/*
    * $Id: MessageResources.java 471754 2006-11-06 14:55:09Z husted $
    *
    * 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.struts.util;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  
  import java.io.Serializable;
  
  import java.text.MessageFormat;
  
  import java.util.HashMap;
  import java.util.Locale;
  
  /**
   * General purpose abstract class that describes an API for retrieving
   * Locale-sensitive messages from underlying resource locations of an
   * unspecified design, and optionally utilizing the <code>MessageFormat</code>
   * class to produce internationalized messages with parametric replacement.
   * <p> Calls to <code>getMessage()</code> variants without a
   * <code>Locale</code> argument are presumed to be requesting a message string
   * in the default <code>Locale</code> for this JVM. <p> Calls to
   * <code>getMessage()</code> with an unknown key, or an unknown
   * <code>Locale</code> will return <code>null</code> if the
   * <code>returnNull</code> property is set to <code>true</code>.  Otherwise, a
   * suitable error message will be returned instead. <p> <strong>IMPLEMENTATION
   * NOTE</strong> - Classes that extend this class must be Serializable so that
   * instances may be used in distributable application server environments.
   *
   * @version $Rev: 471754 $ $Date: 2005-08-29 23:57:50 -0400 (Mon, 29 Aug 2005)
   *          $
   */
  public abstract class MessageResources implements Serializable {
      // ------------------------------------------------------------- Properties
  
      /**
       * Commons Logging instance.
       */
      protected static Log log = LogFactory.getLog(MessageResources.class);
  
      // --------------------------------------------------------- Static Methods
  
      /**
       * The default MessageResourcesFactory used to create MessageResources
       * instances.
       */
      protected static MessageResourcesFactory defaultFactory = null;
  
      /**
       * The configuration parameter used to initialize this MessageResources.
       */
      protected String config = null;
  
      /**
       * The default Locale for our environment.
       */
      protected Locale defaultLocale = Locale.getDefault();
  
      /**
       * The <code>MessageResourcesFactory</code> that created this instance.
       */
      protected MessageResourcesFactory factory = null;
  
      /**
       * The set of previously created MessageFormat objects, keyed by the key
       * computed in <code>messageKey()</code>.
       */
      protected HashMap formats = new HashMap();
  
      /**
       * Indicate is a <code>null</code> is returned instead of an error message
       * string when an unknown Locale or key is requested.
       */
      protected boolean returnNull = false;
  
      /**
       * Indicates whether 'escape processing' should be performed on the error
       * message string.
       */
      private boolean escape = true;
  
     // ----------------------------------------------------------- Constructors
 
     /**
      * Construct a new MessageResources according to the specified
      * parameters.
      *
      * @param factory The MessageResourcesFactory that created us
      * @param config  The configuration parameter for this MessageResources
      */
     public MessageResources(MessageResourcesFactory factory, String config) {
         this(factory, config, false);
     }
 
     /**
      * Construct a new MessageResources according to the specified
      * parameters.
      *
      * @param factory    The MessageResourcesFactory that created us
      * @param config     The configuration parameter for this
      *                   MessageResources
      * @param returnNull The returnNull property we should initialize with
      */
     public MessageResources(MessageResourcesFactory factory, String config,
         boolean returnNull) {
         super();
         this.factory = factory;
         this.config = config;
         this.returnNull = returnNull;
     }
 
     /**
      * The configuration parameter used to initialize this MessageResources.
      *
      * @return parameter used to initialize this MessageResources
      */
     public String getConfig() {
         return (this.config);
     }
 
     /**
      * The <code>MessageResourcesFactory</code> that created this instance.
      *
      * @return <code>MessageResourcesFactory</code> that created instance
      */
     public MessageResourcesFactory getFactory() {
         return (this.factory);
     }
 
     /**
      * Indicates that a <code>null</code> is returned instead of an error
      * message string if an unknown Locale or key is requested.
      *
      * @return true if null is returned if unknown key or locale is requested
      */
     public boolean getReturnNull() {
         return (this.returnNull);
     }
 
     /**
      * Indicates that a <code>null</code> is returned instead of an error
      * message string if an unknown Locale or key is requested.
      *
      * @param returnNull true Indicates that a <code>null</code> is returned
      *                   if an unknown Locale or key is requested.
      */
     public void setReturnNull(boolean returnNull) {
         this.returnNull = returnNull;
     }
 
     /**
      * Indicates whether 'escape processing' should be performed on the error
      * message string.
      *
      * @since Struts 1.2.8
      */
     public boolean isEscape() {
         return escape;
     }
 
     /**
      * Set whether 'escape processing' should be performed on the error
      * message string.
      *
      * @since Struts 1.2.8
      */
     public void setEscape(boolean escape) {
         this.escape = escape;
     }
 
     // --------------------------------------------------------- Public Methods
 
     /**
      * Returns a text message for the specified key, for the default Locale.
      *
      * @param key The message key to look up
      */
     public String getMessage(String key) {
         return this.getMessage((Locale) null, key, null);
     }
 
     /**
      * Returns a text message after parametric replacement of the specified
      * parameter placeholders.
      *
      * @param key  The message key to look up
      * @param args An array of replacement parameters for placeholders
      */
     public String getMessage(String key, Object[] args) {
         return this.getMessage((Locale) null, key, args);
     }
 
     /**
      * Returns a text message after parametric replacement of the specified
      * parameter placeholders.
      *
      * @param key  The message key to look up
      * @param arg0 The replacement for placeholder {0} in the message
      */
     public String getMessage(String key, Object arg0) {
         return this.getMessage((Locale) null, key, arg0);
     }
 
     /**
      * Returns a text message after parametric replacement of the specified
      * parameter placeholders.
      *
      * @param key  The message key to look up
      * @param arg0 The replacement for placeholder {0} in the message
      * @param arg1 The replacement for placeholder {1} in the message
      */
     public String getMessage(String key, Object arg0, Object arg1) {
         return this.getMessage((Locale) null, key, arg0, arg1);
     }
 
     /**
      * Returns a text message after parametric replacement of the specified
      * parameter placeholders.
      *
      * @param key  The message key to look up
      * @param arg0 The replacement for placeholder {0} in the message
      * @param arg1 The replacement for placeholder {1} in the message
      * @param arg2 The replacement for placeholder {2} in the message
      */
     public String getMessage(String key, Object arg0, Object arg1, Object arg2) {
         return this.getMessage((Locale) null, key, arg0, arg1, arg2);
     }
 
     /**
      * Returns a text message after parametric replacement of the specified
      * parameter placeholders.
      *
      * @param key  The message key to look up
      * @param arg0 The replacement for placeholder {0} in the message
      * @param arg1 The replacement for placeholder {1} in the message
      * @param arg2 The replacement for placeholder {2} in the message
      * @param arg3 The replacement for placeholder {3} in the message
      */
     public String getMessage(String key, Object arg0, Object arg1, Object arg2,
         Object arg3) {
         return this.getMessage((Locale) null, key, arg0, arg1, arg2, arg3);
     }
 
     /**
      * Returns a text message for the specified key, for the default Locale. A
      * null string result will be returned by this method if no relevant
      * message resource is found for this key or Locale, if the
      * <code>returnNull</code> property is set.  Otherwise, an appropriate
      * error message will be returned. <p> This method must be implemented by
      * a concrete subclass.
      *
      * @param locale The requested message Locale, or <code>null</code> for
      *               the system default Locale
      * @param key    The message key to look up
      */
     public abstract String getMessage(Locale locale, String key);
 
     /**
      * Returns a text message after parametric replacement of the specified
      * parameter placeholders.  A null string result will be returned by this
      * method if no resource bundle has been configured.
      *
      * @param locale The requested message Locale, or <code>null</code> for
      *               the system default Locale
      * @param key    The message key to look up
      * @param args   An array of replacement parameters for placeholders
      */
     public String getMessage(Locale locale, String key, Object[] args) {
         // Cache MessageFormat instances as they are accessed
         if (locale == null) {
             locale = defaultLocale;
         }
 
         MessageFormat format = null;
         String formatKey = messageKey(locale, key);
 
         synchronized (formats) {
             format = (MessageFormat) formats.get(formatKey);
 
             if (format == null) {
                 String formatString = getMessage(locale, key);
 
                 if (formatString == null) {
                     return returnNull ? null : ("???" + formatKey + "???");
                 }
 
                 format = new MessageFormat(escape(formatString));
                 format.setLocale(locale);
                 formats.put(formatKey, format);
             }
         }
 
         return format.format(args);
     }
 
     /**
      * Returns a text message after parametric replacement of the specified
      * parameter placeholders.  A null string result will never be returned by
      * this method.
      *
      * @param locale The requested message Locale, or <code>null</code> for
      *               the system default Locale
      * @param key    The message key to look up
      * @param arg0   The replacement for placeholder {0} in the message
      */
     public String getMessage(Locale locale, String key, Object arg0) {
         return this.getMessage(locale, key, new Object[] { arg0 });
     }
 
     /**
      * Returns a text message after parametric replacement of the specified
      * parameter placeholders.  A null string result will never be returned by
      * this method.
      *
      * @param locale The requested message Locale, or <code>null</code> for
      *               the system default Locale
      * @param key    The message key to look up
      * @param arg0   The replacement for placeholder {0} in the message
      * @param arg1   The replacement for placeholder {1} in the message
      */
     public String getMessage(Locale locale, String key, Object arg0, Object arg1) {
         return this.getMessage(locale, key, new Object[] { arg0, arg1 });
     }
 
     /**
      * Returns a text message after parametric replacement of the specified
      * parameter placeholders.  A null string result will never be returned by
      * this method.
      *
      * @param locale The requested message Locale, or <code>null</code> for
      *               the system default Locale
      * @param key    The message key to look up
      * @param arg0   The replacement for placeholder {0} in the message
      * @param arg1   The replacement for placeholder {1} in the message
      * @param arg2   The replacement for placeholder {2} in the message
      */
     public String getMessage(Locale locale, String key, Object arg0,
         Object arg1, Object arg2) {
         return this.getMessage(locale, key, new Object[] { arg0, arg1, arg2 });
     }
 
     /**
      * Returns a text message after parametric replacement of the specified
      * parameter placeholders.  A null string result will never be returned by
      * this method.
      *
      * @param locale The requested message Locale, or <code>null</code> for
      *               the system default Locale
      * @param key    The message key to look up
      * @param arg0   The replacement for placeholder {0} in the message
      * @param arg1   The replacement for placeholder {1} in the message
      * @param arg2   The replacement for placeholder {2} in the message
      * @param arg3   The replacement for placeholder {3} in the message
      */
     public String getMessage(Locale locale, String key, Object arg0,
         Object arg1, Object arg2, Object arg3) {
         return this.getMessage(locale, key,
             new Object[] { arg0, arg1, arg2, arg3 });
     }
 
     /**
      * Return <code>true</code> if there is a defined message for the
      * specified key in the system default locale.
      *
      * @param key The message key to look up
      */
     public boolean isPresent(String key) {
         return this.isPresent(null, key);
     }
 
     /**
      * Return <code>true</code> if there is a defined message for the
      * specified key in the specified Locale.
      *
      * @param locale The requested message Locale, or <code>null</code> for
      *               the system default Locale
      * @param key    The message key to look up
      */
     public boolean isPresent(Locale locale, String key) {
         String message = getMessage(locale, key);
 
         if (message == null) {
             return false;
         } else if (message.startsWith("???") && message.endsWith("???")) {
             return false; // FIXME - Only valid for default implementation
         } else {
             return true;
         }
     }
 
     // ------------------------------------------------------ Protected Methods
 
     /**
      * Escape any single quote characters that are included in the specified
      * message string.
      *
      * @param string The string to be escaped
      */
     protected String escape(String string) {
         if (!isEscape()) {
             return string;
         }
 
         if ((string == null) || (string.indexOf('\'') < 0)) {
             return string;
         }
 
         int n = string.length();
         StringBuffer sb = new StringBuffer(n);
 
         for (int i = 0; i < n; i++) {
             char ch = string.charAt(i);
 
             if (ch == '\'') {
                 sb.append('\'');
             }
 
             sb.append(ch);
         }
 
         return sb.toString();
     }
 
     /**
      * Compute and return a key to be used in caching information by a Locale.
      * <strong>NOTE</strong> - The locale key for the default Locale in our
      * environment is a zero length String.
      *
      * @param locale The locale for which a key is desired
      */
     protected String localeKey(Locale locale) {
         return (locale == null) ? "" : locale.toString();
     }
 
     /**
      * Compute and return a key to be used in caching information by Locale
      * and message key.
      *
      * @param locale The Locale for which this format key is calculated
      * @param key    The message key for which this format key is calculated
      */
     protected String messageKey(Locale locale, String key) {
         return (localeKey(locale) + "." + key);
     }
 
     /**
      * Compute and return a key to be used in caching information by locale
      * key and message key.
      *
      * @param localeKey The locale key for which this cache key is calculated
      * @param key       The message key for which this cache key is
      *                  calculated
      */
     protected String messageKey(String localeKey, String key) {
         return (localeKey + "." + key);
     }
 
     /**
      * Create and return an instance of <code>MessageResources</code> for the
      * created by the default <code>MessageResourcesFactory</code>.
      *
      * @param config Configuration parameter for this message bundle.
      */
     public synchronized static MessageResources getMessageResources(
         String config) {
         if (defaultFactory == null) {
             defaultFactory = MessageResourcesFactory.createFactory();
         }
 
         return defaultFactory.createResources(config);
     }
 
     /**
      * Log a message to the Writer that has been configured for our use.
      *
      * @param message The message to be logged
      */
     public void log(String message) {
         log.debug(message);
     }
 
     /**
      * Log a message and exception to the Writer that has been configured for
      * our use.
      *
      * @param message   The message to be logged
      * @param throwable The exception to be logged
      */
     public void log(String message, Throwable throwable) {
         log.debug(message, throwable);
     }
 }