addCustomLocale method

Future<void> addCustomLocale({ required String localeCode, required String direction, List<String>? existingLocales, })

T038: Adds a custom locale with ISO validation and direction specification. Validates locale code against ISO standards, checks for duplicates, and stores direction. Also verifies that the specified direction is consistent with the language's natural direction.

Implementation

Future<void> addCustomLocale({
  required String localeCode,
  required String direction, // 'ltr' or 'rtl'
  List<String>? existingLocales,
}) async {
  // Normalize the locale code (convert hyphens to underscores, lowercase)
  final normalized = localeCode.trim().replaceAll('-', '_').toLowerCase();

  if (normalized.isEmpty) {
    throw CatalogOperationException('Locale code cannot be empty.');
  }

  // Check if locale already exists
  final dataset = await _repository.load();
  if (dataset.locales.contains(normalized)) {
    throw CatalogOperationException('Locale "$normalized" already exists.');
  }

  // Validate direction
  if (direction != 'ltr' && direction != 'rtl') {
    throw CatalogOperationException('Direction must be "ltr" or "rtl".');
  }

  // FR-007: Verify text direction is consistent with the language
  // Check if the direction conflicts with the language's natural direction
  final languageCode = getLanguageCode(normalized);
  const rtlLanguages = {
    'ar', // Arabic
    'fa', // Farsi/Persian
    'he', // Hebrew
    'ku', // Kurdish
    'ps', // Pashto
    'sd', // Sindhi
    'ur', // Urdu
    'yi', // Yiddish
  };

  final isRtlLanguage = rtlLanguages.contains(languageCode);
  final isRtlDirection = direction == 'rtl';

  // Check for direction mismatch with known language directionality
  // RTL languages should use 'rtl', LTR languages should use 'ltr'
  if (isRtlLanguage && !isRtlDirection) {
    throw CatalogOperationException(
      'Locale "$normalized" is an RTL language ($languageCode) '
      'but was assigned LTR direction. RTL languages must use RTL direction.',
    );
  } else if (!isRtlLanguage && isRtlDirection) {
    throw CatalogOperationException(
      'Locale "$normalized" is an LTR language ($languageCode) '
      'but was assigned RTL direction. LTR languages must use LTR direction.',
    );
  }

  // Create the locale file
  await _repository.createLocaleFile(normalized);

  // Store custom locale direction in state
  final state = await _stateStore.load(
    config: config,
    projectRootPath: projectRootPath,
  );

  final updatedDirections = Map<String, String>.from(state.customLocaleDirections);
  updatedDirections[normalized] = direction;

  final updatedState = state.copyWith(customLocaleDirections: updatedDirections);
  await _stateStore.save(
    config: config,
    projectRootPath: projectRootPath,
    state: updatedState,
  );
}