/* ======================================================================
   Parts Copyright 2006 University of Leeds, Oxford University, University of the Highlands and Islands.

   Licensed under the Apache 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.apache.org/licenses/LICENSE-2.0

   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.bodington.xml;

// Imported JAVA API for XML Parsing classes
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

import org.xml.sax.InputSource;

import java.net.URL;
import java.io.File;
import java.io.InputStream;
import java.io.StringReader;

import org.apache.log4j.Logger;
import org.bodington.server.BuildingServerException;

import org.w3c.dom.Document;

/**
 * XML utility class for creating DOMs.
 * @author Antony Corfield; Colin Tatham
 */
public class DOMFactory
{
    
    private static DocumentBuilderFactory factory;
    private static Logger log = Logger.getLogger( DOMFactory.class );
    
    static
    {
        factory = DocumentBuilderFactory.newInstance();
        factory.setNamespaceAware( true );
    }

    /**
     * Gets a document builder from the factory.
     * @return A new instance of a DocumentBuilder
     */
    private static synchronized DocumentBuilder getDocumentBuilder()
    {
        DocumentBuilder builder = null;
        try
        {
            builder = factory.newDocumentBuilder();
            builder.setErrorHandler( new ErrorListener() );
        }
        catch ( ParserConfigurationException e )
        {
            String message = "DOMFactory, static initialization: "
                + "Parser with specified options cannot be built!";
            log.error( message, e );
            System.err.print( "FATAL: " + message
                + " Could not initialize DOMFactory." );
            System.exit( -1 );
        }

        return builder;
    }

    /**
     * Create a new DOM document.
     * @return A new instance of a Document
     */
    public static Document newDocument()
    {
        return getDocumentBuilder().newDocument();
    }

    /**
     * Create a new DOM Document by parsing an XML resource specified by a URL.
     * @param resource The URL defining the resource location
     * @return A new instance of a Document
     * @throws BuildingServerException
     */
    public static Document parse( URL resource ) throws BuildingServerException
    {
        try
        {
            return parse( new File( resource.getPath() ) );
        }
        catch ( NullPointerException npe )
        {
            String message = "Error creating file from URL: " + npe.getMessage();
            log.debug( message );
            throw new BuildingServerException( message );
        }
    }

    /**
     * Create a new DOM Document by parsing XML contained in a File.
     * @param file The File containing XML
     * @return A new instance of a Document
     * @throws BuildingServerException
     */
    public static Document parse( File file ) throws BuildingServerException
    {
        Document document = null;
        try
        {
            DocumentBuilder builder = getDocumentBuilder();
            document = builder.parse( file );
        }
        catch ( Exception e )
        {
            log.debug( "Cannot parse XML file: " + e.getMessage() );
            throw new BuildingServerException( e.getMessage() );
        }

        return document;
    }

    /**
     * Create a new DOM Document by parsing XML from an InputStream.
     * @param inStream InputStream of XML
     * @return A new instance of a Document
     * @throws BuildingServerException
     */
    public static Document parse( InputStream inStream )
        throws BuildingServerException
    {
        Document document = null;
        try
        {
            DocumentBuilder builder = getDocumentBuilder();
            document = builder.parse( inStream );
        }
        catch ( Exception e )
        {
            log.debug( "Cannot parse XML InputStream: " + e.getMessage() );
            throw new BuildingServerException( e.getMessage() );
        }

        return document;
    }

    /**
     * Create a new DOM Document by parsing XML markup in a String.
     * @param data The String of XML markup
     * @return A new instance of a Document
     * @throws BuildingServerException
     */
    public static Document parse( String data ) throws BuildingServerException
    {
        Document document = null;
        try
        {
            DocumentBuilder builder = getDocumentBuilder();
            document = builder
                .parse( new InputSource( new StringReader( data ) ) );
        }
        catch ( Exception e )
        {
            log.debug( "Cannot parse XML string data: " + e.getMessage() );
            throw new BuildingServerException( e.getMessage() );
        }

        return document;
    }
}