envoy/src/main/java/envoy/client/ui/ContextMenu.java

package envoy.client.ui;

import java.awt.Component;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.util.HashMap;
import java.util.Map;

import javax.swing.*;

/**
 * This class defines a menu that will be automatically called if
 * {@link MouseEvent#isPopupTrigger()} returns true for the parent component.
 * The user has the possibility to directly add actions to be performed when
 * clicking on the element with the selected String. Additionally, for each
 * element an {@link Icon} can be added, but it must not be.
 * If the key(text) of an element starts with one of the predefined values, a
 * special component will be called: either a {@link JRadioButtonMenuItem}, a
 * {@link JCheckBoxMenuItem} or a {@link JMenu} will be created.<br>
 * <br>
 * Project: <strong>envoy-client</strong><br>
 * File: <strong>ContextMenu.java</strong><br>
 * Created: <strong>17 Mar 2020</strong><br>
 *
 * @author Leon Hofmeister
 * @since Envoy Client v0.1-beta
 */
public class ContextMenu extends JPopupMenu {

	private static final long serialVersionUID = 0L;

	/**
	 * If a key starts with this String, a {@link JCheckBoxMenuItem} will be created
	 */
	public static final String	checkboxMenuItem	= "ChBoMI";
	/**
	 * If a key starts with this String, a {@link JRadioButtonMenuItem} will be
	 * created
	 */
	public static final String	radioButtonMenuItem	= "RaBuMI";
	/**
	 * If a key starts with this String, a {@link JMenu} will be created
	 */
	public static final String	subMenuItem			= "SubMI";

	private Map<String, ActionListener>	items		= new HashMap<>();
	private Map<String, Icon>			icons		= new HashMap<>();
	private Map<String, Integer>		mnemonics	= new HashMap<>();

	private ButtonGroup	radioButtonGroup	= new ButtonGroup();
	private boolean		built				= false;

	/**
	 * @param parent the component which will call this
	 *               {@link ContextMenu}
	 * @since Envoy Client v0.1-beta
	 */
	public ContextMenu(Component parent) { setInvoker(parent); }

	/**
	 * @param label            the string that a UI may use to display as a title
	 *                         for the pop-up menu
	 * @param parent           the component which will call this
	 *                         {@link ContextMenu}
	 * @param itemsWithActions a map of all strings to be displayed with according
	 *                         actions
	 * @param itemIcons        the icons to be displayed before a name, if wanted.
	 *                         Only keys in here will have an Icon displayed. More
	 *                         precisely, all keys here not included in the first
	 *                         map will be thrown out.
	 * @param itemMnemonics    the keyboard shortcuts that need to be pressed to
	 *                         automatically execute the {@link JMenuItem} with the
	 *                         given text
	 * @since Envoy Client v0.1-beta
	 */
	public ContextMenu(String label, Component parent, Map<String, ActionListener> itemsWithActions, Map<String, Icon> itemIcons,
			Map<String, Integer> itemMnemonics) {
		super(label);
		setInvoker(parent);
		this.items		= (itemsWithActions != null) ? itemsWithActions : items;
		this.icons		= (itemIcons != null) ? itemIcons : icons;
		this.mnemonics	= (itemMnemonics != null) ? itemMnemonics : mnemonics;
	}

	/**
	 * Prepares the PopupMenu to be displayed. Should only be used once all map
	 * values have been set.
	 *
	 * @return this instance of {@link ContextMenu} to allow chaining behind the
	 *         constructor
	 * @since Envoy Client v0.1-beta
	 */
	public ContextMenu build() {
		items.forEach((text, action) -> {
			// case radio button wanted
			AbstractButton item;
			if (text.startsWith(radioButtonMenuItem)) {
				item = new JRadioButtonMenuItem(text.substring(radioButtonMenuItem.length()), icons.containsKey(text) ? icons.get(text) : null);
				radioButtonGroup.add(item);
				// case check box wanted
			} else if (text.startsWith(checkboxMenuItem))
				item = new JCheckBoxMenuItem(text.substring(checkboxMenuItem.length()), icons.containsKey(text) ? icons.get(text) : null);
			// case sub-menu wanted
			else if (text.startsWith(subMenuItem)) item = new JMenu(text.substring(subMenuItem.length()));
			else // normal JMenuItem wanted
				item = new JMenuItem(text, icons.containsKey(text) ? icons.get(text) : null);
			item.addActionListener(action);
			if (mnemonics.containsKey(text)) item.setMnemonic(mnemonics.get(text));
			add(item);
		});
		if (getInvoker() != null) {
			getInvoker().addMouseListener(getShowingListener());
			built = true;
		}
		return this;
	}

	/**
	 * @param label the string that a UI may use to display as a title for the
	 *              pop-up menu.
	 * @since Envoy Client v0.1-beta
	 */
	public ContextMenu(String label) { super(label); }

	private MouseAdapter getShowingListener() {
		return new MouseAdapter() {

			@Override
			public void mouseClicked(MouseEvent e) { action(e); }

			@Override
			public void mousePressed(MouseEvent e) { action(e); }

			@Override
			public void mouseReleased(MouseEvent e) { action(e); }

			private void action(MouseEvent e) {
				if (!built) build();
				if (e.isPopupTrigger()) // hides the menu if already visible
					if (!isVisible()) show(e.getComponent(), e.getX(), e.getY());
				else setVisible(false);
			}
		};
	}

	/**
	 * Removes all subcomponents of this menu.
	 *
	 * @since Envoy Client v0.1-beta
	 */
	public void clear() {
		removeAll();
		items		= new HashMap<>();
		icons		= new HashMap<>();
		mnemonics	= new HashMap<>();
	}

	/**
	 * @return the items
	 * @since Envoy Client v0.1-beta
	 */
	public Map<String, ActionListener> getItems() { return items; }

	/**
	 * @param items the items with the displayed text and the according action to
	 *              take once called
	 * @since Envoy Client v0.1-beta
	 */
	public void setItems(Map<String, ActionListener> items) { this.items = items; }

	/**
	 * @return the icons
	 * @since Envoy Client v0.1-beta
	 */
	public Map<String, Icon> getIcons() { return icons; }

	/**
	 * @param icons the icons to set
	 * @since Envoy Client v0.1-beta
	 */
	public void setIcons(Map<String, Icon> icons) { this.icons = icons; }

	/**
	 * @return the mnemonics (the keyboard shortcuts that automatically execute the
	 *         command for a {@link JMenuItem} with corresponding text)
	 * @since Envoy Client v0.1-beta
	 */
	public Map<String, Integer> getMnemonics() { return mnemonics; }

	/**
	 * @param mnemonics the keyboard shortcuts that need to be pressed to
	 *                  automatically execute the {@link JMenuItem} with the given
	 *                  text
	 * @since Envoy Client v0.1-beta
	 */
	public void setMnemonics(Map<String, Integer> mnemonics) { this.mnemonics = mnemonics; }
}