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/*******************************************************************************
 * Copyright (c) 2004, 2012 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
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/

package org.eclipse.jface.bindings;

import java.util.Collection;
import java.util.Map;

import org.eclipse.core.commands.ParameterizedCommand;
import org.eclipse.core.commands.common.AbstractBitSetEvent;
import org.eclipse.jface.util.Util;

/**
 * An instance of this class describes changes to an instance of
 * BindingManager.
 * 
 * This class is not intended to be extended by clients.
 * 
 * 
 * @since 3.1
 * @see IBindingManagerListener#bindingManagerChanged(BindingManagerEvent)
 */
public final class BindingManagerEvent extends AbstractBitSetEvent {
	
	private final static TriggerSequence[] EMTPY_SEQUENCE = new TriggerSequence[0];

	/**
	 * The bit used to represent whether the map of active bindings has changed.
	 */
	private static final int CHANGED_ACTIVE_BINDINGS = 1;

	/**
	 * The bit used to represent whether the active scheme has changed.
	 */
	private static final int CHANGED_ACTIVE_SCHEME = 1 << 1;

	/**
	 * The bit used to represent whether the active locale has changed.
	 */
	private static final int CHANGED_LOCALE = 1 << 2;

	/**
	 * The bit used to represent whether the active platform has changed.
	 */
	private static final int CHANGED_PLATFORM = 1 << 3;

	/**
	 * The bit used to represent whether the scheme's defined state has changed.
	 */
	private static final int CHANGED_SCHEME_DEFINED = 1 << 4;

	/**
	 * The binding manager that has changed; this value is never
	 * null.
	 */
	private final BindingManager manager;

	/**
	 * The map of triggers (Collection of
	 * TriggerSequence) by parameterized command (ParameterizedCommand)
	 * before the change occurred. This map may be empty and it may be
	 * null.
	 */
	private final Map previousTriggersByParameterizedCommand;

	/**
	 * The scheme that became defined or undefined. This value may be
	 * null if no scheme changed its defined state.
	 */
	private final Scheme scheme;

	/**
	 * Creates a new instance of this class.
	 * 
	 * @param manager
	 *            the instance of the binding manager that changed; must not be
	 *            null.
	 * @param activeBindingsChanged
	 *            Whether the active bindings have changed.
	 * @param previousTriggersByParameterizedCommand
	 *            The map of triggers (TriggerSequence) by
	 *            fully-parameterized command (ParameterizedCommand)
	 *            before the change occured. This map may be null
	 *            or empty.
	 * @param activeSchemeChanged
	 *            true, iff the active scheme changed.
	 * @param scheme
	 *            The scheme that became defined or undefined; null
	 *            if no scheme changed state.
	 * @param schemeDefined
	 *            true if the given scheme became defined;
	 *            false otherwise.
	 * @param localeChanged
	 *            true iff the active locale changed
	 * @param platformChanged
	 *            true iff the active platform changed
	 */
	public BindingManagerEvent(final BindingManager manager,
			final boolean activeBindingsChanged,
			final Map previousTriggersByParameterizedCommand,
			final boolean activeSchemeChanged, final Scheme scheme,
			final boolean schemeDefined, final boolean localeChanged,
			final boolean platformChanged) {
		if (manager == null) {
			throw new NullPointerException(
					"A binding manager event needs a binding manager"); //$NON-NLS-1$
		}
		this.manager = manager;

		if (schemeDefined && (scheme == null)) {
			throw new NullPointerException(
					"If a scheme changed defined state, then there should be a scheme identifier"); //$NON-NLS-1$
		}
		this.scheme = scheme;

		this.previousTriggersByParameterizedCommand = previousTriggersByParameterizedCommand;

		if (activeBindingsChanged) {
			changedValues |= CHANGED_ACTIVE_BINDINGS;
		}
		if (activeSchemeChanged) {
			changedValues |= CHANGED_ACTIVE_SCHEME;
		}
		if (localeChanged) {
			changedValues |= CHANGED_LOCALE;
		}
		if (platformChanged) {
			changedValues |= CHANGED_PLATFORM;
		}
		if (schemeDefined) {
			changedValues |= CHANGED_SCHEME_DEFINED;
		}
	}

	/**
	 * Returns the instance of the manager that changed.
	 * 
	 * @return the instance of the manager that changed. Guaranteed not to be
	 *         null.
	 */
	public final BindingManager getManager() {
		return manager;
	}

	/**
	 * Returns the scheme that changed.
	 * 
	 * @return The changed scheme
	 */
	public final Scheme getScheme() {
		return scheme;
	}

	/**
	 * Returns whether the active bindings have changed.
	 * 
	 * @return true if the active bindings have changed;
	 *         false otherwise.
	 */
	public final boolean isActiveBindingsChanged() {
		return ((changedValues & CHANGED_ACTIVE_BINDINGS) != 0);
	}

	/**
	 * Computes whether the active bindings have changed for a given command
	 * identifier.
	 * 
	 * @param parameterizedCommand
	 *            The fully-parameterized command whose bindings might have
	 *            changed; must not be null.
	 * @return true if the active bindings have changed for the
	 *         given command identifier; false otherwise.
	 */
	public final boolean isActiveBindingsChangedFor(
			final ParameterizedCommand parameterizedCommand) {
		final TriggerSequence[] currentBindings = manager
				.getActiveBindingsFor(parameterizedCommand);
		final TriggerSequence[] previousBindings;
		if (previousTriggersByParameterizedCommand != null) {
			final Collection previousBindingCollection = (Collection) previousTriggersByParameterizedCommand
					.get(parameterizedCommand);
			if (previousBindingCollection == null) {
				previousBindings = EMTPY_SEQUENCE;
			} else {
				previousBindings = (TriggerSequence[]) previousBindingCollection
						.toArray(new TriggerSequence[previousBindingCollection
								.size()]);
			}
		} else {
			previousBindings = EMTPY_SEQUENCE;
		}

		return !Util.equals(currentBindings, previousBindings);
	}

	/**
	 * Returns whether or not the active scheme changed.
	 * 
	 * @return true, iff the active scheme property changed.
	 */
	public final boolean isActiveSchemeChanged() {
		return ((changedValues & CHANGED_ACTIVE_SCHEME) != 0);
	}

	/**
	 * Returns whether the locale has changed
	 * 
	 * @return true if the locale changed; false
	 *         otherwise.
	 */
	public boolean isLocaleChanged() {
		return ((changedValues & CHANGED_LOCALE) != 0);
	}

	/**
	 * Returns whether the platform has changed
	 * 
	 * @return true if the platform changed; false
	 *         otherwise.
	 */
	public boolean isPlatformChanged() {
		return ((changedValues & CHANGED_PLATFORM) != 0);
	}

	/**
	 * Returns whether the list of defined scheme identifiers has changed.
	 * 
	 * @return true if the list of scheme identifiers has
	 *         changed; false otherwise.
	 */
	public final boolean isSchemeChanged() {
		return (scheme != null);
	}

	/**
	 * Returns whether or not the scheme became defined
	 * 
	 * @return true if the scheme became defined.
	 */
	public final boolean isSchemeDefined() {
		return (((changedValues & CHANGED_SCHEME_DEFINED) != 0) && (scheme != null));
	}
}