/*
 * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code 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 General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package com.sun.tools.doclets.internal.toolkit.builders;

import com.sun.tools.doclets.internal.toolkit.*;
import com.sun.tools.doclets.internal.toolkit.util.*;
import java.io.*;
import java.util.*;
import org.xml.sax.*;
import org.xml.sax.helpers.DefaultHandler;
import javax.xml.parsers.*;

/**
 * Parse the XML that specified the order of operation for the builders. This
 * Parser uses SAX parsing.
 * 
 * @author Jamie Ho
 * @since 1.5
 * @see SAXParser
 */
public class LayoutParser extends DefaultHandler {

  /**
   * The map of XML elements that have been parsed.
   */
  private Map<String, XMLNode> xmlElementsMap;
  private XMLNode currentNode;
  private Configuration configuration;
  private static LayoutParser instance;
  private String currentRoot;
  private boolean isParsing;

  /**
   * This class is a singleton.
   */
  private LayoutParser(Configuration configuration) {
    xmlElementsMap = new HashMap<String, XMLNode>();
    this.configuration = configuration;
  }

  /**
   * Return an instance of the BuilderXML.
   * 
   * @param configuration
   *          the current configuration of the doclet.
   * @return an instance of the BuilderXML.
   */
  public static LayoutParser getInstance(Configuration configuration) {
    if (instance == null) {
      instance = new LayoutParser(configuration);
    }
    return instance;
  }

  /**
   * Parse the XML specifying the layout of the documentation.
   * 
   * @return the list of XML elements parsed.
   */
  public XMLNode parseXML(String root) {
    if (xmlElementsMap.containsKey(root)) {
      return xmlElementsMap.get(root);
    }
    try {
      currentRoot = root;
      isParsing = false;
      SAXParserFactory factory = SAXParserFactory.newInstance();
      SAXParser saxParser = factory.newSAXParser();
      InputStream in = configuration.getBuilderXML();
      saxParser.parse(in, this);
      return xmlElementsMap.get(root);
    } catch (Throwable t) {
      t.printStackTrace();
      throw new DocletAbortException();
    }
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public void startElement(String namespaceURI, String sName, String qName,
      Attributes attrs) throws SAXException {
    if (isParsing || qName.equals(currentRoot)) {
      isParsing = true;
      currentNode = new XMLNode(currentNode, qName);
      for (int i = 0; i < attrs.getLength(); i++)
        currentNode.attrs.put(attrs.getLocalName(i), attrs.getValue(i));
      if (qName.equals(currentRoot))
        xmlElementsMap.put(qName, currentNode);
    }
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public void endElement(String namespaceURI, String sName, String qName)
      throws SAXException {
    if (!isParsing) {
      return;
    }
    currentNode = currentNode.parent;
    isParsing = !qName.equals(currentRoot);
  }
}
