/*

 * 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.

 *

 * 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 jnlp.converter.parser.xml;

import javax.xml.parsers.ParserConfigurationException;

import javax.xml.parsers.SAXParser;

import javax.xml.parsers.SAXParserFactory;

import org.xml.sax.InputSource;

import org.xml.sax.Attributes;

import org.xml.sax.SAXException;

import org.xml.sax.helpers.DefaultHandler;

import java.io.StringReader;

import java.io.IOException;

import java.util.Stack;

public class XMLParser extends DefaultHandler {

    private XMLNode _root;

    private final String _source;

    private Stack<XMLNode> _inProgress;

    private String _characters;

    // although defined in com.sun.org.apache.xerces.internal.impl.Constants,

    // we should not be able to access that, so defined here

    private final static String DTD_DOWNLOAD =

        "http://apache.org/xml/features/nonvalidating/load-external-dtd";

    private static final SAXParserFactory SPF = SAXParserFactory.newInstance();

    /*

     * Construct an <code>XMLParser</code>.

     *

     * @param source  - the source text to parse.

     */

    public XMLParser(String source) {

        _source = source.trim();

    }

    public XMLNode parse() throws SAXException {

        // normally we parse without validating, but leave option to parse

        // with validation, possibly controlled by config option.

        return parse(false);

    }

    public XMLNode parse(boolean validating) throws SAXException {

        _root = null;

        _inProgress = new Stack<>();

        try {

            InputSource is = new InputSource(new StringReader(_source));

            SPF.setValidating(validating);

            // only download dtd file from DOCTYPE if we are doing validation

            try {

                SPF.setFeature(DTD_DOWNLOAD, validating);

            } catch (Exception e) {

            }

            SAXParser sp = SPF.newSAXParser();

            sp.parse(is, this);

        } catch (ParserConfigurationException | IOException pce) {

            throw new SAXException(pce);

        }

        return _root;

    }

    @Override

    public void startElement(String uri, String localeName, String qName,

            Attributes attributes) throws SAXException {

        XMLAttribute first = null;

        XMLAttribute last = null;

        int len = attributes.getLength();

        for (int i = 0; i < len; i++) {

            XMLAttribute att = new XMLAttribute(

                    // in old implementation attribute names and values were trimmed

                    attributes.getQName(i).trim(), attributes.getValue(i).trim());

            if (first == null) {

                first = att;

            }

            if (last != null) {

                last.setNext(att);

            }

            last = att;

        }

        _inProgress.push(new XMLNode(qName, first));

        _characters = null;

    }

    @Override

    public void endElement(String uri, String localeName, String elementName)

            throws SAXException {

        XMLNode node = _inProgress.pop();

        // <information>

        //  <title>Title</title>

        //  <vendor>Vendor</vendor> "Some whitespaces"

        // </information>

        // In example above when we receive end of <information> we will

        // have _characters set to whitespace and new line and it will be

        // added as child node to <information>. This will break our cache code

        // which will think that JNLP file changed on server even if it is not

        // and thus we might not load properly.

        //

        // <application-desc name="HelloWorld" main-class="HelloWorld">

        //  <argument>  test with whitespaces </argument>

        // </application-desc>

        // From example above we want to include whitespaces for <argument>.

        //

        // <node1>

        //  <node2>abc</node2>

        //  xyz (might be whitespaces)

        // </node1>

        // In JNLP spec we do not have cases when node have nested nodes as

        // well as text which is whitespaces only.

        //

        // So to fix it lets check if ending node have nested nodes, then do

        // not add whitespaces only node.

        if (node != null && node.getNested() != null && _characters != null) {

            String trimCharacters = _characters.trim();

            if ((trimCharacters == null) || (trimCharacters.length() == 0)) {

                _characters = null; // No need to add whitespaces only

            }

        }

        if ((_characters != null) && (_characters.trim().length() > 0)) {

            addChild(node, new XMLNode(_characters));

        }

        if (_inProgress.isEmpty()) {

            _root = node;

        } else {

            addChild(_inProgress.peek(), node);

        }

        _characters = null;

    }

    @Override

    public void ignorableWhitespace(char[] chars, int start, int length)

            throws SAXException {

        String s = new String(chars, start, length);

        _characters = ((_characters == null) ? s : _characters + s);

    }

    private void addChild(XMLNode parent, XMLNode child) {

        child.setParent(parent);

        XMLNode sibling = parent.getNested();

        if (sibling == null) {

            parent.setNested(child); // set us as only child

        } else {

            while (sibling.getNext() != null) {

                sibling = sibling.getNext();

            }

            sibling.setNext(child); // sets us as youngest child

        }

    }

}