/* ======================================================================
   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.server.ims;

import java.io.*;
import java.util.Hashtable;
import org.xml.sax.*;

import javax.xml.parsers.ParserConfigurationException;  
import javax.xml.parsers.DocumentBuilderFactory;  
import javax.xml.parsers.FactoryConfigurationError;  
import javax.xml.parsers.DocumentBuilder;

/*
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.Element;
import org.w3c.dom.CharacterData;
import org.w3c.dom.NodeList;
import org.w3c.dom.DOMException;
*/

import org.xml.sax.ext.LexicalHandler;
import org.xml.sax.EntityResolver;
import org.xml.sax.InputSource;
import org.xml.sax.helpers.*;


import org.bodington.assessment.*;
import org.bodington.server.BuildingServerException;


public class PackageResourcesHandler extends DefaultHandler
    {
    private Hashtable resources=null;

    private boolean done=false;
    private boolean in_resources=false;
    private boolean in_resource=false;
    private boolean ref_file_found=false;

    private String resources_baseurl;
    private String resource_baseurl;
    private String file_baseurl;
    private String type, identifier, href, filehref;
    
    //===========================================================
    // SAX DocumentHandler methods
    //===========================================================
    public PackageResourcesHandler()
        {
        }

    public Hashtable getResources()
        {
        return resources;
        }

    public void startDocument ()
    throws SAXException
        {
        done=false;
        resources = null;
        in_resources=false;
        in_resource=false;
        }

    public void endDocument ()
    throws SAXException
        {
        if ( resources == null )
            throw new SAXException( "The package manifest lacked the compulsory resources element." );
        }

    public void startElement (  String uri, String localName, String name, Attributes attrs )
    throws SAXException
        {
        
        if ( done )
            return;
            
        if ( name.equals( "resources" ) )
            {
            in_resources=true;
            resources = new Hashtable();
            resources_baseurl = attrs.getValue( "xml:base" );
            return;
            }
            
        if ( !in_resources )
            return;
            
        if ( name.equals( "manifestref" ) )
            {
            throw new SAXException( "Nested packages are not yet supported." );
            }
            
        if ( name.equals( "xinclude:include" ) )
            {
            throw new SAXException( "External resources not supported" );
            }
            
        if ( name.equals( "resource" ) )
            {
            if ( in_resource )
                throw new SAXException( "A resource element is not allowed inside another resource element." );
            in_resource=true;
            type = attrs.getValue( "type" );
            if ( type==null || !type.equals( "webcontent" ) )
                throw new SAXException( "Type content other than 'webcontent' not supported." );
            
            resource_baseurl = attrs.getValue( "xml:base" );
            identifier = attrs.getValue( "identifier" );

            href = attrs.getValue( "href" );
            if ( href==null || href.length()==0 )
                throw new SAXException( "Resource element without href attribute not supported." );

            if ( resource_baseurl !=null && resource_baseurl.length()>0 )
                href = resource_baseurl + href;
            else if ( resources_baseurl !=null && resources_baseurl.length()>0 )
                href = resources_baseurl + href;
 

            ref_file_found=false;
            }
            
        if ( name.equals( "file" ) )
            {
            if ( !in_resource )
                throw new SAXException( "A file element must appear inside a resource element." );
            file_baseurl = attrs.getValue( "xml:base" );

            filehref = attrs.getValue( "href" );
            if ( file_baseurl !=null && file_baseurl.length()>0 )
                filehref = file_baseurl + filehref;
            else if ( resource_baseurl !=null && resource_baseurl.length()>0 )
                filehref = resource_baseurl + filehref;
            else if ( resources_baseurl !=null && resources_baseurl.length()>0 )
                filehref = resources_baseurl + filehref;

            if ( filehref.equals( href ) )
                ref_file_found=true;
            }
        }

    public void endElement (  String uri, String localName, String name)
        throws SAXException
        {
        if ( name.equals( "resources" ) )
            {
            in_resources=false;
            done=true;
            }
        if ( name.equals( "resource" ) )
            {
            if ( !ref_file_found )
                throw new SAXException( "A resource element specified an entry point href that doesn't exist as a file element." );
            resources.put( identifier, href );
            in_resource=false;
            }
        return;
        }


    public void characters (char buf [], int offset, int len)
        throws SAXException
        {
        return;
        }

    }