Copyright (c) 2006 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
/*******************************************************************************
 * Copyright (c) 2006 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.core.internal.registry;

public class RegistryIndexChildren {

	static final int[] EMPTY_ARRAY = new int[0];

	private int[] children;

	public RegistryIndexChildren() {
		children = EMPTY_ARRAY;
	}

	public RegistryIndexChildren(int[] children) {
		this.children = children;
	}

	public int[] getChildren() {
		return children;
	}

	public int findChild(int id) {
		for (int i = 0; i < children.length; i++) {
			if (children[i] == id)
				return i;
		}
		return -1;
	}

	public boolean unlinkChild(int id) {
		int index = findChild(id);
		if (index == -1)
			return false; // there is no such element

		// copy the array except one element at index
		int[] result = new int[children.length - 1];
		System.arraycopy(children, 0, result, 0, index);
		System.arraycopy(children, index + 1, result, index, children.length - index - 1);
		children = result;
		return true;
	}

	public boolean linkChild(int id) {
		if (children.length == 0) {
			children = new int[] {id};
			return true;
		}

		// add new element at the end
		int[] result = new int[children.length + 1];
		System.arraycopy(children, 0, result, 0, children.length);
		result[children.length] = id;
		children = result;
		return true;
	}

	public boolean linkChildren(int[] IDs) {
		if (children.length == 0) {
			children = IDs;
			return true;
		}
		int[] result = new int[children.length + IDs.length];
		System.arraycopy(children, 0, result, 0, children.length);
		System.arraycopy(IDs, 0, result, children.length, IDs.length);
		children = result;
		return true;
	}

	public boolean unlinkChildren(int[] IDs) {
		if (children.length == 0)
			return (IDs.length == 0);

		int size = children.length;
		for (int i = 0; i < IDs.length; i++) {
			int index = findChild(IDs[i]);
			if (index != -1) {
				children[i] = -1;
				size--;
			}
		}
		if (size == 0) {
			children = EMPTY_ARRAY;
			return true;
		}
		int[] result = new int[size];
		int pos = 0;
		for (int i = 0; i < children.length; i++) {
			if (children[i] == -1)
				continue;
			result[pos] = children[i];
			pos++;
		}
		return true;
	}
}