package ie.dcu.swt.layout;

import org.eclipse.swt.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.widgets.*;

/**
 * Port of the AWT BorderLayout.
 * 
 * @author Kevin McGuinness
 */
public class BorderLayout extends Layout {

	// Typedef indices
	private static final int N = BorderData.North.index;
	private static final int S = BorderData.South.index;
	private static final int C = BorderData.Center.index;
	private static final int E = BorderData.East.index;
	private static final int W = BorderData.West.index;

	// Controls in all the regions.
	private Control[] controls = new Control[5];

	// Cached sizes.
	private Point[] sizes;

	// Preferred width and height
	int width, height;

	// Spacing between components
	int hgap, vgap;

	public BorderLayout() {
		this(0);
	}

	public BorderLayout(int space) {
		hgap = vgap = space;
	}

	public BorderLayout(int hgap, int vgap) {
		this.hgap = hgap;
		this.vgap = vgap;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see
	 * org.eclipse.swt.widgets.Layout#computeSize(org.eclipse.swt.widgets.Composite
	 * , int, int, boolean)
	 */
	protected Point computeSize(Composite composite, int wHint, int hHint,
		boolean flushCache) {

		if (sizes == null || flushCache == true) {
			refreshSizes(composite.getChildren());
		}

		int w = wHint;
		int h = hHint;

		if (w == SWT.DEFAULT)
			w = width;
		if (h == SWT.DEFAULT)
			h = height;

		return new Point(w, h);
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see
	 * org.eclipse.swt.widgets.Layout#layout(org.eclipse.swt.widgets.Composite,
	 * boolean)
	 */
	protected void layout(Composite composite, boolean flushCache) {

		if (flushCache || sizes == null) {
			refreshSizes(composite.getChildren());
		}

		Rectangle r = composite.getClientArea();

		int tg = 0;
		int bg = 0;
		int lg = 0;
		int rg = 0;

		if (controls[N] != null) {
			int x = r.x;
			int y = r.y;
			int w = r.width;
			int h = sizes[N].y;

			controls[N].setBounds(x, y, w, h);

			tg += hgap;
		}

		if (controls[S] != null) {
			int x = r.x;
			int y = r.y + r.height - sizes[S].y;
			int w = r.width;
			int h = sizes[S].y;

			controls[S].setBounds(x, y, w, h);

			bg += hgap;
		}

		if (controls[W] != null) {
			int x = r.x;
			int y = r.y + sizes[N].y + tg;
			int w = sizes[W].x;
			int h = r.height - sizes[N].y - sizes[S].y - (tg + bg);

			controls[W].setBounds(x, y, w, h);

			lg += vgap;
		}

		if (controls[E] != null) {
			int x = r.x + r.width - sizes[E].x;
			int y = r.y + sizes[N].y + tg;
			int w = sizes[E].x;
			int h = r.height - sizes[N].y - sizes[S].y - (tg + bg);

			controls[E].setBounds(x, y, w, h);

			rg += vgap;
		}

		if (controls[C] != null) {
			int x = r.x + sizes[W].x + lg;
			int y = r.y + sizes[N].y + tg;
			int w = r.width - sizes[W].x - sizes[E].x - (lg + rg);
			int h = r.height - sizes[N].y - sizes[S].y - (tg + bg);

			controls[C].setBounds(x, y, w, h);
		}

		return;
	}

	private void refreshSizes(Control[] children) {
		for (Control c : children) {
			Object o = c.getLayoutData();

			if (o instanceof BorderData) {
				BorderData data = (BorderData) o;
				if (data != BorderData.Ignore) {
					controls[data.index] = c;
				}
			} else {
				// Default
				controls[C] = c;
			}
		}

		width = height = 0;

		if (sizes == null) {
			sizes = new Point[5];
		}

		for (int i = 0; i < controls.length; i++) {
			Control control = controls[i];

			if (control == null) {
				sizes[i] = new Point(0, 0);
			} else {
				sizes[i] = control.computeSize(SWT.DEFAULT, SWT.DEFAULT, true);
			}
		}

		width = Math.max(width, sizes[N].x);
		width = Math.max(width, sizes[W].x + sizes[C].x + sizes[E].x);
		width = Math.max(width, sizes[S].x);

		height = Math.max(Math.max(sizes[W].y, sizes[E].y), sizes[C].y)
			+ sizes[N].y + sizes[S].y;

		return;
	}
}