import 'package:flutter/foundation.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:hl_lieferservice/bloc/app_events.dart';
import 'package:hl_lieferservice/bloc/app_states.dart';
import 'package:hl_lieferservice/data/network/backend_config.dart';
import 'package:hl_lieferservice/data/network/backend_environment.dart';
import 'package:hl_lieferservice/data/network/environment_repository.dart';

/// Aktiviert das Networking für eine Umgebung (Registrierung im Locator).
typedef EnvironmentActivator = void Function(BackendConfig config);

/// App-Bootstrap-Bloc.
///
/// Liest die Server-Umgebungen aus `assets/hl_server_config.json`,
/// bestimmt die aktive Umgebung (gespeicherte Wahl, sonst Default) und
/// registriert dafür das Networking. Ein Umgebungswechsel läuft über
/// denselben Weg; die UI baut ihren Bloc-Baum pro Umgebung neu auf.
class AppBloc extends Bloc<AppEvents, AppState> {
  AppBloc({
    required EnvironmentRepository repository,
    required EnvironmentActivator activate,
  })  : _repository = repository,
        _activate = activate,
        super(const AppInitial()) {
    on<AppLoadConfig>(_onLoad);
    on<AppSwitchEnvironment>(_onSwitch);
  }

  final EnvironmentRepository _repository;
  final EnvironmentActivator _activate;

  Future<void> _onLoad(AppLoadConfig event, Emitter<AppState> emit) async {
    emit(const AppConfigLoading());
    try {
      final catalog = await _repository.loadCatalog('assets/${event.path}');
      final storedId = await _repository.loadSelectedId();
      // Unbekannte ID (Umgebung aus der Config entfernt) → Default.
      final active = catalog.byId(storedId) ?? catalog.defaultEnvironment;
      _activate(catalog.configFor(active));
      emit(AppConfigLoaded(catalog: catalog, active: active));
    } catch (e, st) {
      debugPrint('AppBloc: Server-Config nicht ladbar: $e\n$st');
      emit(AppConfigLoadingFailed(
        message: 'Server-Konfiguration konnte nicht geladen werden.\n$e',
      ));
    }
  }

  Future<void> _onSwitch(
    AppSwitchEnvironment event,
    Emitter<AppState> emit,
  ) async {
    final current = state;
    if (current is! AppConfigLoaded) return;
    if (current.active.id == event.environmentId) return;

    final BackendEnvironment? next = current.catalog.byId(event.environmentId);
    if (next == null) return;

    await _repository.saveSelectedId(next.id);
    _activate(current.catalog.configFor(next));
    emit(AppConfigLoaded(catalog: current.catalog, active: next));
  }
}