content: /*
   *  Licensed to the Apache Software Foundation (ASF) under one
   *  or more contributor license agreements.  See the NOTICE file
   *  distributed with this work for additional information
   *  regarding copyright ownership.  The ASF licenses this file
   *  to you under the Apache License, Version 2.0 (the
   *  "License"); you may not use this file except in compliance
   *  with the License.  You may obtain a copy of the License at
   *
   *        http://www.apache.org/licenses/LICENSE-2.0
   *
   *  Unless required by applicable law or agreed to in writing,
   *  software distributed under the License is distributed on an
   *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   *  KIND, either express or implied.  See the License for the
   *  specific language governing permissions and limitations
   *  under the License.
   */
  package org.apache.causeway.core.runtimeservices.locale;
  
  import java.util.List;
  import java.util.Locale;
  import java.util.stream.Stream;
  
  import jakarta.annotation.Priority;
  import jakarta.inject.Inject;
  import jakarta.inject.Named;
  
  import org.springframework.beans.factory.annotation.Qualifier;
  import org.springframework.stereotype.Service;
  
  import org.apache.causeway.applib.annotation.PriorityPrecedence;
  import org.apache.causeway.applib.services.locale.LocaleChoiceProvider;
  import org.apache.causeway.commons.collections.Can;
  import org.apache.causeway.core.runtimeservices.CausewayModuleCoreRuntimeServices;
  
  import lombok.AccessLevel;
  import lombok.Getter;
  import lombok.RequiredArgsConstructor;
  
  /**
   * Default implementation of {@link LocaleChoiceProvider}.
   *
   * @since 2.0 {@index}
   */
  @Service
  @Named(CausewayModuleCoreRuntimeServices.NAMESPACE + ".LocaleChoiceProviderDefault")
  @Priority(PriorityPrecedence.MIDPOINT)
  @Qualifier("Default")
  @RequiredArgsConstructor(onConstructor_ = {@Inject})
  public class LocaleChoiceProviderDefault
  implements LocaleChoiceProvider {
  
      @Override
      public List<Locale> getAvailableLocales() {
          return getSupportedLanguages().toList();
      }
  
      // -- HELPER
  
      @Getter(value = AccessLevel.PROTECTED, lazy = true)
      private final Can<Locale> supportedLanguages = streamSupportedLanguages()
          .collect(Can.toCan());
  
      /**
       * Stream subset of {@link Locale#getISOLanguages()} that supports round-tripping.
       */
      private Stream<Locale> streamSupportedLanguages() {
          return Stream.of(Locale.getISOLanguages())
                  .sorted()
                  .map(this::localeForIsoLanguage)
                  .filter(this::isRoundtripSupported);
      }
  
      private boolean isRoundtripSupported(final Locale locale) {
          return locale.equals(Locale.forLanguageTag(locale.toLanguageTag()));
      }
  
      private Locale localeForIsoLanguage(final String isoLanguage) {
          return new Locale.Builder().setLanguage(isoLanguage).build();
      }
  
  }
  