/*

 * Copyright (c) 2015, 2017, 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 jdk.internal.module;

import java.io.IOException;

import java.io.OutputStream;

import java.lang.module.ModuleDescriptor;

import java.nio.ByteBuffer;

import java.util.Map;

import java.util.stream.Stream;

import jdk.internal.org.objectweb.asm.ClassWriter;

import jdk.internal.org.objectweb.asm.ModuleVisitor;

import jdk.internal.org.objectweb.asm.Opcodes;

import jdk.internal.org.objectweb.asm.commons.ModuleTargetAttribute;

import static jdk.internal.org.objectweb.asm.Opcodes.*;

/**

 * Utility class to write a ModuleDescriptor as a module-info.class.

 */

public final class ModuleInfoWriter {

    private static final Map<ModuleDescriptor.Modifier, Integer>

        MODULE_MODS_TO_FLAGS = Map.of(

            ModuleDescriptor.Modifier.OPEN, ACC_OPEN,

            ModuleDescriptor.Modifier.SYNTHETIC, ACC_SYNTHETIC,

            ModuleDescriptor.Modifier.MANDATED, ACC_MANDATED

        );

    private static final Map<ModuleDescriptor.Requires.Modifier, Integer>

        REQUIRES_MODS_TO_FLAGS = Map.of(

            ModuleDescriptor.Requires.Modifier.TRANSITIVE, ACC_TRANSITIVE,

            ModuleDescriptor.Requires.Modifier.STATIC, ACC_STATIC_PHASE,

            ModuleDescriptor.Requires.Modifier.SYNTHETIC, ACC_SYNTHETIC,

            ModuleDescriptor.Requires.Modifier.MANDATED, ACC_MANDATED

        );

    private static final Map<ModuleDescriptor.Exports.Modifier, Integer>

        EXPORTS_MODS_TO_FLAGS = Map.of(

            ModuleDescriptor.Exports.Modifier.SYNTHETIC, ACC_SYNTHETIC,

            ModuleDescriptor.Exports.Modifier.MANDATED, ACC_MANDATED

        );

    private static final Map<ModuleDescriptor.Opens.Modifier, Integer>

        OPENS_MODS_TO_FLAGS = Map.of(

            ModuleDescriptor.Opens.Modifier.SYNTHETIC, ACC_SYNTHETIC,

            ModuleDescriptor.Opens.Modifier.MANDATED, ACC_MANDATED

        );

    private static final String[] EMPTY_STRING_ARRAY = new String[0];

    private ModuleInfoWriter() { }

    /**

     * Writes the given module descriptor to a module-info.class file,

     * returning it in a byte array.

     */

    private static byte[] toModuleInfo(ModuleDescriptor md, ModuleTarget target) {

        ClassWriter cw = new ClassWriter(0);

        int moduleFlags = md.modifiers().stream()

                .map(MODULE_MODS_TO_FLAGS::get)

                .reduce(0, (x, y) -> (x | y));

        String vs = md.rawVersion().orElse(null);

        ModuleVisitor mv = cw.visitModule(md.name(), moduleFlags, vs);

        // requires

        for (ModuleDescriptor.Requires r : md.requires()) {

            int flags = r.modifiers().stream()

                    .map(REQUIRES_MODS_TO_FLAGS::get)

                    .reduce(0, (x, y) -> (x | y));

            vs = r.rawCompiledVersion().orElse(null);

            mv.visitRequire(r.name(), flags, vs);

        }

        // exports

        for (ModuleDescriptor.Exports e : md.exports()) {

            int flags = e.modifiers().stream()

                    .map(EXPORTS_MODS_TO_FLAGS::get)

                    .reduce(0, (x, y) -> (x | y));

            String[] targets = e.targets().toArray(EMPTY_STRING_ARRAY);

            mv.visitExport(e.source().replace('.', '/'), flags, targets);

        }

        // opens

        for (ModuleDescriptor.Opens opens : md.opens()) {

            int flags = opens.modifiers().stream()

                    .map(OPENS_MODS_TO_FLAGS::get)

                    .reduce(0, (x, y) -> (x | y));

            String[] targets = opens.targets().toArray(EMPTY_STRING_ARRAY);

            mv.visitOpen(opens.source().replace('.', '/'), flags, targets);

        }

        // uses

        md.uses().stream().map(sn -> sn.replace('.', '/')).forEach(mv::visitUse);

        // provides

        for (ModuleDescriptor.Provides p : md.provides()) {

            mv.visitProvide(p.service().replace('.', '/'),

                            p.providers()

                                .stream()

                                .map(pn -> pn.replace('.', '/'))

                                .toArray(String[]::new));

        }

        // add the ModulePackages attribute when there are packages that aren't

        // exported or open

        Stream<String> exported = md.exports().stream()

                .map(ModuleDescriptor.Exports::source);

        Stream<String> open = md.opens().stream()

                .map(ModuleDescriptor.Opens::source);

        long exportedOrOpen = Stream.concat(exported, open).distinct().count();

        if (md.packages().size() > exportedOrOpen) {

            md.packages().stream()

                    .map(pn -> pn.replace('.', '/'))

                    .forEach(mv::visitPackage);

        }

        // ModuleMainClass attribute

        md.mainClass()

            .map(mc -> mc.replace('.', '/'))

            .ifPresent(mv::visitMainClass);

        mv.visitEnd();

        // write ModuleTarget attribute if there is a target platform

        if (target != null && target.targetPlatform().length() > 0) {

            cw.visitAttribute(new ModuleTargetAttribute(target.targetPlatform()));

        }

        cw.visitEnd();

        return cw.toByteArray();

    }

    /**

     * Writes a module descriptor to the given output stream as a

     * module-info.class.

     */

    public static void write(ModuleDescriptor descriptor,

                             ModuleTarget target,

                             OutputStream out)

        throws IOException

    {

        byte[] bytes = toModuleInfo(descriptor, target);

        out.write(bytes);

    }

    /**

     * Writes a module descriptor to the given output stream as a

     * module-info.class.

     */

    public static void write(ModuleDescriptor descriptor, OutputStream out)

        throws IOException

    {

        write(descriptor, null, out);

    }

    /**

     * Returns a {@code ByteBuffer} containing the given module descriptor

     * in module-info.class format.

     */

    public static ByteBuffer toByteBuffer(ModuleDescriptor descriptor) {

        byte[] bytes = toModuleInfo(descriptor, null);

        return ByteBuffer.wrap(bytes);

    }

}