/*

 * Copyright (c) 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.io.UncheckedIOException;

import java.nio.file.FileVisitResult;

import java.nio.file.Files;

import java.nio.file.Path;

import java.nio.file.SimpleFileVisitor;

import java.nio.file.attribute.BasicFileAttributes;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.List;

import java.util.stream.Collectors;

import java.util.stream.Stream;

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

     */

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

        throws IOException

    {

        JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();

        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.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();

    }

    /**

     * Compile the specified module from the given module sourcepath

     *

     * 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

     */

    public static boolean compileModule(Path source, Path destination,

                                        String moduleName, String... options) {

        JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();

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

        try {

            Files.createDirectories(destination);

            jfm.setLocationFromPaths(StandardLocation.CLASS_OUTPUT,

                                     Arrays.asList(destination));

        } catch (IOException e) {

            throw new UncheckedIOException(e);

        }

        Stream<String> opts = Arrays.stream(new String[] {

            "-modulesourcepath", source.toString(), "-m", moduleName

        });

        List<String> javacOpts = Stream.concat(opts, Arrays.stream(options))

                                        .collect(Collectors.toList());

        JavaCompiler.CompilationTask task

            = compiler.getTask(null, jfm, null, javacOpts, null, null);

        return task.call();

    }

    public static void cleanDir(Path dir) throws IOException {

        if (Files.notExists(dir)) return;

        Files.walkFileTree(dir, new SimpleFileVisitor<Path>() {

            @Override

            public FileVisitResult visitFile(Path file, BasicFileAttributes attrs)

                    throws IOException

            {

                Files.delete(file);

                return FileVisitResult.CONTINUE;

            }

            @Override

            public FileVisitResult postVisitDirectory(Path dir, IOException e)

                    throws IOException

            {

                if (e == null) {

                    Files.delete(dir);

                    return FileVisitResult.CONTINUE;

                } else {

                    // directory iteration failed

                    throw e;

                }

            }

        });

        Files.deleteIfExists(dir);

    }

}