package org.erlide.ui.util;

/*******************************************************************************
 * Copyright (c) 2005, 2007 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
 *******************************************************************************/

import org.eclipse.jface.util.Util;

import com.google.common.collect.Iterables;

/**
 * A simple data structure that is useful for implemented tree models. This can
 * be returned by
 * {@link org.eclipse.jface.viewers.IStructuredContentProvider#getElements(Object)}
 * . It allows simple delegation of methods from
 * {@link org.eclipse.jface.viewers.ITreeContentProvider} such as
 * {@link org.eclipse.jface.viewers.ITreeContentProvider#getChildren(Object)},
 * {@link org.eclipse.jface.viewers.ITreeContentProvider#getParent(Object)} and
 * {@link org.eclipse.jface.viewers.ITreeContentProvider#hasChildren(Object)}
 *
 */
public class ETreeNode {

    /**
     * The array of child tree nodes for this tree node. If there are no
     * children, then this value may either by an empty array or
     * <code>null</code>. There should be no <code>null</code> children in the
     * array.
     */
    private Iterable<ETreeNode> children;

    /**
     * The parent tree node for this tree node. This value may be
     * <code>null</code> if there is no parent.
     */
    private ETreeNode parent;

    /**
     * The value contained in this node. This value may be anything.
     */
    protected Object value;

    /**
     * Constructs a new instance of <code>TreeNode</code>.
     *
     * @param value
     *            The value held by this node; may be anything.
     */
    public ETreeNode(final Object value) {
        this.value = value;
    }

    @Override
    public boolean equals(final Object object) {
        if (object instanceof ETreeNode) {
            return Util.equals(value, ((ETreeNode) object).value);
        }

        return false;
    }

    /**
     * Returns the child nodes. Empty arrays are converted to <code>null</code>
     * before being returned.
     *
     * @return The child nodes; may be <code>null</code>, but never empty. There
     *         should be no <code>null</code> children in the array.
     */
    public Iterable<ETreeNode> getChildren() {
        if (children != null && Iterables.size(children) == 0) {
            return null;
        }
        return children;
    }

    /**
     * Returns the parent node.
     *
     * @return The parent node; may be <code>null</code> if there are no parent
     *         nodes.
     */
    public ETreeNode getParent() {
        return parent;
    }

    /**
     * Returns the value held by this node.
     *
     * @return The value; may be anything.
     */
    public Object getValue() {
        return value;
    }

    /**
     * Returns whether the tree has any children.
     *
     * @return <code>true</code> if its array of children is not
     *         <code>null</code> and is non-empty; <code>false</code> otherwise.
     */
    public boolean hasChildren() {
        return children != null && Iterables.size(children) > 0;
    }

    @Override
    public int hashCode() {
        return Util.hashCode(value);
    }

    /**
     * Sets the children for this node.
     *
     * @param children
     *            The child nodes; may be <code>null</code> or empty. There
     *            should be no <code>null</code> children in the array.
     */
    public void setChildren(final Iterable<ETreeNode> children) {
        this.children = children;
    }

    /**
     * Sets the parent for this node.
     *
     * @param parent
     *            The parent node; may be <code>null</code>.
     */
    public void setParent(final ETreeNode parent) {
        this.parent = parent;
    }
}