/*
 * JBoss, Home of Professional Open Source
 * Copyright 2005, JBoss Inc., and individual contributors as indicated
 * by the @authors tag. See the copyright.txt in the distribution for a
 * full listing of individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.jbpm.jpdl.internal.convert.node;

import java.io.InputStream;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;


/**
 * This originates from jbpm3 code base
 * 
 * Basically, it maps a type string to a Node class.
 */
public class NodeConverterTypes {

	  public static Set<String> getNodeTypes() {
	    return nodeTypes.keySet();
	  }
	  
	  public static Set<Class<? extends Node>> getNodeNames() {
	    return nodeNames.keySet();
	  }
	  
	  public static Class<? extends Node> getNodeType(String name) {
	    return nodeTypes.get(name);
	  }
	  
	  public static String getNodeName(Class<? extends Node> type) {
	    return nodeNames.get(type);
	  }
	  
	  private static final Log log = LogFactory.getLog(NodeConverterTypes.class);
      private static SAXReader reader = new SAXReader();
	  static Map<String, Class<? extends Node>> nodeTypes = initialiseNodeTypes();
	  static Map<Class<? extends Node>, String> nodeNames = createInverseMapping(nodeTypes);
	  
	  static Map<String, Class<? extends Node>> initialiseNodeTypes() {
	    Map<String, Class<? extends Node>> types = new HashMap<String, Class<? extends Node>>();
        InputStream nodeTypesStream = NodeConverterTypes.class.getClassLoader().getResourceAsStream("node.converter.types.xml");
        Element nodeTypesElement = null;
		try {
			nodeTypesElement = reader.read(nodeTypesStream).getRootElement();
		} catch (DocumentException e1) {
			log.error("Failed to parse the node.converter.types.xml", e1);
		}       
	    Iterator<?> nodeTypeIterator = nodeTypesElement.elementIterator("node-type");
	    while(nodeTypeIterator.hasNext()) {
	      Element nodeTypeElement = (Element) nodeTypeIterator.next();

	      String elementTag = nodeTypeElement.attributeValue("element");
	      String className = nodeTypeElement.attributeValue("class");
	      try {
	        Class<?> nodeClass =  NodeConverterTypes.class.forName(className);
	        types.put(elementTag, nodeClass.asSubclass(Node.class));
	        
	      } catch (Exception e) {
	        if (!"org.jboss.seam.jbpm.Page".equals(className)) {
	          if(log.isDebugEnabled())
	          {
	        	  log.debug("node '"+elementTag+"' will not be available. class '"+className+"' couldn't be loaded");
	          }
	        }
	      }
	    }

	    return types; 
	  }

	  public static <K, V> Map<V, K> createInverseMapping(Map<K, V> map) {
	    Map<V, K> inverse = new HashMap<V, K>();
	    for (Map.Entry<K, V> entry : map.entrySet()) {
	      inverse.put(entry.getValue(), entry.getKey());      
	    }
	    return inverse;
	  }
	}