/**

  * Copyright (c) 2013-2017, xembly.org

  * All rights reserved.

  *

  * Redistribution and use in source and binary forms, with or without

  * modification, are permitted provided that the following conditions

  * are met: 1) Redistributions of source code must retain the above

  * copyright notice, this list of conditions and the following

  * disclaimer. 2) Redistributions in binary form must reproduce the above

  * copyright notice, this list of conditions and the following

  * disclaimer in the documentation and/or other materials provided

  * with the distribution. 3) Neither the name of the xembly.org nor

  * the names of its contributors may be used to endorse or promote

  * products derived from this software without specific prior written

  * permission.

  *

  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT

  * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND

  * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL

  * THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,

  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES

  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR

  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,

  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED

  * OF THE POSSIBILITY OF SUCH DAMAGE.

  */

 package org.xembly;

 import java.util.Map;

 import java.util.concurrent.ConcurrentHashMap;

 import java.util.concurrent.ConcurrentMap;

 import javax.xml.xpath.XPath;

 import javax.xml.xpath.XPathConstants;

 import javax.xml.xpath.XPathExpressionException;

 import javax.xml.xpath.XPathFactory;

 import lombok.EqualsAndHashCode;

 import org.w3c.dom.Node;

 /**

  * XSET directive.

  *

  * <p>The class is immutable and thread-safe.

  *

  * @author Yegor Bugayenko (yegor256@gmail.com)

  * @version $Id: 4756ac89ea2c1ac3e8fd86b6dac69de321a2fac8 $

  * @since 0.1

  */

 @EqualsAndHashCode(of = "expr")

 final class XsetDirective implements Directive {

     /**

      * XPath factory.

      */

     private static final XPathFactory FACTORY = XPathFactory.newInstance();

     /**

      * XPath to use.

      */

     private final transient Arg expr;

     /**

      * Public ctor.

      * @param val Text value to set

      * @throws XmlContentException If invalid input

      */

     XsetDirective(final String val) throws XmlContentException {

         this.expr = new Arg(val);

     }

     @Override

     public String toString() {

         return String.format("XSET %s", this.expr);

     }

     @Override

     public Directive.Cursor exec(final Node dom,

         final Directive.Cursor cursor, final Directive.Stack stack)

         throws ImpossibleModificationException {

         final XPath xpath = XsetDirective.FACTORY.newXPath();

         final ConcurrentMap<Node, String> values =

             new ConcurrentHashMap<Node, String>(0);

         for (final Node node : cursor) {

             try {

                 values.put(

                     node,

                     xpath.evaluate(

                         this.expr.raw(), node, XPathConstants.STRING

                     ).toString()

                 );

             } catch (final XPathExpressionException ex) {

                 throw new ImpossibleModificationException(

                     String.format("invalid XPath expr '%s'", this.expr), ex

                 );

             }

         }

         for (final Map.Entry<Node, String> entry : values.entrySet()) {

             entry.getKey().setTextContent(entry.getValue());

         }

         return cursor;

     }

 }