/*******************************************************************************
 * Copyright (c) 2004, 2010 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.editparts;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

import org.eclipse.draw2d.FreeformLayer;
import org.eclipse.draw2d.IFigure;
import org.eclipse.draw2d.geometry.Dimension;
import org.eclipse.draw2d.geometry.Rectangle;

/**
 * This is a layer where the guide lines are displayed. The figures in this
 * layer should have a Boolean constraint indicating whether or not they are
 * horizontal guide lines.
 * 
 * @author Pratik Shah
 * @since 3.0
 */
public class GuideLayer extends FreeformLayer {

	private Map constraints;

	/**
	 * @param child
	 *            the figure whose constraint is to be found
	 * @return the constraint (Boolean indicating whether or not it is
	 *         horizontal) set for the given IFigure; <code>null</code>, if none
	 *         exists
	 */
	public Object getConstraint(IFigure child) {
		return getConstraints().get(child);
	}

	/**
	 * @return the Map of IFigures to their constraints (Booleans indicating
	 *         whether or not they are horizontal guide lines)
	 */
	public Map getConstraints() {
		if (constraints == null) {
			constraints = new HashMap();
		}
		return constraints;
	}

	/**
	 * @see org.eclipse.draw2d.FreeformFigure#getFreeformExtent()
	 */
	public Rectangle getFreeformExtent() {
		/*
		 * The freeform extents are just big enough to include all the children:
		 * tall enough to include the highest and the lowest horizontal guide
		 * lines, and wide enough to include the leftmost and the rightmost
		 * vertical guide lines. They always include the point 5,5 and are
		 * further expanded by 5-pixels in all directions so that none of the
		 * guide lines are on the edge.
		 */
		/*
		 * These ints are initialized to 5, and not 0, so that when the final
		 * extent is expanded by 5, the bounds do not go into the negative
		 * (unless necessary).
		 */
		int maxX = 5, minX = 5, maxY = 5, minY = 5;
		Iterator children = getChildren().iterator();
		while (children.hasNext()) {
			IFigure child = (IFigure) children.next();
			Boolean isHorizontal = (Boolean) getConstraint(child);
			if (isHorizontal != null) {
				if (isHorizontal.booleanValue()) {
					int position = child.getBounds().y;
					minY = Math.min(minY, position);
					maxY = Math.max(maxY, position);
				} else {
					int position = child.getBounds().x;
					minX = Math.min(minX, position);
					maxX = Math.max(maxX, position);
				}
			}
		}
		Rectangle r = new Rectangle(minX, minY, maxX - minX + 1, maxY - minY
				+ 1);
		if (r.width > 1)
			r.expand(5, 0);
		if (r.height > 1)
			r.expand(0, 5);
		return r;
	}

	/**
	 * @see org.eclipse.draw2d.IFigure#getPreferredSize(int, int)
	 */
	public Dimension getPreferredSize(int wHint, int hHint) {
		Rectangle extents = getFreeformExtent();
		return new Dimension(extents.right(), extents.bottom());
	}

	/**
	 * @see org.eclipse.draw2d.IFigure#remove(org.eclipse.draw2d.IFigure)
	 */
	public void remove(IFigure child) {
		getConstraints().remove(child);
		super.remove(child);
	}

	/**
	 * @see org.eclipse.draw2d.IFigure#setBounds(org.eclipse.draw2d.geometry.Rectangle)
	 */
	public void setBounds(Rectangle rect) {
		super.setBounds(rect);
		Iterator children = getChildren().iterator();
		while (children.hasNext()) {
			IFigure child = (IFigure) children.next();
			Boolean isHorizontal = (Boolean) getConstraint(child);
			if (isHorizontal != null) {
				if (isHorizontal.booleanValue()) {
					Rectangle.SINGLETON.setLocation(getBounds().x,
							child.getBounds().y);
					Rectangle.SINGLETON.setSize(getBounds().width, 1);
				} else {
					Rectangle.SINGLETON.setLocation(child.getBounds().x,
							getBounds().y);
					Rectangle.SINGLETON.setSize(1, getBounds().height);
				}
				child.setBounds(Rectangle.SINGLETON);
			}
		}
	}

	/**
	 * The constraint is expected to be a Boolean indicating whether the given
	 * guide line figure is horizontal or not.
	 * 
	 * @see org.eclipse.draw2d.IFigure#setConstraint(org.eclipse.draw2d.IFigure,
	 *      java.lang.Object)
	 */
	public void setConstraint(IFigure child, Object constraint) {
		getConstraints().put(child, constraint);
	}

}