/*******************************************************************************
 * Copyright (c) 2004, 2005 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
 *******************************************************************************/

package org.eclipse.gef.examples.text.model.commands;

import org.eclipse.gef.examples.text.edit.TextEditPart;
import org.eclipse.gef.examples.text.model.Container;
import org.eclipse.gef.examples.text.model.ModelElement;
import org.eclipse.gef.examples.text.model.ModelLocation;
import org.eclipse.gef.examples.text.model.TextRun;

/**
 * Attempts to merge an element with the previous element which will accept it.
 * @since 3.1
 */
public class MergeWithPrevious extends MiniEdit {

private int index;
private Container container;
private TextRun run;

public MergeWithPrevious(TextEditPart part) {
	run = (TextRun)part.getModel();
	container = run.getContainer();
	index = container.getChildren().indexOf(run);
}

private TextRun getPreviousTextRun() {
	ModelElement candidate = (ModelElement)container.getChildren().get(index - 1);
	while (candidate instanceof Container) {
		candidate = (ModelElement)((Container)candidate).getChildren().get(
				((Container)candidate).size() - 1);
	}
	return (TextRun)candidate;
}

public void apply() {
	container.remove(run);
	TextRun previous = getPreviousTextRun();
	previous.insertText(run.getText(), previous.size());
}

public boolean canApply() {
	return index > 0;
}

public ModelLocation getResultingLocation() {
	TextRun previous = getPreviousTextRun();
	return new ModelLocation(previous, previous.size() - run.size());
}

public void rollback() {
	throw new RuntimeException("not implemented");
}

}