package org.djunits.locale;
   
   import java.io.Serializable;
   import java.util.Locale;
   import java.util.MissingResourceException;
   import java.util.ResourceBundle;
   
   /**
    * Localization object for language specific reporting of units.
   * <p>
   * Copyright (c) 2013-2022 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved. <br>
   * BSD-style license. See <a href="https://djunits.org/docs/license.html">DJUNITS License</a>
   * </p>
   * @author <a href="https://www.tudelft.nl/averbraeck">Alexander Verbraeck</a>
   * @author <a href="https://tudelft.nl/pknoppers">Peter Knoppers</a>
   */
  public class Localization implements Serializable
  {
      /** */
      private static final long serialVersionUID = 20200118L;
  
      /** filename without .properties, to be found in the /resources folder. */
      private final String bundleNamePrefix;
  
      /** the resource bundle. */
      private transient ResourceBundle resourceBundle;
  
      /** current locale. */
      private Locale currentLocale = null;
  
      /** the default resource bundle. */
      private transient ResourceBundle defaultResourceBundle;
  
      /** default locale. */
      private Locale defaultLocale = null;
  
      /**
       * Create a Localization object.
       * @param prefix String; the prefix of the properties files to use.
       */
      public Localization(final String prefix)
      {
          this.bundleNamePrefix = prefix;
          getString("xyz"); // initialize the default locale
      }
  
      /**
       * Retrieve a string from a locale bundle. If retrieval fails the value of key string, surrounded by exclamation marks is
       * returned.
       * @param key String; the key for the locale in the properties file
       * @return String; localized string, or, if a translation could not be found return the key surrounded by exclamation marks
       */
      public final String getString(final String key)
      {
          if (this.currentLocale == null || !this.currentLocale.equals(DefaultLocale.getLocale()))
          {
              if (DefaultLocale.getLocale() == null)
              {
                  DefaultLocale.setLocale(new Locale("en"));
              }
              this.currentLocale = DefaultLocale.getLocale();
              Locale.setDefault(this.currentLocale);
              try
              {
                  this.resourceBundle = ResourceBundle.getBundle("resources/" + this.bundleNamePrefix, this.currentLocale);
              }
              catch (MissingResourceException e)
              {
                  return '!' + key.substring(key.indexOf('.') + 1) + '!';
              }
          }
          if (null == this.resourceBundle)
          {
              // Failed to find the resourceBundle (on a previous call to getString)
              return '!' + key.substring(key.indexOf('.') + 1) + '!';
          }
          try
          {
              return this.resourceBundle.getString(key);
          }
          catch (MissingResourceException e)
          {
              return '!' + key.substring(key.indexOf('.') + 1) + '!';
          }
      }
  
      /**
       * Retrieve a string from the default locale bundle. If retrieval fails the value of key string, surrounded by exclamation
       * marks is returned.
       * @param key String; the key for the locale in the properties file
       * @return String; localized string, or, if a translation could not be found return the key surrounded by exclamation marks
       */
      public final String getDefaultString(final String key)
      {
          if (this.defaultLocale == null)
          {
              this.defaultLocale = new Locale("en");
              try
              {
                 this.defaultResourceBundle = ResourceBundle.getBundle("resources/" + this.bundleNamePrefix, this.defaultLocale);
             }
             catch (MissingResourceException e)
             {
                 return '!' + key.substring(key.indexOf('.') + 1) + '!';
             }
         }
         if (null == this.defaultResourceBundle)
         {
             // Failed to find the resourceBundle (on a previous call to getString)
             return '!' + key.substring(key.indexOf('.') + 1) + '!';
         }
         try
         {
             return this.defaultResourceBundle.getString(key);
         }
         catch (MissingResourceException e)
         {
             return '!' + key.substring(key.indexOf('.') + 1) + '!';
         }
     }
 
     /**
      * Return whether the current locale is the default (English) locale.
      * @return boolean; true if the current locale is the default; false if the current locale is not the default
      */
     public boolean isDefault()
     {
         if (this.currentLocale == null || this.defaultLocale == null || !this.currentLocale.equals(this.defaultLocale)
                 || !this.currentLocale.equals(DefaultLocale.getLocale()))
         {
             return false;
         }
         return true;
     }
 
     /** {@inheritDoc} */
     @Override
     public String toString()
     {
         return "Localization [bundleNamePrefix=" + this.bundleNamePrefix + ", resourceBundle=" + this.resourceBundle
                 + ", currentLocale=" + this.currentLocale + ", defaultResourceBundle=" + this.defaultResourceBundle
                 + ", defaultLocale=" + this.defaultLocale + "]";
     }
 
 }