/**

  * 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.IOException;

 import java.io.InputStream;

 import java.io.StringReader;

 import java.net.URI;

 import java.net.URL;

 import java.util.Collection;

 import java.util.concurrent.CopyOnWriteArrayList;

 import javax.xml.XMLConstants;

 import javax.xml.transform.Source;

 import javax.xml.transform.stream.StreamSource;

 import javax.xml.validation.Schema;

 import javax.xml.validation.SchemaFactory;

 import javax.xml.validation.Validator;

 import lombok.EqualsAndHashCode;

 import org.xml.sax.ErrorHandler;

 import org.xml.sax.SAXException;

 import org.xml.sax.SAXParseException;

 /**

  * Implementation of {@link XSD}.

  *

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

  *

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

  * @version $Id: 0fc5670d929cb6f6f8ce51038a17ae56ac6dacbb $

  * @since 0.5

  */

 @EqualsAndHashCode(of = "xsd")

 public final class XSDDocument implements XSD {

     /**

      * XSD document.

      */

     private final transient String xsd;

     /**

      * Public ctor, from XSD as a source.

      * @param src XSD document body

      */

     public XSDDocument(final XML src) {

         this(src.toString());

     }

     /**

      * Public ctor, from XSD as a string.

      * @param src XSD document body

      */

     public XSDDocument(final String src) {

         this.xsd = src;

     }

     /**

      * Public ctor, from URL.

      * @param url Location of document

      * @throws IOException If fails to read

      * @since 0.7.4

      */

     public XSDDocument(final URL url) throws IOException {

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

     }

     /**

      * Public ctor, from URI.

      * @param uri Location of document

      * @throws IOException If fails to read

      * @since 0.15

      */

     public XSDDocument(final URI uri) throws IOException {

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

     }

     /**

      * Public ctor, from XSD as an input stream.

      * @param stream XSD input stream

      */

     public XSDDocument(final InputStream stream) {

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

     }

     /**

      * Make an instance of XSD schema without I/O exceptions.

      *

      * <p>This factory method is useful when you need to create

      * an instance of XSD schema as a static final variable. In this

      * case you can't catch an exception but this method can help, for example:

      *

      * <pre> class Foo {

      *   private static final XSD SCHEMA = XSDDocument.make(

      *     Foo.class.getResourceAsStream("my-schema.xsd")

      *   );

      * }</pre>

      *

      * @param stream Input stream

      * @return XSD schema

      */

     public static XSD make(final InputStream stream) {

         return new XSDDocument(stream);

     }

     /**

      * Make an instance of XSD schema without I/O exceptions.

      * @param url URL with content

      * @return XSD schema

      * @see #make(InputStream)

      * @since 0.7.4

      */

     public static XSD make(final URL url) {

         try {

             return new XSDDocument(url);

         } catch (final IOException ex) {

             throw new IllegalStateException(ex);

         }

     }

     @Override

     public String toString() {

         return new XMLDocument(this.xsd).toString();

     }

     @Override

     public Collection<SAXParseException> validate(final Source xml) {

         final Schema schema;

         try {

             synchronized (XSDDocument.class) {

                 schema = SchemaFactory

                     .newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI)

                     .newSchema(new StreamSource(new StringReader(this.xsd)));

             }

         } catch (final SAXException ex) {

             throw new IllegalStateException(

                 String.format("failed to create XSD schema from %s", this.xsd),

                 ex

             );

         }

         final Collection<SAXParseException> errors =

             new CopyOnWriteArrayList<SAXParseException>();

         final Validator validator = schema.newValidator();

         validator.setErrorHandler(new ValidationHandler(errors));

         try {

             synchronized (XSDDocument.class) {

                 validator.validate(xml);

             }

         } catch (final SAXException ex) {

             throw new IllegalStateException(ex);

         } catch (final IOException ex) {

             throw new IllegalStateException(ex);

         }

         Logger.debug(

             this, "%s detected %d error(s)",

             schema.getClass().getName(), errors.size()

         );

         return errors;

     }

     /**

      * Validation error handler.

      */

     static final class ValidationHandler implements ErrorHandler {

         /**

          * Errors.

          */

         private final transient Collection<SAXParseException> errors;

         /**

          * Constructor.

          * @param errs Collection of errors

          */

         ValidationHandler(final Collection<SAXParseException> errs) {

             this.errors = errs;

         }

         @Override

         public void warning(final SAXParseException error) {

             this.errors.add(error);

         }

         @Override

         public void error(final SAXParseException error) {

             this.errors.add(error);

         }

         @Override

         public void fatalError(final SAXParseException error) {

             this.errors.add(error);

         }

     }

 }