/*******************************************************************************
 * Copyright (c) 2004, 2019 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
 *******************************************************************************/
package org.eclipse.ui.themes;

import java.util.Set;
import org.eclipse.jface.resource.ColorRegistry;
import org.eclipse.jface.resource.FontRegistry;
import org.eclipse.jface.util.IPropertyChangeListener;

/**
 * A theme is a collection of colors, fonts and supporting data that may be used
 * by plugins to help provide uniform look and feel to their components. The
 * workbench has a default theme (one whos id has the value
 * {@link org.eclipse.ui.themes.IThemeManager#DEFAULT_THEME}) that defines the
 * initial values for a collection of fonts and colors. Other themes may extend
 * and override the default theme to provide new values.
 *
 * <p>
 * Clients may obtain themes via
 * {@link org.eclipse.ui.themes.IThemeManager#getTheme(String)}.
 * </p>
 *
 * <p>
 * This interface is not intended to be implemented or extended by clients.
 * </p>
 *
 * @see org.eclipse.ui.IWorkbench#getThemeManager()
 * @since 3.0
 * @noimplement This interface is not intended to be implemented by clients.
 */
public interface ITheme {

	/**
	 * Adds a property listener to the theme. Any events fired by the underlying
	 * registries will cause an event to be fired. This event is the same event that
	 * was fired by the registry. As such, the "source" attribute of the event will
	 * not be this theme, but rather the color or font registry.
	 *
	 * @param listener the listener to add
	 */
	void addPropertyChangeListener(IPropertyChangeListener listener);

	/**
	 * Dispose of this theme. This method is called by the workbench when
	 * appropriate and should never be called by a user.
	 */
	void dispose();

	/**
	 * Get arbitrary data associated with this theme.
	 *
	 * @param key the key
	 * @return the data, or the default value <code>false</code> if none exists or
	 *         if the value cannot be treated as a boolean.
	 */
	boolean getBoolean(String key);

	/**
	 * Return this themes color registry.
	 *
	 * @return this themes color registry
	 */
	ColorRegistry getColorRegistry();

	/**
	 * Return this themes font registry.
	 *
	 * @return this themes font registry
	 */
	FontRegistry getFontRegistry();

	/**
	 * Returns the id of this theme.
	 *
	 * @return the id of this theme. Guaranteed not to be <code>null</code>.
	 */
	String getId();

	/**
	 * Get arbitrary data associated with this theme.
	 *
	 * @param key the key
	 * @return the data, or the default value <code>0</code> if none exists or if
	 *         the value cannot be treated as an integer.
	 */
	int getInt(String key);

	/**
	 * Returns the label of this theme.
	 *
	 * @return the label of this theme. Guaranteed not be <code>null</code>.
	 */
	String getLabel();

	/**
	 * Get arbitrary data associated with this theme.
	 *
	 * @param key the key
	 * @return the data, or <code>null</code> if none exists.
	 */
	String getString(String key);

	/**
	 * Get the set of keys associated with this theme.
	 *
	 * @return the Set of keys
	 */
	Set<String> keySet();

	/**
	 * Removes a property listener from the theme.
	 *
	 * @param listener the listener to remove
	 */
	void removePropertyChangeListener(IPropertyChangeListener listener);
}
