/*******************************************************************************
 * 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
 * Port to the D programming language:
 *     Frank Benoit <benoit@tionex.de>
 *******************************************************************************/
module org.eclipse.jface.viewers.TreePath;

import org.eclipse.jface.viewers.IElementComparer;

import org.eclipse.core.runtime.Assert;

import java.lang.all;

/**
 * A tree path denotes a model element in a tree viewer. Tree path objects have
 * value semantics. A model element is represented by a path of elements in the
 * tree from the root element to the leaf element.
 * <p>
 * Clients may instantiate this class. Not intended to be subclassed.
 * </p>
 *
 * @since 3.2
 */
public final class TreePath {

    /**
     * Constant for representing an empty tree path.
     */
    public static const TreePath EMPTY;

    private Object[] segments;

    private int hash;

    static this(){
        EMPTY = new TreePath(new Object[0]);
    }

    /**
     * Constructs a path identifying a leaf node in a tree.
     *
     * @param segments
     *            path of elements to a leaf node in a tree, starting with the
     *            root element
     */
    public this(Object[] segments) {
//         Assert.isNotNull(segments);
        for (int i = 0; i < segments.length; i++) {
            Assert.isNotNull(segments[i]);
        }
        this.segments = segments;
    }

    /**
     * Returns the element at the specified index in this path.
     *
     * @param index
     *            index of element to return
     * @return element at the specified index
     */
    public Object getSegment(int index) {
        return segments[index];
    }

    /**
     * Returns the number of elements in this path.
     *
     * @return the number of elements in this path
     */
    public int getSegmentCount() {
        return segments.length;
    }

    /**
     * Returns the first element in this path, or <code>null</code> if this
     * path has no segments.
     *
     * @return the first element in this path
     */
    public Object getFirstSegment() {
        if (segments.length is 0) {
            return null;
        }
        return segments[0];
    }

    /**
     * Returns the last element in this path, or <code>null</code> if this
     * path has no segments.
     *
     * @return the last element in this path
     */
    public Object getLastSegment() {
        if (segments.length is 0) {
            return null;
        }
        return segments[segments.length - 1];
    }

    /*
     * (non-Javadoc)
     *
     * @see java.lang.Object#equals(java.lang.Object)
     */
    public override int opEquals(Object other) {
        if (!(cast(TreePath)other )) {
            return false;
        }
        return opEquals(cast(TreePath) other, null);
    }

    /**
     * (non-Javadoc)
     *
     * @see java.lang.Object#hashCode()
     */
    public override hash_t toHash() {
        if (hash is 0) {
            hash = toHash(null);
        }
        return hash;
    }

    /**
     * Returns a hash code computed from the hash codes of the segments, using
     * the given comparer to compute the hash codes of the segments.
     *
     * @param comparer
     *            comparer to use or <code>null</code> if the segments' hash
     *            codes should be computed by calling their hashCode() methods.
     * @return the computed hash code
     */
    public hash_t toHash(IElementComparer comparer) {
        int result = 0;
        for (int i = 0; i < segments.length; i++) {
            if (comparer is null) {
                result += segments[i].toHash();
            } else {
                result += comparer.toHash(segments[i]);
            }
        }
        return result;
    }

    /**
     * Returns whether this path is equivalent to the given path using the
     * specified comparer to compare individual elements.
     *
     * @param otherPath
     *            tree path to compare to
     * @param comparer
     *            comparator to use or <code>null</code> if segments should be
     *            compared using equals()
     * @return whether the paths are equal
     */
    public int opEquals(TreePath otherPath, IElementComparer comparer) {
        if (otherPath is null) {
            return false;
        }
        if (segments.length !is otherPath.segments.length) {
            return false;
        }
        for (int i = 0; i < segments.length; i++) {
            if (comparer is null) {
                if (!segments[i].opEquals(otherPath.segments[i])) {
                    return false;
                }
            } else {
                if (!comparer.opEquals(segments[i], otherPath.segments[i])) {
                    return false;
                }
            }
        }
        return true;
    }

    /**
     * Returns whether this path starts with the same segments as the given
     * path, using the given comparer to compare segments.
     *
     * @param treePath
     *            path to compare to
     * @param comparer
     *            the comparer to use, or <code>null</code> if equals() should
     *            be used to compare segments
     * @return whether the given path is a prefix of this path, or the same as
     *         this path
     */
    public bool startsWith(TreePath treePath, IElementComparer comparer) {
        int thisSegmentCount = getSegmentCount();
        int otherSegmentCount = treePath.getSegmentCount();
        if (otherSegmentCount is thisSegmentCount) {
            return opEquals(treePath, comparer) !is 0;
        }
        if (otherSegmentCount > thisSegmentCount) {
            return false;
        }
        for (int i = 0; i < otherSegmentCount; i++) {
            Object otherSegment = treePath.getSegment(i);
            if (comparer is null) {
                if (!otherSegment.opEquals(segments[i])) {
                    return false;
                }
            } else {
                if (!comparer.opEquals(otherSegment, segments[i])) {
                    return false;
                }
            }
        }
        return true;
    }

    /**
     * Returns a copy of this tree path with one segment removed from the end,
     * or <code>null</code> if this tree path has no segments.
     * @return a tree path
     */
    public TreePath getParentPath() {
        int segmentCount = getSegmentCount();
        if (segmentCount < 1) {
            return null;
        } else if (segmentCount is 1) {
            return EMPTY;
        }
        Object[] parentSegments = new Object[segmentCount - 1];
        System.arraycopy(segments, 0, parentSegments, 0, segmentCount - 1);
        return new TreePath(parentSegments);
    }

    /**
     * Returns a copy of this tree path with the given segment added at the end.
     * @param newSegment
     * @return a tree path
     */
    public TreePath createChildPath(Object newSegment) {
        int segmentCount = getSegmentCount();
        Object[] childSegments = new Object[segmentCount + 1];
        if(segmentCount>0) {
            System.arraycopy(segments, 0, childSegments, 0, segmentCount);
        }
        childSegments[segmentCount] = newSegment;
        return new TreePath(childSegments);
    }
}