/*******************************************************************************
 * Copyright (c) 2006 Sybase, Inc. 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:
 *     Sybase, Inc. - initial API and implementation
 *******************************************************************************/
package org.eclipse.jst.pagedesigner.commands;

import org.eclipse.core.runtime.Assert;
import org.eclipse.gef.commands.Command;
import org.eclipse.jface.text.TextSelection;
import org.eclipse.jface.viewers.ISelection;
import org.eclipse.jst.jsf.common.ui.internal.logging.Logger;
import org.eclipse.jst.pagedesigner.PDPlugin;
import org.eclipse.wst.html.core.internal.format.HTMLFormatProcessorImpl;
import org.eclipse.wst.sse.ui.StructuredTextEditor;
import org.eclipse.wst.sse.ui.internal.provisional.extensions.ISourceEditingTextTools;
import org.eclipse.wst.xml.core.internal.provisional.document.IDOMModel;
import org.eclipse.wst.xml.core.internal.provisional.document.IDOMNode;
import org.eclipse.wst.xml.ui.internal.provisional.IDOMSourceEditingTextTools;
import org.w3c.dom.Document;
import org.w3c.dom.Node;

/**
 * @author mengbo
 */
public abstract class SourceViewerCommand extends Command {
	/**
	 * the structured text editor containing the viewer
	 */
	protected final StructuredTextEditor _editor;

	private Document _document;

	private Logger _log = PDPlugin.getLogger(SourceViewerCommand.class);

	/**
	 * @param label 
	 * @param editor 
	 */
	public SourceViewerCommand(String label, StructuredTextEditor editor) {
		super();
		_editor = editor;
		IDOMSourceEditingTextTools tools = getSourceEditingTextTools();
		_document = tools.getDOMDocument();
	}

	/**
	 * @return the text tools
	 */
	protected IDOMSourceEditingTextTools getSourceEditingTextTools() {
		IDOMSourceEditingTextTools tools = (IDOMSourceEditingTextTools) _editor
				.getAdapter(ISourceEditingTextTools.class);
		return tools;
	}

	/**
	 * preExecute and postExecute is a pair. () SHOULD NOT throw any exception,
	 * if it throw any exception, it should catch itself and return false to
	 * indicate not continue.
	 * @return true if preExec succeeded
	 */
	protected final boolean preExecute() {
		int position = 0;
		int length = 0;
		ISelection selection = _editor.getTextViewer().getSelection();
		if (selection instanceof TextSelection) {
			position = ((TextSelection) selection).getOffset();
			length = ((TextSelection) selection).getLength();
		}
		getModel().beginRecording(this, getLabel(), position, length);
		getModel().aboutToChangeModel();
		return true;
	}

	/**
	 * if preExecute() return true, then this method will always be called even
	 * preExecute()/doExecute() and postExecute() fail.
	 */
	protected final void postExecute() {
		getModel().changedModel();
		getModel().endRecording(this);
		setSelection();
	}

	/**
	 * format the specified node in source code. Utility method that can be
	 * called by child classes
	 * 
	 * @param node
	 */
	public final void formatNode(Node node) {
		new HTMLFormatProcessorImpl().formatNode(node);
	}

	/**
	 * @return the dom model
	 */
	protected IDOMModel getModel() {
		Assert.isTrue(_document != null && _document instanceof IDOMNode);
		return ((IDOMNode) _document).getModel();
	}

	public final void execute() {
		boolean ok = preExecute();
		if (ok) {
			try {
				doExecute();
			} catch (Exception ex) {
				// "Error in command execution"
				_log.error("Error.SourceViewerCommand.Execution", ex); //$NON-NLS-1$
			} finally {
				postExecute();
			}
		}
	}

	/**
	 * execute
	 */
	public abstract void doExecute();

	/**
	 * set the selection
	 */
	public abstract void setSelection();
}