Copyright (c) 2004, 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) 2004, 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;

import org.eclipse.core.runtime.Assert;
import org.eclipse.core.runtime.InvalidRegistryObjectException;

// This object is used to keep track on a contributor basis of the extension and extension points being contributed.
// It is mainly used on removal so we can quickly  find objects to remove.
// Each contribution is made in the context of a namespace.
public class Contribution implements KeyedElement {
	static final int[] EMPTY_CHILDREN = new int[] {0, 0};

	//The registry that owns this object
	protected ExtensionRegistry registry;

	// The actual contributor of the contribution
	final protected String contributorId;

	// Value is derived from the contributorId and cached for performance
	private String defaultNamespace = null;

	// indicates if this contribution needs to be saved in the registry cache
	protected boolean persist;

	// This array stores the identifiers of both the extension points and the extensions.
	// The array has always a minimum size of 2.
	// The first element of the array is the number of extension points and the second the number of extensions.
	// [numberOfExtensionPoints, numberOfExtensions, extensionPoint#1, extensionPoint#2, extensionPoint..., ext#1, ext#2, ext#3, ... ].
	// The size of the array is 2 + (numberOfExtensionPoints +  numberOfExtensions).
	private int[] children = EMPTY_CHILDREN;
	static final public byte EXTENSION_POINT = 0;
	static final public byte EXTENSION = 1;

	protected Contribution(String contributorId, ExtensionRegistry registry, boolean persist) {
		this.contributorId = contributorId;
		this.registry = registry;
		this.persist = persist;
	}

	void mergeContribution(Contribution addContribution) {
		Assert.isTrue(contributorId.equals(addContribution.contributorId));
		Assert.isTrue(registry == addContribution.registry);

		// persist?
		// Old New Result
		//  F   F   F
		//  F   T   T	=> needs to be adjusted
		//  T   F   T
		//  T   T   T
		if (shouldPersist() != addContribution.shouldPersist())
			persist = true;

		int[] existing = getRawChildren();
		int[] addition = addContribution.getRawChildren();

		int extensionPoints = existing[EXTENSION_POINT] + addition[EXTENSION_POINT];
		int extensions = existing[EXTENSION] + addition[EXTENSION];
		int[] allChildren = new int[2 + extensionPoints + extensions];

		allChildren[EXTENSION_POINT] = extensionPoints;
		System.arraycopy(existing, 2, allChildren, 2, existing[EXTENSION_POINT]);
		System.arraycopy(addition, 2, allChildren, 2 + existing[EXTENSION_POINT], addition[EXTENSION_POINT]);
		allChildren[EXTENSION] = extensions;
		System.arraycopy(existing, 2 + existing[EXTENSION_POINT], allChildren, 2 + extensionPoints, existing[EXTENSION]);
		System.arraycopy(addition, 2 + addition[EXTENSION_POINT], allChildren, 2 + extensionPoints + existing[EXTENSION], addition[EXTENSION]);

		children = allChildren;
	}

	void setRawChildren(int[] children) {
		this.children = children;
	}

	protected String getContributorId() {
		return contributorId;
	}

	protected int[] getRawChildren() {
		return children;
	}

	protected int[] getExtensions() {
		int[] results = new int[children[EXTENSION]];
		System.arraycopy(children, 2 + children[EXTENSION_POINT], results, 0, children[EXTENSION]);
		return results;
	}

	protected int[] getExtensionPoints() {
		int[] results = new int[children[EXTENSION_POINT]];
		System.arraycopy(children, 2, results, 0, children[EXTENSION_POINT]);
		return results;
	}

	public String getDefaultNamespace() {
		if (defaultNamespace == null)
			defaultNamespace = registry.getObjectManager().getContributor(contributorId).getName();
		return defaultNamespace;
	}

	@Override
	public String toString() {
		return "Contribution: " + contributorId + " in namespace" + getDefaultNamespace(); //$NON-NLS-1$ //$NON-NLS-2$
	}

	//Implements the KeyedElement interface
	@Override
	public int getKeyHashCode() {
		return getKey().hashCode();
	}

	@Override
	public Object getKey() {
		return contributorId;
	}

	@Override
	public boolean compare(KeyedElement other) {
		return contributorId.equals(((Contribution) other).contributorId);
	}

	public boolean shouldPersist() {
		return persist;
	}

	public void unlinkChild(int id) {
		// find index of the child being unlinked:
		int index = -1;
		for (int i = 2; i < children.length; i++) {
			if (children[i] == id) {
				index = i;
				break;
			}
		}
		if (index == -1)
			throw new InvalidRegistryObjectException();

		// copy all 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);

		// fix sizes
		if (index < children[EXTENSION_POINT] + 2)
			result[EXTENSION_POINT]--;
		else
			result[EXTENSION]--;

		children = result;
	}

	
Contribution is empty if it has no children.
/**
	 * Contribution is empty if it has no children.
	 */
	public boolean isEmpty() {
		return (children[EXTENSION_POINT] == 0 || children[EXTENSION] == 0);
	}

	
Find if this contribution has a children with ID = id.
Params:
id – possible ID of the child
Returns:
true: contribution has this child/**
	 * Find if this contribution has a children with ID = id.
	 * @param id possible ID of the child
	 * @return true: contribution has this child
	 */
	public boolean hasChild(int id) {
		for (int i = 2; i < children.length; i++) {
			if (children[i] == id)
				return true;
		}
		return false;
	}
}