/*
    * Copyright 2005-2008 The Kuali Foundation
    *
    *
    * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php
   *
   * 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 org.kuali.rice.edl.impl;
  
  import org.kuali.rice.core.api.util.RiceUtilities;
  import org.w3c.dom.Document;
  import org.w3c.dom.Element;
  import org.w3c.dom.NodeList;
  
  import javax.xml.parsers.DocumentBuilderFactory;
  import javax.xml.xpath.XPath;
  import javax.xml.xpath.XPathConstants;
  import javax.xml.xpath.XPathFactory;
  import java.io.InputStream;
  import java.util.LinkedHashMap;
  import java.util.Map;
  
  /**
   * Builds a EDLGlobalConfig.
   *
   * @author Kuali Rice Team (rice.collab@kuali.org)
   */
  public class EDLGlobalConfigFactory {
  
  	private static final String CONFIG_PROCESSOR_XPATH_XPRSN = "xpathExp";
  	private static final String CONFIG_PROCESSOR_CLASS_NAME = "className";
  
  
  	public static EDLGlobalConfig createEDLGlobalConfig(String edlConfigLocation) throws Exception {
  		EDLGlobalConfig edlConfig = new EDLGlobalConfig();
  		InputStream configStream = RiceUtilities.getResourceAsStream(edlConfigLocation);
  		Document configXml = DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(configStream);
  
  		edlConfig.setPreProcessors(createProcessorMap("//preProcessors/preProcessor", configXml));
  		edlConfig.setPostProcessors(createProcessorMap("//postProcessors/postProcessor", configXml));
  		edlConfig.setStateComponents(createProcessorMap("//stateComponents/stateComponent", configXml));
  		edlConfig.setConfigProcessors(createConfigProcessorMap("//configProcessors/configProcessor", configXml));
  
  		return edlConfig;
  	}
  
  	private static Map createProcessorMap(String xpathExpression, Document doc) throws Exception {
  		Map processors = new LinkedHashMap();//preserve parsing order
  		XPath xpath = XPathFactory.newInstance().newXPath();
  		NodeList globalProcessorDeclarations = (NodeList)xpath.evaluate(xpathExpression, doc, XPathConstants.NODESET);
  		for (int i = 0; i < globalProcessorDeclarations.getLength(); i++) {
  			Element globalProcessorDeclaraion = (Element)globalProcessorDeclarations.item(i);
  			processors.put(globalProcessorDeclaraion, Class.forName(globalProcessorDeclaraion.getFirstChild().getNodeValue()));
  		}
  		return processors;
  	}
  
  	private static Map createConfigProcessorMap(String xpathExpression, Document doc) throws Exception {
  		Map configProcessors = new LinkedHashMap();//preserve parsing order
  		XPath xpath = XPathFactory.newInstance().newXPath();
  		NodeList globalConfigProcessorDeclarations = (NodeList)xpath.evaluate(xpathExpression, doc, XPathConstants.NODESET);
  		for (int i = 0; i < globalConfigProcessorDeclarations.getLength(); i++) {
  			Element globalProcessorDeclaraion = (Element)globalConfigProcessorDeclarations.item(i);
  			String xpathEx = (String)xpath.evaluate(CONFIG_PROCESSOR_XPATH_XPRSN, globalProcessorDeclaraion, XPathConstants.STRING);
  			String className = (String)xpath.evaluate(CONFIG_PROCESSOR_CLASS_NAME, globalProcessorDeclaraion, XPathConstants.STRING);
  			configProcessors.put(xpathEx, Class.forName(className));
  		}
  		return configProcessors;
  	}
  }