/*

 * Copyright (c) 2010, 2013, 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.nashorn.internal.runtime;

import java.lang.module.ModuleDescriptor;

import java.lang.reflect.Module;

import java.security.CodeSource;

import java.util.Objects;

/**

 * Responsible for loading script generated classes.

 *

 */

final class ScriptLoader extends NashornLoader {

    private static final String NASHORN_PKG_PREFIX = "jdk.nashorn.internal.";

    private volatile boolean structureAccessAdded;

    private final Context context;

    private final Module scriptModule;

    /*package-private*/ Context getContext() {

        return context;

    }

    /**

     * Constructor.

     */

    ScriptLoader(final Context context) {

        super(context.getStructLoader());

        this.context = context;

        // new scripts module, it's specific exports and read-edges

        scriptModule = createModule("jdk.scripting.nashorn.scripts");

        // specific exports from nashorn to new scripts module

        NASHORN_MODULE.addExports(OBJECTS_PKG, scriptModule);

        NASHORN_MODULE.addExports(RUNTIME_PKG, scriptModule);

        NASHORN_MODULE.addExports(RUNTIME_ARRAYS_PKG, scriptModule);

        NASHORN_MODULE.addExports(RUNTIME_LINKER_PKG, scriptModule);

        NASHORN_MODULE.addExports(SCRIPTS_PKG, scriptModule);

        // nashorn needs to read scripts module methods,fields

        NASHORN_MODULE.addReads(scriptModule);

    }

    private Module createModule(final String moduleName) {

        final Module structMod = context.getStructLoader().getModule();

        final ModuleDescriptor descriptor

                = new ModuleDescriptor.Builder(moduleName)

                    .requires(NASHORN_MODULE.getName())

                    .requires(structMod.getName())

                    .conceals(SCRIPTS_PKG)

                    .build();

        final Module mod = Context.createModuleTrusted(structMod.getLayer(), descriptor, this);

        loadModuleManipulator();

        return mod;

    }

    @Override

    protected Class<?> loadClass(final String name, final boolean resolve) throws ClassNotFoundException {

        checkPackageAccess(name);

        final Class<?> cl = super.loadClass(name, resolve);

        if (!structureAccessAdded) {

            final StructureLoader structLoader = context.getStructLoader();

            if (cl.getClassLoader() == structLoader) {

                structureAccessAdded = true;

                structLoader.addModuleExport(scriptModule);

            }

        }

        return cl;

    }

    @Override

        final ClassLoader appLoader = context.getAppLoader();

        /*

         * If the appLoader is null, don't bother side-delegating to it!

         * Bootloader has been already attempted via parent loader

         * delegation from the "loadClass" method.

         *

         * Also, make sure that we don't delegate to the app loader

         * for nashorn's own classes or nashorn generated classes!

         */

        if (appLoader == null || name.startsWith(NASHORN_PKG_PREFIX)) {

            throw new ClassNotFoundException(name);

        }

        /*

         * This split-delegation is used so that caller loader

         * based resolutions of classes would work. For example,

         * java.sql.DriverManager uses caller's class loader to

         * get Driver instances. Without this split-delegation

         * a script class evaluating DriverManager.getDrivers()

         * will not get back any JDBC driver!

         */

        return appLoader.loadClass(name);

    }

    // package-private and private stuff below this point

    /**

     * Install a class for use by the Nashorn runtime

     *

     * @param name Binary name of class.

     * @param data Class data bytes.

     * @param cs CodeSource code source of the class bytes.

     *

     * @return Installed class.

     */

    synchronized Class<?> installClass(final String name, final byte[] data, final CodeSource cs) {

        return defineClass(name, data, 0, data.length, Objects.requireNonNull(cs));

    }

}