/*

 * Copyright (c) 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 com.oracle.mxtool.junit;

import java.lang.reflect.Method;

import java.util.Arrays;

import java.util.Set;

/**

 * Facade for the {@code java.lang.Module} class introduced in JDK9 that allows tests to be

 * developed against JDK8 but use module logic if deployed on JDK9.

 */

class JLModule {

    private final Object realModule;

    JLModule(Object module) {

        this.realModule = module;

    }

    private static final Class<?> moduleClass;

    private static final Class<?> layerClass;

    private static final Method bootMethod;

    private static final Method modulesMethod;

    private static final Method getModuleMethod;

    private static final Method getUnnamedModuleMethod;

    private static final Method getNameMethod;

    private static final Method getPackagesMethod;

    private static final Method isExportedMethod;

    private static final Method isExported2Method;

    private static final Method addExportsMethod;

    private static final Method addOpensMethod;

    static {

        try {

            moduleClass = findModuleClass();

            Class<?> modulesClass = Class.forName("jdk.internal.module.Modules");

            layerClass = findModuleLayerClass();

            bootMethod = layerClass.getMethod("boot");

            modulesMethod = layerClass.getMethod("modules");

            getModuleMethod = Class.class.getMethod("getModule");

            getUnnamedModuleMethod = ClassLoader.class.getMethod("getUnnamedModule");

            getNameMethod = moduleClass.getMethod("getName");

            getPackagesMethod = moduleClass.getMethod("getPackages");

            isExportedMethod = moduleClass.getMethod("isExported", String.class);

            isExported2Method = moduleClass.getMethod("isExported", String.class, moduleClass);

            addExportsMethod = modulesClass.getDeclaredMethod("addExports", moduleClass, String.class, moduleClass);

            addOpensMethod = getDeclaredMethodOptional(modulesClass, "addOpens", moduleClass, String.class, moduleClass);

        } catch (Exception e) {

            throw new AssertionError(e);

        }

    }

    // API change http://hg.openjdk.java.net/jdk9/dev/hotspot/rev/afedee84773e.

    protected static Class<?> findModuleClass() throws ClassNotFoundException {

        try {

            return Class.forName("java.lang.Module");

        } catch (ClassNotFoundException e) {

            return Class.forName("java.lang.reflect.Module");

        }

    }

    // API change http://hg.openjdk.java.net/jdk9/dev/hotspot/rev/afedee84773e.

    protected static Class<?> findModuleLayerClass() throws ClassNotFoundException {

        try {

            return Class.forName("java.lang.ModuleLayer");

        } catch (ClassNotFoundException e) {

            return Class.forName("java.lang.reflect.Layer");

        }

    }

    private static Method getDeclaredMethodOptional(Class<?> declaringClass, String name, Class<?>... parameterTypes) {

        try {

            return declaringClass.getDeclaredMethod(name, parameterTypes);

        } catch (NoSuchMethodException e) {

            return null;

        }

    }

    public static JLModule fromClass(Class<?> cls) {

        try {

            return new JLModule(getModuleMethod.invoke(cls));

        } catch (Exception e) {

            throw new AssertionError(e);

        }

    }

    @SuppressWarnings("unchecked")

    public static JLModule find(String name) {

        try {

            Object bootLayer = bootMethod.invoke(null);

            Set<Object> modules = (Set<Object>) modulesMethod.invoke(bootLayer);

            for (Object m : modules) {

                JLModule module = new JLModule(m);

                String mname = module.getName();

                if (mname.equals(name)) {

                    return module;

                }

            }

        } catch (Exception e) {

            throw new InternalError(e);

        }

        return null;

    }

    public static JLModule getUnnamedModuleFor(ClassLoader cl) {

        try {

            return new JLModule(getUnnamedModuleMethod.invoke(cl));

        } catch (Exception e) {

            throw new AssertionError(e);

        }

    }

    public String getName() {

        try {

            return (String) getNameMethod.invoke(realModule);

        } catch (Exception e) {

            throw new AssertionError(e);

        }

    }

    /**

     * Exports all packages in this module to a given module.

     */

    public void exportAllPackagesTo(JLModule module) {

        if (this != module) {

            for (String pkg : getPackages()) {

                // Export all JVMCI packages dynamically instead

                // of requiring a long list of -XaddExports

                // options on the JVM command line.

                if (!isExported(pkg, module)) {

                    addExports(pkg, module);

                    addOpens(pkg, module);

                }

            }

        }

    }

    @SuppressWarnings("unchecked")

    public Iterable<String> getPackages() {

        try {

            // API change http://hg.openjdk.java.net/jdk9/dev/hotspot/rev/afedee84773e#l1.15

            Object res = getPackagesMethod.invoke(realModule);

            if (res instanceof String[]) {

                return Arrays.asList((String[]) res);

            }

            return (Set<String>) res;

        } catch (Exception e) {

            throw new AssertionError(e);

        }

    }

    public boolean isExported(String pn) {

        try {

            return (Boolean) isExportedMethod.invoke(realModule, pn);

        } catch (Exception e) {

            throw new AssertionError(e);

        }

    }

    public boolean isExported(String pn, JLModule other) {

        try {

            return (Boolean) isExported2Method.invoke(realModule, pn, other.realModule);

        } catch (Exception e) {

            throw new AssertionError(e);

        }

    }

    public void addExports(String pn, JLModule other) {

        try {

            addExportsMethod.invoke(null, realModule, pn, other.realModule);

        } catch (Exception e) {

            throw new AssertionError(e);

        }

    }

    public void addOpens(String pn, JLModule other) {

        if (addOpensMethod != null) {

            try {

                addOpensMethod.invoke(null, realModule, pn, other.realModule);

            } catch (Exception e) {

                throw new AssertionError(e);

            }

        }

    }

    @Override

    public String toString() {

        return realModule.toString();

    }

}