/*******************************************************************************
 * Copyright (c) 2001, 2004 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *     Jens Lukowski/Innoopract - initial renaming/restructuring
 *     
 *******************************************************************************/
package org.eclipse.wst.xml.ui.internal;


import java.util.Timer;
import java.util.TimerTask;

import org.eclipse.wst.sse.core.internal.provisional.INodeAdapter;
import org.eclipse.wst.sse.core.internal.provisional.INodeNotifier;
import org.eclipse.wst.sse.core.internal.provisional.IStructuredModel;
import org.eclipse.wst.xml.core.internal.contentmodel.modelquery.CMDocumentManager;
import org.eclipse.wst.xml.core.internal.contentmodel.modelquery.ModelQuery;
import org.eclipse.wst.xml.core.internal.contentmodel.modelqueryimpl.CMDocumentLoader;
import org.eclipse.wst.xml.core.internal.contentmodel.modelqueryimpl.InferredGrammarBuildingCMDocumentLoader;
import org.eclipse.wst.xml.core.internal.modelquery.ModelQueryUtil;
import org.eclipse.wst.xml.core.internal.provisional.document.IDOMModel;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;


/**
 * This class is used to observe changes in the DOM and perform
 * occasional'scans' to deduce information. We use a delay timer mechanism to
 * ensure scans are made every couple of seconds to avoid performance
 * problems. Currently this class is used to keep track of referenced grammar
 * uri's within the document ensure that they are loaded by the
 * CMDocumentManager. We might want to generalize this class to perform other
 * suplimental information gathering that is suitable for 'time delayed'
 * computation (error hints etc.).
 */
// TODO: Where should this class go?
public class DOMObserver {


	// An abstract adapter that ensures that the children of a new Node are
	// also adapted
	//
	abstract class DocumentAdapter implements INodeAdapter {
		public DocumentAdapter(Document document) {
			((INodeNotifier) document).addAdapter(this);
			adapt(document.getDocumentElement());
		}

		public void adapt(Element element) {
			if (element != null) {
				if (((INodeNotifier) element).getExistingAdapter(this) == null) {
					((INodeNotifier) element).addAdapter(this);

					for (Node child = element.getFirstChild(); child != null; child = child.getNextSibling()) {
						if (child.getNodeType() == Node.ELEMENT_NODE) {
							adapt((Element) child);
						}
					}
				}
			}
		}

		public boolean isAdapterForType(Object type) {
			return type == this;
		}

		abstract public void notifyChanged(INodeNotifier notifier, int eventType, Object feature, Object oldValue, Object newValue, int index);
	}

	/**
	 * This class listens to the changes in the CMDocument and triggers a
	 * CMDocument load
	 */
	class MyDocumentAdapter extends DocumentAdapter {
		MyDocumentAdapter(Document document) {
			super(document);
		}

		public void notifyChanged(INodeNotifier notifier, int eventType, Object feature, Object oldValue, Object newValue, int index) {
			switch (eventType) {
				case INodeNotifier.ADD : {
					if (newValue instanceof Element) {
						// System.out.println("ADD (to " +
						// ((Node)notifier).getNodeName() + ") " +
						// ((Element)newValue).getNodeName() + " old " +
						// oldValue);
						adapt((Element) newValue);
					}
					break;
				}
				// case INodeNotifier.REMOVE:
				case INodeNotifier.CHANGE :
				case INodeNotifier.STRUCTURE_CHANGED :
				case INodeNotifier.CONTENT_CHANGED : {
					Node node = (Node) notifier;
					if (node.getNodeType() == Node.ELEMENT_NODE) {
						Element element = (Element) node;
						switch (eventType) {
							case INodeNotifier.CHANGE : {
								invokeDelayedCMDocumentLoad();
								break;
							}
							case INodeNotifier.STRUCTURE_CHANGED : {
								// structure change
								invokeDelayedCMDocumentLoad();
								break;
							}
							case INodeNotifier.CONTENT_CHANGED : {
								// some content changed
								break;
							}
						}
					}
					else if (node.getNodeType() == Node.DOCUMENT_NODE) {
						invokeDelayedCMDocumentLoad();
					}
					break;
				}
			}
		}
	}

	class MyTimerTask extends TimerTask {
		public MyTimerTask() {
			super();
			timerTaskCount++;
		}

		public void run() {
			timerTaskCount--;
			if (timerTaskCount == 0) {
				invokeCMDocumentLoad();
			}
		}
	}

	protected static Timer timer = new Timer(true);
	protected Document document;
	protected boolean isGrammarInferenceEnabled;
	protected IStructuredModel model;
	protected int timerTaskCount = 0;

	public DOMObserver(IStructuredModel model) {
		this.document = (model instanceof IDOMModel) ? ((IDOMModel) model).getDocument() : null;

		if (document != null) {
			ModelQuery modelQuery = ModelQueryUtil.getModelQuery(document);
			if (modelQuery != null && modelQuery.getCMDocumentManager() != null) {
				CMDocumentManager cmDocumentManager = modelQuery.getCMDocumentManager();
				cmDocumentManager.setPropertyEnabled(CMDocumentManager.PROPERTY_AUTO_LOAD, false);
			}

			MyDocumentAdapter myDocumentAdapter = new MyDocumentAdapter(document);
		}
	}

	public void init() {
		// CS: we seem to expose an XSD initialization problem when we do this
		// immediately
		// very nasty... I need to revist this problem with Ed Merks
		//
		// invokeCMDocumentLoad();
		invokeDelayedCMDocumentLoad();
	}

	public void invokeCMDocumentLoad() {
		ModelQuery modelQuery = ModelQueryUtil.getModelQuery(document);
		if (modelQuery != null && modelQuery.getCMDocumentManager() != null) {
			CMDocumentLoader loader = isGrammarInferenceEnabled ? new InferredGrammarBuildingCMDocumentLoader(document, modelQuery) : new CMDocumentLoader(document, modelQuery);
			loader.loadCMDocuments();
		}
	}

	public void invokeDelayedCMDocumentLoad() {
		// Display.getCurrent().timerExec(2000, new MyTimerTask());
		timer.schedule(new MyTimerTask(), 2000);
	}

	public void setGrammarInferenceEnabled(boolean isEnabled) {
		isGrammarInferenceEnabled = isEnabled;
	}
}