packages/flutter/lib/src/material/material_localizations.dart

// Copyright 2017 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'dart:async';

import 'package:flutter/foundation.dart';
import 'package:flutter/widgets.dart';
import 'package:intl/intl.dart';

import 'i18n/localizations.dart';

/// Defines the localized resource values used by the Material widgts.
///
/// See also:
///
///  * [DefaultMaterialLocalizations], which implements this interface
///    and supports a variety of locales.
abstract class MaterialLocalizations {
  /// The tooltip for the leading [AppBar] menu (aka 'hamburger') button.
  String get openAppDrawerTooltip;

  /// The [BackButton]'s tooltip.
  String get backButtonTooltip;

  /// The [CloseButton]'s tooltip.
  String get closeButtonTooltip;

  /// The tooltip for the [MonthPicker]'s "next month" button.
  String get nextMonthTooltip;

  /// The tooltip for the [MonthPicker]'s "previous month" button.
  String get previousMonthTooltip;

  /// The tooltip for the [PaginatedDataTables]'s "next page" button.
  String get nextPageTooltip;

  /// The tooltip for the [PaginatedDataTables]'s "previous page" button.
  String get previousPageTooltip;

  /// The default [PopupMenuButton] tooltip.
  String get showMenuTooltip;

  /// Title for the [LicensePage] widget.
  String get licensesPageTitle;

  /// Title for the [PaginatedDataTable]'s row info footer.
  String pageRowsInfoTitle(int firstRow, int lastRow, int rowCount, bool rowCountIsApproximate);

  /// Title for the [PaginatedDataTable]'s "rows per page" footer.
  String get rowsPerPageTitle;

  /// Title for the PaginatedDataTable's selected row count header.
  String selectedRowCountTitle(int selectedRowCount);

  /// Label for "cancel" buttons and menu items.
  String get cancelButtonLabel;

  /// Label for "close" buttons and menu items.
  String get closeButtonLabel;

  /// Label for "continue" buttons and menu items.
  String get continueButtonLabel;

  /// Label for "copy" edit buttons and menu items.
  String get copyButtonLabel;

  /// Label for "cut" edit buttons and menu items.
  String get cutButtonLabel;

  /// Label for OK buttons and menu items.
  String get okButtonLabel;

  /// Label for "paste" edit buttons and menu items.
  String get pasteButtonLabel;

  /// Label for "select all" edit buttons and menu items.
  String get selectAllButtonLabel;

  /// Label for the [AboutBox] button that shows the [LicensePage].
  String get viewLicensesButtonLabel;

  /// The `MaterialLocalizations` from the closest [Localizations] instance
  /// that encloses the given context.
  ///
  /// This method is just a convenient shorthand for:
  /// `Localizations.of<MaterialLocalizations>(context, MaterialLocalizations)`.
  ///
  /// References to the localized resources defined by this class are typically
  /// written in terms of this method. For example:
  ///
  /// ```dart
  /// tooltip: MaterialLocalizations.of(context).backButtonTooltip,
  /// ```
  static MaterialLocalizations of(BuildContext context) {
    return Localizations.of<MaterialLocalizations>(context, MaterialLocalizations);
  }
}

/// Localized strings for the material widgets.
class DefaultMaterialLocalizations implements MaterialLocalizations {
  /// Construct an object that defines the material widgets' localized strings
  /// for the given `locale`.
  ///
  /// [LocalizationsDelegate] implementations typically call the static [load]
  /// function, rather than constructing this class directly.
  DefaultMaterialLocalizations(this.locale) {
    assert(locale != null);
    _nameToValue = localizations[_localeName]
      ?? localizations[locale.languageCode]
      ?? localizations['en']
      ?? <String, String>{};
  }

  Map<String, String> _nameToValue;

  /// The locale for which the values of this class's localized resources
  /// have been translated.
  final Locale locale;

  String get _localeName {
    final String localeName = locale.countryCode.isEmpty ? locale.languageCode : locale.toString();
    return Intl.canonicalizedLocale(localeName);
  }

  // TODO(hmuller): the rules for mapping from an integer value to
  // "one" or "two" etc. are locale specific and an additional "few" category
  // is needed. See http://cldr.unicode.org/index/cldr-spec/plural-rules
  String _nameToPluralValue(int count, String key) {
    String text;
    if (count == 0)
      text = _nameToValue['${key}Zero'];
    else if (count == 1)
      text = _nameToValue['${key}One'];
    else if (count == 2)
      text = _nameToValue['${key}Two'];
    else if (count > 2)
      text = _nameToValue['${key}Many'];
    text ??= _nameToValue['${key}Other'];
    assert(text != null);
    return text;
  }

  String _formatInteger(int n) {
    final String localeName = _localeName;
    if (!NumberFormat.localeExists(localeName))
      return n.toString();
    return new NumberFormat.decimalPattern(localeName).format(n);

  }

  @override
  String get openAppDrawerTooltip => _nameToValue['openAppDrawerTooltip'];

  @override
  String get backButtonTooltip => _nameToValue['backButtonTooltip'];

  @override
  String get closeButtonTooltip => _nameToValue['closeButtonTooltip'];

  @override
  String get nextMonthTooltip => _nameToValue['nextMonthTooltip'];

  @override
  String get previousMonthTooltip => _nameToValue['previousMonthTooltip'];

  @override
  String get nextPageTooltip => _nameToValue['nextPageTooltip'];

  @override
  String get previousPageTooltip => _nameToValue['previousPageTooltip'];

  @override
  String get showMenuTooltip => _nameToValue['showMenuTooltip'];

  @override
  String get licensesPageTitle => _nameToValue['licensesPageTitle'];

  @override
  String pageRowsInfoTitle(int firstRow, int lastRow, int rowCount, bool rowCountIsApproximate) {
    String text = rowCountIsApproximate ? _nameToValue['pageRowsInfoTitleApproximate'] : null;
    text ??= _nameToValue['pageRowsInfoTitle'];
    assert(text != null, 'A $locale localization was not found for pageRowsInfoTitle or pageRowsInfoTitleApproximate');
    // TODO(hansmuller): this could be more efficient.
    return text
      .replaceFirst(r'$firstRow', _formatInteger(firstRow))
      .replaceFirst(r'$lastRow', _formatInteger(lastRow))
      .replaceFirst(r'$rowCount', _formatInteger(rowCount));
  }

  @override
  String get rowsPerPageTitle => _nameToValue['rowsPerPageTitle'];

  @override
  String selectedRowCountTitle(int selectedRowCount) {
    return _nameToPluralValue(selectedRowCount, 'selectedRowCountTitle') // asserts on no match
      .replaceFirst(r'$selectedRowCount', _formatInteger(selectedRowCount));
  }

  @override
  String get cancelButtonLabel => _nameToValue['cancelButtonLabel'];

  @override
  String get closeButtonLabel => _nameToValue['closeButtonLabel'];

  @override
  String get continueButtonLabel => _nameToValue['continueButtonLabel'];

  @override
  String get copyButtonLabel => _nameToValue['copyButtonLabel'];

  @override
  String get cutButtonLabel => _nameToValue['cutButtonLabel'];

  @override
  String get okButtonLabel => _nameToValue['okButtonLabel'];

  @override
  String get pasteButtonLabel => _nameToValue['pasteButtonLabel'];

  @override
  String get selectAllButtonLabel => _nameToValue['selectAllButtonLabel'];

  @override
  String get viewLicensesButtonLabel => _nameToValue['viewLicensesButtonLabel'];

  /// Creates an object that provides localized resource values for the
  /// for the widgets of the material library.
  ///
  /// This method is typically used to create a [LocalizationsDelegate].
  /// The [MaterialApp] does so by default.
  static Future<MaterialLocalizations> load(Locale locale) {
    return new SynchronousFuture<MaterialLocalizations>(new DefaultMaterialLocalizations(locale));
  }
}