/*
 * Copyright 2003 Federal Chancellery Austria
 * MOA-ID has been developed in a cooperation between BRZ, the Federal
 * Chancellery Austria - ICT staff unit, and Graz University of Technology.
 *
 * Licensed under the EUPL, Version 1.1 or - as soon they will be approved by
 * the European Commission - subsequent versions of the EUPL (the "Licence");
 * You may not use this work except in compliance with the Licence.
 * You may obtain a copy of the Licence at:
 * http://www.osor.eu/eupl/
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the Licence is distributed on an "AS IS" basis,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the Licence for the specific language governing permissions and
 * limitations under the Licence.
 *
 * This product combines work with different licenses. See the "NOTICE" text
 * file for details on the various modules and licenses.
 * The "NOTICE" text file is part of the distribution. Any derivative works
 * that you distribute must include a readable copy of the "NOTICE" text file.
 */


package at.gv.egovernment.moa.util;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.MissingResourceException;
import java.util.ResourceBundle;

/**
 * A class to chain <code>ResourceBundle</code>s.
 * 
 * @author Patrick Peck
 * @version $Id$
 */
public class ResourceBundleChain {
  /** Error message indicating the resource is not available. */
  private static final String ERROR_MISSING_RESOURCE = "Missing resource";
  /** The <code>ResourceBundle</code>s contained in this chain. */
  private List resourceBundles = new ArrayList();

  /**
   * Add a <code>ResourceBundle</code> to the chain.
   * 
   * @param resourceBundle The <code>ResourceBundle</code> to add.
   */
  public void addResourceBundle(ResourceBundle resourceBundle) {
    resourceBundles.add(resourceBundle);
  }

  /**
   * Return the value of the resource.
   * 
   * @param key The key to access the <code>String</code> resource.
   * @return The resource value. All the registered <code>ResourceBundle</code>s
   * are searched in the order in which they have previously been added to this
   * <code>ResourceBundleChain</code>.
   * @throws MissingResourceException The resource coult not be found in any of
   * the bundles.
   */
  public String getString(String key) throws MissingResourceException {
    MissingResourceException lastException = null;
    Iterator iter;

    // handle case where no resource bundles have been added
    if (resourceBundles.size() == 0) {
      throw new MissingResourceException(
        ERROR_MISSING_RESOURCE,
        this.getClass().getName(),
        key);
    }

    // try to find the resource in one of the bundles; if it cannot be found,
    // return the exception thrown by the last bundle in the list
    for (iter = resourceBundles.iterator(); iter.hasNext();) {
      ResourceBundle resourceBundle = (ResourceBundle) iter.next();
      try {
        String value = resourceBundle.getString(key);
        return value;
      } catch (MissingResourceException e) {
        lastException = e;
      }
    }
    throw lastException;
  }

}