/*

 * Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

import javax.tools.JavaCompiler;

import javax.tools.StandardJavaFileManager;

import javax.tools.StandardLocation;

import javax.tools.ToolProvider;

import java.io.IOException;

import java.nio.file.Files;

import java.nio.file.Path;

import java.util.Arrays;

import java.util.Collections;

import java.util.List;

import java.util.stream.Collectors;

/**

 * This class consists exclusively of static utility methods for invoking the

 * java compiler.

 */

public final class CompilerUtils {

    private CompilerUtils() { }

    /**

     * Compile all the java sources in {@code <source>/**} to

     * {@code <destination>/**}. The destination directory will be created if

     * it doesn't exist.

     *

     * All warnings/errors emitted by the compiler are output to System.out/err.

     *

     * @return true if the compilation is successful

     *

     * @throws IOException

     *         if there is an I/O error scanning the source tree or

     *         creating the destination directory

     * @throws UnsupportedOperationException

     *         if there is no system java compiler

     */

    public static boolean compile(Path source, Path destination, String ... options)

        throws IOException

    {

        JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();

        if (compiler == null) {

            // no compiler available

            throw new UnsupportedOperationException("Unable to get system java compiler. " +

                "Perhaps, jdk.compiler module is not available.");

        }

        StandardJavaFileManager jfm = compiler.getStandardFileManager(null, null, null);

        List<Path> sources

            = Files.find(source, Integer.MAX_VALUE,

                (file, attrs) -> (file.toString().endsWith(".java")))

                .collect(Collectors.toList());

        Files.createDirectories(destination);

        jfm.setLocation(StandardLocation.CLASS_PATH, Collections.EMPTY_LIST);

        jfm.setLocationFromPaths(StandardLocation.CLASS_OUTPUT,

                                 Arrays.asList(destination));

        List<String> opts = Arrays.asList(options);

        JavaCompiler.CompilationTask task

            = compiler.getTask(null, jfm, null, opts, null,

                jfm.getJavaFileObjectsFromPaths(sources));

        return task.call();

    }

}