/*
 * Copyright (c) 2005, 2006, 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
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 */
package com.sun.tools.internal.xjc.reader.internalizer;

import java.io.IOException;
import java.io.File;
import java.net.URI;
import java.net.URISyntaxException;

import com.sun.istack.internal.SAXParseException2;

import org.xml.sax.Attributes;
import org.xml.sax.Locator;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
import org.xml.sax.helpers.XMLFilterImpl;

/**
 * XMLFilter that finds references to other schema files from
 * SAX events.
 * 
 * This implementation is a base implementation for typical case
 * where we just need to look for a particular attribute which
 * contains an URL to another schema file.
 * 
 * @author
 *  Kohsuke Kawaguchi (kohsuke.kawaguchi@sun.com)
 */
public abstract class AbstractReferenceFinderImpl extends XMLFilterImpl {
    protected final DOMForest parent;
        
    protected AbstractReferenceFinderImpl( DOMForest _parent ) {
        this.parent = _parent;
    }
    
    /**
     * IF the given element contains a reference to an external resource,
     * return its URL.
     * 
     * @param nsURI
     *      Namespace URI of the current element
     * @param localName
     *      Local name of the current element
     * @return
     *      It's OK to return a relative URL.
     */
    protected abstract String findExternalResource( String nsURI, String localName, Attributes atts);
    
    public void startElement(String namespaceURI, String localName, String qName, Attributes atts)
        throws SAXException {
        super.startElement(namespaceURI, localName, qName, atts);
        
        String relativeRef = findExternalResource(namespaceURI,localName,atts);
        if(relativeRef==null)   return; // non found
        
        try {
            // absolutize URL.
            String ref = new URI(locator.getSystemId()).resolve(new URI(relativeRef)).toString();

            // then parse this schema as well,
            // but don't mark this document as a root.
            parent.parse(ref,false);
        } catch( URISyntaxException e ) {
            String msg = e.getMessage();
            if(new File(relativeRef).exists()) {
                msg = Messages.format(Messages.ERR_FILENAME_IS_NOT_URI)+' '+msg;
            }

            SAXParseException spe = new SAXParseException2(
                Messages.format(Messages.ERR_UNABLE_TO_PARSE,relativeRef, msg),
                locator, e );
                
            fatalError(spe);
            throw spe;
        } catch( IOException e ) {
            SAXParseException spe = new SAXParseException2(
                Messages.format(Messages.ERR_UNABLE_TO_PARSE,relativeRef,e.getMessage()),
                locator, e );

            fatalError(spe);
            throw spe;
        }
    }
        
    private Locator locator;
        
    public void setDocumentLocator(Locator locator) {
        super.setDocumentLocator(locator);
        this.locator = locator;
    }
};