/* $Id: SAXParserBase.java 17832 2010-01-12 19:02:29Z linus $

  *****************************************************************************

  * Copyright (c) 2009 Contributors - see below

  * 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:

  *    tfmorris

  *****************************************************************************

  *

  * Some portions of this file was previously release using the BSD License:

  */

 // Copyright (c) 1996-2006 The Regents of the University of California. All

 // Rights Reserved. Permission to use, copy, modify, and distribute this

 // software and its documentation without fee, and without a written

 // agreement is hereby granted, provided that the above copyright notice

 // and this paragraph appear in all copies.  This software program and

 // documentation are copyrighted by The Regents of the University of

 // California. The software program and documentation are supplied "AS

 // IS", without any accompanying services from The Regents. The Regents

 // does not warrant that the operation of the program will be

 // uninterrupted or error-free. The end-user understands that the program

 // was developed for research purposes and is advised not to rely

 // exclusively on the program for any reason.  IN NO EVENT SHALL THE

 // UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT,

 // SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING LOST PROFITS,

 // ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF

 // THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF

 // SUCH DAMAGE. THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY

 // WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF

 // MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE

 // PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND THE UNIVERSITY OF

 // CALIFORNIA HAS NO OBLIGATIONS TO PROVIDE MAINTENANCE, SUPPORT,

 // UPDATES, ENHANCEMENTS, OR MODIFICATIONS.

 package org.argouml.persistence;

 import java.io.FileInputStream;

 import java.io.IOException;

 import java.io.InputStream;

 import java.io.Reader;

 import java.net.URL;

 import javax.xml.parsers.ParserConfigurationException;

 import javax.xml.parsers.SAXParser;

 import javax.xml.parsers.SAXParserFactory;

 import org.apache.log4j.Logger;

 import org.xml.sax.Attributes;

 import org.xml.sax.InputSource;

 import org.xml.sax.SAXException;

 import org.xml.sax.helpers.DefaultHandler;

 /**

  * @author Jim Holt

  */

 abstract class SAXParserBase extends DefaultHandler {

     /**

      * Logger.

      */

     private static final Logger LOG = Logger.getLogger(SAXParserBase.class);

     /**

      * The constructor.

      */

     public SAXParserBase() {

         // empty constructor

     }

     ////////////////////////////////////////////////////////////////

     // static variables

     /**

      * Switching this to true gives some extra logging messages.

      */

     protected static final boolean DBG = false;

     /**

      * This acts as a stack of elements.<p>

      *

      * {@link #startElement(String, String, String, Attributes)} places

      * an item on the stack end {@link #endElement(String, String, String)}

      * removes it.

      */

     private   static  XMLElement[]  elements      = new XMLElement[100];

     /**

      * The number of items actually in use on the elements stack.

      */

     private   static  int           nElements     = 0;

     /**

      * This acts as a stack of elements.<p>

      *

      * {@link #startElement(String, String, String, Attributes)} places

      * an item on the stack end {@link #endElement(String, String, String)}

      * removes it.

      */

     private   static  XMLElement[]  freeElements  = new XMLElement[100];

     private   static  int           nFreeElements = 0;

     private   static  boolean       stats         = true;

     private   static  long          parseTime     = 0;

     ////////////////////////////////////////////////////////////////

     // accessors

     /**

      * @param s true if statistics have to be shown

      */

     public void    setStats(boolean s) { stats = s; }

     /**

      * @return  true if statistics have to be shown

      */

     public boolean getStats()              { return stats; }

     /**

      * @return the parsing time

      */

     public long getParseTime() {

         return parseTime;

     }

     /**

      * @param reader the reader to read

      * @throws SAXException when parsing xml

      */

     public void parse(Reader reader) throws SAXException {

         parse(new InputSource(reader));

     }

     /**

      * @param input the InputSource to read

      * @throws SAXException when parsing xml

      */

     public void parse(InputSource input) throws SAXException {

         long start, end;

         SAXParserFactory factory = SAXParserFactory.newInstance();

         factory.setNamespaceAware(false);

         factory.setValidating(false);

         try {

             SAXParser parser = factory.newSAXParser();

             // If we weren't given a system ID, attempt to use the URL for the

             // JAR that we were loaded from.  (Why? - tfm)

             if (input.getSystemId() == null) {

                 input.setSystemId(getJarResource("org.argouml.kernel.Project"));

             }

             start = System.currentTimeMillis();

             parser.parse(input, this);

             end = System.currentTimeMillis();

             parseTime = end - start;

         } catch (IOException e) {

             throw new SAXException(e);

         } catch (ParserConfigurationException e) {

             throw new SAXException(e);

         }

         if (stats && LOG.isInfoEnabled()) {

             LOG.info("Elapsed time: " + (end - start) + " ms");

         }

     }

     ////////////////////////////////////////////////////////////////

     // abstract methods

     /**

      * Implement in the concrete class to handle reaching the start tag of

      * an element of interest.

      * @param e the element.

      * @throws SAXException on any error parsing the element.

      */

     protected abstract void handleStartElement(XMLElement e)

         throws SAXException;

     /**

      * Implement in the concrete class to handle reaching the end tag of

      * an element of interest.

      * @param e the element.

      * @throws SAXException on any error parsing the element.

      */

     protected abstract void handleEndElement(XMLElement e)

         throws SAXException;

     ////////////////////////////////////////////////////////////////

     // non-abstract methods

     /*

      * @see org.xml.sax.ContentHandler#startElement(java.lang.String,

      *         java.lang.String, java.lang.String, org.xml.sax.Attributes)

      */

     public void startElement(String uri,

             String localname,

             String name,

             Attributes atts) throws SAXException {

         if (isElementOfInterest(name)) {

             XMLElement element = createXmlElement(name, atts);

             if (LOG.isDebugEnabled()) {

                 StringBuffer buf = new StringBuffer();

                 buf.append("START: ").append(name).append(' ').append(element);

                 for (int i = 0; i < atts.getLength(); i++) {

                         buf.append("   ATT: ")

                         .append(atts.getLocalName(i))

                             .append(' ')

                                 .append(atts.getValue(i));

                 }

                 LOG.debug(buf.toString());

             }

             elements[nElements++] = element;

             handleStartElement(element);

         }

     }

     /**

      * Factory method to return an XMLElement.

      * This will reuse previously created elements when possible.

      * @param name The element name.

      * @param atts The element attributes.

      * @return the element.

      */

     private XMLElement createXmlElement(String name, Attributes atts) {

         if (nFreeElements == 0) {

             return new XMLElement(name, atts);

         }

         XMLElement e = freeElements[--nFreeElements];

         e.setName(name);

         e.setAttributes(atts);

         e.resetText();

         return e;

     }

     /*

      * @see org.xml.sax.ContentHandler#endElement(java.lang.String,

      *         java.lang.String, java.lang.String)

      */

     public void endElement(String uri, String localname, String name)

         throws SAXException {

         if (isElementOfInterest(name)) {

             XMLElement e = elements[--nElements];

             if (LOG.isDebugEnabled()) {

                 StringBuffer buf = new StringBuffer();

                 buf.append("END: " + e.getName() + " ["

                            + e.getText() + "] " + e + "\n");

                 for (int i = 0; i < e.getNumAttributes(); i++) {

                     buf.append("   ATT: " + e.getAttributeName(i) + " "

                                + e.getAttributeValue(i) + "\n");

                 }

                 LOG.debug(buf);

             }

             handleEndElement(e);

         }

     }

     /**

      * Determine if an element of the given name is of interest to

      * the parser. The base implementation assumes always true.

      *

      * @param name the element name.

      * @return true if the element name is of interest.

      */

     protected boolean isElementOfInterest(String name) {

         return true;

     }

     // TODO: remove when code below in characters() is removed

 //    private static final String    RETURNSTRING  = "\n      ";

     /*

      * @see org.xml.sax.ContentHandler#characters(char[], int, int)

      */

     public void characters(char[] ch, int start, int length)

         throws SAXException {

         elements[nElements - 1].addText(ch, start, length);

         // TODO: Remove this old implementation after 0.22 if it's

         // demonstrated that it's not needed. - tfm

         // Why does the text get added to ALL the elements on the stack? - tfm

 //        for (int i = 0; i < nElements; i++) {

 //            XMLElement e = elements[i];

 //            if (e.length() > 0) {

 //                // This seems wrong since this method can be called

 //                // multiple times at the parser's discretion - tfm

 //                e.addText(RETURNSTRING);

 //            }

 //            e.addText(ch, start, length);

 //        }

     }

     /*

      * @see org.xml.sax.EntityResolver#resolveEntity(java.lang.String,

      *         java.lang.String)

      */

     public InputSource resolveEntity (String publicId, String systemId)

         throws SAXException {

         try {

             URL testIt = new URL(systemId);

             InputSource s = new InputSource(testIt.openStream());

             return s;

         } catch (Exception e) {

             LOG.info("NOTE: Could not open DTD " + systemId

                     + " due to exception");

             String dtdName = systemId.substring(systemId.lastIndexOf('/') + 1);

             String dtdPath = "/org/argouml/persistence/" + dtdName;

             InputStream is = SAXParserBase.class.getResourceAsStream(dtdPath);

             if (is == null) {

                 try {

                     is = new FileInputStream(dtdPath.substring(1));

                 } catch (Exception ex) {

                     throw new SAXException(e);

                 }

             }

             return new InputSource(is);

         }

     }

     /**

      * @param cls the class

      * @return the jar

      */

     public String getJarResource(String cls) {

           //e.g:org.argouml.uml.generator.ui.ClassGenerationDialog -> poseidon.jar

         String jarFile = "";

         String fileSep = System.getProperty("file.separator");

         String classFile = cls.replace('.', fileSep.charAt(0)) + ".class";

         ClassLoader thisClassLoader = this.getClass().getClassLoader();

         URL url = thisClassLoader.getResource(classFile);

         if (url != null) {

             String urlString = url.getFile();

             int idBegin = urlString.indexOf("file:");

             int idEnd = urlString.indexOf("!");

             if (idBegin > -1 && idEnd > -1 && idEnd > idBegin) {

                 jarFile = urlString.substring(idBegin + 5, idEnd);

             }

         }

         return jarFile;

     }

     ////////////////////////////////////////////////////////////////

     // convenience methods

     /**

      * @param e the element

      */

     public void ignoreElement(XMLElement e) {

         if (LOG.isDebugEnabled()) {

             LOG.debug("NOTE: ignoring tag:" + e.getName());

         }

     }

     /**

      * @param e the element

      */

     public void notImplemented(XMLElement e) {

         if (LOG.isDebugEnabled()) {

             LOG.debug("NOTE: element not implemented: " + e.getName());

         }

     }

 } /* end class SAXParserBase */