/*******************************************************************************
 * Copyright (c) 2000, 2007 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.jface.action;

import org.eclipse.core.runtime.Assert;
import org.eclipse.jface.util.Util;
import org.eclipse.swt.SWT;
import org.eclipse.swt.custom.CLabel;
import org.eclipse.swt.graphics.FontMetrics;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Label;

/**
 * A contribution item to be used with status line managers.
 * <p>
 * This class may be instantiated; it is not intended to be subclassed.
 * </p>
 * 
 * @since 3.4
 */
public class StatusLineContributionItem extends ContributionItem {

	private final static int DEFAULT_CHAR_WIDTH = 40;

	private int charWidth;

	private CLabel label;

	/**
	 * The composite into which this contribution item has been placed. This
	 * will be <code>null</code> if this instance has not yet been
	 * initialized.
	 */
	private Composite statusLine = null;

	private String text = Util.ZERO_LENGTH_STRING;

	private int widthHint = -1;

	private int heightHint = -1;

	/**
	 * Creates a status line contribution item with the given id.
	 * 
	 * @param id
	 *            the contribution item's id, or <code>null</code> if it is to
	 *            have no id
	 */
	public StatusLineContributionItem(String id) {
		this(id, DEFAULT_CHAR_WIDTH);
	}

	/**
	 * Creates a status line contribution item with the given id that displays
	 * the given number of characters.
	 * 
	 * @param id
	 *            the contribution item's id, or <code>null</code> if it is to
	 *            have no id
	 * @param charWidth
	 *            the number of characters to display
	 */
	public StatusLineContributionItem(String id, int charWidth) {
		super(id);
		this.charWidth = charWidth;
		setVisible(false); // no text to start with
	}

	public void fill(Composite parent) {
		statusLine = parent;

		Label sep = new Label(parent, SWT.SEPARATOR);
		label = new CLabel(statusLine, SWT.SHADOW_NONE);

		if (widthHint < 0) {
			GC gc = new GC(statusLine);
			gc.setFont(statusLine.getFont());
			FontMetrics fm = gc.getFontMetrics();
			widthHint = fm.getAverageCharWidth() * charWidth;
			heightHint = fm.getHeight();
			gc.dispose();
		}

		StatusLineLayoutData data = new StatusLineLayoutData();
		data.widthHint = widthHint;
		label.setLayoutData(data);
		label.setText(text);

		data = new StatusLineLayoutData();
		data.heightHint = heightHint;
		sep.setLayoutData(data);
	}

	/**
	 * An accessor for the current location of this status line contribution
	 * item -- relative to the display.
	 * 
	 * @return The current location of this status line; <code>null</code> if
	 *         not yet initialized.
	 */
	public Point getDisplayLocation() {
		if ((label != null) && (statusLine != null)) {
			return statusLine.toDisplay(label.getLocation());
		}

		return null;
	}

	/**
	 * Retrieves the text that is being displayed in the status line.
	 * 
	 * @return the text that is currently being displayed
	 */
	public String getText() {
		return text;
	}

	/**
	 * Sets the text to be displayed in the status line.
	 * 
	 * @param text
	 *            the text to be displayed, must not be <code>null</code>
	 */
	public void setText(String text) {
		Assert.isNotNull(text);

		this.text = escape(text);

		if (label != null && !label.isDisposed()) {
			label.setText(this.text);
		}

		if (this.text.length() == 0) {
			if (isVisible()) {
				setVisible(false);
				IContributionManager contributionManager = getParent();

				if (contributionManager != null) {
					contributionManager.update(true);
				}
			}
		} else {
			if (!isVisible()) {
				setVisible(true);
				IContributionManager contributionManager = getParent();

				if (contributionManager != null) {
					contributionManager.update(true);
				}
			}
		}
	}

	private String escape(String text) {
		return Util.replaceAll(text, "&", "&&");  //$NON-NLS-1$//$NON-NLS-2$
	}
}