/*

 * reserved comment block

 * DO NOT REMOVE OR ALTER!

 */

/**

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements. See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership. The ASF licenses this file

 * to you 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.

 */

/*

 * Copyright (c) 2005, Oracle and/or its affiliates. All rights reserved.

 */

package org.jcp.xml.dsig.internal.dom;

import javax.xml.crypto.NodeSetData;

import java.util.ArrayList;

import java.util.Iterator;

import java.util.List;

import java.util.ListIterator;

import java.util.NoSuchElementException;

import org.w3c.dom.NamedNodeMap;

import org.w3c.dom.Node;

/**

 * This is a subtype of NodeSetData that represents a dereferenced

 * same-document URI as the root of a subdocument. The main reason is

 * for efficiency and performance, as some transforms can operate

 * directly on the subdocument and there is no need to convert it

 * first to an XPath node-set.

 */

public class DOMSubTreeData implements NodeSetData<Node> {

    private boolean excludeComments;

    private Node root;

    public DOMSubTreeData(Node root, boolean excludeComments) {

        this.root = root;

        this.excludeComments = excludeComments;

    }

    @Override

    public Iterator<Node> iterator() {

        return new DelayedNodeIterator(root, excludeComments);

    }

    public Node getRoot() {

        return root;

    }

    public boolean excludeComments() {

        return excludeComments;

    }

    /**

     * This is an Iterator that contains a backing node-set that is

     * not populated until the caller first attempts to advance the iterator.

     */

    static class DelayedNodeIterator implements Iterator<Node> {

        private Node root;

        private List<Node> nodeSet;

        private ListIterator<Node> li;

        private boolean withComments;

        DelayedNodeIterator(Node root, boolean excludeComments) {

            this.root = root;

            this.withComments = !excludeComments;

        }

        public boolean hasNext() {

            if (nodeSet == null) {

                nodeSet = dereferenceSameDocumentURI(root);

                li = nodeSet.listIterator();

            }

            return li.hasNext();

        }

        public Node next() {

            if (nodeSet == null) {

                nodeSet = dereferenceSameDocumentURI(root);

                li = nodeSet.listIterator();

            }

            if (li.hasNext()) {

                return li.next();

            } else {

                throw new NoSuchElementException();

            }

        }

        public void remove() {

            throw new UnsupportedOperationException();

        }

        /**

         * Dereferences a same-document URI fragment.

         *

         * @param node the node (document or element) referenced by the

         *     URI fragment. If null, returns an empty set.

         * @return a set of nodes (minus any comment nodes)

         */

        private List<Node> dereferenceSameDocumentURI(Node node) {

            List<Node> nodes = new ArrayList<>();

            if (node != null) {

                nodeSetMinusCommentNodes(node, nodes, null);

            }

            return nodes;

        }

        /**

         * Recursively traverses the subtree, and returns an XPath-equivalent

         * node-set of all nodes traversed, excluding any comment nodes,

         * if specified.

         *

         * @param node the node to traverse

         * @param nodeSet the set of nodes traversed so far

         * @param prevSibling the previous sibling node

         */

        @SuppressWarnings("fallthrough")

        private void nodeSetMinusCommentNodes(Node node, List<Node> nodeSet,

                                              Node prevSibling)

        {

            switch (node.getNodeType()) {

                case Node.ELEMENT_NODE :

                    NamedNodeMap attrs = node.getAttributes();

                    if (attrs != null) {

                        for (int i = 0, len = attrs.getLength(); i < len; i++) {

                            nodeSet.add(attrs.item(i));

                        }

                    }

                    nodeSet.add(node);

                    Node pSibling = null;

                    for (Node child = node.getFirstChild(); child != null;

                        child = child.getNextSibling()) {

                        nodeSetMinusCommentNodes(child, nodeSet, pSibling);

                        pSibling = child;

                    }

                    break;

                case Node.DOCUMENT_NODE :

                    pSibling = null;

                    for (Node child = node.getFirstChild(); child != null;

                        child = child.getNextSibling()) {

                        nodeSetMinusCommentNodes(child, nodeSet, pSibling);

                        pSibling = child;

                    }

                    break;

                case Node.TEXT_NODE :

                case Node.CDATA_SECTION_NODE:

                    // emulate XPath which only returns the first node in

                    // contiguous text/cdata nodes

                    if (prevSibling != null &&

                        (prevSibling.getNodeType() == Node.TEXT_NODE ||

                         prevSibling.getNodeType() == Node.CDATA_SECTION_NODE)) {

                        return;

                    }

                    nodeSet.add(node);

                    break;

                case Node.PROCESSING_INSTRUCTION_NODE :

                    nodeSet.add(node);

                    break;

                case Node.COMMENT_NODE:

                    if (withComments) {

                        nodeSet.add(node);

                    }

            }

        }

    }

}