/*

 * Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

package com.sun.jndi.dns;

import java.util.Hashtable;

/**

 * A NameNode represents a node in the DNS namespace.  Each node

 * has a label, which is its name relative to its parent (so the

 * node at Sun.COM has label "Sun").  Each node has a hashtable of

 * children indexed by their labels converted to lower-case.

 *

 * <p> A node may be addressed from another by giving a DnsName

 * consisting of the sequence of labels from one node to the other.

 *

 * <p> Each node also has an <tt>isZoneCut</tt> flag, used to indicate

 * if the node is a zone cut.  A zone cut is a node with an NS record

 * that is contained in one zone, but that actually belongs to a child zone.

 *

 * <p> All access is unsynchronized.

 *

 * @author Scott Seligman

 */

class NameNode {

    private String label;               // name of this node relative to its

                                        // parent, or null for root of a tree

    private Hashtable<String,NameNode> children = null;  // child nodes

    private boolean isZoneCut = false;  // true if this node is a zone cut

    private int depth = 0;              // depth in tree (0 for root)

    NameNode(String label) {

        this.label = label;

    }

    /*

     * Returns a newly-allocated NameNode.  Used to allocate new nodes

     * in a tree.  Should be overridden in a subclass to return an object

     * of the subclass's type.

     */

    protected NameNode newNameNode(String label) {

        return new NameNode(label);

    }

    /*

     * Returns the name of this node relative to its parent, or null for

     * the root of a tree.

     */

    String getLabel() {

        return label;

    }

    /*

     * Returns the depth of this node in the tree.  The depth of the root

     * is 0.

     */

    int depth() {

        return depth;

    }

    boolean isZoneCut() {

        return isZoneCut;

    }

    void setZoneCut(boolean isZoneCut) {

        this.isZoneCut = isZoneCut;

    }

    /*

     * Returns the children of this node, or null if there are none.

     * The caller must not modify the Hashtable returned.

     */

    Hashtable<String,NameNode> getChildren() {

        return children;

    }

    /*

     * Returns the child node given the hash key (the down-cased label)

     * for its name relative to this node, or null if there is no such

     * child.

     */

    NameNode get(String key) {

        return (children != null)

            ? children.get(key)

            : null;

    }

    /*

     * Returns the node at the end of a path, or null if the

     * node does not exist.

     * The path is specified by the labels of <tt>name</tt>, beginning

     * at index idx.

     */

    NameNode get(DnsName name, int idx) {

        NameNode node = this;

        for (int i = idx; i < name.size() && node != null; i++) {

            node = node.get(name.getKey(i));

        }

        return node;

    }

    /*

     * Returns the node at the end of a path, creating it and any

     * intermediate nodes as needed.

     * The path is specified by the labels of <tt>name</tt>, beginning

     * at index idx.

     */

    NameNode add(DnsName name, int idx) {

        NameNode node = this;

        for (int i = idx; i < name.size(); i++) {

            String label = name.get(i);

            String key = name.getKey(i);

            NameNode child = null;

            if (node.children == null) {

                node.children = new Hashtable<>();

            } else {

                child = node.children.get(key);

            }

            if (child == null) {

                child = newNameNode(label);

                child.depth = node.depth + 1;

                node.children.put(key, child);

            }

            node = child;

        }

        return node;

    }

}