/*
 * Copyright 1999-2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.commons.jrcs.rcs;

/**
 * Represents a branch node in a version control archive.
 * This class is NOT thread safe.
 *
 * <p>A {@link BranchNode BranchNode} stores the deltas between the previous revision
 * and the current revision; that is, when the deltas are applied
 * to the previous revision, the text of the current revision is obtained.
 * The {@link Node#rcsnext rcsnext} field of a BranchNode points to
 * the next revision in the branch.
 * </p>
 *
 * @see Node
 * @see Archive
 *
 * @author <a href="mailto:juanco@suigeneris.org">Juanco Anez</a>
 * @version $Id: BranchNode.java,v 1.5 2004/02/28 03:35:36 bayard Exp $
 */
class BranchNode
        extends Node
{
    /**
     * Create a BranchNode with the given version number.
     * The next field in a Branch node points to the next higher
     * revision on the same branch.
     * @param vernum the version number for the node
     * @param next   the next node in the logical RCS hierarchy.
     */
    BranchNode(Version vernum, BranchNode next)
    {
        super(vernum, next);
        if (vernum == null)
        {
            throw new IllegalArgumentException(vernum.toString());
        }
    }


    /**
     * Return the last (leaf) node in the branch this node belongs to.
     * @return The leaf node.
     */
    public BranchNode getLeafNode()
    {
        BranchNode result = this;
        while (result.getRCSNext() != null)
        {
            result = (BranchNode) result.getRCSNext();
        }
        return result;
    }


    /**
     * Set the next node in the RCS logical hierarcy.
     * Update the _parent and _child node accordingly.
     * For BranchNodes, the RCS-next is a child, that is,
     * a node with a larger version number.
     */
    public void setRCSNext(Node node)
    {
        super.setRCSNext(node);
        if (this.getChild() != null)
        {
            this.getChild().parent = null;
        }
        this.child = node;
        if (this.getChild() != null)
        {
            this.getChild().parent = this;
        }
    }

    public Node deltaRevision()
    {
        return this;
    }

    public Node nextInPathTo(Version vernum, boolean soft)
            throws NodeNotFoundException
    {
        Version branchPoint = vernum.getBase(this.version.size());
        Version thisBase = this.version.getBase(branchPoint.size());
        if (thisBase.isGreaterThan(branchPoint) && !soft)
        {
            throw new NodeNotFoundException(vernum);
        } //!!! InternalError, really

        if (this.version.equals(vernum))
        {
            return null;
        }
        else if (this.version.isLessThan(branchPoint))
        {
            return getChild();
        }
        else if (vernum.size() <= this.version.size())
        {
            if (vernum.size() < this.version.size() || branchPoint.last() == 0)
            {
                return getChild();
            } // keep going
            else
            {
                return null;
            }
        }
        else
        {
            Node branch = getBranch(vernum.at(this.version.size()));
            if (branch != null || soft)
            {
                return branch;
            }
            else
            {
                throw new BranchNotFoundException(vernum.getBase(this.version.size() + 1));
            }
        }
    }
}