/**
 * Copyright (c) 2008 IBM Corporation and others.
 * All rights reserved.   This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v2.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v20.html
 * 
 * Contributors: 
 *   IBM - Initial API and implementation
 */
package org.eclipse.emf.ecore.plugin;


import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.core.runtime.RegistryFactory;

import org.eclipse.emf.ecore.EPackage;

/**
 * A plugin extension reader that populates the
 * {@link org.eclipse.emf.ecore.EPackage.Registry#INSTANCE global} package registry.
 * Clients are not expected to use this class directly.
 */
class DynamicPackageRegistryReader extends RegistryReader
{
  static final String TAG_RESOURCE = "resource";
  static final String ATT_URI = "uri";
  static final String ATT_LOCATION = "location";

  public DynamicPackageRegistryReader()
  {
    super
      (RegistryFactory.getRegistry(),
       EcorePlugin.INSTANCE.getSymbolicName(), 
       EcorePlugin.DYNAMIC_PACKAGE_PPID);
  }

  @Override
  protected boolean readElement(IConfigurationElement element, boolean add)
  {
    if (element.getName().equals(TAG_RESOURCE))
    {
      String packageURI = element.getAttribute(ATT_URI);
      if (packageURI == null)
      {
        logMissingAttribute(element, ATT_URI);
      }
      else if (element.getAttribute(ATT_LOCATION) == null)
      {
        logMissingAttribute(element, ATT_LOCATION);
      }
      else if (add)
      {
        Object previous = EPackage.Registry.INSTANCE.put(packageURI, new EPackageDescriptor.Dynamic(element, ATT_LOCATION));
        if (previous instanceof PluginClassDescriptor)
        {
          PluginClassDescriptor descriptor = (PluginClassDescriptor)previous;
          EcorePlugin.INSTANCE.log
            ("Both '" + descriptor.element.getContributor().getName() + "' and '" + element.getContributor().getName() + "' register a package for '" + packageURI + "'");
        }
        
        return true;
      }
      else
      {
        EPackage.Registry.INSTANCE.remove(packageURI);
        return true;
      }
    }

    return false;
  }
}
