/*******************************************************************************
 * Copyright (c) 2004, 2005 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - Initial API and implementation
 *     Jens Lukowski/Innoopract - initial renaming/restructuring
 *******************************************************************************/
package org.eclipse.wst.common.uriresolver.internal;

import java.util.ArrayList;
import java.util.List;

import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.core.runtime.IExtensionPoint;
import org.eclipse.core.runtime.IExtensionRegistry;
import org.eclipse.core.runtime.Platform;
import org.eclipse.wst.common.uriresolver.internal.provisional.URIResolverPlugin;

/**
 * This class reads the URI resolver extension point and registers extension
 * resolvers with the URI resolver registry.
 */
public class URIResolverExtensionRegistryReader
{

	protected static final String EXTENSION_POINT_ID = "resolverExtensions";

	protected static final String TAG_NAME = "resolverExtension";

	protected static final String ATT_ID = "id";

	protected static final String ELEM_PROJECT_NATURE_ID = "projectNature";

	protected static final String ATT_RESOURCE_TYPE = "resourceType";

	protected static final String ATT_CLASS = "class";

	protected static final String ATT_STAGE = "stage";

	protected static final String VAL_STAGE_PRE = "prenormalization";

	protected static final String VAL_STAGE_POST = "postnormalization";

	protected static final String VAL_STAGE_PHYSICAL = "physical";

	protected static final String ATT_VALUE = "value";

	protected static final String ATT_PRIORITY = "priority";

	protected URIResolverExtensionRegistry registry;

	public URIResolverExtensionRegistryReader(URIResolverExtensionRegistry registry)
	{
		this.registry = registry;
	}

	/**
	 * read from plugin registry and parse it.
	 */
	public void readRegistry()
	{
		IExtensionRegistry pluginRegistry = Platform.getExtensionRegistry();
		IExtensionPoint point = pluginRegistry.getExtensionPoint(URIResolverPlugin
				.getInstance().getBundle().getSymbolicName(), EXTENSION_POINT_ID);
		if (point != null)
		{
			IConfigurationElement[] elements = point.getConfigurationElements();
			for (int i = 0; i < elements.length; i++)
			{
				readElement(elements[i]);
			}
		}
	}

	/**
	 * readElement() - parse and deal with an extension like:
	 * 
	 * <extension point="org.eclipse.wst.contentmodel.util_implementation">
	 * <util_implementation class =
	 * org.eclipse.wst.baseutil.CMUtilImplementationImpl /> </extension>
	 */
	protected void readElement(IConfigurationElement element)
	{
		if (element.getName().equals(TAG_NAME))
		{
			// String id = element.getAttribute(ATT_ID);
			String className = element.getAttribute(ATT_CLASS);
			// String projectNatureId = element.getAttribute(ATT_PROJECT_NATURE_ID);
			String resourceType = element.getAttribute(ATT_RESOURCE_TYPE);
			String stage = element.getAttribute(ATT_STAGE);
			String priority = element.getAttribute(ATT_PRIORITY);
			if (priority == null || priority.equals(""))
			{
				priority = URIResolverExtensionRegistry.PRIORITY_MEDIUM;
			}
			List projectNatureIds = new ArrayList();
			IConfigurationElement[] ids = element.getChildren(ELEM_PROJECT_NATURE_ID);
			int numids = ids.length;
			for (int i = 0; i < numids; i++)
			{
				String tempid = ids[i].getAttribute(ATT_VALUE);

				if (tempid != null)
				{
					projectNatureIds.add(tempid);
				}
			}
			if (className != null)
			{
				try
				{
					String pluginId = element.getDeclaringExtension().getNamespaceIdentifier();

					int stageint = URIResolverExtensionRegistry.STAGE_POSTNORMALIZATION;
					if (stage.equalsIgnoreCase(VAL_STAGE_PRE))
					{
						stageint = URIResolverExtensionRegistry.STAGE_PRENORMALIZATION;
					} else if (stage.equalsIgnoreCase(VAL_STAGE_PHYSICAL))
					{
						stageint = URIResolverExtensionRegistry.STAGE_PHYSICAL;
					}
					registry.put(className, pluginId, projectNatureIds, resourceType,
							stageint, priority);
				} catch (Exception e)
				{
					// TODO: Log exception as this will cause an extension resolver
					//       from loading.
				}
			}
		}
	}
}