/*******************************************************************************
 * Copyright (c) 2007, 2018 Wind River Systems 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:
 *     Wind River Systems - initial API and implementation
 *******************************************************************************/
package org.eclipse.cdt.dsf.ui.viewmodel;

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

import org.eclipse.cdt.dsf.concurrent.DataRequestMonitor;
import org.eclipse.cdt.dsf.debug.internal.ui.viewmodel.VMViewerUpdateTracing;
import org.eclipse.cdt.dsf.internal.DsfPlugin;
import org.eclipse.cdt.dsf.internal.LoggingUtils;
import org.eclipse.cdt.dsf.internal.ui.DsfUIPlugin;
import org.eclipse.debug.internal.ui.viewers.model.provisional.IChildrenUpdate;
import org.eclipse.debug.internal.ui.viewers.model.provisional.IModelDelta;
import org.eclipse.debug.internal.ui.viewers.model.provisional.IPresentationContext;
import org.eclipse.debug.internal.ui.viewers.model.provisional.IViewerUpdate;
import org.eclipse.jface.viewers.TreePath;

/**
 * Helper class implementation of the {@link IChildrenUpdate} update object.
 *
 * @see VMViewerUpdate
 *
 * @since 1.0
 */
public class VMChildrenUpdate extends VMViewerUpdate implements IChildrenUpdate {
	private final int fOffset;
	private final int fLength;
	protected final List<Object> fElements;

	public VMChildrenUpdate(IViewerUpdate clientUpdate, int offset, int length,
			DataRequestMonitor<List<Object>> requestMonitor) {
		super(clientUpdate, requestMonitor);
		fOffset = offset;
		fLength = length;
		fElements = length > 0 ? new ArrayList<>(length) : new ArrayList<>();
	}

	public VMChildrenUpdate(IModelDelta delta, IPresentationContext presentationContext, int offset, int length,
			DataRequestMonitor<List<Object>> rm) {
		super(delta, presentationContext, rm);
		fOffset = offset;
		fLength = length;
		fElements = length > 0 ? new ArrayList<>(length) : new ArrayList<>();
	}

	public VMChildrenUpdate(TreePath elementPath, Object viewerInput, IPresentationContext presentationContext,
			int offset, int length, DataRequestMonitor<List<Object>> rm) {
		super(elementPath, viewerInput, presentationContext, rm);
		fOffset = offset;
		fLength = length;
		fElements = length > 0 ? new ArrayList<>(length) : new ArrayList<>();
	}

	@Override
	public int getOffset() {
		return fOffset;
	}

	@Override
	public int getLength() {
		return fLength;
	}

	@Override
	public void setChild(Object element, int offset) {
		// Calculate the index in array based on configured offset.
		int idx = offset - (fOffset > 0 ? fOffset : 0);

		// To make sure that index is in valid range.
		if (idx < 0 || (fLength > 0 && idx >= fLength))
			return;

		// Increase the list size if needed.
		ensureElementsSize(idx + 1);

		// Finally set the element in elements list.
		fElements.set(idx, element);
	}

	private void ensureElementsSize(int size) {
		while (fElements.size() < size) {
			fElements.add(null);
		}
	}

	@Override
	public String toString() {
		return "VMChildrenUpdate:" + getElement() + " {" + getOffset() + "->" + (getOffset() + getLength()) + "}"; //$NON-NLS-1$ //$NON-NLS-2$//$NON-NLS-3$ //$NON-NLS-4$
	}

	@Override
	public void done() {
		@SuppressWarnings("unchecked")
		DataRequestMonitor<List<Object>> rm = (DataRequestMonitor<List<Object>>) getRequestMonitor();

		/* See https://bugs.eclipse.org/bugs/show_bug.cgi?id=202109
		 *
		 * A flexible hierarchy bug/optimization causes query with incorrect
		 * IChildrenUpdate[] array length.
		 *
		 * The problem manifests itself while deleting a register node.
		 * For example, if the register view displays:
		 *     PC
		 *     EAX
		 *     EBX
		 *     ECX
		 *     EDX
		 *  And EBX is deleted, forcing a refresh, the viewer will query
		 *  for IChildrenUpdate[5] and IChildrenCountUpdate at the same time.
		 *
		 *  To avoid this problem do not generate an error if the list of
		 *  children is smaller than the list of requested indexes.  Also,
		 *  do not check if any of the elements are null.
		 */
		rm.setData(fElements);

		// trace our result
		if (VMViewerUpdateTracing.DEBUG_VMUPDATES && !isCanceled()
				&& VMViewerUpdateTracing.matchesFilterRegex(this.getClass())) {
			StringBuilder str = new StringBuilder();
			str.append(DsfPlugin.getDebugTime()).append(' ').append(LoggingUtils.toString(this))
					.append(" marked done; element = ").append(LoggingUtils.toString(getElement())); //$NON-NLS-1$
			if (fElements != null && !fElements.isEmpty()) {
				for (Object element : fElements) {
					str.append("   ").append(LoggingUtils.toString(element)).append('\n'); //$NON-NLS-1$
				}
				str.deleteCharAt(str.length() - 1); // remove trailing \n
			}
			DsfUIPlugin.debug(str.toString());
		}

		super.done();
	}

}
