/*
* Copyright 2003 Federal Chancellery Austria
*
* Licensed 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 at.gv.egovernment.moa.util;

import java.text.MessageFormat;
import java.util.Locale;
import java.util.MissingResourceException;
import java.util.PropertyResourceBundle;

import at.gv.egovernment.moa.logging.Logger;

/**
 * Provides access to the system messages resource used for exception handling
 * and logging messages.
 * 
 * Messages must be provided as a resource bundle at the path.
 * 
 * @author Patrick Peck
 * @version $Id$
 */
public class Messages {
  /** Error message indicating that no messages are avaiable. */
  private static final String ERROR_MESSAGES_UNAVAILABLE =
    "Fehler in der Server-Konfiguration. "
      + "Die Fehlertexte konnten nicht geladen werden.";
  /** Error message indicating that the message is not available. */
  private static final String ERROR_NO_MESSAGE =
    "Keine Fehlermeldung für Fehler-Nr.={0}";

  /** The names of the resources containing the messages. */
  private String[] resourceNames;
  /** The corresponding <code>Locale</code>s of the resources. */
  private Locale[] locales;
  /** The <code>ResourceBundle</code>s containing the messages. */
  private ResourceBundleChain messages;

  /**
   * Create a new <code>Message</code> object containing the messages
   * in the given resources.
   * 
   * @param resourceNames The names of the resources containing the messages.
   * @param locales The corresponding locales.
   */
  public Messages(String[] resourceNames, Locale[] locales) {
    this.resourceNames = resourceNames;
    this.locales = locales;
    this.messages = null;
  }

  /**
   * Get the message corresponding to a given message ID.
   *
   * @param messageId The ID of the message.
   * @param parameters The parameters to fill in into the message arguments.
   * @return The formatted message. 
   */
  public String getMessage(String messageId, Object[] parameters) {
    // initialize messages
    if (messages == null) {
      initMessages();
    }

    // create the message
    if (messages == null) {
      return ERROR_MESSAGES_UNAVAILABLE;
    } else {
      try {
        String rawMessage = messages.getString(messageId);
        return MessageFormat.format(rawMessage, parameters);
      } catch (MissingResourceException e2) {
        // couldn't find any message -> set to default error message 
        return MessageFormat.format(
          ERROR_NO_MESSAGE,
          new Object[] { messageId });
      }
    }
  }

  /**
   * Return the names of the resources containing the messages.
   * 
   * @return String[] The names of the resource bundles containing the messages.
   */
  private String[] getResourceNames() {
    return resourceNames;
  }

  /**
   * Return the <code>Locale</code>s of the resources containing the messages.
   * 
   * @return Locale[] The <code>Locale</code>s of the resource bundles
   * containing the messages.
   */
  private Locale[] getLocales() {
    return locales;
  }

  /**
   * Initialize the <code>messages</code> <code>ResourceBundle</code> containing
   * the MOA error messages.
   */
  private void initMessages() {
    messages = new ResourceBundleChain();
    int i;

    // initialize the message resources
    for (i = 0; i < resourceNames.length; i++) {
      try {
        messages.addResourceBundle(
          PropertyResourceBundle.getBundle(
            getResourceNames()[i],
            getLocales()[i]));
      } catch (MissingResourceException e) {
        Logger.error(ERROR_MESSAGES_UNAVAILABLE, e);
      }
    }
  }

}