/**

  * Copyright (c) 2012-2017, jcabi.com

  * 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 jcabi.com 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 com.jcabi.xml;

 import com.jcabi.log.Logger;

 import java.io.ByteArrayInputStream;

 import java.io.IOException;

 import java.io.UnsupportedEncodingException;

 import java.util.regex.Pattern;

 import javax.xml.parsers.DocumentBuilderFactory;

 import javax.xml.parsers.ParserConfigurationException;

 import lombok.EqualsAndHashCode;

 import lombok.ToString;

 import org.w3c.dom.Document;

 import org.xml.sax.SAXException;

 /**

  * Convenient parser of XML to DOM.

  *

  * <p>Objects of this class are immutable and thread-safe.

  *

  * @author Yegor Bugayenko (yegor@teamed.io)

  * @version $Id: 8c877ef25e09a2e271adfc7a5224d5dc84b10904 $

  * @since 0.1

  */

 @ToString

 @EqualsAndHashCode(of = "xml")

 final class DomParser {

     /**

      * Pattern to detect if passed txt looks like xml. Patterns constants are

      * auto-generated by Maven at compile time using the script in

      * "src/main/groovy/GeneratePatterns.groovy".

      */

     private static final Pattern PATTERN = Pattern.compile(Patterns.XML);

     /**

      * The XML as a text.

      */

     private final transient String xml;

     /**

      * Document builder factory to use for parsing.

      */

     private final transient DocumentBuilderFactory factory;

     /**

      * Public ctor.

      *

      * <p>An {@link IllegalArgumentException} may be thrown if the parameter

      * passed is not in XML format. It doesn't perform a strict validation

      * and is not guaranteed that an exception will be thrown whenever

      * the parameter is not XML.

      *

      * @param fct Document builder factory to use

      * @param txt The XML in text

      */

     DomParser(final DocumentBuilderFactory fct, final String txt) {

         if (txt.isEmpty()) {

             throw new IllegalArgumentException("Empty document, not an XML");

         }

         if (!DomParser.PATTERN.matcher(txt.replaceAll("\\s", "")).matches()) {

             throw new IllegalArgumentException(

                 String.format("Doesn't look like XML: '%s'", txt)

             );

         }

         this.xml = txt;

         this.factory = fct;

     }

     /**

      * Get document of body.

      * @return The document

      */

     public Document document() {

         final Document doc;

         try {

             doc = this.factory.newDocumentBuilder().parse(

                 new ByteArrayInputStream(this.xml.getBytes("UTF-8"))

             );

         } catch (final UnsupportedEncodingException ex) {

             throw new IllegalStateException(ex);

         } catch (final IOException ex) {

             throw new IllegalStateException(ex);

         } catch (final ParserConfigurationException ex) {

             throw new IllegalStateException(ex);

         } catch (final SAXException ex) {

             throw new IllegalArgumentException(

                 Logger.format("Invalid XML: \"%s\"", this.xml), ex

             );

         }

         return doc;

     }

 }