// Copyright 2014 The Flutter 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:convert';
import 'dart:io';

import 'localizations_utils.dart';

// The set of date formats that can be automatically localized.
//
// The localizations generation tool makes use of the intl library's
// DateFormat class to properly format dates based on the locale, the
// desired format, as well as the passed in [DateTime]. For example, using
// DateFormat.yMMMMd("en_US").format(DateTime.utc(1996, 7, 10)) results
// in the string "July 10, 1996".
//
// Since the tool generates code that uses DateFormat's constructor, it is
// necessary to verify that the constructor exists, or the
// tool will generate code that may cause a compile-time error.
//
// See also:
//
// * <https://pub.dev/packages/intl>
// * <https://pub.dev/documentation/intl/latest/intl/DateFormat-class.html>
// * <https://api.dartlang.org/stable/2.7.0/dart-core/DateTime-class.html>
const Set<String> _validDateFormats = <String>{
  'd',
  'E',
  'EEEE',
  'LLL',
  'LLLL',
  'M',
  'Md',
  'MEd',
  'MMM',
  'MMMd',
  'MMMEd',
  'MMMM',
  'MMMMd',
  'MMMMEEEEd',
  'QQQ',
  'QQQQ',
  'y',
  'yM',
  'yMd',
  'yMEd',
  'yMMM',
  'yMMMd',
  'yMMMEd',
  'yMMMM',
  'yMMMMd',
  'yMMMMEEEEd',
  'yQQQ',
  'yQQQQ',
  'H',
  'Hm',
  'Hms',
  'j',
  'jm',
  'jms',
  'jmv',
  'jmz',
  'jv',
  'jz',
  'm',
  'ms',
  's',
};

// The set of number formats that can be automatically localized.
//
// The localizations generation tool makes use of the intl library's
// NumberFormat class to properly format numbers based on the locale and
// the desired format. For example, using
// NumberFormat.compactLong("en_US").format(1200000) results
// in the string "1.2 million".
//
// Since the tool generates code that uses NumberFormat's constructor, it is
// necessary to verify that the constructor exists, or the
// tool will generate code that may cause a compile-time error.
//
// See also:
//
// * <https://pub.dev/packages/intl>
// * <https://pub.dev/documentation/intl/latest/intl/NumberFormat-class.html>
const Set<String> _validNumberFormats = <String>{
  'compact',
  'compactCurrency',
  'compactSimpleCurrency',
  'compactLong',
  'currency',
  'decimalPattern',
  'decimalPercentPattern',
  'percentPattern',
  'scientificPattern',
  'simpleCurrency',
};

// The names of the NumberFormat factory constructors which have named
// parameters rather than positional parameters.
//
// This helps the tool correctly generate number formmatting code correctly.
//
// Example of code that uses named parameters:
// final NumberFormat format = NumberFormat.compact(
//   locale: localeName,
// );
//
// Example of code that uses positional parameters:
// final NumberFormat format = NumberFormat.scientificPattern(localeName);
const Set<String> _numberFormatsWithNamedParameters = <String>{
  'compact',
  'compactCurrency',
  'compactSimpleCurrency',
  'compactLong',
  'currency',
  'decimalPercentPattern',
  'simpleCurrency',
};

class L10nException implements Exception {
  L10nException(this.message);

  final String message;
}

// One optional named parameter to be used by a NumberFormat.
//
// Some of the NumberFormat factory constructors have optional named parameters.
// For example NumberFormat.compactCurrency has a decimalDigits parameter that
// specifies the number of decimal places to use when formatting.
//
// Optional parameters for NumberFormat placeholders are specified as a
// JSON map value for optionalParameters in a resource's "@" ARB file entry:
//
// "@myResourceId": {
//   "placeholders": {
//     "myNumberPlaceholder": {
//       "type": "double",
//       "format": "compactCurrency",
//       "optionalParameters": {
//         "decimalDigits": 2
//       }
//     }
//   }
// }
class OptionalParameter {
  const OptionalParameter(this.name, this.value) : assert(name != null), assert(value != null);

  final String name;
  final Object value;
}

// One message parameter: one placeholder from an @foo entry in the template ARB file.
//
// Placeholders are specified as a JSON map with one entry for each placeholder.
// One placeholder must be specified for each message "{parameter}".
// Each placeholder entry is also a JSON map. If the map is empty, the placeholder
// is assumed to be an Object value whose toString() value will be displayed.
// For example:
//
// "greeting": "{hello} {world}",
// "@greeting": {
//   "description": "A message with a two parameters",
//   "placeholders": {
//     "hello": {},
//     "world": {}
//   }
// }
//
// Each placeholder can optionally specify a valid Dart type. If the type
// is NumberFormat or DateFormat then a format which matches one of the
// type's factory constructors can also be specified. In this example the
// date placeholder is to be formated with DateFormat.yMMMMd:
//
// "helloWorldOn": "Hello World on {date}",
// "@helloWorldOn": {
//   "description": "A message with a date parameter",
//   "placeholders": {
//     "date": {
//       "type": "DateTime",
//       "format": "yMMMMd"
//     }
//   }
// }
//
class Placeholder {
  Placeholder(this.resourceId, this.name, Map<String, dynamic> attributes)
    : assert(resourceId != null),
      assert(name != null),
      example = _stringAttribute(resourceId, name, attributes, 'example'),
      type = _stringAttribute(resourceId, name, attributes, 'type') ?? 'Object',
      format = _stringAttribute(resourceId, name, attributes, 'format'),
      optionalParameters = _optionalParameters(resourceId, name, attributes);

  final String resourceId;
  final String name;
  final String example;
  final String type;
  final String format;
  final List<OptionalParameter> optionalParameters;

  bool get requiresFormatting => <String>['DateTime', 'double', 'int', 'num'].contains(type);
  bool get isNumber => <String>['double', 'int', 'num'].contains(type);
  bool get hasValidNumberFormat => _validNumberFormats.contains(format);
  bool get hasNumberFormatWithParameters => _numberFormatsWithNamedParameters.contains(format);
  bool get isDate => 'DateTime' == type;
  bool get hasValidDateFormat => _validDateFormats.contains(format);

  static String _stringAttribute(
    String resourceId,
    String name,
    Map<String, dynamic> attributes,
    String attributeName,
  ) {
    final dynamic value = attributes[attributeName];
    if (value == null)
      return null;
    if (value is! String || (value as String).isEmpty) {
      throw L10nException(
        'The "$attributeName" value of the "$name" placeholder in message $resourceId '
        'must be a non-empty string.',
      );
    }
    return value as String;
  }

  static List<OptionalParameter> _optionalParameters(
    String resourceId,
    String name,
    Map<String, dynamic> attributes
  ) {
    final dynamic value = attributes['optionalParameters'];
    if (value == null)
      return <OptionalParameter>[];
    if (value is! Map<String, Object>) {
      throw L10nException(
        'The "optionalParameters" value of the "$name" placeholder in message '
        '$resourceId is not a properly formatted Map. Ensure that it is a map '
        'with keys that are strings.'
      );
    }
    final Map<String, dynamic> optionalParameterMap = value as Map<String, dynamic>;
    return optionalParameterMap.keys.map<OptionalParameter>((String parameterName) {
      return OptionalParameter(parameterName, optionalParameterMap[parameterName]);
    }).toList();
  }
}

// One translation: one pair of foo,@foo entries from the template ARB file.
//
// The template ARB file must contain an entry called @myResourceId for each
// message named myResourceId. The @ entry describes message parameters
// called "placeholders" and can include an optional description.
// Here's a simple example message with no parameters:
//
// "helloWorld": "Hello World",
// "@helloWorld": {
//   "description": "The conventional newborn programmer greeting"
// }
//
// The value of this Message is "Hello World". The Message's value is the
// localized string to be shown for the template ARB file's locale.
// The docs for the Placeholder explain how placeholder entries are defined.
class Message {
  Message(Map<String, dynamic> bundle, this.resourceId)
    : assert(bundle != null),
      assert(resourceId != null && resourceId.isNotEmpty),
      value = _value(bundle, resourceId),
      description = _description(bundle, resourceId),
      placeholders = _placeholders(bundle, resourceId),
      _pluralMatch = _pluralRE.firstMatch(_value(bundle, resourceId));

  static final RegExp _pluralRE = RegExp(r'\s*\{([\w\s,]*),\s*plural\s*,');

  final String resourceId;
  final String value;
  final String description;
  final List<Placeholder> placeholders;
  final RegExpMatch _pluralMatch;

  bool get isPlural => _pluralMatch != null && _pluralMatch.groupCount == 1;

  bool get placeholdersRequireFormatting => placeholders.any((Placeholder p) => p.requiresFormatting);

  Placeholder getCountPlaceholder() {
    assert(isPlural);
    final String countPlaceholderName = _pluralMatch[1];
    return placeholders.firstWhere(
      (Placeholder p) => p.name == countPlaceholderName,
      orElse: () {
        throw L10nException('Cannot find the $countPlaceholderName placeholder in plural message "$resourceId".');
      }
    );
  }

  static String _value(Map<String, dynamic> bundle, String resourceId) {
    final dynamic value = bundle[resourceId];
    if (value == null)
      throw L10nException('A value for resource "$resourceId" was not found.');
    if (value is! String)
      throw L10nException('The value of "$resourceId" is not a string.');
    return bundle[resourceId] as String;
  }

  static Map<String, dynamic> _attributes(Map<String, dynamic> bundle, String resourceId) {
    final dynamic attributes = bundle['@$resourceId'];
    if (attributes == null) {
      throw L10nException(
        'Resource attribute "@$resourceId" was not found. Please '
        'ensure that each resource has a corresponding @resource.'
      );
    }
    if (attributes is! Map<String, dynamic>) {
      throw L10nException(
        'The resource attribute "@$resourceId" is not a properly formatted Map. '
        'Ensure that it is a map with keys that are strings.'
      );
    }
    return attributes as Map<String, dynamic>;
  }

  static String _description(Map<String, dynamic> bundle, String resourceId) {
    final dynamic value = _attributes(bundle, resourceId)['description'];
    if (value == null)
      return null;
    if (value is! String) {
      throw L10nException(
        'The description for "@$resourceId" is not a properly formatted String.'
      );
    }
    return value as String;
  }

  static List<Placeholder> _placeholders(Map<String, dynamic> bundle, String resourceId) {
    final dynamic value = _attributes(bundle, resourceId)['placeholders'];
    if (value == null)
      return <Placeholder>[];
    if (value is! Map<String, dynamic>) {
      throw L10nException(
        'The "placeholders" attribute for message $resourceId, is not '
        'properly formatted. Ensure that it is a map with string valued keys.'
      );
    }
    final Map<String, dynamic> allPlaceholdersMap = value as Map<String, dynamic>;
    return allPlaceholdersMap.keys.map<Placeholder>((String placeholderName) {
      final dynamic value = allPlaceholdersMap[placeholderName];
      if (value is! Map<String, dynamic>) {
        throw L10nException(
          'The value of the "$placeholderName" placeholder attribute for message '
          '"$resourceId", is not properly formatted. Ensure that it is a map '
          'with string valued keys.'
        );
      }
      return Placeholder(resourceId, placeholderName, value as Map<String, dynamic>);
    }).toList();
  }
}

// Represents the contents of one ARB file.
class AppResourceBundle {
  factory AppResourceBundle(File file) {
    assert(file != null);
    // Assuming that the caller has verified that the file exists and is readable.

    final Map<String, dynamic> resources = json.decode(file.readAsStringSync()) as Map<String, dynamic>;
    String localeString = resources['@@locale'] as String;
    if (localeString == null) {
      final RegExp filenameRE = RegExp(r'^[^_]*_(\w+)\.arb$');
      final RegExpMatch match = filenameRE.firstMatch(file.path);
      localeString = match == null ? null : match[1];
    }
    if (localeString == null) {
      throw L10nException(
        "The following .arb file's locale could not be determined: \n"
        '${file.path} \n'
        "Make sure that the locale is specified in the file's '@@locale' "
        'property or as part of the filename (e.g. file_en.arb)'
       );
     }

    final Iterable<String> ids = resources.keys.where((String key) => !key.startsWith('@'));
    return AppResourceBundle._(file, LocaleInfo.fromString(localeString), resources, ids);
  }

  const AppResourceBundle._(this.file, this.locale, this.resources, this.resourceIds);

  final File file;
  final LocaleInfo locale;
  final Map<String, dynamic> resources;
  final Iterable<String> resourceIds;

  String translationFor(Message message) => resources[message.resourceId] as String;

  @override
  String toString() {
    return 'AppResourceBundle($locale, ${file.path})';
  }
}

// Represents all of the ARB files in [directory] as [AppResourceBundle]s.
class AppResourceBundleCollection {
  factory AppResourceBundleCollection(Directory directory) {
    assert(directory != null);
    // Assuming that the caller has verified that the directory is readable.

    final RegExp filenameRE = RegExp(r'(\w+)\.arb$');
    final Map<LocaleInfo, AppResourceBundle> localeToBundle = <LocaleInfo, AppResourceBundle>{};
    final Map<String, List<LocaleInfo>> languageToLocales = <String, List<LocaleInfo>>{};
    final List<File> files = directory.listSync().whereType<File>().toList()..sort(sortFilesByPath);
    for (final File file in files) {
      if (filenameRE.hasMatch(file.path)) {
        final AppResourceBundle bundle = AppResourceBundle(file);
        if (localeToBundle[bundle.locale] != null) {
          throw L10nException(
            "Multiple arb files with the same '${bundle.locale}' locale detected. \n"
            'Ensure that there is exactly one arb file for each locale.'
          );
        }
        localeToBundle[bundle.locale] = bundle;
        languageToLocales[bundle.locale.languageCode] ??= <LocaleInfo>[];
        languageToLocales[bundle.locale.languageCode].add(bundle.locale);
      }
    }

    languageToLocales.forEach((String language, List<LocaleInfo> listOfCorrespondingLocales) {
      final List<String> localeStrings = listOfCorrespondingLocales.map((LocaleInfo locale) {
        return locale.toString();
      }).toList();
      if (!localeStrings.contains(language)) {
        throw L10nException(
          'Arb file for a fallback, $language, does not exist, even though \n'
          'the following locale(s) exist: $listOfCorrespondingLocales. \n'
          'When locales specify a script code or country code, a \n'
          'base locale (without the script code or country code) should \n'
          'exist as the fallback. Please create a {fileName}_$language.arb \n'
          'file.'
        );
      }
    });

    return AppResourceBundleCollection._(directory, localeToBundle, languageToLocales);
  }

  const AppResourceBundleCollection._(this._directory, this._localeToBundle, this._languageToLocales);

  final Directory _directory;
  final Map<LocaleInfo, AppResourceBundle> _localeToBundle;
  final Map<String, List<LocaleInfo>> _languageToLocales;

  Iterable<LocaleInfo> get locales => _localeToBundle.keys;
  Iterable<AppResourceBundle> get bundles => _localeToBundle.values;
  AppResourceBundle bundleFor(LocaleInfo locale) => _localeToBundle[locale];

  Iterable<String> get languages => _languageToLocales.keys;
  Iterable<LocaleInfo> localesForLanguage(String language) => _languageToLocales[language] ?? <LocaleInfo>[];

  @override
  String toString() {
    return 'AppResourceBundleCollection(${_directory.path}, ${locales.length} locales)';
  }
}