/*
 * Consumer.java
 * Copyright (C) 2001 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 program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * As a special exception, if you link this library with other files to
 * produce an executable, this library does not by itself cause the
 * resulting executable to be covered by the GNU General Public License.
 * This exception does not however invalidate any other reasons why the
 * executable file might be covered by the GNU General Public License. 
 */


package gnu.xml.dom;

import java.io.IOException;

import org.w3c.dom.Document;
import org.w3c.dom.DocumentType;
import org.w3c.dom.DOMImplementation;
import org.w3c.dom.Node;
import org.w3c.dom.Text;

import org.xml.sax.Attributes;
import org.xml.sax.ErrorHandler;
import org.xml.sax.SAXException;
import org.xml.sax.ext.Attributes2;

import gnu.xml.pipeline.DomConsumer;
import gnu.xml.pipeline.EventConsumer;


/**
 * Event consumer which constructs DOM documents using the implementation
 * in this package, using SAX2 events.  This packages various backdoors
 * into this DOM implementation, as needed to address DOM requirements
 * that can't be met by strictly conforming implementations of DOM.
 *
 * <p> These requirements all relate to {@link DocumentType} nodes and
 * features of that node type.  These features are normally not used,
 * because that interface only exposes a subset of the information found
 * in DTDs.  More, that subset does not include the most important typing
 * information.  For example, it excludes element content models and
 * attribute typing.  It does expose some entity management issues,
 * although entity management doesn't relate to document typing.
 *
 * <p> Note that SAX2 does not expose the literal text of the DTD's
 * internal subset, so it will not be present in DOM trees constructed
 * using this API.  (Though with a good SAX2 implementation, it could
 * be partially recreated...)
 *
 * @author David Brownell
 */
public class Consumer extends DomConsumer
{
    /**
     * Constructs an unconfigured event consumer,
     * as a terminus in a SAX event pipeline.
     */
    // used by PipelineFactory [terminus]
    public Consumer ()
    throws SAXException
    {
	super (DomDocument.class);
	setHandler (new Backdoor (this));
    }

    /**
     * Constructs an unconfigured event consumer,
     * as a stage in a SAX event pipeline.
     */
    // used by PipelineFactory [filter]
    public Consumer (EventConsumer next)
    throws SAXException
    {
	super (DomDocument.class, next);
	setHandler (new Backdoor (this));
    }

    /**
     * Implements the backdoors needed by DOM.
     * All methods in this class use implementation-specific APIs that are
     * implied by the DOM specification (needed to implement testable
     * behavior) but which are excluded from the DOM specification.
     */
    public static class Backdoor extends DomConsumer.Handler
    {
	/**
	 * Constructor.
	 * @param consumer must have been initialized to use the
	 *	{@link DomDocument} class (or a subclass) for
	 *	constructing DOM trees
	 */
	protected Backdoor (DomConsumer consumer)
	throws SAXException
	    { super (consumer); }

	// helper routine
	private DomDoctype getDoctype ()
	throws SAXException
	{
	    DomDocument		doc = (DomDocument) getDocument ();
	    DocumentType	dt = doc.getDoctype ();

	    if (dt == null)
		throw new SAXException ("doctype missing!");
	    return (DomDoctype) dt;
	}

	// SAX2 "lexical" event
	public void startDTD (String name, String publicId, String systemId)
	throws SAXException
	{
	    DomDocument		doc = (DomDocument) getDocument ();

	    super.startDTD (name, publicId, systemId);
	    // DOM L2 doctype creation model is bizarre
	    doc.appendChild (new DomDoctype (doc, name, publicId, systemId));
	}

	// SAX2 "lexical" event
	public void endDTD ()
	throws SAXException
	{
	    super.endDTD ();
	    // DOM L2 has no way to make things readonly
	    getDoctype ().makeReadonly ();
	}

	// SAX1 DTD event
	public void notationDecl (
	    String name,
	    String publicId, String systemId
	) throws SAXException
	{
	    // DOM L2 can't create/save notation nodes
	    getDoctype ().declareNotation (name, publicId, systemId);
	}

	// SAX1 DTD event
	public void unparsedEntityDecl (
	    String name,
	    String publicId, String systemId,
	    String notationName
	) throws SAXException
	{
	    // DOM L2 can't create/save entity nodes
	    getDoctype ().declareEntity (name, publicId, systemId,
	    	notationName);
	}

	// SAX2 declaration event
	public void internalEntityDecl (String name, String value)
	throws SAXException
	{
	    // DOM L2 can't create/save entity nodes
	    // NOTE:  this doesn't save the value as a child of this
	    // node, though it could realistically do so.
	    getDoctype ().declareEntity (name, null, null, null);
	}

	// SAX2 declaration event
	public void externalEntityDecl (
	    String name,
	    String publicId,
	    String systemId
	) throws SAXException
	{
	    // DOM L2 can't create/save entity nodes
	    // NOTE:  DOM allows for these to have children, if
	    // they don't have unbound namespace references.
	    getDoctype ().declareEntity (name, publicId, systemId, null);
	}

	// SAX2 element
	public void startElement (
	    String uri,
	    String localName,
	    String qName,
	    Attributes atts
	) throws SAXException
	{
	    Node		top;

	    super.startElement (uri, localName, qName, atts);

	    // might there be more work?
	    top = getTop ();
	    if (!top.hasAttributes () || !(atts instanceof Attributes2))
		return;

	    // remember any attributes that got defaulted
	    DomNamedNodeMap	map = (DomNamedNodeMap) top.getAttributes ();
	    Attributes2		attrs = (Attributes2) atts;
	    int			length = atts.getLength ();

	    map.compact ();
	    for (int i = 0; i < length; i++) {
		if (attrs.isSpecified (i))
		    continue;

		// value was defaulted.
		String		temp = attrs.getQName (i);
		DomAttr		attr;

		if ("".equals (temp))
		    attr = (DomAttr) map.getNamedItemNS (attrs.getURI (i),
			    atts.getLocalName (i));
		else
		    attr = (DomAttr) map.getNamedItem (temp);

		// DOM L2 can't write this flag, only read it
		attr.setSpecified (false);
	    }
	}

	public void endElement (
	    String uri,
	    String localName,
	    String qName
	) throws SAXException
	{
	    DomNode	top = (DomNode) getTop ();
	    top.compact ();
	    super.endElement (uri, localName, qName);
	}

	protected Text createText (
	    boolean	isCDATA,
	    char	buf [],
	    int		off,
	    int		len
	) {
	    DomDocument	doc = (DomDocument) getDocument ();

	    if (isCDATA)
		return doc.createCDATASection (buf, off, len);
	    else
		return doc.createTextNode (buf, off, len);
	}


	public void attributeDecl (
	    String	ename,
	    String	aname,
	    String	type,
	    String	mode,
	    String	value
	) throws SAXException
	{
	    if (value == null && !"ID".equals (type))
		return;
	    
	    DomDoctype.ElementInfo	info;

	    info = getDoctype ().getElementInfo (ename);
	    if (value != null)
		info.setAttrDefault (aname, value);
	    if ("ID".equals (type))
		info.setIdAttr (aname);
	}

	// force duplicate name checking off while we're
	// using parser output (don't duplicate the work)
	public void startDocument () throws SAXException
	{
	    DomDocument		doc;

	    super.startDocument ();
	    ((DomDocument) getDocument ()).setCheckingCharacters (false);
	}

	public void endDocument ()
	throws SAXException
	{
	    DomDocument		doc = (DomDocument) getDocument ();
	    doc.setCheckingCharacters (true);
	    doc.compact ();
	    super.endDocument ();
	}

	// these three methods collaborate to populate entity
	// refs, marking contents readonly on end-of-entity

	public boolean canPopulateEntityRefs ()
	    { return true; }

	public void startEntity (String name)
	throws SAXException
	{
	    if (name.charAt (0) == '%' || "[dtd]".equals (name))
		return;
	    super.startEntity (name);

	    DomNode	top = (DomNode) getTop ();

	    if (top.getNodeType () == Node.ENTITY_REFERENCE_NODE)
		top.readonly = false;
	}

	public void endEntity (String name)
	throws SAXException
	{
	    if (name.charAt (0) == '%' || "[dtd]".equals (name))
		return;
	    DomNode	top = (DomNode) getTop ();

	    if (top.getNodeType () == Node.ENTITY_REFERENCE_NODE) {
		top.compact ();
		top.makeReadonly ();
	    }
	    super.endEntity (name);
	}
    }
}