        (valor) => valor as String,
        subsistema: 'ecualizador',
        coleccion: key,
      );
      return resultado.validas;
    } catch (e) {
      registrarSaltoPersistencia(
        subsistema: 'ecualizador',
        detalle: key,
        razon: e.toString(),
      );
      return {};
    }
  }

  Future<void> _guardarMapaStrings(
    SharedPreferences prefs,
    String key,
    Map<String, String> mapa,
  ) async {
    await prefs.setString(key, jsonEncode(mapa));
  }

  /// Reads the single principal-preset key. Single-value (not a collection)
  /// so there is nothing to skip per-entry; a decode failure still falls
  /// back to [PresetEcualizador.flat] (unchanged behavior) but is now
  /// logged too (persistence-resilience D6, diagnostics).
  PresetEcualizador _leerPresetPrincipal(SharedPreferences prefs) {
    final raw = prefs.getString(_keyPresetPrincipal);
    if (raw == null || raw.isEmpty) {
      return PresetEcualizador.flat;
    }
    try {
      return PresetEcualizador.desdeJson(
        Map<String, dynamic>.from(jsonDecode(raw) as Map),
      );
    } catch (e) {
      registrarSaltoPersistencia(
        subsistema: 'ecualizador',
        detalle: _keyPresetPrincipal,
        razon: e.toString(),
      );
      return PresetEcualizador.flat;
    }
  }

  /// Reads the per-station preset map with per-entry tolerance
  /// (persistence-resilience D6) via the same shared helper as [_leerMapa];
  /// a station whose preset value fails to parse is skipped and logged, its
  /// siblings survive under their original uuid keys.
  Map<String, PresetEcualizador> _leerPresetsPorEmisora(
    SharedPreferences prefs,
  ) {
    final raw = prefs.getString(_keyPresetsPorEmisora);
    if (raw == null || raw.isEmpty) {
      return {};
    }
    try {
      final data = Map<String, dynamic>.from(jsonDecode(raw) as Map);
      final resultado = parseMapaTolerante<PresetEcualizador>(
        data,
        (valor) => PresetEcualizador.desdeJson(
          Map<String, dynamic>.from(valor as Map),
        ),
        subsistema: 'ecualizador',
        coleccion: _keyPresetsPorEmisora,
      );
      return resultado.validas;
    } catch (e) {
      registrarSaltoPersistencia(
        subsistema: 'ecualizador',
        detalle: _keyPresetsPorEmisora,
        razon: e.toString(),
      );
      return {};
    }
  }

  Future<void> _guardarPresetsPorEmisora(
    SharedPreferences prefs,
    Map<String, PresetEcualizador> mapa,
  ) async {
    final serializado = mapa.map(
      (uuid, preset) => MapEntry(uuid, preset.toJson()),
    );
    await prefs.setString(_keyPresetsPorEmisora, jsonEncode(serializado));
  }
}