/**

  * 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 java.io.File;

 import java.io.IOException;

 import java.io.InputStream;

 import java.io.StringWriter;

 import java.net.URI;

 import java.net.URL;

 import java.util.ArrayList;

 import java.util.Collections;

 import java.util.List;

 import javax.xml.namespace.NamespaceContext;

 import javax.xml.namespace.QName;

 import javax.xml.parsers.DocumentBuilderFactory;

 import javax.xml.parsers.ParserConfigurationException;

 import javax.xml.transform.OutputKeys;

 import javax.xml.transform.Source;

 import javax.xml.transform.Transformer;

 import javax.xml.transform.TransformerConfigurationException;

 import javax.xml.transform.TransformerException;

 import javax.xml.transform.TransformerFactory;

 import javax.xml.transform.dom.DOMResult;

 import javax.xml.transform.dom.DOMSource;

 import javax.xml.transform.stream.StreamResult;

 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.Document;

 import org.w3c.dom.Node;

 import org.w3c.dom.NodeList;

 /**

  * Implementation of {@link XML}.

  *

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

  *

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

  * @version $Id: d54bc5c86d5968a13c7f2b389fc2eea9d6e555a8 $

  * @since 0.1

  * @checkstyle ClassDataAbstractionCoupling (500 lines)

  * @checkstyle ClassFanOutComplexity (500 lines)

  */

 @EqualsAndHashCode(of = { "xml", "leaf" })

 @SuppressWarnings("PMD.ExcessiveImports")

 public final class XMLDocument implements XML {

     /**

      * XPath factory.

      */

     private static final XPathFactory XFACTORY =

         XPathFactory.newInstance();

     /**

      * Transformer factory.

      */

     private static final TransformerFactory TFACTORY =

         TransformerFactory.newInstance();

     /**

      * DOM document builder factory.

      */

     private static final DocumentBuilderFactory DFACTORY =

         DocumentBuilderFactory.newInstance();

     /**

      * Namespace context to use for {@link #xpath(String)}

      * and {@link #nodes(String)} methods.

      */

     private final transient XPathContext context;

     /**

      * Encapsulated String representation of this XML document.

      */

     private final transient String xml;

     /**

      * Is it a leaf node (Element, not a Document)?

      */

     private final transient boolean leaf;

     /**

      * Actual XML document node. Needs to be an Object so the class is still

      * recognized as @Immutable.

      */

     private final transient Object cache;

     static {

         if (XMLDocument.DFACTORY.getClass().getName().contains("xerces")) {

             try {

                 XMLDocument.DFACTORY.setFeature(

                     // @checkstyle LineLength (1 line)

                     "http://apache.org/xml/features/nonvalidating/load-external-dtd",

                     false

                 );

             } catch (final ParserConfigurationException ex) {

                 throw new IllegalStateException(ex);

             }

         }

         XMLDocument.DFACTORY.setNamespaceAware(true);

     }

     /**

      * Public ctor, from XML as a text.

      *

      * <p>The object is created with a default implementation of

      * {@link NamespaceContext}, which already defines a

      * number of namespaces, for convenience, including:

      *

      * <pre> xhtml: http://www.w3.org/1999/xhtml

      * xs: http://www.w3.org/2001/XMLSchema

      * xsi: http://www.w3.org/2001/XMLSchema-instance

      * xsl: http://www.w3.org/1999/XSL/Transform

      * svg: http://www.w3.org/2000/svg</pre>

      *

      * <p>In future versions we will add more namespaces (submit a ticket if

      * you need more of them defined here).

      *

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

      * passed is not in XML format.

      *

      * @param text XML document body

      */

     public XMLDocument(final String text) {

         this(

             new DomParser(XMLDocument.DFACTORY, text).document(),

             new XPathContext(),

             false

         );

     }

     /**

      * Public ctor, from a DOM node.

      *

      * <p>The object is created with a default implementation of

      * {@link NamespaceContext}, which already defines a

      * number of namespaces, see {@link XMLDocument#XMLDocument(String)}.

      *

      * @param node DOM source

      * @since 0.2

      */

     public XMLDocument(final Node node) {

         this(node, new XPathContext(), !(node instanceof Document));

     }

     /**

      * Public ctor, from a source.

      *

      * <p>The object is created with a default implementation of

      * {@link NamespaceContext}, which already defines a

      * number of namespaces, see {@link XMLDocument#XMLDocument(String)}.

      *

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

      * passed is not in XML format.

      *

      * @param source Source of XML document

      */

     public XMLDocument(final Source source) {

         this(XMLDocument.transform(source), new XPathContext(), false);

     }

     /**

      * Public ctor, from XML in a file.

      *

      * <p>The object is created with a default implementation of

      * {@link NamespaceContext}, which already defines a

      * number of namespaces, see {@link XMLDocument#XMLDocument(String)}.

      *

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

      * passed is not in XML format.

      *

      * @param file XML file

      * @throws IOException In case of I/O problems

      */

     public XMLDocument(final File file) throws IOException {

         this(new TextResource(file).toString());

     }

     /**

      * Public ctor, from XML in the URL.

      *

      * <p>The object is created with a default implementation of

      * {@link NamespaceContext}, which already defines a

      * number of namespaces, see {@link XMLDocument#XMLDocument(String)}.

      *

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

      * passed is not in XML format.

      *

      * @param url The URL to load from

      * @throws IOException In case of I/O problems

      */

     public XMLDocument(final URL url) throws IOException {

         this(new TextResource(url).toString());

     }

     /**

      * Public ctor, from XML in the URI.

      *

      * <p>The object is created with a default implementation of

      * {@link NamespaceContext}, which already defines a

      * number of namespaces, see {@link XMLDocument#XMLDocument(String)}.

      *

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

      * passed is not in XML format.

      *

      * @param uri The URI to load from

      * @throws IOException In case of I/O problems

      */

     public XMLDocument(final URI uri) throws IOException {

         this(new TextResource(uri).toString());

     }

     /**

      * Public ctor, from input stream.

      *

      * <p>The object is created with a default implementation of

      * {@link NamespaceContext}, which already defines a

      * number of namespaces, see {@link XMLDocument#XMLDocument(String)}.

      *

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

      * passed is not in XML format.

      *

      * <p>The provided input stream will be closed automatically after

      * getting data from it.

      *

      * @param stream The input stream, which will be closed automatically

      * @throws IOException In case of I/O problem

      */

     public XMLDocument(final InputStream stream) throws IOException {

         this(new TextResource(stream).toString());

         stream.close();

     }

     /**

      * Private ctor.

      * @param node The source

      * @param ctx Namespace context

      * @param lfe Is it a leaf node?

      */

     private XMLDocument(final Node node, final XPathContext ctx,

         final boolean lfe) {

         this.xml = XMLDocument.asString(node);

         this.context = ctx;

         this.leaf = lfe;

         this.cache = node;

     }

     @Override

     public String toString() {

         return this.xml;

     }

     @Override

     public Node node() {

         final Node castCache = Node.class.cast(this.cache);

         final Node answer;

         if (castCache instanceof Document) {

             answer = castCache.cloneNode(true);

         } else {

             answer = this.createImportedNode(castCache);

         }

         return answer;

     }

     @Override

     @SuppressWarnings

         (

             {

                 "PMD.ExceptionAsFlowControl",

                 "PMD.PreserveStackTrace"

             }

         )

     public List<String> xpath(final String query) {

         List<String> items;

         try {

             final NodeList nodes = this.fetch(query, NodeList.class);

             items = new ArrayList<String>(nodes.getLength());

             for (int idx = 0; idx < nodes.getLength(); ++idx) {

                 final int type = nodes.item(idx).getNodeType();

                 if (type != Node.TEXT_NODE && type != Node.ATTRIBUTE_NODE

                     && type != Node.CDATA_SECTION_NODE) {

                     throw new IllegalArgumentException(

                         String.format(

                             // @checkstyle LineLength (1 line)

                             "Only text() nodes or attributes are retrievable with xpath() '%s': %d",

                             query, type

                         )

                     );

                 }

                 items.add(nodes.item(idx).getNodeValue());

             }

         } catch (final XPathExpressionException ex) {

             try {

                 items = Collections.singletonList(

                     this.fetch(query, String.class)

                 );

             } catch (final XPathExpressionException exp) {

                 throw new IllegalArgumentException(

                     // @checkstyle MultipleStringLiterals (1 line)

                     String.format(

                         "invalid XPath query '%s' at %s",

                         query, XMLDocument.XFACTORY.getClass().getName()

                     ), exp

                 );

             }

         }

         return new ListWrapper<String>(items, this.node(), query);

     }

     @Override

     public XML registerNs(final String prefix, final Object uri) {

         return new XMLDocument(

             this.node(), this.context.add(prefix, uri), this.leaf

         );

     }

     @Override

     @SuppressWarnings("PMD.AvoidInstantiatingObjectsInLoops")

     public List<XML> nodes(final String query) {

         final List<XML> items;

         try {

             final NodeList nodes = this.fetch(query, NodeList.class);

             items = new ArrayList<XML>(nodes.getLength());

             for (int idx = 0; idx < nodes.getLength(); ++idx) {

                 items.add(

                     new XMLDocument(

                         nodes.item(idx),

                         this.context, true

                     )

                 );

             }

         } catch (final XPathExpressionException ex) {

             throw new IllegalArgumentException(

                 String.format(

                     "invalid XPath query '%s' by %s",

                     query, XMLDocument.XFACTORY.getClass().getName()

                 ), ex

             );

         }

         return new ListWrapper<XML>(items, this.node(), query);

     }

     @Override

     public XML merge(final NamespaceContext ctx) {

         return new XMLDocument(this.node(), this.context.merge(ctx), this.leaf);

     }

     /**

      * Clones a node and imports it in a new document.

      * @param node A node to clone.

      * @return A cloned node imported in a dedicated document.

      */

     private Node createImportedNode(final Node node) {

         final Document document;

         try {

             document = DFACTORY.newDocumentBuilder().newDocument();

         } catch (final ParserConfigurationException ex) {

             throw new IllegalStateException(ex);

         }

         final Node imported = document.importNode(node, true);

         document.appendChild(imported);

         return imported;

     }

     /**

      * Retrieve XPath query result. Supports returning {@link NodeList} and

      * {@link String} types.

      *

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

      * passed is not a valid XPath expression or an unsupported type is

      * specified.

      *

      * @param <T> The type to return

      * @param query XPath query

      * @param type The return type

      * @return Result of XPath query

      * @throws XPathExpressionException If an error occurs when evaluating XPath

      */

     @SuppressWarnings("unchecked")

     private <T> T fetch(final String query, final Class<T> type)

         throws XPathExpressionException {

         final XPath xpath;

         synchronized (XMLDocument.class) {

             xpath = XMLDocument.XFACTORY.newXPath();

         }

         xpath.setNamespaceContext(this.context);

         final QName qname;

         if (type.equals(String.class)) {

             qname = XPathConstants.STRING;

         } else if (type.equals(NodeList.class)) {

             qname = XPathConstants.NODESET;

         } else {

             throw new IllegalArgumentException(

                 String.format(

                     "Unsupported type: %s", type.getName()

                 )

             );

         }

         return (T) xpath.evaluate(query, this.node(), qname);

     }

     /**

      * Transform node to String.

      *

      * @param node The DOM node.

      * @return String representation

      */

     private static String asString(final Node node) {

         final StringWriter writer = new StringWriter();

         try {

             final Transformer trans;

             synchronized (XMLDocument.class) {

                 trans = XMLDocument.TFACTORY.newTransformer();

             }

             // @checkstyle MultipleStringLiterals (1 line)

             trans.setOutputProperty(OutputKeys.INDENT, "yes");

             trans.setOutputProperty(OutputKeys.VERSION, "1.0");

             if (!(node instanceof Document)) {

                 trans.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");

             }

             synchronized (node) {

                 trans.transform(

                     new DOMSource(node),

                     new StreamResult(writer)

                 );

             }

         } catch (final TransformerConfigurationException ex) {

             throw new IllegalStateException(ex);

         } catch (final TransformerException ex) {

             throw new IllegalArgumentException(ex);

         }

         return writer.toString();

     }

     /**

      * Transform source to DOM node.

      * @param source The source

      * @return The node

      */

     private static Node transform(final Source source) {

         final DOMResult result = new DOMResult();

         try {

             final Transformer trans;

             synchronized (XMLDocument.class) {

                 trans = XMLDocument.TFACTORY.newTransformer();

             }

             trans.transform(source, result);

         } catch (final TransformerConfigurationException ex) {

             throw new IllegalStateException(ex);

         } catch (final TransformerException ex) {

             throw new IllegalStateException(ex);

         }

         return result.getNode();

     }

 }