/*

 * reserved comment block

 * DO NOT REMOVE OR ALTER!

 */

// CatalogResolver.java - A SAX EntityResolver/JAXP URI Resolver

/*

 * Copyright 2001-2004 The Apache Software Foundation or its licensors,

 * as applicable.

 *

 * 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 com.sun.org.apache.xml.internal.resolver.tools;

import java.io.IOException;

import java.io.InputStream;

import java.net.URL;

import java.net.MalformedURLException;

import org.xml.sax.SAXException;

import org.xml.sax.XMLReader;

import org.xml.sax.InputSource;

import org.xml.sax.EntityResolver;

import javax.xml.transform.sax.SAXSource;

import javax.xml.transform.Source;

import javax.xml.transform.URIResolver;

import javax.xml.transform.TransformerException;

import javax.xml.parsers.ParserConfigurationException;

import javax.xml.parsers.SAXParserFactory;

import com.sun.org.apache.xml.internal.resolver.Catalog;

import com.sun.org.apache.xml.internal.resolver.CatalogManager;

import com.sun.org.apache.xml.internal.resolver.helpers.FileURL;

/**

 * A SAX EntityResolver/JAXP URIResolver that uses catalogs.

 *

 * <p>This class implements both a SAX EntityResolver and a JAXP URIResolver.

 * </p>

 *

 * <p>This resolver understands OASIS TR9401 catalogs, XCatalogs, and the

 * current working draft of the OASIS Entity Resolution Technical

 * Committee specification.</p>

 *

 * @see Catalog

 * @see org.xml.sax.EntityResolver

 * @see javax.xml.transform.URIResolver

 *

 * @author Norman Walsh

 * <a href="mailto:Norman.Walsh@Sun.COM">Norman.Walsh@Sun.COM</a>

 *

 */

public class CatalogResolver implements EntityResolver, URIResolver {

  /** Make the parser Namespace aware? */

  public boolean namespaceAware = true;

  /** Make the parser validating? */

  public boolean validating = false;

  /** The underlying catalog */

  private Catalog catalog = null;

  /** The catalog manager */

  private CatalogManager catalogManager = CatalogManager.getStaticManager();

  /** Constructor */

  public CatalogResolver() {

    initializeCatalogs(false);

  }

  /** Constructor */

  public CatalogResolver(boolean privateCatalog) {

    initializeCatalogs(privateCatalog);

  }

  /** Constructor */

  public CatalogResolver(CatalogManager manager) {

    catalogManager = manager;

    initializeCatalogs(!catalogManager.getUseStaticCatalog());

  }

  /** Initialize catalog */

  private void initializeCatalogs(boolean privateCatalog) {

    catalog = catalogManager.getCatalog();

  }

  /** Return the underlying catalog */

  public Catalog getCatalog() {

    return catalog;

  }

  /**

   * Implements the guts of the <code>resolveEntity</code> method

   * for the SAX interface.

   *

   * <p>Presented with an optional public identifier and a system

   * identifier, this function attempts to locate a mapping in the

   * catalogs.</p>

   *

   * <p>If such a mapping is found, it is returned.  If no mapping is

   * found, null is returned.</p>

   *

   * @param publicId  The public identifier for the entity in question.

   * This may be null.

   *

   * @param systemId  The system identifier for the entity in question.

   * XML requires a system identifier on all external entities, so this

   * value is always specified.

   *

   * @return The resolved identifier (a URI reference).

   */

  public String getResolvedEntity (String publicId, String systemId) {

    String resolved = null;

    if (catalog == null) {

      catalogManager.debug.message(1, "Catalog resolution attempted with null catalog; ignored");

      return null;

    }

    if (systemId != null) {

      try {

        resolved = catalog.resolveSystem(systemId);

      } catch (MalformedURLException me) {

        catalogManager.debug.message(1, "Malformed URL exception trying to resolve",

                      publicId);

        resolved = null;

      } catch (IOException ie) {

        catalogManager.debug.message(1, "I/O exception trying to resolve", publicId);

        resolved = null;

      }

    }

    if (resolved == null) {

      if (publicId != null) {

        try {

          resolved = catalog.resolvePublic(publicId, systemId);

        } catch (MalformedURLException me) {

          catalogManager.debug.message(1, "Malformed URL exception trying to resolve",

                        publicId);

        } catch (IOException ie) {

          catalogManager.debug.message(1, "I/O exception trying to resolve", publicId);

        }

      }

      if (resolved != null) {

        catalogManager.debug.message(2, "Resolved public", publicId, resolved);

      }

    } else {

      catalogManager.debug.message(2, "Resolved system", systemId, resolved);

    }

    return resolved;

  }

  /**

   * Implements the <code>resolveEntity</code> method

   * for the SAX interface.

   *

   * <p>Presented with an optional public identifier and a system

   * identifier, this function attempts to locate a mapping in the

   * catalogs.</p>

   *

   * <p>If such a mapping is found, the resolver attempts to open

   * the mapped value as an InputSource and return it. Exceptions are

   * ignored and null is returned if the mapped value cannot be opened

   * as an input source.</p>

   *

   * <p>If no mapping is found (or an error occurs attempting to open

   * the mapped value as an input source), null is returned and the system

   * will use the specified system identifier as if no entityResolver

   * was specified.</p>

   *

   * @param publicId  The public identifier for the entity in question.

   * This may be null.

   *

   * @param systemId  The system identifier for the entity in question.

   * XML requires a system identifier on all external entities, so this

   * value is always specified.

   *

   * @return An InputSource for the mapped identifier, or null.

   */

  public InputSource resolveEntity (String publicId, String systemId) {

    String resolved = getResolvedEntity(publicId, systemId);

    if (resolved != null) {

      try {

        InputSource iSource = new InputSource(resolved);

        iSource.setPublicId(publicId);

        // Ideally this method would not attempt to open the

        // InputStream, but there is a bug (in Xerces, at least)

        // that causes the parser to mistakenly open the wrong

        // system identifier if the returned InputSource does

        // not have a byteStream.

        //

        // It could be argued that we still shouldn't do this here,

        // but since the purpose of calling the entityResolver is

        // almost certainly to open the input stream, it seems to

        // do little harm.

        //

        URL url = new URL(resolved);

        InputStream iStream = url.openStream();

        iSource.setByteStream(iStream);

        return iSource;

      } catch (Exception e) {

        catalogManager.debug.message(1, "Failed to create InputSource", resolved);

        return null;

      }

    }

    return null;

  }

  /** JAXP URIResolver API */

  public Source resolve(String href, String base)

    throws TransformerException {

    String uri = href;

    String fragment = null;

    int hashPos = href.indexOf("#");

    if (hashPos >= 0) {

      uri = href.substring(0, hashPos);

      fragment = href.substring(hashPos+1);

    }

    String result = null;

    try {

      result = catalog.resolveURI(href);

    } catch (Exception e) {

      // nop;

    }

    if (result == null) {

      try {

        URL url = null;

        if (base==null) {

          url = new URL(uri);

          result = url.toString();

        } else {

          URL baseURL = new URL(base);

          url = (href.length()==0 ? baseURL : new URL(baseURL, uri));

          result = url.toString();

        }

      } catch (java.net.MalformedURLException mue) {

        // try to make an absolute URI from the current base

        String absBase = makeAbsolute(base);

        if (!absBase.equals(base)) {

          // don't bother if the absBase isn't different!

          return resolve(href, absBase);

        } else {

          throw new TransformerException("Malformed URL "

                                         + href + "(base " + base + ")",

                                         mue);

        }

      }

    }

    catalogManager.debug.message(2, "Resolved URI", href, result);

    SAXSource source = new SAXSource();

    source.setInputSource(new InputSource(result));

    setEntityResolver(source);

    return source;

  }

  /**

   * <p>Establish an entityResolver for newly resolved URIs.</p>

   *

   * <p>This is called from the URIResolver to set an EntityResolver

   * on the SAX parser to be used for new XML documents that are

   * encountered as a result of the document() function, xsl:import,

   * or xsl:include.  This is done because the XSLT processor calls

   * out to the SAXParserFactory itself to create a new SAXParser to

   * parse the new document.  The new parser does not automatically

   * inherit the EntityResolver of the original (although arguably

   * it should).  See below:</p>

   *

   * <tt>"If an application wants to set the ErrorHandler or

   * EntityResolver for an XMLReader used during a transformation,

   * it should use a URIResolver to return the SAXSource which

   * provides (with getXMLReader) a reference to the XMLReader"</tt>

   *

   * <p>...quoted from page 118 of the Java API for XML

   * Processing 1.1 specification</p>

   *

   */

  private void setEntityResolver(SAXSource source) throws TransformerException {

    XMLReader reader = source.getXMLReader();

    if (reader == null) {

      SAXParserFactory spFactory = SAXParserFactory.newInstance();

      spFactory.setNamespaceAware(true);

      try {

        reader = spFactory.newSAXParser().getXMLReader();

      }

      catch (ParserConfigurationException ex) {

        throw new TransformerException(ex);

      }

      catch (SAXException ex) {

        throw new TransformerException(ex);

      }

    }

    reader.setEntityResolver(this);

    source.setXMLReader(reader);

  }

  /** Attempt to construct an absolute URI */

  private String makeAbsolute(String uri) {

    if (uri == null) {

      uri = "";

    }

    try {

      URL url = new URL(uri);

      return url.toString();

    } catch (MalformedURLException mue) {

      try {

        URL fileURL = FileURL.makeURL(uri);

        return fileURL.toString();

      } catch (MalformedURLException mue2) {

        // bail

        return uri;

      }

    }

  }

}