/*

 * Copyright (c) 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.

 *

 * 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 p4;

import java.io.IOException;

import java.io.InputStream;

import java.lang.module.ModuleDescriptor;

import java.lang.module.ModuleFinder;

import java.net.URI;

import java.nio.file.FileSystem;

import java.nio.file.FileSystems;

import java.nio.file.Files;

import java.nio.file.Path;

import java.util.Collections;

import java.util.Set;

import jdk.internal.module.ClassFileAttributes;

import jdk.internal.module.ClassFileAttributes.ModuleTargetAttribute;

import jdk.internal.module.ClassFileConstants;

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

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

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

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

public class Main {

    private static boolean hasModuleTarget(InputStream in) throws IOException {

        ModuleTargetAttribute[] modTargets = new ModuleTargetAttribute[1];

        ClassVisitor cv = new ClassVisitor(Opcodes.ASM5) {

            @Override

            public void visitAttribute(Attribute attr) {

                if (attr instanceof ModuleTargetAttribute) {

                    modTargets[0] = (ModuleTargetAttribute)attr;

                }

            }

        };

        // prototype of attributes that should be parsed

        Attribute[] attrs = new Attribute[] {

            new ModuleTargetAttribute()

        };

        // parse module-info.class

        ClassReader cr = new ClassReader(in);

        cr.accept(cv, attrs, 0);

        return modTargets[0] != null &&

            (modTargets[0].osName() != null || modTargets[0].osArch() != null);

    }

    private static boolean hasModuleTarget(String modName) throws IOException {

        FileSystem fs = FileSystems.newFileSystem(URI.create("jrt:/"),

                                                  Collections.emptyMap());

        Path path = fs.getPath("/", "modules", modName, "module-info.class");

        try (InputStream in = Files.newInputStream(path)) {

            return hasModuleTarget(in);

        }

    }

    // the system module plugin by default drops ModuleTarget attribute

    private static boolean expectModuleTarget = false;

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

        if (args.length > 0) {

            if (!args[0].equals("retainModuleTarget")) {

                throw new IllegalArgumentException(args[0]);

            }

            expectModuleTarget = true;

        }

        // java.base is packaged with osName/osArch/osVersion

        if (! hasModuleTarget("java.base")) {

            throw new RuntimeException("ModuleTarget absent for java.base");

        }

        // verify module-info.class for m1 and m4

        checkModule("m1", "p1", "p2");

        checkModule("m4", "p4");

    }

    private static void checkModule(String mn, String... packages) throws IOException {

        // verify ModuleDescriptor from the runtime module

                                   .getDescriptor();

        checkModuleDescriptor(md, packages);

        // verify ModuleDescriptor from module-info.class read from ModuleReader

        try (InputStream in = ModuleFinder.ofSystem().find(mn).get()

            .open().open("module-info.class").get()) {

            checkModuleDescriptor(ModuleDescriptor.read(in), packages);

        }

        // verify ModuleDescriptor from module-info.class read from jimage

        FileSystem fs = FileSystems.newFileSystem(URI.create("jrt:/"),

            Collections.emptyMap());

        Path path = fs.getPath("/", "modules", mn, "module-info.class");

        checkModuleDescriptor(ModuleDescriptor.read(Files.newInputStream(path)), packages);

    }

    static void checkModuleDescriptor(ModuleDescriptor md, String... packages) throws IOException {

        String mainClass = md.name().replace('m', 'p') + ".Main";

        if (!md.mainClass().get().equals(mainClass)) {

            throw new RuntimeException(md.mainClass().toString());

        }

        if (expectModuleTarget) {

            // ModuleTarget attribute is retained

            if (! hasModuleTarget(md.name())) {

                throw new RuntimeException("ModuleTarget missing for " + md.name());

            }

        } else {

            // by default ModuleTarget attribute is dropped

            if (hasModuleTarget(md.name())) {

                throw new RuntimeException("ModuleTarget present for " + md.name());

            }

        }

        Set<String> pkgs = md.packages();

        if (!pkgs.equals(Set.of(packages))) {

            throw new RuntimeException(pkgs + " expected: " + Set.of(packages));

        }

    }

}