core/plugins/org.eclipse.dltk.ui/src/org/eclipse/dltk/internal/ui/wizards/buildpath/newsourcepage/BuildpathModifierDropDownAction.java

/*******************************************************************************
 * Copyright (c) 2000, 2017 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
 *
 *******************************************************************************/
package org.eclipse.dltk.internal.ui.wizards.buildpath.newsourcepage;

import java.util.ArrayList;
import java.util.List;

import org.eclipse.dltk.core.ModelException;
import org.eclipse.jface.action.ActionContributionItem;
import org.eclipse.jface.action.IAction;
import org.eclipse.jface.action.IMenuCreator;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Menu;

/**
 * Drop down action for toolbars containing
 * <code>BuildpathModifierAction</code>s. The drop down action manages a list of
 * actions that are displayed when invocing the drop down. If there is at least
 * one valid action, then the drop down action itself will also be valid and
 * invocing run will delegate the call to the first valid action in the list.
 */
public class BuildpathModifierDropDownAction extends BuildpathModifierAction
		implements IMenuCreator {

	/** The menu to be populated with items */
	private Menu fMenu;
	/**
	 * A list of actions that will be used as drop down items
	 */
	protected List<BuildpathModifierAction> fActions;
	/**
	 * Index of the action that can be executed when clicking directly on the
	 * dropdown button.
	 */
	private int fIndex;

	/**
	 * Create a drop down action using the same descriptors as the provided
	 * action, but it's on tool tip text. The action will automatically be put
	 * in the list of actions that are managed by this drop down menu.
	 *
	 * @param action
	 *            an action to be added to the dropdown menu
	 * @param text
	 *            a label text for the action
	 * @param toolTipText
	 *            the tooltip text for the drop down menu
	 */
	public BuildpathModifierDropDownAction(BuildpathModifierAction action,
			String text, String toolTipText) {
		super(action.getOperation(), action.getImageDescriptor(),
				action.getDisabledImageDescriptor(), text, toolTipText,
				IAction.AS_DROP_DOWN_MENU);
		fActions = new ArrayList<>();
		fActions.add(action);
		fIndex = 0;
	}

	/**
	 * Runs the first action of the list of managed actions that is valid.
	 */
	@Override
	public void run() {
		BuildpathModifierAction action = fActions.get(fIndex);
		action.run();
	}

	@Override
	public IMenuCreator getMenuCreator() {
		return this;
	}

	@Override
	public Menu getMenu(Control parent) {
		if (fMenu != null) {
			fMenu.dispose();
		}
		fMenu = new Menu(parent);
		createEntries(fMenu);
		return fMenu;

	}

	@Override
	public Menu getMenu(Menu parent) {
		return fMenu;
	}

	/**
	 * Add dynamically an action to the drop down menu.
	 *
	 * @param action
	 *            the action to be added
	 */
	public void addAction(BuildpathModifierAction action) {
		fActions.add(action);
	}

	/**
	 * Add dynamically an array of actions to the drop down menu.
	 *
	 * @param actions
	 *            an array of actions to be added
	 */
	public void addActions(BuildpathModifierAction[] actions) {
		for (int i = 0; i < actions.length; i++) {
			addAction(actions[i]);
		}
	}

	/**
	 * Remove an action from the drop down menu
	 *
	 * @param action
	 *            the action to be removed
	 */
	public void removeAction(BuildpathModifierAction action) {
		fActions.remove(action);
	}

	/**
	 * Get all actions within this drop down menu.
	 *
	 * @return an array of actions
	 */
	public BuildpathModifierAction[] getActions() {
		return fActions.toArray(new BuildpathModifierAction[fActions.size()]);
	}

	/**
	 * Populate the menu with the given action item
	 *
	 * @param parent
	 *            the menu to add an action for
	 * @param action
	 *            the action to be added
	 */
	private void addActionToMenu(Menu parent, IAction action) {
		ActionContributionItem item = new ActionContributionItem(action);
		item.fill(parent, -1);
	}

	/**
	 * Fill the menu with all actions
	 *
	 * @param menu
	 *            the menu to be populated
	 */
	private void createEntries(Menu menu) {
		for (int i = 0; i < fActions.size(); i++) {
			IAction action = fActions.get(i);
			addActionToMenu(menu, action);
		}
	}

	@Override
	public void dispose() {
		if (fMenu != null) {
			fMenu.dispose();
			fMenu = null;
		}
	}

	/**
	 * Check all managed actions to find out if at least one is valid. The first
	 * valid action that is found will be used when calling <code>run()</code>.
	 *
	 * @return <code>true</code> if at least one of the managed actions is
	 *         valid, <code>false</code> otherwise.
	 */
	@Override
	public boolean isValid(List selectedElements, int[] types)
			throws ModelException {
		for (int i = 0; i < fActions.size(); i++) {
			BuildpathModifierAction action = fActions.get(i);
			if (action.isValid(selectedElements, types)) {
				fIndex = i;
				return true;
			}
		}
		return false;
	}
}