NodeJsLessCompiler.java

/* Copyright 2013 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.lesscss.mojo;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Arrays;
import java.util.List;

import org.apache.commons.io.FileUtils;
import org.apache.commons.io.IOUtils;
import org.apache.maven.plugin.logging.Log;
import org.lesscss.LessException;
import org.lesscss.LessSource;

public class NodeJsLessCompiler {

	private static final List<String> resources = Arrays.asList(
			"lessc.js",
			"less/browser.js", 
			"less/colors.js",
			"less/functions.js",
			"less/index.js",
			"less/lessc_helper.js",
			"less/parser.js",
			"less/rhino.js",
			"less/tree.js",
			"less/tree/alpha.js",
			"less/tree/anonymous.js",
			"less/tree/assignment.js",
			"less/tree/call.js",
			"less/tree/color.js",
			"less/tree/comment.js",
			"less/tree/condition.js",
			"less/tree/dimension.js",
			"less/tree/directive.js",
			"less/tree/element.js",
			"less/tree/expression.js",
			"less/tree/import.js",
			"less/tree/javascript.js",
			"less/tree/keyword.js",
			"less/tree/media.js",
			"less/tree/mixin.js",
			"less/tree/operation.js",
			"less/tree/paren.js",
			"less/tree/quoted.js",
			"less/tree/ratio.js",
			"less/tree/rule.js",
			"less/tree/ruleset.js",
			"less/tree/selector.js",
			"less/tree/unicode-descriptor.js",
			"less/tree/url.js",
			"less/tree/value.js",
			"less/tree/variable.js");

	private final Log log;
	private final boolean compress;
	private final String encoding;
	private final File tempDir;
	private final File nodeExecutable;
	
	public NodeJsLessCompiler(File nodeExecutable, boolean compress, String encoding, Log log) throws IOException {
		this.nodeExecutable = nodeExecutable;
		this.compress = compress;
		this.encoding = encoding;
		this.log = log;

		tempDir = createTempDir("lessc");
		new File(tempDir, "less/tree").mkdirs();
		for (String resource : resources) {
			InputStream in = NodeJsLessCompiler.class.getClassLoader()
					.getResourceAsStream("org/lesscss/mojo/js/" + resource);
			FileOutputStream out = new FileOutputStream(new File(tempDir, resource));
			IOUtils.copy(in, out);
			in.close();
			out.close();
		}
	}

	public void close() {
		for (String resource : resources) {
			File tempFile = new File(tempDir, resource);
			if (!tempFile.delete()) {
				log.warn("Could not delete temp file: " + tempFile.getAbsolutePath());
			}
		}
		File lessSubdir = new File(tempDir, "less");
		File treeSubdir = new File(lessSubdir, "tree");
		if (!treeSubdir.delete()) {
			log.warn("Could not delete temp dir: " + treeSubdir.getAbsolutePath());
		}
		if (!lessSubdir.delete()) {
			log.warn("Could not delete temp dir: " + lessSubdir.getAbsolutePath());
		}
		if (!tempDir.delete()) {
			log.warn("Could not delete temp dir: " + tempDir.getAbsolutePath());
		}
	}

	public void compile(LessSource input, File output, boolean force)
			throws IOException, LessException, InterruptedException {
		if (force || !output.exists() || output.lastModified() < input.getLastModifiedIncludingImports()) {
			String data = compile(input.getNormalizedContent());
			FileUtils.writeStringToFile(output, data, encoding);
		}
	}

	private String compile(String input) throws LessException, IOException, InterruptedException {
		long start = System.currentTimeMillis();

		File inputFile = File.createTempFile("lessc-input-", ".less");
		FileOutputStream out = new FileOutputStream(inputFile);
		IOUtils.write(input, out);
		out.close();
		File outputFile = File.createTempFile("lessc-output-", ".css");
		File lesscJsFile = new File(tempDir, "lessc.js");

		ProcessBuilder pb = new ProcessBuilder(nodeExecutable.getAbsolutePath(), lesscJsFile.getAbsolutePath(),
				inputFile.getAbsolutePath(), outputFile.getAbsolutePath(), String.valueOf(compress));
		pb.redirectErrorStream(true);
		Process process = pb.start();
		IOUtils.copy(process.getInputStream(), System.out);

		int exitStatus = process.waitFor();

		FileInputStream in = new FileInputStream(outputFile);
		String result = IOUtils.toString(in);
		in.close();
		if (!inputFile.delete()) {
			log.warn("Could not delete temp file: " + inputFile.getAbsolutePath());
		}
		if (!outputFile.delete()) {
			log.warn("Could not delete temp file: " + outputFile.getAbsolutePath());
		}
		if (exitStatus != 0) {
			throw new LessException(result, null);
		}

		log.debug("Finished compilation of LESS source in " + (System.currentTimeMillis() - start) + " ms.");

		return result;
	}

	// copied from guava's Files.createTempDir, with added prefix
	private static File createTempDir(String prefix) {
		final int tempDirAttempts = 10000;
		File baseDir = new File(System.getProperty("java.io.tmpdir"));
		String baseName = prefix + "-" + System.currentTimeMillis() + "-";
		for (int counter = 0; counter < tempDirAttempts; counter++) {
			File tempDir = new File(baseDir, baseName + counter);
			if (tempDir.mkdir()) {
				return tempDir;
			}
		}
		throw new IllegalStateException("Failed to create directory within " + tempDirAttempts
				+ " attempts (tried " + baseName + "0 to " + baseName + (tempDirAttempts - 1) + ')');
	}
}