/*******************************************************************************
 * Copyright (c) 2000, 2020 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *     Christoph Läubrich - Bug 513185
 *******************************************************************************/
package org.eclipse.swt.layout;

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

/**
 * <code>FillLayout</code> is the simplest layout class. It lays out
 * controls in a single row or column, forcing them to be the same size.
 * <p>
 * Initially, the controls will all be as tall as the tallest control,
 * and as wide as the widest. <code>FillLayout</code> does not wrap,
 * but you can specify margins and spacing. You might use it to
 * lay out buttons in a task bar or tool bar, or to stack checkboxes
 * in a <code>Group</code>. <code>FillLayout</code> can also be used
 * when a <code>Composite</code> only has one child. For example,
 * if a <code>Shell</code> has a single <code>Group</code> child,
 * <code>FillLayout</code> will cause the <code>Group</code> to
 * completely fill the <code>Shell</code> (if margins are 0).
 * </p>
 * <p>
 * Example code: first a <code>FillLayout</code> is created and
 * its type field is set, and then the layout is set into the
 * <code>Composite</code>. Note that in a <code>FillLayout</code>,
 * children are always the same size, and they fill all available space.
 * </p>
 * <pre>
 * 		FillLayout fillLayout = new FillLayout();
 * 		fillLayout.type = SWT.VERTICAL;
 * 		shell.setLayout(fillLayout);
 * </pre>
 *
 * @see <a href="https://eclipse.dev/eclipse/swt/examples.html">SWT Example: LayoutExample</a>
 * @see <a href="https://eclipse.dev/eclipse/swt/">Sample code and further information</a>
 */
public final class FillLayout extends Layout {
	/**
	 * type specifies how controls will be positioned
	 * within the layout.
	 *
	 * The default value is HORIZONTAL.
	 *
	 * Possible values are: <ul>
	 *    <li>HORIZONTAL: Position the controls horizontally from left to right</li>
	 *    <li>VERTICAL: Position the controls vertically from top to bottom</li>
	 * </ul>
	 */
	public int type = SWT.HORIZONTAL;

	/**
	 * marginWidth specifies the number of points of horizontal margin
	 * that will be placed along the left and right edges of the layout.
	 *
	 * The default value is 0.
	 *
	 * @since 3.0
	 */
	public int marginWidth = 0;

	/**
	 * marginHeight specifies the number of points of vertical margin
	 * that will be placed along the top and bottom edges of the layout.
	 *
	 * The default value is 0.
	 *
	 * @since 3.0
	 */
	public int marginHeight = 0;

	/**
	 * spacing specifies the number of points between the edge of one cell
	 * and the edge of its neighbouring cell.
	 *
	 * The default value is 0.
	 *
	 * @since 3.0
	 */
	public int spacing = 0;

/**
 * Constructs a new instance of this class.
 */
public FillLayout () {
}

/**
 * Constructs a new instance of this class given the type.
 *
 * @param type the type of fill layout
 *
 * @since 2.0
 */
public FillLayout (int type) {
	this.type = type;
}

@Override
protected Point computeSize (Composite composite, int wHint, int hHint, boolean flushCache) {
	Control [] children = composite.getChildren ();
	int count = children.length;
	int maxWidth = 0, maxHeight = 0;
	for (int i=0; i<count; i++) {
		Control child = children [i];
		int w = wHint, h = hHint;
		if (count > 0) {
			if (type == SWT.HORIZONTAL && wHint != SWT.DEFAULT) {
				w = Math.max (0, (wHint - (count - 1) * spacing) / count);
			}
			if (type == SWT.VERTICAL && hHint != SWT.DEFAULT) {
				h = Math.max (0, (hHint - (count - 1) * spacing) / count);
			}
		}
		Point size = computeChildSize (child, w, h, flushCache);
		maxWidth = Math.max (maxWidth, size.x);
		maxHeight = Math.max (maxHeight, size.y);
	}
	int width = 0, height = 0;
	if (type == SWT.HORIZONTAL) {
		width = count * maxWidth;
		if (count != 0) width += (count - 1) * spacing;
		height = maxHeight;
	} else {
		width = maxWidth;
		height = count * maxHeight;
		if (count != 0) height += (count - 1) * spacing;
	}
	width += marginWidth * 2;
	height += marginHeight * 2;
	if (wHint != SWT.DEFAULT) width = wHint;
	if (hHint != SWT.DEFAULT) height = hHint;
	return new Point (width, height);
}

Point computeChildSize (Control control, int wHint, int hHint, boolean flushCache) {
	Object data = control.getLayoutData ();
	FillData fillData;
	if (data instanceof FillData) {
		fillData = (FillData) data;
	} else {
		fillData = new FillData ();
		if (data == null) {
			control.setLayoutData(fillData);
		}
	}
	Point size = null;
	if (wHint == SWT.DEFAULT && hHint == SWT.DEFAULT) {
		size = fillData.computeSize (control, wHint, hHint, flushCache);
	} else {
		// TEMPORARY CODE
		int trimX, trimY;
		if (control instanceof Scrollable) {
			Rectangle rect = ((Scrollable) control).computeTrim (0, 0, 0, 0);
			trimX = rect.width;
			trimY = rect.height;
		} else {
			trimX = trimY = control.getBorderWidth () * 2;
		}
		int w = wHint == SWT.DEFAULT ? wHint : Math.max (0, wHint - trimX);
		int h = hHint == SWT.DEFAULT ? hHint : Math.max (0, hHint - trimY);
		size = fillData.computeSize (control, w, h, flushCache);
	}
	return size;
}

@Override
protected boolean flushCache (Control control) {
	Object data = control.getLayoutData();
	if (data instanceof FillData) {
		((FillData)data).flushCache();
		return true;
	}
	return false;
}

String getName () {
	String string = getClass ().getName ();
	int index = string.lastIndexOf ('.');
	if (index == -1) return string;
	return string.substring (index + 1, string.length ());
}

@Override
protected void layout (Composite composite, boolean flushCache) {
	Rectangle rect = composite.getClientArea ();
	Control [] children = composite.getChildren ();
	int count = children.length;
	if (count == 0) return;
	int width = rect.width - marginWidth * 2;
	int height = rect.height - marginHeight * 2;
	if (type == SWT.HORIZONTAL) {
		width -= (count - 1) * spacing;
		int x = rect.x + marginWidth, extra = width % count;
		int y = rect.y + marginHeight, cellWidth = width / count;
		for (int i=0; i<count; i++) {
			Control child = children [i];
			int childWidth = cellWidth;
			if (i == 0) {
				childWidth += extra / 2;
			} else {
				if (i == count - 1) childWidth += (extra + 1) / 2;
			}
			child.setBounds (x, y, childWidth, height);
			x += childWidth + spacing;
		}
	} else {
		height -= (count - 1) * spacing;
		int x = rect.x + marginWidth, cellHeight = height / count;
		int y = rect.y + marginHeight, extra = height % count;
		for (int i=0; i<count; i++) {
			Control child = children [i];
			int childHeight = cellHeight;
			if (i == 0) {
				childHeight += extra / 2;
			} else {
				if (i == count - 1) childHeight += (extra + 1) / 2;
			}
			child.setBounds (x, y, width, childHeight);
			y += childHeight + spacing;
		}
	}
}

/**
 * Returns a string containing a concise, human-readable
 * description of the receiver.
 *
 * @return a string representation of the layout
 */
@Override
public String toString () {
	String string = getName ()+" {";
	string += "type="+((type == SWT.VERTICAL) ? "SWT.VERTICAL" : "SWT.HORIZONTAL")+" ";
	if (marginWidth != 0) string += "marginWidth="+marginWidth+" ";
	if (marginHeight != 0) string += "marginHeight="+marginHeight+" ";
	if (spacing != 0) string += "spacing="+spacing+" ";
	string = string.trim();
	string += "}";
	return string;
}
}
