/// Application-level runtime configuration.
class AppConfig {
  AppConfig._();

  static const String _defaultBaseUrl = String.fromEnvironment(
    'BACKEND_BASE_URL',
    defaultValue: 'https://api.example.com',
  );

  static String? _baseUrlOverride;

  /// Returns the configured backend base URL.
  static String get backendBaseUrl {
    final String? override = _baseUrlOverride;
    if (override != null && override.trim().isNotEmpty) {
      return override.trim();
    }
    return _defaultBaseUrl;
  }

  /// Enables fake backend implementation for local/offline development.
  static bool get useFakeBackend =>
      const bool.fromEnvironment('USE_FAKE_BACKEND', defaultValue: true);

  /// Runtime override for backend URL (e.g. local settings screen).
  static void overrideBackendBaseUrl(String? baseUrl) {
    _baseUrlOverride = baseUrl;
  }
}