/*

 * Copyright (c) 2017, 2018, 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.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * 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.

 */

package build.tools.symbolgenerator;

import java.io.IOException;

import java.io.PrintWriter;

import java.io.Writer;

import java.nio.charset.Charset;

import java.nio.file.Files;

import java.nio.file.Path;

import java.nio.file.Paths;

import java.util.ArrayDeque;

import java.util.Arrays;

import java.util.Deque;

import java.util.HashSet;

import java.util.LinkedList;

import java.util.List;

import java.util.Locale;

import java.util.Set;

import java.util.stream.Collectors;

import javax.lang.model.element.ModuleElement.RequiresDirective;

import javax.lang.model.util.Elements;

import javax.tools.JavaCompiler;

import com.sun.tools.javac.api.JavacTaskImpl;

import com.sun.tools.javac.api.JavacTool;

import com.sun.tools.javac.code.Source;

import com.sun.tools.javac.code.Symbol.ModuleSymbol;

import com.sun.tools.javac.jvm.Target;

/**

 * Write reflexive transitive closure of the given modules along their requires transitive edges into

 * file <version>/system-modules in the specified directory.

 */

public class TransitiveDependencies {

    private static void help() {

        System.err.println("java TransitiveDependencies <target-directory> <module-source-path> <root-modules>");

    }

    public static void main(String... args) throws IOException {

        if (args.length < 2) {

            help();

            return ;

        }

        JavaCompiler compiler = JavacTool.create();

        List<String> options = List.of("-source", Source.DEFAULT.name,

                                       "-target", Target.DEFAULT.name,

                                       "-proc:only",

                                       "--system", "none",

                                       "--module-source-path", args[1],

                                       "--add-modules", Arrays.stream(args)

                                                              .skip(2)

                                                              .collect(Collectors.joining(",")));

        List<String> jlObjectList = List.of("java.lang.Object");

        JavacTaskImpl task = (JavacTaskImpl) compiler.getTask(null, null, null, options, jlObjectList, null);

        task.enter();

        Elements elements = task.getElements();

        Deque<String> todo = new ArrayDeque<>();

        Arrays.stream(args).skip(2).forEach(todo::add);

        Set<String> allModules = new HashSet<>();

        while (!todo.isEmpty()) {

            String current = todo.removeFirst();

            if (!allModules.add(current))

                continue;

            ModuleSymbol mod = (ModuleSymbol) elements.getModuleElement(current);

            if (mod == null) {

                throw new IllegalStateException("Missing: " + current);

            }

             //use the internal structure to avoid unnecesarily completing the symbol using the UsesProvidesVisitor:

            for (RequiresDirective rd : mod.requires) {

                if (rd.isTransitive()) {

                    todo.offerLast(rd.getDependency().getQualifiedName().toString());

                }

            }

        }

        allModules.add("java.base");

        allModules.add("jdk.unsupported");

        String version =

                Integer.toString(Integer.parseInt(Source.DEFAULT.name), Character.MAX_RADIX);

        version = version.toUpperCase(Locale.ROOT);

        Path targetFile = Paths.get(args[0]).resolve(version).resolve("system-modules");

        Files.createDirectories(targetFile.getParent());

        try (Writer w = Files.newBufferedWriter(targetFile);

             PrintWriter out = new PrintWriter(w)) {

            allModules.stream()

                      .sorted()

                      .forEach(out::println);

        }

    }

}