package org.madore.damlengine;

import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.MalformedURLException;
import javax.xml.parsers.SAXParserFactory;
import org.w3c.dom.ls.LSResourceResolver;
import org.w3c.dom.ls.LSInput;
import org.xml.sax.SAXException;
import org.xml.sax.EntityResolver;
import org.xml.sax.ext.EntityResolver2;
import org.xml.sax.InputSource;
import org.apache.xml.resolver.CatalogManager;
import org.apache.xml.resolver.Catalog;
import org.apache.xml.resolver.readers.SAXCatalogReader;
import org.apache.xml.resolver.readers.OASISXMLCatalogReader;
import org.apache.xerces.dom.DOMInputImpl;
import org.apache.xerces.jaxp.SAXParserFactoryImpl;

public final class Resolver
    implements LSResourceResolver, EntityResolver, EntityResolver2 {

    private static final String catalogFiles[] = { "/etc/xml/catalog" };

    private CatalogManager catalogManager = null;
    private Catalog catalog = null;

    public static final class BootstrapResolver
	extends org.apache.xml.resolver.helpers.BootstrapResolver {
	@Override
	public InputSource resolveEntity(String publicId, String systemId) {
	    String resolved = null;
	    if ( publicId.equals("-//GlobalTransCorp//DTD XML Catalogs "
				 +"V1.0-Based Extension V1.0//EN") ) {
		resolved
		    = "file:///usr/share/xml/schema/xml-core/tr9401.dtd";
	    }
	    if ( resolved != null ) {
		InputSource source = new InputSource(resolved);
		source.setPublicId(publicId);
		return source;
	    }
	    return super.resolveEntity(publicId, systemId);
	}
    }

    public Resolver() {
	catalogManager = new CatalogManager();
	// catalogManager.setVerbosity(42);
	catalogManager.setPreferPublic(true);
	catalogManager.setRelativeCatalogs(false);
	catalogManager.setBootstrapResolver(new BootstrapResolver());
	catalog = new Catalog(catalogManager);
        SAXParserFactory spf = new SAXParserFactoryImpl();
        spf.setNamespaceAware(true);
        spf.setValidating(false);
        SAXCatalogReader saxReader = new SAXCatalogReader(spf);
        saxReader.setCatalogParser(OASISXMLCatalogReader.namespaceName,
				   "catalog", 
				   "org.apache.xml.resolver.readers."
				   +"OASISXMLCatalogReader");
        catalog.addReader("application/xml", saxReader);
	for ( String f : catalogFiles ) {
	    try {
		catalog.parseCatalog(f);
	    } catch (MalformedURLException e) {
		throw new RuntimeException(e);
	    } catch (IOException e) {
		throw new RuntimeException(e);
	    }
	}
    }

    public String resolvePublic(String publicId, String systemId) {
	try {
	    return catalog.resolvePublic(publicId, systemId);
	} catch (MalformedURLException e) {
	    throw new RuntimeException(e);
	} catch (IOException e) {
	    throw new RuntimeException(e);
	}
    }

    public String resolveSystem(String systemId) {
	try {
	    return catalog.resolveSystem(systemId);
	} catch (MalformedURLException e) {
	    throw new RuntimeException(e);
	} catch (IOException e) {
	    throw new RuntimeException(e);
	}
    }

    @SuppressWarnings("unused") // namespaceURI parameter is unused
    protected String resolve(String namespaceURI,
			     String publicId,
			     String systemId,
			     String baseURI) {
	String resolved;
	if ( publicId != null )
	    resolved = resolvePublic(publicId, systemId);
	else
	    resolved = resolveSystem(systemId);
	if ( resolved != null )
	    return resolved;
	if ( baseURI != null ) {
	    try {
		URI u = new URI(baseURI);
		URI v = u.resolve(systemId);
		return v.toString();
	    } catch ( URISyntaxException e ) {
		// Fail and continue to next return.
	    }
	}
	return systemId;
    }

    // Interface LSResourceResolver

    public LSInput resolveResource(String type,
				   String namespaceURI,
				   String publicId,
				   String systemId,
				   String baseURI) {
	String resolved = resolve(namespaceURI, publicId, systemId, baseURI);
	return new DOMInputImpl(publicId, resolved, baseURI);
    }

    // Interface EntityResolver

    public InputSource resolveEntity(String publicId, String systemId)
	throws SAXException {
	String resolved = resolve(null, publicId, systemId, null);
	InputSource source = new InputSource(resolved);
	source.setPublicId(publicId);
	return source;
    }

    // Interface EntityResolver2

    public InputSource resolveEntity(String name, String publicId,
				     String baseURI, String systemId)
	throws SAXException {
	String resolved = resolve(null, publicId, systemId, baseURI);
	InputSource source = new InputSource(resolved);
	source.setPublicId(publicId);
	return source;
    }

    public InputSource getExternalSubset(String name,
					 String baseURI) {
	return null;
    }

}