/*
 * 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.
 */

import java.io.InputStream;
import java.io.IOException;
import java.lang.module.ModuleReader;
import java.lang.module.ModuleReference;
import java.net.URI;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;

import jdk.internal.module.ModuleInfo;
import jdk.internal.module.ModuleInfo.Attributes;

public class ModuleTargetHelper {
    private ModuleTargetHelper() {}

    public static final class ModuleTarget {
        private String targetPlatform;

        public ModuleTarget(String targetPlatform) {
            this.targetPlatform = targetPlatform;
        }

        public String targetPlatform() {
            return targetPlatform;
        }
    }

    public static ModuleTarget getJavaBaseTarget() throws IOException {
        Path p = Paths.get(URI.create("jrt:/modules/java.base/module-info.class"));
        try (InputStream in = Files.newInputStream(p)) {
            return read(in);
        }
    }

    public static ModuleTarget read(InputStream in) throws IOException {
        ModuleInfo.Attributes attrs = ModuleInfo.read(in, null);
        if (attrs.target() != null) {
            return new ModuleTarget(attrs.target().targetPlatform());
        } else {
            return null;
        }
    }

    public static ModuleTarget read(ModuleReference modRef) throws IOException {
        ModuleReader reader = modRef.open();
        try (InputStream in = reader.open("module-info.class").get()) {
            return read(in);
        } finally {
            reader.close();
        }
    }
}