/*

* Copyright (c) 2007 Nokia Corporation and/or its subsidiary(-ies). 

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of "Eclipse Public License v1.0"

* which accompanies this distribution, and is available

* at the URL "http://www.eclipse.org/legal/epl-v10.html".

*

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description:

*

* State listener for tree viewer check boxes

*

*/

package com.nokia.tracebuilder.view;

import java.util.Iterator;

import org.eclipse.jface.viewers.CheckStateChangedEvent;

import org.eclipse.jface.viewers.CheckboxTreeViewer;

import org.eclipse.jface.viewers.ICheckStateListener;

import com.nokia.tracebuilder.engine.CheckListDialogEntry;

/**

 * State listener for tree viewer check boxes

 * 

 */

final class CheckListCheckStateListener implements ICheckStateListener {

	/**

	 * Content provider

	 */

	private final CheckboxTreeViewer viewer;

	/**

	 * Constructor

	 * 

	 * @param viewer

	 *            the viewer

	 */

	CheckListCheckStateListener(CheckboxTreeViewer viewer) {

		this.viewer = viewer;

	}

	/*

	 * (non-Javadoc)

	 * 

	 * @see org.eclipse.jface.viewers.ICheckStateListener#

	 *      checkStateChanged(org.eclipse.jface.viewers.CheckStateChangedEvent)

	 */

	public void checkStateChanged(CheckStateChangedEvent event) {

		CheckListDialogEntry entry = (CheckListDialogEntry) event.getElement();

		boolean newState = event.getChecked();

		// View update is not needed with the entry that was clicked by user

		checkEntryAndRelatives(entry, newState, false);

	}

	/**

	 * Changes the state of an entry, its parent and children

	 * 

	 * @param entry

	 *            the entry

	 * @param newState

	 *            the new entry state

	 * @param updateView

	 *            true if view needs to be updated

	 * @return true if entries were changed

	 */

	private boolean checkEntryAndRelatives(CheckListDialogEntry entry,

			boolean newState, boolean updateView) {

		boolean changed = checkEntry(entry, newState, updateView);

		if (changed) {

			viewer.setSubtreeChecked(entry, newState);

			checkChildren(entry, newState);

			checkParent(entry);

		}

		return changed;

	}

	/**

	 * Checks the children of given entry

	 * 

	 * @param entry

	 *            the entry

	 * @param newState

	 *            the new state

	 */

	private void checkChildren(CheckListDialogEntry entry, boolean newState) {

		for (CheckListDialogEntry child : entry) {

			child.setChecked(newState);

			checkChildren(child, newState);

		}

	}

	/**

	 * Checks an entry and unchecks the partially checked flag if it exists

	 * 

	 * @param entry

	 *            the entry

	 * @param newState

	 *            the new entry state

	 * @param updateView

	 *            true if view needs to be updated

	 * @return true if entry was changed

	 */

	private boolean checkEntry(CheckListDialogEntry entry, boolean newState,

			boolean updateView) {

		boolean retval;

		if (entry.isChecked() != newState) {

			entry.setChecked(newState);

			if (entry.isPartiallyChecked()) {

				entry.setPartiallyChecked(false);

				viewer.setGrayChecked(entry, false);

			}

			if (updateView) {

				viewer.setChecked(entry, newState);

			}

			retval = true;

		} else {

			retval = false;

		}

		return retval;

	}

	/**

	 * Recursively checks the parent of the checked element. If all children are

	 * checked, the parent is checked. If all children are unchecked, the parent

	 * is unchecked. If children are partially checked, the parent is grayed.

	 * 

	 * @param entry

	 *            the entry whose parent needs to be checked

	 */

	private void checkParent(CheckListDialogEntry entry) {

		CheckListDialogEntry parent = entry.getParent();

		if (parent != null && parent.hasChildren()) {

			boolean checked = false;

			boolean unchecked = false;

			boolean partiallyChecked = false;

			Iterator<CheckListDialogEntry> children = parent.getChildren();

			while (children.hasNext() && !partiallyChecked) {

				CheckListDialogEntry child = children.next();

				boolean childChecked = child.isChecked();

				boolean childPartial = child.isPartiallyChecked();

				if (childPartial) {

					partiallyChecked = true;

				} else if (childChecked) {

					checked = true;

					if (unchecked) {

						partiallyChecked = true;

					}

				} else {

					unchecked = true;

					if (checked) {

						partiallyChecked = true;

					}

				}

			}

			if (partiallyChecked) {

				if (!parent.isPartiallyChecked()) {

					viewer.setGrayChecked(parent, true);

					parent.setPartiallyChecked(true);

				} else if (!parent.isChecked()) {

					viewer.setChecked(parent, true);

				}

				// Checked flag needs to be set in both cases

				parent.setChecked(true);

			} else if (checked) {

				if (parent.isPartiallyChecked()) {

					viewer.setGrayed(parent, false);

					parent.setPartiallyChecked(false);

				}

				if (!parent.isChecked()) {

					viewer.setChecked(parent, true);

					parent.setChecked(true);

				}

			} else {

				if (parent.isPartiallyChecked()) {

					viewer.setGrayChecked(parent, false);

					parent.setPartiallyChecked(false);

				} else if (parent.isChecked()) {

					viewer.setChecked(parent, false);

				}

				// Checked flag needs to be set in both cases

				parent.setChecked(false);

			}

			checkParent(parent);

		}

	}

}