/*******************************************************************************
 * Copyright (c) 2000, 2003 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/

package org.eclipse.ui.internal.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;

import org.eclipse.jface.action.ContributionItem;
import org.eclipse.jface.action.IContributionManager;
import org.eclipse.jface.action.StatusLineLayoutData;

/**
 * @issue needs Javadoc
 */
public class StatusLineContributionItem extends ContributionItem {

	public 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;

	public StatusLineContributionItem(String id) {
		this(id, DEFAULT_CHAR_WIDTH);
	}

	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;
	}

	public String getText() {
		return text;
	}

	public void setText(String text) {
		if (text == null)
			throw new NullPointerException();

		this.text = 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);
			}
		}
	}
}