/*
 * GnomeDocumentBuilder.java
 * Copyright (C) 2004 The Free Software Foundation
 * 
 * This file is part of GNU JAXP, a library.
 * 
 * GNU JAXP is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * 
 * GNU JAXP 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 for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Linking this library statically or dynamically with other modules is
 * making a combined work based on this library.  Thus, the terms and
 * conditions of the GNU General Public License cover the whole
 * combination.
 *
 * As a special exception, the copyright holders of this library give you
 * permission to link this library with independent modules to produce an
 * executable, regardless of the license terms of these independent
 * modules, and to copy and distribute the resulting executable under
 * terms of your choice, provided that you also meet, for each linked
 * independent module, the terms and conditions of the license of that
 * module.  An independent module is a module which is not derived from
 * or based on this library.  If you modify this library, you may extend
 * this exception to your version of the library, but you are not
 * obliged to do so.  If you do not wish to do so, delete this
 * exception statement from your version.
 */
package gnu.xml.libxmlj.dom;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.InputStream;
import java.io.IOException;
import java.io.PushbackInputStream;
import java.net.MalformedURLException;
import java.net.URL;
import javax.xml.parsers.DocumentBuilder;

import org.w3c.dom.Document;
import org.w3c.dom.DocumentType;
import org.w3c.dom.DOMImplementation;
import org.xml.sax.EntityResolver;
import org.xml.sax.ErrorHandler;
import org.xml.sax.InputSource;
import org.xml.sax.Locator;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;

import gnu.xml.libxmlj.util.NamedInputStream;
import gnu.xml.libxmlj.util.StandaloneDocumentType;
import gnu.xml.libxmlj.util.StandaloneLocator;
import gnu.xml.libxmlj.util.XMLJ;

/**
 * A JAXP DOM implementation that uses Gnome libxml2 as the underlying
 * parser and node representation.
 *
 * @author <a href='mailto:dog@gnu.org'>Chris Burdess</a>
 */
public class GnomeDocumentBuilder
  extends DocumentBuilder
  implements DOMImplementation
{

  static
  {
    XMLJ.init();
  }

  // -- DocumentBuilder --

  private boolean validate;
  private boolean coalesce;
  private boolean expandEntities;
  private EntityResolver entityResolver;
  private ErrorHandler errorHandler;
  private boolean seenFatalError;

  /**
   * Constructs a new validating document builder.
   */
  public GnomeDocumentBuilder()
  {
    this(true, false, false);
  }
  
  /**
   * Constructs a new document builder.
   * @param validate whether to validate during parsing
   * @param coalesce whether to merge CDATA as text nodes
   * @param expandEntities whether to expand entity references
   */
  public GnomeDocumentBuilder(boolean validate,
                              boolean coalesce,
                              boolean expandEntities)
  {
    this.validate = validate;
    this.coalesce = coalesce;
    this.expandEntities = expandEntities;
  }

  public DOMImplementation getDOMImplementation()
  {
    return this;
  }

  public boolean isNamespaceAware()
  {
    return true;
  }

  public boolean isValidating()
  {
    return validate;
  }

  public Document newDocument()
  {
    return createDocument(null, null, null);
  }

  public Document parse(InputSource input)
    throws SAXException, IOException
  {
    NamedInputStream in = XMLJ.getInputStream(input);
    byte[] detectBuffer = in.getDetectBuffer();
    String publicId = input.getPublicId();
    String systemId = input.getSystemId();
    String base = XMLJ.getBaseURI(systemId);
    // Handle zero-length document
    if (detectBuffer == null)
      {
        throw new SAXParseException("No document element", publicId,
                                    systemId, 0, 0);
      }
    seenFatalError = false;
    return parseStream(in,
                       detectBuffer,
                       publicId,
                       systemId,
                       base,
                       validate,
                       coalesce,
                       expandEntities,
                       true, //entityResolver != null,
                       errorHandler != null);
  }
  
  private native Document parseStream(InputStream in,
                                      byte[] detectBuffer,
                                      String publicId,
                                      String systemId,
                                      String base,
                                      boolean validate,
                                      boolean coalesce,
                                      boolean expandEntities,
                                      boolean entityResolver,
                                      boolean errorHandler);
  
  public void setEntityResolver(EntityResolver resolver)
  {
    entityResolver = resolver;
  }

  public void setErrorHandler(ErrorHandler handler)
  {
    errorHandler = handler;
  }

  // -- DOMImplementation --

  public boolean hasFeature(String name, String version)
  {
    if (name.length() == 0)
      {
        return false;
      }
    name = name.toLowerCase();
    if (name.charAt(0) == '+')
      {
        name = name.substring(1);
      }
    
    if ("xml".equals(name) || "core".equals(name))
      {
        return (version == null ||
                "".equals(version) ||
                "1.0".equals(version) ||
                "2.0".equals(version) ||
                "3.0".equals(version));
      
      }
    else if ("ls".equals(name) || "ls-async".equals(name))
      {
        // TODO
        /*
        return (version == null ||
                "".equals(version) ||
                "3.0".equals(version));
                */
        return false;
      }
    else if ("traversal".equals(name))
      {
        return (version == null ||
                "".equals(version) ||
		"2.0".equals(version));
      }
    else if ("xpath".equals(name))
      {
        return (version == null ||
                "".equals(version) ||
                "3.0".equals(version));
      }
    return false;
  }
  
  // DOM Level 3

  public Object getFeature(String feature, String version)
  {
    if (hasFeature(feature, version))
      {
        return this;
      }
    return null;
  }
  
  public native Document createDocument(String namespaceURI,
                                        String qualifiedName,
                                        DocumentType doctype);
  
  public DocumentType createDocumentType(String qualifiedName,
                                         String publicId,
                                         String systemId)
  {
    return new StandaloneDocumentType(qualifiedName, publicId, systemId);
  }
  
  // Callback hooks from JNI
  
  private void setDocumentLocator(Object ctx, Object loc)
  {
    // ignore
  }
  
  private InputStream resolveEntity(String publicId, String systemId,
                                    String base)
    throws SAXException, IOException
  {
    String url = XMLJ.getAbsoluteURI(base, systemId);
    InputStream in = null;
    if (entityResolver != null)
      {
        InputSource source = entityResolver.resolveEntity(publicId, url);
        if (source != null)
          {
            in = XMLJ.getInputStream(source);
          }
      }
    if (in == null)
      {
        in  = XMLJ.getInputStream(new URL(url));
      }
    return in;
  }
  
  private void warning(String message,
                       int lineNumber,
                       int columnNumber,
                       String publicId,
                       String systemId)
    throws SAXException
  {
    if (!seenFatalError && errorHandler != null)
      {
        Locator l = new StandaloneLocator(lineNumber,
                                          columnNumber,
                                          publicId,
                                          systemId);
        errorHandler.warning(new SAXParseException(message, l));
      }
  }

  private void error(String message,
                     int lineNumber,
                     int columnNumber,
                     String publicId,
                     String systemId)
    throws SAXException
  {
    if (!seenFatalError && errorHandler != null)
      {
        Locator l = new StandaloneLocator(lineNumber,
                                          columnNumber,
                                          publicId,
                                          systemId);
        errorHandler.error(new SAXParseException(message, l));
      }
  }

  private void fatalError(String message,
                          int lineNumber,
                          int columnNumber,
                          String publicId,
                          String systemId)
    throws SAXException
  {
    if (!seenFatalError && errorHandler != null)
      {
        seenFatalError = true;
        Locator l = new StandaloneLocator(lineNumber,
                                          columnNumber,
                                          publicId,
                                          systemId);
        errorHandler.fatalError(new SAXParseException(message, l));
      }
  }

}
