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.applib.services.i18n;
  
  /**
   * Provides translated versions of the various elements within the framework's
   * metamodel: service and object classes, properties, collections, actions,
   * action parameters; and also to translate business rule (disable/valid)
   * messages, and exceptions. These translations provide for both singular and
   * plural forms.
   *
   * <p>
   * As such, this domain service is the cornerstone of the framework's i18n
   * support.
   * </p>
   *
   * @since 1.x {@index}
   */
  public interface TranslationService {
  
      /**
       * Return a translation of the text, in the locale of the &quot;current user&quot;.
       *
       * <p>
       *     The mechanism to determine the locale is implementation-specific.
       * </p>
       *
       * @param context
       * @param text
       */
      String translate(
              final TranslationContext context,
              final String text);
  
      /**
       * Return a translation of either the singular or the plural text, dependent on the <tt>num</tt> parameter,
       * in the locale of the &quot;current user&quot;.
       *
       * <p>
       *     The mechanism to determine the locale is implementation-specific.
       * </p>
       *
       * @param context
       * @param singularText
       * @param pluralText
       * @param num - whether to return the translation of the singular (if =1) or of the plural (if != 1)
       */
      String translate(
              final TranslationContext context,
              final String singularText,
              final String pluralText,
              int num);
  
      /**
       * Whether this implementation is operating in read or in write mode.
       *
       * <p>
       *     If in read mode, then the translations are expected to be present.  In such cases, the
       *     {@link #translate(TranslationContext, String) translate}
       *     {@link #translate(TranslationContext, String, String, int) method}s should be <i>lazily</i> called,
       *     if only because there will (most likely) need to be a session in progress (such that the locale of the
       *     current user can be determined).
       * </p>
       *
       * <p>
       *     If in write mode, then the implementation is saving translation keys, and will
       *     always return the untranslated translation.  In such cases, the {@link #translate(TranslationContext, String) translate}
       *     {@link #translate(TranslationContext, String, String, int) method}s should be <i>eagerly</i> called
       *     such that all pathways are exercised..
       * </p>
       */
      Mode getMode();
          
      /**
       * Can be used as fallback in the absence of a {@link TranslationService} implementation.
       * Acts as a text pass-through, not translating anything.
       */
      public static TranslationService identity() {
          return new TranslationService() {
              @Override public String translate(TranslationContext context, String text) {
                  return text;
              }
              @Override public String translate(TranslationContext context, String singularText, String pluralText, int num) {
                  return num==1 ? singularText : pluralText;
              }
              @Override public Mode getMode() { 
                  return Mode.READ; 
              }
          };
      }
  
  }
  