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/*
 * Copyright (c) 1997, 2022 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Distribution License v. 1.0, which is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

package com.sun.xml.wss.impl.dsig;

import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;

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;

/**
 * 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 {

    private boolean excludeComments;
    private Iterator ni;
    private Node root;

    public DOMSubTreeData(Node root, boolean excludeComments) {
    this.root = root;
    this.ni = new DelayedNodeIterator(root, excludeComments);
    this.excludeComments = excludeComments;
    }

    @Override
    public Iterator iterator() {
    return ni;
    }

    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 {
        private Node root;
    private List nodeSet;
    private ListIterator li;
    private boolean withComments;

    DelayedNodeIterator(Node root, boolean excludeComments) {
            this.root = root;
            this.withComments = !excludeComments;
    }

        @Override
        public boolean hasNext() {
            if (nodeSet == null) {
        nodeSet = dereferenceSameDocumentURI(root);
        li = nodeSet.listIterator();
            }
        return li.hasNext();
        }

        @Override
        public Object next() {
            if (nodeSet == null) {
        nodeSet = dereferenceSameDocumentURI(root);
        li = nodeSet.listIterator();
            }
            if (li.hasNext()) {
        return li.next();
            } else {
                throw new NoSuchElementException();
        }
        }

        @Override
        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 dereferenceSameDocumentURI(Node node) {
            List nodeSet = new ArrayList();
            if (node != null) {
        nodeSetMinusCommentNodes(node, nodeSet, null);
            }
            return nodeSet;
    }

        /**
         * 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
         */
        private void nodeSetMinusCommentNodes(Node node, List 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);
        case Node.DOCUMENT_NODE :
                    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;
                    }
        case Node.PROCESSING_INSTRUCTION_NODE :
                    nodeSet.add(node);
                break;
        case Node.COMMENT_NODE:
            if (withComments) {
                        nodeSet.add(node);
            }
            }
    }
    }
}