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/*******************************************************************************
 * Copyright (c) 2000, 2015 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.dialogs;

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

import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;

/**
 * Helper class to save the enable/disable state of a control including all its
 * descendent controls.
 */
public class ControlEnableState {
	/**
	 * List of exception controls (element type: Control);
	 * null if none.
	 */
	private List exceptions = null;

	/**
	 * List of saved states (element type: ItemState).
	 */
	private List states;

	/**
	 * Internal class for recording the enable/disable state of a single
	 * control.
	 */
	private static class ItemState {
		/** the control */
		protected Control item;

		/** the state */
		protected boolean state;

		/**
		 * Create a new instance of the receiver.
		 */
		public ItemState(Control item, boolean state) {
			this.item = item;
			this.state = state;
		}

		/**
		 * Restore the enabled state to the original value.
		 */
		public void restore() {
			if (item == null || item.isDisposed()) {
				return;
			}
			item.setEnabled(state);
		}
	}

	/**
	 * Creates a new object and saves in it the current enable/disable state of
	 * the given control and its descendents; the controls that are saved are
	 * also disabled.
	 *
	 * @param w
	 *            the control
	 */
	protected ControlEnableState(Control w) {
		this(w, null);
	}

	/**
	 * Creates a new object and saves in it the current enable/disable state of
	 * the given control and its descendents except for the given list of
	 * exception cases; the controls that are saved are also disabled.
	 *
	 * @param w
	 *            the control
	 * @param exceptions
	 *            the list of controls to not disable (element type:
	 *            Control), or null if none
	 */
	protected ControlEnableState(Control w, List exceptions) {
		super();
		states = new ArrayList<>();
		this.exceptions = exceptions;
		readStateForAndDisable(w);
	}

	/**
	 * Saves the current enable/disable state of the given control and its
	 * descendents in the returned object; the controls are all disabled.
	 *
	 * @param w
	 *            the control
	 * @return an object capturing the enable/disable state
	 */
	public static ControlEnableState disable(Control w) {
		return new ControlEnableState(w);
	}

	/**
	 * Saves the current enable/disable state of the given control and its
	 * descendents in the returned object except for the given list of exception
	 * cases; the controls that are saved are also disabled.
	 *
	 * @param w
	 *            the control
	 * @param exceptions
	 *            the list of controls to not disable (element type:
	 *            Control)
	 * @return an object capturing the enable/disable state
	 */
	public static ControlEnableState disable(Control w, List exceptions) {
		return new ControlEnableState(w, exceptions);
	}

	/**
	 * Recursively reads the enable/disable state for the given window and
	 * disables all controls.
	 * @param control Control
	 */
	private void readStateForAndDisable(Control control) {
		if ((exceptions != null && exceptions.contains(control))) {
			return;
		}
		if (control instanceof Composite) {
			Composite c = (Composite) control;
			Control[] children = c.getChildren();
			for (Control element : children) {
				readStateForAndDisable(element);
			}
		}
		// XXX: Workaround for 1G2Q8SS: ITPUI:Linux - Combo box is not enabled
		// in "File->New->Solution"
		states.add(new ItemState(control, control.getEnabled()));
		control.setEnabled(false);
	}

	/**
	 * Restores the window enable state saved in this object.
	 */
	public void restore() {
		int size = states.size();
		for (int i = 0; i < size; i++) {
			states.get(i).restore();
		}
	}
}