// 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.

// This program generates a getMaterialTranslation() and a
// getCupertinoTranslation() function that look up the translations provided by
// the arb files. The returned value is a generated instance of a
// GlobalMaterialLocalizations or a GlobalCupertinoLocalizations that
// corresponds to a single locale.
//
// The *.arb files are in packages/flutter_localizations/lib/src/l10n.
//
// The arb (JSON) format files must contain a single map indexed by locale.
// Each map value is itself a map with resource identifier keys and localized
// resource string values.
//
// The arb filenames are expected to have the form "material_(\w+)\.arb" or
// "cupertino_(\w+)\.arb" where the group following "_" identifies the language
// code and the country code, e.g. "material_en.arb" or "material_en_GB.arb".
// In most cases both codes are just two characters.
//
// This app is typically run by hand when a module's .arb files have been
// updated.
//
// ## Usage
//
// Run this program from the root of the git repository.
//
// The following outputs the generated Dart code to the console as a dry run:
//
// ```
// dart dev/tools/localization/bin/gen_localizations.dart
// ```
//
// If the data looks good, use the `-w` or `--overwrite` option to overwrite the
// packages/flutter_localizations/lib/src/l10n/generated_material_localizations.dart
// and packages/flutter_localizations/lib/src/l10n/generated_cupertino_localizations.dart file:
//
// ```
// dart dev/tools/localization/bin/gen_localizations.dart --overwrite
// ```

import 'dart:async';
import 'dart:io';

import 'package:path/path.dart' as path;
import 'package:meta/meta.dart';

import '../gen_cupertino_localizations.dart';
import '../gen_material_localizations.dart';
import '../localizations_utils.dart';
import '../localizations_validator.dart';

/// This is the core of this script; it generates the code used for translations.
String generateArbBasedLocalizationSubclasses({
  @required Map<LocaleInfo, Map<String, String>> localeToResources,
  @required Map<LocaleInfo, Map<String, dynamic>> localeToResourceAttributes,
  @required String generatedClassPrefix,
  @required String baseClass,
  @required HeaderGenerator generateHeader,
  @required ConstructorGenerator generateConstructor,
  @required String factoryName,
  @required String factoryDeclaration,
  @required String factoryArguments,
  @required String supportedLanguagesConstant,
  @required String supportedLanguagesDocMacro,
}) {
  assert(localeToResources != null);
  assert(localeToResourceAttributes != null);
  assert(generatedClassPrefix.isNotEmpty);
  assert(baseClass.isNotEmpty);
  assert(generateHeader != null);
  assert(generateConstructor != null);
  assert(factoryName.isNotEmpty);
  assert(factoryDeclaration.isNotEmpty);
  assert(factoryArguments.isNotEmpty);
  assert(supportedLanguagesConstant.isNotEmpty);
  assert(supportedLanguagesDocMacro.isNotEmpty);

  final StringBuffer output = StringBuffer();
  output.writeln(generateHeader('dart dev/tools/localization/bin/gen_localizations.dart --overwrite'));

  final StringBuffer supportedLocales = StringBuffer();

  final Map<String, List<LocaleInfo>> languageToLocales = <String, List<LocaleInfo>>{};
  final Map<String, Set<String>> languageToScriptCodes = <String, Set<String>>{};
  // Used to calculate if there are any corresponding countries for a given language and script.
  final Map<LocaleInfo, Set<String>> languageAndScriptToCountryCodes = <LocaleInfo, Set<String>>{};
  final Set<String> allResourceIdentifiers = <String>{};
  for (LocaleInfo locale in localeToResources.keys.toList()..sort()) {
    if (locale.scriptCode != null) {
      languageToScriptCodes[locale.languageCode] ??= <String>{};
      languageToScriptCodes[locale.languageCode].add(locale.scriptCode);
    }
    if (locale.countryCode != null && locale.scriptCode != null) {
      final LocaleInfo key = LocaleInfo.fromString(locale.languageCode + '_' + locale.scriptCode);
      languageAndScriptToCountryCodes[key] ??= <String>{};
      languageAndScriptToCountryCodes[key].add(locale.countryCode);
    }
    languageToLocales[locale.languageCode] ??= <LocaleInfo>[];
    languageToLocales[locale.languageCode].add(locale);
    allResourceIdentifiers.addAll(localeToResources[locale].keys.toList()..sort());
  }

  // We generate one class per supported language (e.g.
  // `MaterialLocalizationEn`). These implement everything that is needed by the
  // superclass (e.g. GlobalMaterialLocalizations).

  // We also generate one subclass for each locale with a script code (e.g.
  // `MaterialLocalizationZhHant`). Their superclasses are the aforementioned
  // language classes for the same locale but without a script code (e.g.
  // `MaterialLocalizationZh`).

  // We also generate one subclass for each locale with a country code (e.g.
  // `MaterialLocalizationEnGb`). Their superclasses are the aforementioned
  // language classes for the same locale but without a country code (e.g.
  // `MaterialLocalizationEn`).

  // If scriptCodes for a language are defined, we expect a scriptCode to be
  // defined for locales that contain a countryCode. The superclass becomes
  // the script sublcass (e.g. `MaterialLocalizationZhHant`) and the generated
  // subclass will also contain the script code (e.g. `MaterialLocalizationZhHantTW`).

  // When scriptCodes are not defined for languages that use scriptCodes to distinguish
  // between significantly differing scripts, we assume the scriptCodes in the
  // [LocaleInfo.fromString] factory and add it to the [LocaleInfo]. We then generate
  // the script classes based on the first locale that we assume to use the script.

  final List<String> allKeys = allResourceIdentifiers.toList()..sort();
  final List<String> languageCodes = languageToLocales.keys.toList()..sort();
  final LocaleInfo canonicalLocale = LocaleInfo.fromString('en');
  for (String languageName in languageCodes) {
    final LocaleInfo languageLocale = LocaleInfo.fromString(languageName);
    output.writeln(generateClassDeclaration(languageLocale, generatedClassPrefix, baseClass));
    output.writeln(generateConstructor(languageLocale));

    final Map<String, String> languageResources = localeToResources[languageLocale];
    for (String key in allKeys) {
      final Map<String, dynamic> attributes = localeToResourceAttributes[canonicalLocale][key] as Map<String, dynamic>;
      output.writeln(generateGetter(key, languageResources[key], attributes, languageLocale));
    }
    output.writeln('}');
    int countryCodeCount = 0;
    int scriptCodeCount = 0;
    if (languageToScriptCodes.containsKey(languageName)) {
      scriptCodeCount = languageToScriptCodes[languageName].length;
      // Language has scriptCodes, so we need to properly fallback countries to corresponding
      // script default values before language default values.
      for (String scriptCode in languageToScriptCodes[languageName]) {
        final LocaleInfo scriptBaseLocale = LocaleInfo.fromString(languageName + '_' + scriptCode);
        output.writeln(generateClassDeclaration(
          scriptBaseLocale,
          generatedClassPrefix,
          '$generatedClassPrefix${camelCase(languageLocale)}',
        ));
        output.writeln(generateConstructor(scriptBaseLocale));
        final Map<String, String> scriptResources = localeToResources[scriptBaseLocale];
        for (String key in scriptResources.keys.toList()..sort()) {
          if (languageResources[key] == scriptResources[key])
            continue;
          final Map<String, dynamic> attributes = localeToResourceAttributes[canonicalLocale][key] as Map<String, dynamic>;
          output.writeln(generateGetter(key, scriptResources[key], attributes, languageLocale));
        }
        output.writeln('}');

        final List<LocaleInfo> localeCodes = languageToLocales[languageName]..sort();
        for (LocaleInfo locale in localeCodes) {
          if (locale.originalString == languageName)
            continue;
          if (locale.originalString == languageName + '_' + scriptCode)
            continue;
          if (locale.scriptCode != scriptCode)
            continue;
          countryCodeCount += 1;
          output.writeln(generateClassDeclaration(
            locale,
            generatedClassPrefix,
            '$generatedClassPrefix${camelCase(scriptBaseLocale)}',
          ));
          output.writeln(generateConstructor(locale));
          final Map<String, String> localeResources = localeToResources[locale];
          for (String key in localeResources.keys) {
            // When script fallback contains the key, we compare to it instead of language fallback.
            if (scriptResources.containsKey(key) ? scriptResources[key] == localeResources[key] : languageResources[key] == localeResources[key])
              continue;
            final Map<String, dynamic> attributes = localeToResourceAttributes[canonicalLocale][key] as Map<String, dynamic>;
            output.writeln(generateGetter(key, localeResources[key], attributes, languageLocale));
          }
         output.writeln('}');
        }
      }
    } else {
      // No scriptCode. Here, we do not compare against script default (because it
      // doesn't exist).
      final List<LocaleInfo> localeCodes = languageToLocales[languageName]..sort();
      for (LocaleInfo locale in localeCodes) {
        if (locale.originalString == languageName)
          continue;
        countryCodeCount += 1;
        final Map<String, String> localeResources = localeToResources[locale];
        output.writeln(generateClassDeclaration(
          locale,
          generatedClassPrefix,
          '$generatedClassPrefix${camelCase(languageLocale)}',
        ));
        output.writeln(generateConstructor(locale));
        for (String key in localeResources.keys) {
          if (languageResources[key] == localeResources[key])
            continue;
          final Map<String, dynamic> attributes = localeToResourceAttributes[canonicalLocale][key] as Map<String, dynamic>;
          output.writeln(generateGetter(key, localeResources[key], attributes, languageLocale));
        }
       output.writeln('}');
      }
    }
    final String scriptCodeMessage = scriptCodeCount == 0 ? '' : ' and $scriptCodeCount script' + (scriptCodeCount == 1 ? '' : 's');
    if (countryCodeCount == 0) {
      if (scriptCodeCount == 0)
        supportedLocales.writeln('///  * `$languageName` - ${describeLocale(languageName)}');
      else
        supportedLocales.writeln('///  * `$languageName` - ${describeLocale(languageName)} (plus $scriptCodeCount script' + (scriptCodeCount == 1 ? '' : 's') + ')');

    } else if (countryCodeCount == 1) {
      supportedLocales.writeln('///  * `$languageName` - ${describeLocale(languageName)} (plus one country variation$scriptCodeMessage)');
    } else {
      supportedLocales.writeln('///  * `$languageName` - ${describeLocale(languageName)} (plus $countryCodeCount country variations$scriptCodeMessage)');
    }
  }

  // Generate the factory function. Given a Locale it returns the corresponding
  // base class implementation.
  output.writeln('''

/// The set of supported languages, as language code strings.
///
/// The [$baseClass.delegate] can generate localizations for
/// any [Locale] with a language code from this set, regardless of the region.
/// Some regions have specific support (e.g. `de` covers all forms of German,
/// but there is support for `de-CH` specifically to override some of the
/// translations for Switzerland).
///
/// See also:
///
///  * [$factoryName], whose documentation describes these values.
final Set<String> $supportedLanguagesConstant = HashSet<String>.from(const <String>[
${languageCodes.map<String>((String value) => "  '$value', // ${describeLocale(value)}").toList().join('\n')}
]);

/// Creates a [$baseClass] instance for the given `locale`.
///
/// All of the function's arguments except `locale` will be passed to the [
/// $baseClass] constructor. (The `localeName` argument of that
/// constructor is specified by the actual subclass constructor by this
/// function.)
///
/// The following locales are supported by this package:
///
/// {@template $supportedLanguagesDocMacro}
$supportedLocales/// {@endtemplate}
///
/// Generally speaking, this method is only intended to be used by
/// [$baseClass.delegate].
$factoryDeclaration
  switch (locale.languageCode) {''');
  for (String language in languageToLocales.keys) {
    // Only one instance of the language.
    if (languageToLocales[language].length == 1) {
      output.writeln('''
    case '$language':
      return $generatedClassPrefix${camelCase(languageToLocales[language][0])}($factoryArguments);''');
    } else if (!languageToScriptCodes.containsKey(language)) { // Does not distinguish between scripts. Switch on countryCode directly.
      output.writeln('''
    case '$language': {
      switch (locale.countryCode) {''');
      for (LocaleInfo locale in languageToLocales[language]) {
        if (locale.originalString == language)
          continue;
        assert(locale.length > 1);
        final String countryCode = locale.countryCode;
        output.writeln('''
        case '$countryCode':
          return $generatedClassPrefix${camelCase(locale)}($factoryArguments);''');
      }
      output.writeln('''
      }
      return $generatedClassPrefix${camelCase(LocaleInfo.fromString(language))}($factoryArguments);
    }''');
    } else { // Language has scriptCode, add additional switch logic.
      bool hasCountryCode = false;
      output.writeln('''
    case '$language': {
      switch (locale.scriptCode) {''');
      for (String scriptCode in languageToScriptCodes[language]) {
        final LocaleInfo scriptLocale = LocaleInfo.fromString(language + '_' + scriptCode);
        output.writeln('''
        case '$scriptCode': {''');
        if (languageAndScriptToCountryCodes.containsKey(scriptLocale)) {
          output.writeln('''
          switch (locale.countryCode) {''');
          for (LocaleInfo locale in languageToLocales[language]) {
            if (locale.countryCode == null)
              continue;
            else
              hasCountryCode = true;
            if (locale.originalString == language)
              continue;
            if (locale.scriptCode != scriptCode && locale.scriptCode != null)
              continue;
            final String countryCode = locale.countryCode;
            output.writeln('''
            case '$countryCode':
              return $generatedClassPrefix${camelCase(locale)}($factoryArguments);''');
          }
        }
        // Return a fallback locale that matches scriptCode, but not countryCode.
        //
        // Explicitly defined scriptCode fallback:
        if (languageToLocales[language].contains(scriptLocale)) {
          if (languageAndScriptToCountryCodes.containsKey(scriptLocale)) {
            output.writeln('''
          }''');
          }
          output.writeln('''
          return $generatedClassPrefix${camelCase(scriptLocale)}($factoryArguments);
        }''');
        } else {
          // Not Explicitly defined, fallback to first locale with the same language and
          // script:
          for (LocaleInfo locale in languageToLocales[language]) {
            if (locale.scriptCode != scriptCode)
              continue;
            if (languageAndScriptToCountryCodes.containsKey(scriptLocale)) {
              output.writeln('''
          }''');
            }
            output.writeln('''
          return $generatedClassPrefix${camelCase(scriptLocale)}($factoryArguments);
        }''');
            break;
          }
        }
      }
      output.writeln('''
      }''');
      if (hasCountryCode) {
      output.writeln('''
      switch (locale.countryCode) {''');
        for (LocaleInfo locale in languageToLocales[language]) {
          if (locale.originalString == language)
            continue;
          assert(locale.length > 1);
          if (locale.countryCode == null)
            continue;
          final String countryCode = locale.countryCode;
          output.writeln('''
        case '$countryCode':
          return $generatedClassPrefix${camelCase(locale)}($factoryArguments);''');
        }
        output.writeln('''
      }''');
      }
      output.writeln('''
      return $generatedClassPrefix${camelCase(LocaleInfo.fromString(language))}($factoryArguments);
    }''');
    }
  }
  output.writeln('''
  }
  assert(false, '$factoryName() called for unsupported locale "\$locale"');
  return null;
}''');

  return output.toString();
}

/// Returns the appropriate type for getters with the given attributes.
///
/// Typically "String", but some (e.g. "timeOfDayFormat") return enums.
///
/// Used by [generateGetter] below.
String generateType(Map<String, dynamic> attributes) {
  if (attributes != null) {
    switch (attributes['x-flutter-type'] as String) {
      case 'icuShortTimePattern':
        return 'TimeOfDayFormat';
      case 'scriptCategory':
        return 'ScriptCategory';
    }
  }
  return 'String';
}

/// Returns the appropriate name for getters with the given attributes.
///
/// Typically this is the key unmodified, but some have parameters, and
/// the GlobalMaterialLocalizations class does the substitution, and for
/// those we have to therefore provide an alternate name.
///
/// Used by [generateGetter] below.
String generateKey(String key, Map<String, dynamic> attributes) {
  if (attributes != null) {
    if (attributes.containsKey('parameters'))
      return '${key}Raw';
    switch (attributes['x-flutter-type'] as String) {
      case 'icuShortTimePattern':
        return '${key}Raw';
    }
  }
  if (key == 'datePickerDateOrder')
    return 'datePickerDateOrderString';
  if (key == 'datePickerDateTimeOrder')
    return 'datePickerDateTimeOrderString';
  return key;
}

const Map<String, String> _icuTimeOfDayToEnum = <String, String>{
  'HH:mm': 'TimeOfDayFormat.HH_colon_mm',
  'HH.mm': 'TimeOfDayFormat.HH_dot_mm',
  "HH 'h' mm": 'TimeOfDayFormat.frenchCanadian',
  'HH:mm น.': 'TimeOfDayFormat.HH_colon_mm',
  'H:mm': 'TimeOfDayFormat.H_colon_mm',
  'h:mm a': 'TimeOfDayFormat.h_colon_mm_space_a',
  'a h:mm': 'TimeOfDayFormat.a_space_h_colon_mm',
  'ah:mm': 'TimeOfDayFormat.a_space_h_colon_mm',
};

const Map<String, String> _scriptCategoryToEnum = <String, String>{
  'English-like': 'ScriptCategory.englishLike',
  'dense': 'ScriptCategory.dense',
  'tall': 'ScriptCategory.tall',
};

/// Returns the literal that describes the value returned by getters
/// with the given attributes.
///
/// This handles cases like the value being a literal `null`, an enum, and so
/// on. The default is to treat the value as a string and escape it and quote
/// it.
///
/// Used by [generateGetter] below.
String generateValue(String value, Map<String, dynamic> attributes, LocaleInfo locale) {
  if (value == null)
    return null;
  // cupertino_en.arb doesn't use x-flutter-type.
  if (attributes != null) {
    switch (attributes['x-flutter-type'] as String) {
      case 'icuShortTimePattern':
        if (!_icuTimeOfDayToEnum.containsKey(value)) {
          throw Exception(
            '"$value" is not one of the ICU short time patterns supported '
            'by the material library. Here is the list of supported '
            'patterns:\n  ' + _icuTimeOfDayToEnum.keys.join('\n  ')
          );
        }
        return _icuTimeOfDayToEnum[value];
      case 'scriptCategory':
        if (!_scriptCategoryToEnum.containsKey(value)) {
          throw Exception(
            '"$value" is not one of the scriptCategory values supported '
            'by the material library. Here is the list of supported '
            'values:\n  ' + _scriptCategoryToEnum.keys.join('\n  ')
          );
        }
        return _scriptCategoryToEnum[value];
    }
  }
  // Localization strings for the Kannada locale ('kn') are encoded because
  // some of the localized strings contain characters that can crash Emacs on Linux.
  // See packages/flutter_localizations/lib/src/l10n/README for more information.
  return locale.languageCode == 'kn' ? generateEncodedString(value) : generateString(value);
}

/// Combines [generateType], [generateKey], and [generateValue] to return
/// the source of getters for the GlobalMaterialLocalizations subclass.
/// The locale is the locale for which the getter is being generated.
String generateGetter(String key, String value, Map<String, dynamic> attributes, LocaleInfo locale) {
  final String type = generateType(attributes);
  key = generateKey(key, attributes);
  value = generateValue(value, attributes, locale);
      return '''

  @override
  $type get $key => $value;''';
}

Future<void> main(List<String> rawArgs) async {
  checkCwdIsRepoRoot('gen_localizations');
  final GeneratorOptions options = parseArgs(rawArgs);

  // filenames are assumed to end in "prefix_lc.arb" or "prefix_lc_cc.arb", where prefix
  // is the 2nd command line argument, lc is a language code and cc is the country
  // code. In most cases both codes are just two characters.

  final Directory directory = Directory(path.join('packages', 'flutter_localizations', 'lib', 'src', 'l10n'));
  final RegExp materialFilenameRE = RegExp(r'material_(\w+)\.arb$');
  final RegExp cupertinoFilenameRE = RegExp(r'cupertino_(\w+)\.arb$');

  try {
    validateEnglishLocalizations(File(path.join(directory.path, 'material_en.arb')));
    validateEnglishLocalizations(File(path.join(directory.path, 'cupertino_en.arb')));
  } on ValidationError catch (exception) {
    exitWithError('$exception');
  }

  await precacheLanguageAndRegionTags();

  // Maps of locales to resource key/value pairs for Material ARBs.
  final Map<LocaleInfo, Map<String, String>> materialLocaleToResources = <LocaleInfo, Map<String, String>>{};
  // Maps of locales to resource key/attributes pairs for Material ARBs..
  // https://github.com/googlei18n/app-resource-bundle/wiki/ApplicationResourceBundleSpecification#resource-attributes
  final Map<LocaleInfo, Map<String, dynamic>> materialLocaleToResourceAttributes = <LocaleInfo, Map<String, dynamic>>{};
  // Maps of locales to resource key/value pairs for Cupertino ARBs.
  final Map<LocaleInfo, Map<String, String>> cupertinoLocaleToResources = <LocaleInfo, Map<String, String>>{};
  // Maps of locales to resource key/attributes pairs for Cupertino ARBs..
  // https://github.com/googlei18n/app-resource-bundle/wiki/ApplicationResourceBundleSpecification#resource-attributes
  final Map<LocaleInfo, Map<String, dynamic>> cupertinoLocaleToResourceAttributes = <LocaleInfo, Map<String, dynamic>>{};

  loadMatchingArbsIntoBundleMaps(
    directory: directory,
    filenamePattern: materialFilenameRE,
    localeToResources: materialLocaleToResources,
    localeToResourceAttributes: materialLocaleToResourceAttributes,
  );
  loadMatchingArbsIntoBundleMaps(
    directory: directory,
    filenamePattern: cupertinoFilenameRE,
    localeToResources: cupertinoLocaleToResources,
    localeToResourceAttributes: cupertinoLocaleToResourceAttributes,
  );

  try {
    validateLocalizations(materialLocaleToResources, materialLocaleToResourceAttributes);
    validateLocalizations(cupertinoLocaleToResources, cupertinoLocaleToResourceAttributes);
  } on ValidationError catch (exception) {
    exitWithError('$exception');
  }

  final String materialLocalizations = options.writeToFile || !options.cupertinoOnly
      ? generateArbBasedLocalizationSubclasses(
        localeToResources: materialLocaleToResources,
        localeToResourceAttributes: materialLocaleToResourceAttributes,
        generatedClassPrefix: 'MaterialLocalization',
        baseClass: 'GlobalMaterialLocalizations',
        generateHeader: generateMaterialHeader,
        generateConstructor: generateMaterialConstructor,
        factoryName: materialFactoryName,
        factoryDeclaration: materialFactoryDeclaration,
        factoryArguments: materialFactoryArguments,
        supportedLanguagesConstant: materialSupportedLanguagesConstant,
        supportedLanguagesDocMacro: materialSupportedLanguagesDocMacro,
      )
      : null;
  final String cupertinoLocalizations = options.writeToFile || !options.materialOnly
      ? generateArbBasedLocalizationSubclasses(
        localeToResources: cupertinoLocaleToResources,
        localeToResourceAttributes: cupertinoLocaleToResourceAttributes,
        generatedClassPrefix: 'CupertinoLocalization',
        baseClass: 'GlobalCupertinoLocalizations',
        generateHeader: generateCupertinoHeader,
        generateConstructor: generateCupertinoConstructor,
        factoryName: cupertinoFactoryName,
        factoryDeclaration: cupertinoFactoryDeclaration,
        factoryArguments: cupertinoFactoryArguments,
        supportedLanguagesConstant: cupertinoSupportedLanguagesConstant,
        supportedLanguagesDocMacro: cupertinoSupportedLanguagesDocMacro,
      )
      : null;

  if (options.writeToFile) {
    final File materialLocalizationsFile = File(path.join(directory.path, 'generated_material_localizations.dart'));
    materialLocalizationsFile.writeAsStringSync(materialLocalizations, flush: true);
    final File cupertinoLocalizationsFile = File(path.join(directory.path, 'generated_cupertino_localizations.dart'));
    cupertinoLocalizationsFile.writeAsStringSync(cupertinoLocalizations, flush: true);
  } else {
    if (!options.cupertinoOnly) {
      stdout.write(materialLocalizations);
    }
    if (!options.materialOnly) {
      stdout.write(cupertinoLocalizations);
    }
  }
}