root/src/jomdoc/trunk/src/jomdoc/org/omdoc/jomdoc/util/resolver/JOMDocURIResolvers.java

/*
 * JOMDoc - A Java library for OMDoc documents (http://omdoc.org/jomdoc).
 *
 * Original author    Dimitar Misev <d.misev@jacobs-university.de>
 * Web                http://kwarc.info/dmisev/
 * Created            Feb 6, 2010, 1:48:42 PM
 *
 * Filename           $Id$
 * Revision           $Revision$
 * Last modified on   $Date$
 *               by   $Author$
 *
 * Copyright (C) 2007,2008 the KWARC group (http://kwarc.info)
 * Licensed under the GNU Public License v3 (GPL3).
 * For other licensing contact Michael Kohlhase <m.kohlhase@jacobs-university.de>
 */

package org.omdoc.jomdoc.util.resolver;

import java.io.InputStream;
import java.net.URI;
import java.util.ArrayList;
import java.util.List;
import javax.xml.transform.Source;
import javax.xml.transform.TransformerException;
import nu.xom.Document;
import org.omdoc.jomdoc.util.etc.Log;
import org.omdoc.jomdoc.util.types.Pair;

/**
 * Register multiple resolvers.
 *
 * @author <a href="mailto:d.misev@jacobs-university.de">Dimitar Misev</a>
 */
public class JOMDocURIResolvers extends AbstractJOMDocURIResolver {

    private List<JOMDocURIResolver> uriResolvers = new ArrayList<JOMDocURIResolver>();

    private interface Resolve {
        Object resolve(String href, String base, JOMDocURIResolver resolver) throws ResolveException, TransformerException;
    }

    public JOMDocURIResolvers(JOMDocURIResolver... resolvers) {
        super("");
        for (JOMDocURIResolver r : resolvers) {
            this.uriResolvers.add(r);
        }
    }

    public Pair<? extends InputStream, URI> resolveInputStream(String href, String base) throws ResolveException {
        try {
            return (Pair<? extends InputStream, URI>) resolve(href, base, new Resolve() {
                public Object resolve(String href, String base, JOMDocURIResolver resolver) throws ResolveException {
                    return resolver.resolveInputStream(href, base);
                }
            });
        } catch (TransformerException ex) {
            return null;
        }
    }

    @Override
    public Source resolve(String href, String base) throws TransformerException {
        try {
            return (Source) resolve(href, base, new Resolve() {
                public Object resolve(String href, String base, JOMDocURIResolver resolver) throws ResolveException, TransformerException {
                    return resolver.resolve(href, base);
                }
            });
        } catch (ResolveException ex) {
            return null;
        }
    }

    public Document resolveDocument(String href, String base) throws ResolveException {
        try {
            return (Document) resolve(href, base, new Resolve() {
                public Object resolve(String href, String base, JOMDocURIResolver resolver) throws ResolveException {
                    return resolver.resolveDocument(href, base);
                }
            });
        } catch (TransformerException ex) {
            return null;
        }
    }

    private Object resolve(String href, String base, Resolve resolve) throws ResolveException, TransformerException {
        boolean supported = false;
        for (JOMDocURIResolver resolver : uriResolvers) {
            if (resolver.isSchemaSupported(href, base, false)) {
                supported = true;
                Object res = resolve.resolve(href, base, resolver);
                if (res != null) {
                    return res;
                }
            }
        }
        log(supported, href, base);
        return null;
    }

    private void log(boolean supported, String href, String base) {
        if (!supported) {
            String uri = base;
            if (uri == null) {
                uri = href;
            }
            log.warn("URI schema of " + uri + "\nis not supported by these URI resolvers");
        }
    }

    public List<JOMDocURIResolver> getUriResolvers() {
        return uriResolvers;
    }

    public void setUriResolvers(List<JOMDocURIResolver> uriResolvers) {
        this.uriResolvers = uriResolvers;
    }
}