/*

 * 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.

 */

package com.sun.org.apache.xml.internal.security.utils.resolver.implementations;

import com.sun.org.apache.xml.internal.security.signature.XMLSignatureInput;

import com.sun.org.apache.xml.internal.security.utils.XMLUtils;

import com.sun.org.apache.xml.internal.security.utils.resolver.ResourceResolverContext;

import com.sun.org.apache.xml.internal.security.utils.resolver.ResourceResolverException;

import com.sun.org.apache.xml.internal.security.utils.resolver.ResourceResolverSpi;

import org.w3c.dom.Document;

import org.w3c.dom.Element;

import org.w3c.dom.Node;

/**

 * Handles barename XPointer Reference URIs.

 * <p></p>

 * To retain comments while selecting an element by an identifier ID,

 * use the following full XPointer: URI='#xpointer(id('ID'))'.

 * <p></p>

 * To retain comments while selecting the entire document,

 * use the following full XPointer: URI='#xpointer(/)'.

 * This XPointer contains a simple XPath expression that includes

 * the root node, which the second to last step above replaces with all

 * nodes of the parse tree (all descendants, plus all attributes,

 * plus all namespaces nodes).

 *

 */

public class ResolverXPointer extends ResourceResolverSpi {

    private static final com.sun.org.slf4j.internal.Logger LOG =

        com.sun.org.slf4j.internal.LoggerFactory.getLogger(ResolverXPointer.class);

    private static final String XP = "#xpointer(id(";

    private static final int XP_LENGTH = XP.length();

    @Override

    public boolean engineIsThreadSafe() {

        return true;

    }

    /**

     * {@inheritDoc}

     */

    @Override

    public XMLSignatureInput engineResolveURI(ResourceResolverContext context)

        throws ResourceResolverException {

        Node resultNode = null;

        Document doc = context.attr.getOwnerElement().getOwnerDocument();

        if (isXPointerSlash(context.uriToResolve)) {

            resultNode = doc;

        } else if (isXPointerId(context.uriToResolve)) {

            String id = getXPointerId(context.uriToResolve);

            resultNode = doc.getElementById(id);

            if (context.secureValidation) {

                Element start = context.attr.getOwnerDocument().getDocumentElement();

                if (!XMLUtils.protectAgainstWrappingAttack(start, id)) {

                    Object exArgs[] = { id };

                    throw new ResourceResolverException(

                        "signature.Verification.MultipleIDs", exArgs, context.uriToResolve, context.baseUri

                    );

                }

            }

            if (resultNode == null) {

                Object exArgs[] = { id };

                throw new ResourceResolverException(

                    "signature.Verification.MissingID", exArgs, context.uriToResolve, context.baseUri

                );

            }

        }

        XMLSignatureInput result = new XMLSignatureInput(resultNode);

        result.setSecureValidation(context.secureValidation);

        result.setMIMEType("text/xml");

        if (context.baseUri != null && context.baseUri.length() > 0) {

            result.setSourceURI(context.baseUri.concat(context.uriToResolve));

        } else {

            result.setSourceURI(context.uriToResolve);

        }

        return result;

    }

    /**

     * {@inheritDoc}

     */

    public boolean engineCanResolveURI(ResourceResolverContext context) {

        if (context.uriToResolve == null) {

            return false;

        }

        if (isXPointerSlash(context.uriToResolve) || isXPointerId(context.uriToResolve)) {

            return true;

        }

        return false;

    }

    /**

     * Method isXPointerSlash

     *

     * @param uri

     * @return true if begins with xpointer

     */

    private static boolean isXPointerSlash(String uri) {

        if (uri.equals("#xpointer(/)")) {

            return true;

        }

        return false;

    }

    /**

     * Method isXPointerId

     *

     * @param uri

     * @return whether it has an xpointer id

     */

    private static boolean isXPointerId(String uri) {

        if (uri.startsWith(XP) && uri.endsWith("))")) {

            String idPlusDelim = uri.substring(XP_LENGTH, uri.length() - 2);

            int idLen = idPlusDelim.length() -1;

            if (idPlusDelim.charAt(0) == '"' && idPlusDelim.charAt(idLen) == '"'

                || idPlusDelim.charAt(0) == '\'' && idPlusDelim.charAt(idLen) == '\'') {

                LOG.debug("Id = {}", idPlusDelim.substring(1, idLen));

                return true;

            }

        }

        return false;

    }

    /**

     * Method getXPointerId

     *

     * @param uri

     * @return xpointerId to search.

     */

    private static String getXPointerId(String uri) {

        if (uri.startsWith(XP) && uri.endsWith("))")) {

            String idPlusDelim = uri.substring(XP_LENGTH, uri.length() - 2);

            int idLen = idPlusDelim.length() -1;

            if (idPlusDelim.charAt(0) == '"' && idPlusDelim.charAt(idLen) == '"'

                || idPlusDelim.charAt(0) == '\'' && idPlusDelim.charAt(idLen) == '\'') {

                return idPlusDelim.substring(1, idLen);

            }

        }

        return null;

    }

}