/**
* The MIT License (MIT)
*
* Copyright (c) 2014-2017 Yegor Bugayenko
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
package org.takes.rs;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URI;
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.URIResolver;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.stream.StreamSource;
import lombok.EqualsAndHashCode;
import lombok.ToString;
import org.takes.Response;
import org.takes.misc.Utf8InputStreamReader;
import org.takes.misc.Utf8OutputStreamWriter;
import org.takes.misc.Utf8String;
/**
* Response that converts XML into HTML using attached XSL stylesheet.
*
* <p>The encapsulated response must produce an XML document with
* an attached XSL stylesheet, for example:
*
* <pre><?xml version="1.0"?>
* <?xml-stylesheet href="/xsl/home.xsl" type="text/xsl"?>
* <page/>
* </pre>
*
* <p>{@link org.takes.rs.RsXslt} will try to find that {@code /xsl/home.xsl}
* resource in classpath. If it's not found a runtime exception will thrown.
*
* <p>The best way to use this decorator is in combination with
* {@link org.takes.rs.xe.RsXembly}, for example:
*
* <pre> new RsXSLT(
* new RsXembly(
* new XsStylesheet("/xsl/home.xsl"),
* new XsAppend(
* "page",
* new XsDate(),
* new XsLocalhost(),
* new XsSLA()
* )
* )
* )</pre>
*
* <p><strong>Note:</strong> It is highly recommended to use
* Saxon as a default XSL transformer. All others, including Apache
* Xalan, won't work correctly in most cases.</p>
*
* <p>The class is immutable and thread-safe.
*
* @author Yegor Bugayenko (yegor256@gmail.com)
* @version $Id: c8bc4ebdc77b30f204a63485787604a96dc5f81d $
* @since 0.1
* @checkstyle ClassDataAbstractionCouplingCheck (500 lines)
* @see org.takes.rs.xe.RsXembly
*/
@ToString(callSuper = true)
@EqualsAndHashCode(callSuper = true)
public final class RsXslt extends RsWrap {
/**
* Ctor.
* @param rsp Original response
*/
public RsXslt(final Response rsp) {
this(rsp, new RsXslt.InClasspath());
}
/**
* Ctor.
* @param rsp Original response
* @param resolver URI resolver
*/
public RsXslt(final Response rsp, final URIResolver resolver) {
super(
new Response() {
@Override
public Iterable<String> head() throws IOException {
return rsp.head();
}
@Override
public InputStream body() throws IOException {
return RsXslt.transform(rsp.body(), resolver);
}
}
);
}
/**
* Build body.
* @param origin Original body
* @param resolver Resolver
* @return Body
* @throws IOException If fails
*/
private static InputStream transform(final InputStream origin,
final URIResolver resolver) throws IOException {
try {
final TransformerFactory factory = TransformerFactory.newInstance();
factory.setURIResolver(resolver);
return RsXslt.transform(factory, origin);
} catch (final TransformerException ex) {
throw new IOException(ex);
}
}
/**
* Transform XML into HTML.
* @param factory Transformer factory
* @param xml XML page to be transformed.
* @return Resulting HTML page.
* @throws TransformerException If fails
*/
private static InputStream transform(final TransformerFactory factory,
final InputStream xml) throws TransformerException {
final byte[] input;
try {
input = RsXslt.consume(xml);
} catch (final IOException ex) {
throw new IllegalStateException(ex);
}
final ByteArrayOutputStream baos = new ByteArrayOutputStream();
final Source xsl = RsXslt.stylesheet(
factory, new StreamSource(
new Utf8InputStreamReader(
new ByteArrayInputStream(new Utf8String(input).bytes())
)
)
);
RsXslt.transformer(factory, xsl).transform(
new StreamSource(
new Utf8InputStreamReader(
new ByteArrayInputStream(new Utf8String(input).bytes())
)
),
new StreamResult(
new Utf8OutputStreamWriter(baos)
)
);
return new ByteArrayInputStream(
new Utf8String(baos.toByteArray()).bytes()
);
}
/**
* Consume input stream.
* @param input Input stream
* @return Bytes found
* @throws IOException If fails
*/
private static byte[] consume(final InputStream input) throws IOException {
final ByteArrayOutputStream baos = new ByteArrayOutputStream();
//@checkstyle MagicNumberCheck (1 line)
final byte[] buf = new byte[4096];
try {
while (true) {
final int bytes = input.read(buf);
if (bytes < 0) {
break;
}
baos.write(buf, 0, bytes);
}
} finally {
input.close();
}
return baos.toByteArray();
}
/**
* Retrieve a stylesheet from this XML (throws an exception if
* no stylesheet is attached).
* @param factory Transformer factory
* @param xml The XML
* @return Stylesheet found
* @throws TransformerConfigurationException If fails
*/
private static Source stylesheet(final TransformerFactory factory,
final Source xml) throws TransformerConfigurationException {
final Source stylesheet = factory.getAssociatedStylesheet(
xml, null, null, null
);
if (stylesheet == null) {
throw new IllegalArgumentException(
"no associated stylesheet found in XML"
);
}
return stylesheet;
}
/**
* Make a transformer from this stylesheet.
* @param factory Transformer factory
* @param stylesheet The stylesheet
* @return Transformer
* @throws TransformerConfigurationException If fails
*/
private static Transformer transformer(final TransformerFactory factory,
final Source stylesheet) throws TransformerConfigurationException {
final Transformer tnfr = factory.newTransformer(stylesheet);
if (tnfr == null) {
throw new TransformerConfigurationException(
String.format(
"%s failed to create new XSL transformer for '%s'",
factory.getClass(),
stylesheet.getSystemId()
)
);
}
return tnfr;
}
/**
* Classpath URI resolver.
*/
private static final class InClasspath implements URIResolver {
@Override
public Source resolve(final String href, final String base)
throws TransformerException {
final URI uri;
if (base == null || base.isEmpty()) {
uri = URI.create(href);
} else {
uri = URI.create(base).resolve(href);
}
final InputStream input = this.getClass().getResourceAsStream(
uri.getPath()
);
if (input == null) {
throw new TransformerException(
String.format(
"\"%s\" not found in classpath, base=\"%s\"",
href, base
)
);
}
return new StreamSource(
new Utf8InputStreamReader(input)
);
}
}
}