/*
* Copyright (C) 2010. All rights reserved.
*/
package ro.isdc.wro.extensions.processor.css;
import java.io.IOException;
import java.io.Reader;
import java.io.Writer;
import org.apache.commons.io.IOUtils;
import org.apache.commons.lang3.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import ro.isdc.wro.WroRuntimeException;
import ro.isdc.wro.extensions.processor.support.ObjectPoolHelper;
import ro.isdc.wro.extensions.processor.support.less.LessCss;
import ro.isdc.wro.model.resource.Resource;
import ro.isdc.wro.model.resource.ResourceType;
import ro.isdc.wro.model.resource.SupportedResourceType;
import ro.isdc.wro.model.resource.processor.Destroyable;
import ro.isdc.wro.model.resource.processor.ResourcePostProcessor;
import ro.isdc.wro.model.resource.processor.ResourcePreProcessor;
import ro.isdc.wro.util.ObjectFactory;
/**
* A processor using lessCss engine: @see http://www.asual.com/lesscss/
* <p>
* The main css goodies are: <br/>
* <ul>
* <li>Variables - Variables allow you to specify widely used values in a single place, and then re-use them throughout
* the style sheet, making global changes as easy as changing one line of code.<br/>
*
* <pre>
* @brand_color: #4D926F;
* #header { color: @brand_color; }
* h2 { color: @brand_color; }
* </pre>
*
* </li>
* <li>Mixins - Mixins allow you to embed all the properties of a class into another class by simply including the class
* name as one of its properties. It's just like variables, but for whole classes. Mixins can also behave like
* functions, and take arguments, as seen in the example bellow.</br>
*
* <pre>
* .rounded_corners (@radius: 5px) {
* -moz-border-radius: @radius;
* -webkit-border-radius: @radius;
* border-radius: @radius;
* }
*
* #header {
* .rounded_corners;
* }
*
* #footer {
* .rounded_corners(10px);
* }
* </pre>
*
* </li>
* <li>Nested Rules - Rather than constructing long selector names to specify inheritance, in Less you can simply nest
* selectors inside other selectors. This makes inheritance clear and style sheets shorter </br>
*
* <pre>
* #header {
* color: red;
* a {
* font-weight: bold;
* text-decoration: none;
* }
* }
* </pre>
*
* </li>
* <li>Operations - Are some elements in your style sheet proportional to other elements? Operations let you add,
* subtract, divide and multiply property values and colors, giving you the power to do create complex relationships
* between properties.</br>
*
* <pre>
* @the-border: 1px;
* @base-color: #111;
*
* #header {
* color: @base-color * 3;
* border-left: @the-border;
* border-right: @the-border * 2;
* }
*
* #footer {
* color: (@base-color + #111) * 1.5;
* }
* </pre>
*
* </li>
* </ul>
* If processing encounter any issues during processing, no change will be applied to the resource.
* <p/>
*
* @author Alex Objelean
* @since 1.2.6
* @created 21 Apr 2010
*/
@SupportedResourceType(ResourceType.CSS)
public class RhinoLessCssProcessor
implements ResourcePreProcessor, ResourcePostProcessor, Destroyable {
private static final Logger LOG = LoggerFactory.getLogger(RhinoLessCssProcessor.class);
public static final String ALIAS = "rhinoLessCss";
private ObjectPoolHelper<LessCss> enginePool;
public RhinoLessCssProcessor() {
enginePool = new ObjectPoolHelper<LessCss>(new ObjectFactory<LessCss>() {
@Override
public LessCss create() {
return newLessCss();
}
});
}
/**
* {@inheritDoc}
*/
@Override
public void process(final Resource resource, final Reader reader, final Writer writer)
throws IOException {
final String content = IOUtils.toString(reader);
final LessCss lessCss = enginePool.getObject();
try {
writer.write(lessCss.less(content));
} catch (final WroRuntimeException e) {
final String resourceUri = resource == null ? StringUtils.EMPTY : "[" + resource.getUri() + "]";
LOG.warn("Exception while applying " + getClass().getSimpleName() + " processor on the " + resourceUri
+ " resource, no processing applied...", e);
onException(e);
} finally {
// return for later reuse
enginePool.returnObject(lessCss);
reader.close();
writer.close();
}
}
/**
* Invoked when a processing exception occurs.
*/
protected void onException(final WroRuntimeException e) {
throw e;
}
/**
* @return the {@link LessCss} engine implementation. Override it to provide a different version of the less.js
* library. Useful for upgrading the processor outside the wro4j release.
*/
protected LessCss newLessCss() {
return new LessCss();
}
/**
* {@inheritDoc}
*/
@Override
public void process(final Reader reader, final Writer writer)
throws IOException {
process(null, reader, writer);
}
@Override
public void destroy() throws Exception {
enginePool.destroy();
}
}