/*
 * Copyright (c) 2014, 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.
 */

package container;

import java.io.File;
import java.lang.module.Configuration;
import java.lang.module.ModuleFinder;
import java.lang.module.ResolvedModule;
import java.lang.reflect.Layer;
import java.lang.reflect.Method;
import java.lang.reflect.Module;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.Set;

/**
 * Exercises dynamic configuration.
 */

public class Main {

    public static void main(String[] args) throws Exception {

        System.out.println("Boot layer");
        Layer.boot()
             .modules()
             .stream()
             .map(Module::getName)
             .sorted()
             .forEach(System.out::println);

        // "start" two applications in their own layers
        start("applib", "app1", "app1.Main");
        start("applib", "app2", "app2.Main");
    }

    static void start(String appModulePath,
                      String appModuleName,
                      String appMainClass) throws Exception {

        System.out.format("Starting %s/%s ...%n", appModuleName, appMainClass);

        String[] dirs = appModulePath.split(File.pathSeparator);
        Path[] paths = new Path[dirs.length];
        int i = 0;
        for (String dir: dirs) {
            paths[i++] = Paths.get(dir);
        }

        ModuleFinder finder = ModuleFinder.of(paths);

        Configuration cf = Layer.boot().configuration()
            .resolveAndBind(finder,
                            ModuleFinder.of(),
                            Set.of(appModuleName));

        System.out.println("Resolved");
        cf.modules().stream()
          .map(ResolvedModule::name)
          .sorted()
          .forEach(mn -> System.out.format("  %s%n", mn));

        // reify the configuration as a Layer
        ClassLoader scl = ClassLoader.getSystemClassLoader();
        Layer layer = Layer.boot().defineModulesWithManyLoaders(cf, scl);

        // invoke application main method
        ClassLoader loader = layer.findLoader(appModuleName);
        Class<?> c = loader.loadClass(appMainClass);
        Main.class.getModule().addReads(c.getModule());
        Method mainMethod = c.getMethod("main", String[].class);

        // set TCCL as that is the EE thing to do
        ClassLoader tccl = Thread.currentThread().getContextClassLoader();
        try {
            Thread.currentThread().setContextClassLoader(loader);
            mainMethod.invoke(null, (Object)new String[0]);
        } finally {
            Thread.currentThread().setContextClassLoader(tccl);
        }

        System.out.println();
    }
}