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/*******************************************************************************
 * Copyright (c) 2000, 2016 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.jface.action;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

import org.eclipse.core.runtime.Assert;
import org.eclipse.core.runtime.ListenerList;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.CoolBar;
import org.eclipse.swt.widgets.Menu;
import org.eclipse.swt.widgets.ToolBar;

/**
 * A SubMenuManager is used to define a set of contribution
 * items within a parent manager.  Once defined, the visibility of the entire set can
 * be changed as a unit.
 * 
 * A client may ask for and make additions to a submenu.  The visibility of these items
 * is also controlled by the visibility of the SubMenuManager.
 * 
 */
public class SubMenuManager extends SubContributionManager implements
		IMenuManager {

	/**
	 * Maps each submenu in the manager to a wrapper.  The wrapper is used to
	 * monitor additions and removals.  If the visibility of the manager is modified
	 * the visibility of the submenus is also modified.
	 */
	private Map mapMenuToWrapper;

	/**
	 * List of registered menu listeners (element type: IMenuListener).
	 */
	private ListenerList menuListeners = new ListenerList<>();

	/**
	 * The menu listener added to the parent.  Lazily initialized
	 * in addMenuListener.
	 */
	private IMenuListener menuListener;

	/**
	 * Constructs a new manager.
	 *
	 * @param mgr the parent manager.  All contributions made to the
	 *      SubMenuManager are forwarded and appear in the
	 *      parent manager.
	 */
	public SubMenuManager(IMenuManager mgr) {
		super(mgr);
	}

	@Override
	public void addMenuListener(IMenuListener listener) {
		menuListeners.add(listener);
		if (menuListener == null) {
			menuListener = manager -> {
				for (IMenuListener localListener : menuListeners) {
					localListener.menuAboutToShow(SubMenuManager.this);
				}
			};
		}
		getParentMenuManager().addMenuListener(menuListener);
	}

	/**
	 * The default implementation of this IContributionItem
	 * method does nothing. Subclasses may override.
	 */
	@Override
	public void dispose() {
		// do nothing
	}

	@Override
	public void disposeManager() {
		if (menuListener != null) {
			getParentMenuManager().removeMenuListener(menuListener);
			menuListener = null;
			menuListeners.clear();
		}
		// Dispose wrapped menus in addition to removing them.
		// See bugs 64024 and 73715 for details.
		// important to dispose menu wrappers before call to super,
		// otherwise super's call to removeAll will remove them
		// before they can be disposed
		if (mapMenuToWrapper != null) {
			Iterator iter = mapMenuToWrapper.values().iterator();
			while (iter.hasNext()) {
				SubMenuManager wrapper = iter.next();
				wrapper.disposeManager();
			}
			mapMenuToWrapper.clear();
			mapMenuToWrapper = null;
		}
		super.disposeManager();
	}

	@Override
	public void fill(Composite parent) {
		if (isVisible()) {
			getParentMenuManager().fill(parent);
		}
	}

	@Override
	public void fill(CoolBar parent, int index) {
		// do nothing
	}

	@Override
	public void fill(Menu parent, int index) {
		if (isVisible()) {
			getParentMenuManager().fill(parent, index);
		}
	}

	@Override
	public void fill(ToolBar parent, int index) {
		if (isVisible()) {
			getParentMenuManager().fill(parent, index);
		}
	}

	/**
	 * Method declared on IContributionManager.
	 *
	 * Returns the item passed to us, not the wrapper. In the case of menu's not
	 * added by this manager, ensure that we return a wrapper for the menu.
	 *
	 * @param id
	 *            of the {@link IContributionItem}
	 */
	@Override
	public IContributionItem find(String id) {
		IContributionItem item = getParentMenuManager().find(id);
		if (item instanceof SubContributionItem) {
			// Return the item passed to us, not the wrapper.
			item = unwrap(item);
		}

		if (item instanceof IMenuManager) {
			// if it is a menu manager wrap it before returning
			IMenuManager menu = (IMenuManager) item;
			item = getWrapper(menu);
		}

		return item;
	}

	/**
	 * 
	 * The menu returned is wrapped within a SubMenuManager to
	 * monitor additions and removals.  If the visibility of this menu is modified
	 * the visibility of the submenus is also modified.
	 * 
	 */
	@Override
	public IMenuManager findMenuUsingPath(String path) {
		IContributionItem item = findUsingPath(path);
		if (item instanceof IMenuManager) {
			return (IMenuManager) item;
		}
		return null;
	}

	/**
	 * Method declared on IMenuManager.
	 *
	 * Returns the item passed to us, not the wrapper.
	 *
	 * We use use the same algorithm as MenuManager.findUsingPath, but unwrap
	 * submenus along so that SubMenuManagers are visible.
	 *
	 * @param path
	 *            which allows to find an {@link IContributionItem} through the
	 *            menu structure.
	 */
	@Override
	public IContributionItem findUsingPath(String path) {
		String id = path;
		String rest = null;
		int separator = path.indexOf('/');
		if (separator != -1) {
			id = path.substring(0, separator);
			rest = path.substring(separator + 1);
		}
		IContributionItem item = find(id); // unwraps item
		if (rest != null && item instanceof IMenuManager) {
			IMenuManager menu = (IMenuManager) item;
			item = menu.findUsingPath(rest);
		}
		return item;
	}

	@Override
	public String getId() {
		return getParentMenuManager().getId();
	}

	/**
	 * @return the parent menu manager that this sub-manager contributes to.
	 */
	protected final IMenuManager getParentMenuManager() {
		// Cast is ok because that's the only
		// thing we accept in the construtor.
		return (IMenuManager) getParent();
	}

	@Override
	public boolean getRemoveAllWhenShown() {
		return false;
	}

	/**
	 * Returns the menu wrapper for a menu manager.
	 * 
	 * The sub menus within this menu are wrapped within a
	 * SubMenuManager to monitor additions and removals. If the
	 * visibility of this menu is modified the visibility of the sub menus is also
	 * modified.
	 * 
	 *
	 * @param mgr the menu manager to be wrapped
	 *
	 * @return the menu wrapper
	 */
	protected IMenuManager getWrapper(IMenuManager mgr) {
		if (mapMenuToWrapper == null) {
			mapMenuToWrapper = new HashMap<>(4);
		}
		SubMenuManager wrapper = mapMenuToWrapper.get(mgr);
		if (wrapper == null) {
			wrapper = wrapMenu(mgr);
			mapMenuToWrapper.put(mgr, wrapper);
		}
		return wrapper;
	}

	@Override
	public boolean isDynamic() {
		return getParentMenuManager().isDynamic();
	}

	@Override
	public boolean isEnabled() {
		return isVisible() && getParentMenuManager().isEnabled();
	}

	@Override
	public boolean isGroupMarker() {
		return getParentMenuManager().isGroupMarker();
	}

	@Override
	public boolean isSeparator() {
		return getParentMenuManager().isSeparator();
	}

	/**
	 * Remove all contribution items.
	 */
	@Override
	public void removeAll() {
		super.removeAll();
		if (mapMenuToWrapper != null) {
			Iterator iter = mapMenuToWrapper.values().iterator();
			while (iter.hasNext()) {
				SubMenuManager wrapper = iter.next();
				wrapper.removeAll();
			}
			mapMenuToWrapper.clear();
			mapMenuToWrapper = null;
		}
	}

	@Override
	public void removeMenuListener(IMenuListener listener) {
		menuListeners.remove(listener);
	}

	@Override
	public void saveWidgetState() {
		// do nothing
	}

	@Override
	public void setParent(IContributionManager parent) {
		// do nothing, our "parent manager's" parent
		// is set when it is added to a manager
	}

	@Override
	public void setRemoveAllWhenShown(boolean removeAll) {
		Assert.isTrue(false, "Should not be called on submenu manager"); //$NON-NLS-1$
	}

	@Override
	public void setVisible(boolean visible) {
		super.setVisible(visible);
		if (mapMenuToWrapper != null) {
			Iterator iter = mapMenuToWrapper.values().iterator();
			while (iter.hasNext()) {
				SubMenuManager wrapper = iter.next();
				wrapper.setVisible(visible);
			}
		}
	}

	@Override
	public void update() {
		// This method is not governed by visibility.  The client may
		// call setVisible and then force an update.  At that
		// point we need to update the parent.
		getParentMenuManager().update();
	}

	@Override
	public void update(boolean force) {
		// This method is not governed by visibility.  The client may
		// call setVisible and then force an update.  At that
		// point we need to update the parent.
		getParentMenuManager().update(force);
	}

	@Override
	public void update(String id) {
		getParentMenuManager().update(id);
	}

	@Override
	public void updateAll(boolean force) {
		// This method is not governed by visibility.  The client may
		// call setVisible and then force an update.  At that
		// point we need to update the parent.
		getParentMenuManager().updateAll(force);
	}

	/**
	 * Wraps a menu manager in a sub menu manager, and returns the new wrapper.
	 * @param menu the menu manager to wrap
	 * @return the new wrapped menu manager
	 */
	protected SubMenuManager wrapMenu(IMenuManager menu) {
		SubMenuManager mgr = new SubMenuManager(menu);
		mgr.setVisible(isVisible());
		return mgr;
	}
}