/*******************************************************************************
 * Copyright (c) 2000, 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.draw2d;

import org.eclipse.draw2d.geometry.Dimension;
import org.eclipse.draw2d.geometry.Insets;
import org.eclipse.draw2d.geometry.Rectangle;

/**
 * @author Pratik Shah
 */
public class BorderLayout extends AbstractHintLayout {

	/**
	 * Constant to be used as a constraint for child figures
	 */
	public static final Integer CENTER = new Integer(PositionConstants.CENTER);
	/**
	 * Constant to be used as a constraint for child figures
	 */
	public static final Integer TOP = new Integer(PositionConstants.TOP);
	/**
	 * Constant to be used as a constraint for child figures
	 */
	public static final Integer BOTTOM = new Integer(PositionConstants.BOTTOM);
	/**
	 * Constant to be used as a constraint for child figures
	 */
	public static final Integer LEFT = new Integer(PositionConstants.LEFT);
	/**
	 * Constant to be used as a constraint for child figures
	 */
	public static final Integer RIGHT = new Integer(PositionConstants.RIGHT);

	private IFigure center, left, top, bottom, right;
	private int vGap = 0, hGap = 0;

	/**
	 * @see org.eclipse.draw2d.AbstractHintLayout#calculateMinimumSize(IFigure,
	 *      int, int)
	 */
	protected Dimension calculateMinimumSize(IFigure container, int wHint,
			int hHint) {
		int minWHint = 0, minHHint = 0;
		if (wHint < 0) {
			minWHint = -1;
		}
		if (hHint < 0) {
			minHHint = -1;
		}
		Insets border = container.getInsets();
		wHint = Math.max(minWHint, wHint - border.getWidth());
		hHint = Math.max(minHHint, hHint - border.getHeight());
		Dimension minSize = new Dimension();
		int middleRowWidth = 0, middleRowHeight = 0;
		int rows = 0, columns = 0;

		if (top != null && top.isVisible()) {
			Dimension childSize = top.getMinimumSize(wHint, hHint);
			hHint = Math.max(minHHint, hHint - (childSize.height + vGap));
			minSize.setSize(childSize);
			rows += 1;
		}
		if (bottom != null && bottom.isVisible()) {
			Dimension childSize = bottom.getMinimumSize(wHint, hHint);
			hHint = Math.max(minHHint, hHint - (childSize.height + vGap));
			minSize.width = Math.max(minSize.width, childSize.width);
			minSize.height += childSize.height;
			rows += 1;
		}
		if (left != null && left.isVisible()) {
			Dimension childSize = left.getMinimumSize(wHint, hHint);
			middleRowWidth = childSize.width;
			middleRowHeight = childSize.height;
			wHint = Math.max(minWHint, wHint - (childSize.width + hGap));
			columns += 1;
		}
		if (right != null && right.isVisible()) {
			Dimension childSize = right.getMinimumSize(wHint, hHint);
			middleRowWidth += childSize.width;
			middleRowHeight = Math.max(childSize.height, middleRowHeight);
			wHint = Math.max(minWHint, wHint - (childSize.width + hGap));
			columns += 1;
		}
		if (center != null && center.isVisible()) {
			Dimension childSize = center.getMinimumSize(wHint, hHint);
			middleRowWidth += childSize.width;
			middleRowHeight = Math.max(childSize.height, middleRowHeight);
			columns += 1;
		}

		rows += columns > 0 ? 1 : 0;
		// Add spacing, insets, and the size of the middle row
		minSize.height += middleRowHeight + border.getHeight()
				+ ((rows - 1) * vGap);
		minSize.width = Math.max(minSize.width, middleRowWidth)
				+ border.getWidth() + ((columns - 1) * hGap);

		return minSize;
	}

	/**
	 * @see AbstractLayout#calculatePreferredSize(IFigure, int, int)
	 */
	protected Dimension calculatePreferredSize(IFigure container, int wHint,
			int hHint) {
		int minWHint = 0, minHHint = 0;
		if (wHint < 0)
			minWHint = -1;

		if (hHint < 0)
			minHHint = -1;

		Insets border = container.getInsets();
		wHint = Math.max(minWHint, wHint - border.getWidth());
		hHint = Math.max(minHHint, hHint - border.getHeight());
		Dimension prefSize = new Dimension();
		int middleRowWidth = 0, middleRowHeight = 0;
		int rows = 0, columns = 0;

		if (top != null && top.isVisible()) {
			Dimension childSize = top.getPreferredSize(wHint, hHint);
			hHint = Math.max(minHHint, hHint - (childSize.height + vGap));
			prefSize.setSize(childSize);
			rows += 1;
		}
		if (bottom != null && bottom.isVisible()) {
			Dimension childSize = bottom.getPreferredSize(wHint, hHint);
			hHint = Math.max(minHHint, hHint - (childSize.height + vGap));
			prefSize.width = Math.max(prefSize.width, childSize.width);
			prefSize.height += childSize.height;
			rows += 1;
		}
		if (left != null && left.isVisible()) {
			Dimension childSize = left.getPreferredSize(wHint, hHint);
			middleRowWidth = childSize.width;
			middleRowHeight = childSize.height;
			wHint = Math.max(minWHint, wHint - (childSize.width + hGap));
			columns += 1;
		}
		if (right != null && right.isVisible()) {
			Dimension childSize = right.getPreferredSize(wHint, hHint);
			middleRowWidth += childSize.width;
			middleRowHeight = Math.max(childSize.height, middleRowHeight);
			wHint = Math.max(minWHint, wHint - (childSize.width + hGap));
			columns += 1;
		}
		if (center != null && center.isVisible()) {
			Dimension childSize = center.getPreferredSize(wHint, hHint);
			middleRowWidth += childSize.width;
			middleRowHeight = Math.max(childSize.height, middleRowHeight);
			columns += 1;
		}

		rows += columns > 0 ? 1 : 0;
		// Add spacing, insets, and the size of the middle row
		prefSize.height += middleRowHeight + border.getHeight()
				+ ((rows - 1) * vGap);
		prefSize.width = Math.max(prefSize.width, middleRowWidth)
				+ border.getWidth() + ((columns - 1) * hGap);

		return prefSize;
	}

	/**
	 * @see org.eclipse.draw2d.LayoutManager#layout(IFigure)
	 */
	public void layout(IFigure container) {
		Rectangle area = container.getClientArea();
		Rectangle rect = new Rectangle();

		Dimension childSize;

		if (top != null && top.isVisible()) {
			childSize = top.getPreferredSize(area.width, -1);
			rect.setLocation(area.x, area.y);
			rect.setSize(childSize);
			rect.width = area.width;
			top.setBounds(rect);
			area.y += rect.height + vGap;
			area.height -= rect.height + vGap;
		}
		if (bottom != null && bottom.isVisible()) {
			childSize = bottom.getPreferredSize(Math.max(area.width, 0), -1);
			rect.setSize(childSize);
			rect.width = area.width;
			rect.setLocation(area.x, area.y + area.height - rect.height);
			bottom.setBounds(rect);
			area.height -= rect.height + vGap;
		}
		if (left != null && left.isVisible()) {
			childSize = left.getPreferredSize(-1, Math.max(0, area.height));
			rect.setLocation(area.x, area.y);
			rect.width = childSize.width;
			rect.height = Math.max(0, area.height);
			left.setBounds(rect);
			area.x += rect.width + hGap;
			area.width -= rect.width + hGap;
		}
		if (right != null && right.isVisible()) {
			childSize = right.getPreferredSize(-1, Math.max(0, area.height));
			rect.width = childSize.width;
			rect.height = Math.max(0, area.height);
			rect.setLocation(area.x + area.width - rect.width, area.y);
			right.setBounds(rect);
			area.width -= rect.width + hGap;
		}
		if (center != null && center.isVisible()) {
			if (area.width < 0)
				area.width = 0;
			if (area.height < 0)
				area.height = 0;
			center.setBounds(area);
		}
	}

	/**
	 * @see org.eclipse.draw2d.AbstractLayout#remove(IFigure)
	 */
	public void remove(IFigure child) {
		if (center == child) {
			center = null;
		} else if (top == child) {
			top = null;
		} else if (bottom == child) {
			bottom = null;
		} else if (right == child) {
			right = null;
		} else if (left == child) {
			left = null;
		}
	}

	/**
	 * Sets the location of hte given child in this layout. Valid constraints:
	 * <UL>
	 * <LI>{@link #CENTER}</LI>
	 * <LI>{@link #TOP}</LI>
	 * <LI>{@link #BOTTOM}</LI>
	 * <LI>{@link #LEFT}</LI>
	 * <LI>{@link #RIGHT}</LI>
	 * <LI><code>null</code> (to remove a child's constraint)</LI>
	 * </UL>
	 * 
	 * <p>
	 * Ensure that the given Figure is indeed a child of the Figure on which
	 * this layout has been set. Proper behaviour cannot be guaranteed if that
	 * is not the case. Also ensure that every child has a valid constraint.
	 * </p>
	 * <p>
	 * Passing a <code>null</code> constraint will invoke
	 * {@link #remove(IFigure)}.
	 * </p>
	 * <p>
	 * If the given child was assigned another constraint earlier, it will be
	 * re-assigned to the new constraint. If there is another child with the
	 * given constraint, it will be over-ridden so that the given child now has
	 * that constraint.
	 * </p>
	 * 
	 * @see org.eclipse.draw2d.AbstractLayout#setConstraint(IFigure, Object)
	 */
	public void setConstraint(IFigure child, Object constraint) {
		remove(child);
		super.setConstraint(child, constraint);
		if (constraint == null) {
			return;
		}

		switch (((Integer) constraint).intValue()) {
		case PositionConstants.CENTER:
			center = child;
			break;
		case PositionConstants.TOP:
			top = child;
			break;
		case PositionConstants.BOTTOM:
			bottom = child;
			break;
		case PositionConstants.RIGHT:
			right = child;
			break;
		case PositionConstants.LEFT:
			left = child;
			break;
		default:
			break;
		}
	}

	/**
	 * Sets the horizontal spacing to be used between the children. Default is
	 * 0.
	 * 
	 * @param gap
	 *            The horizonal spacing
	 */
	public void setHorizontalSpacing(int gap) {
		hGap = gap;
	}

	/**
	 * Sets the vertical spacing ot be used between the children. Default is 0.
	 * 
	 * @param gap
	 *            The vertical spacing
	 */
	public void setVerticalSpacing(int gap) {
		vGap = gap;
	}

}