/*******************************************************************************
 * 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.jface.resource;

import java.text.MessageFormat;
import java.util.MissingResourceException;
import java.util.ResourceBundle;

import org.eclipse.jface.util.Assert;
import org.eclipse.swt.graphics.Font;
import org.eclipse.swt.graphics.Image;

/**
 * Utility methods to access JFace-specific resources.
 * <p>
 * All methods declared on this class are static. This
 * class cannot be instantiated.
 * </p>
 * <p>
 * The following global state is also maintained by this class:
 * <ul>
 *   <li>a font registry</li>
 *   <li>an image registry</li>
 *   <li>a resource bundle</li>
 * </ul>
 * </p>
 */
public class JFaceResources {

	/**
	 * The JFace resource bundle; eagerly initialized.
	 */
	private static final ResourceBundle bundle=
		ResourceBundle.getBundle("org.eclipse.jface.messages");//$NON-NLS-1$
		
	/**
	 * The JFace font registry; <code>null</code> until
	 * lazily initialized or explicitly set.
	 */
	private static FontRegistry fontRegistry = null;

	/**
	 * The JFace image registry; <code>null</code> until
	 * lazily initialized.
	 */
	private static ImageRegistry imageRegistry = null;

	/**
	 * The symbolic font name for the standard font 
	 * (value <code>"org.eclipse.jface.defaultfont"</code>).
	 */
	
	 public static final String DEFAULT_FONT = "org.eclipse.jface.defaultfont";//$NON-NLS-1$

	/**
	 * The symbolic font name for the dialog font 
	 * (value <code>"org.eclipse.jface.dialogfont"</code>).
	 */
	public static final String DIALOG_FONT = "org.eclipse.jface.dialogfont";//$NON-NLS-1$

	/**
	 * The symbolic font name for the banner font 
	 * (value <code>"org.eclipse.jface.bannerfont"</code>).
	 */
	public static final String BANNER_FONT = "org.eclipse.jface.bannerfont";//$NON-NLS-1$

	/**
	 * The symbolic font name for the viewer font 
	 * (value <code>"org.eclipse.jface.viewerfont"</code>).
 	* @deprecated This font is not in use
	 */
	public static final String VIEWER_FONT = "org.eclipse.jface.viewerfont";//$NON-NLS-1$
	
	/**
	 * The symbolic font name for the header font 
	 * (value <code>"org.eclipse.jface.headerfont"</code>).
	 */
	public static final String HEADER_FONT = "org.eclipse.jface.headerfont";//$NON-NLS-1$
	

	/**
	 * The symbolic font name for the text font 
	 * (value <code>"org.eclipse.jface.textfont"</code>).
	 */
	public static final String TEXT_FONT = "org.eclipse.jface.textfont";//$NON-NLS-1$

	/**
	 * The symbolic font name for the window font 
	 * (value <code>"org.eclipse.jface.windowfont"</code>).
	 * @deprecated This font is not in use
	 */
	public static final String WINDOW_FONT = "org.eclipse.jface.windowfont";//$NON-NLS-1$
	
/* (non-Javadoc)
 * Declare a private constructor to block instantiation.
 */
private JFaceResources() {
}
/**
 * Returns the formatted message for the given key in
 * JFace's resource bundle. 
 *
 * @param key the resource name
 * @param args the message arguments
 * @return the string
 */	
public static String format(String key, Object[] args) {
	return MessageFormat.format(getString(key),args);
}
/**
 * Returns the JFace's banner font.
 * Convenience method equivalent to
 * <pre>
 * JFaceResources.getFontRegistry().get(JFaceResources.BANNER_FONT)
 * </pre>
 *
 * @return the font
 */
public static Font getBannerFont() {
	return getFontRegistry().get(BANNER_FONT);
}
/**
 * Returns the resource bundle for JFace itself.
 * The resouble bundle is obtained from
 * <code>ResourceBundle.getBundle("org.eclipse.jface.jface_nls")</code>.
 * <p>
 * Note that several static convenience methods are 
 * also provided on this class for directly accessing
 * resources in this bundle.
 * </p>
 *
 * @return the resource bundle
 */
public static ResourceBundle getBundle() {
	return bundle;
}
/**
 * Returns the JFace's standard font.
 * Convenience method equivalent to
 * <pre>
 * JFaceResources.getFontRegistry().get(JFaceResources.DEFAULT_FONT)
 * </pre>
 *
 * @return the font
 */
public static Font getDefaultFont() {
	return getFontRegistry().defaultFont();
}
/**
 * Returns the JFace's dialog font.
 * Convenience method equivalent to
 * <pre>
 * JFaceResources.getFontRegistry().get(JFaceResources.DIALOG_FONT)
 * </pre>
 *
 * @return the font
 */
public static Font getDialogFont() {
	return getFontRegistry().get(DIALOG_FONT);
}
/**
 * Returns the font in JFace's font registry with the given
 * symbolic font name.
 * Convenience method equivalent to
 * <pre>
 * JFaceResources.getFontRegistry().get(symbolicName)
 * </pre>
 *
 * If an error occurs, return the default font.
 *
 * @param symbolicName the symbolic font name
 * @return the font
 */
public static Font getFont(String symbolicName) {
	return getFontRegistry().get(symbolicName);
}
/**
 * Returns the font registry for JFace itself.
 * If the value has not been established by an earlier
 * call to <code>setFontRegistry</code>, is it
 * initialized to
 * <code>new FontRegistry("org.eclipse.jface.resource.jfacefonts")</code>.
 * <p>
 * Note that several static convenience methods are 
 * also provided on this class for directly accessing
 * JFace's standard fonts.
 * </p>
 */
public static FontRegistry getFontRegistry() {
	if (fontRegistry == null) {
		fontRegistry = new FontRegistry("org.eclipse.jface.resource.jfacefonts");//$NON-NLS-1$
	}
	return fontRegistry;
}
/**
 * Returns the image in JFace's image registry with the given key, 
 * or <code>null</code> if none.
 * Convenience method equivalent to
 * <pre>
 * JFaceResources.getImageRegistry().get(key)
 * </pre>
 *
 * @param key the key
 * @return the image, or <code>null</code> if none
 */
public static Image getImage(String key) {
	return getImageRegistry().get(key);
}
/**
 * Returns the image registry for JFace itself.
 * <p>
 * Note that the static convenience method <code>getImage</code>
 * is also provided on this class.
 * </p>
 */
public static ImageRegistry getImageRegistry() {
	if (imageRegistry == null)
		imageRegistry = new ImageRegistry();
	return imageRegistry;
}
/**
 * Returns the resource object with the given key in
 * JFace's resource bundle. If there isn't any value under
 * the given key, the key is returned.
 *
 * @param key the resource name
 * @return the string
 */	
public static String getString(String key) {
	try {
		return bundle.getString(key);
	} catch (MissingResourceException e) {
		return key;
	}
}
/**
 * Returns a list of string values corresponding to the
 * given list of keys. The lookup is done with <code>getString</code>.
 * The values are in the same order as the keys.
 *
 * @param keys a list of keys
 * @return a list of corresponding string values
 */
public static String[] getStrings(String[] keys) {
	Assert.isNotNull(keys);
	int length = keys.length;
	String[] result = new String[length];
	for (int i = 0; i < length; i++)
		result[i] = getString(keys[i]);
	return result;
}

/**
 * Returns the JFace's header font.
 * Convenience method equivalent to
 * <pre>
 * JFaceResources.getFontRegistry().get(JFaceResources.HEADER_FONT)
 * </pre>
 *
 * @return the font
 */
public static Font getHeaderFont() {
	return getFontRegistry().get(HEADER_FONT);
}

/**
 * Returns the JFace's text font.
 * Convenience method equivalent to
 * <pre>
 * JFaceResources.getFontRegistry().get(JFaceResources.TEXT_FONT)
 * </pre>
 *
 * @return the font
 */
public static Font getTextFont() {
	return getFontRegistry().get(TEXT_FONT);
}
/**
 * Returns the JFace's viewer font.
 * Convenience method equivalent to
 * <pre>
 * JFaceResources.getFontRegistry().get(JFaceResources.VIEWER_FONT)
 * </pre>
 *
 * @return the font
 * @deprecated This font is not in use
 */
public static Font getViewerFont() {
	return getFontRegistry().get(VIEWER_FONT);
}
/**
 * Sets JFace's font registry to the given value.
 * This method may only be called once; the call must occur
 * before <code>JFaceResources.getFontRegistry</code>
 * is invoked (either directly or indirectly). 
 *
 * @param registry a font registry
 */
public static void setFontRegistry(FontRegistry registry) {
	Assert.isTrue(fontRegistry == null, "Font registry can only be set once.");//$NON-NLS-1$
	fontRegistry = registry;
}
}