/*

 * Copyright (c) 2015, 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.  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.internal.module;

import java.lang.module.Configuration;

import java.lang.module.ResolvedModule;

import java.util.HashMap;

import java.util.HashSet;

import java.util.Map;

import java.util.Set;

import java.util.function.Function;

import jdk.internal.loader.ClassLoaders;

/**

 * Supports the mapping of modules to class loaders. The set of modules mapped

 * to the boot and platform class loaders is generated at build time from

 * this source file.

 */

public final class ModuleLoaderMap {

    /**

     * Maps the system modules to the built-in class loaders.

     */

    public static final class Mapper implements Function<String, ClassLoader> {

        private final Map<String, ClassLoader> map;

        Mapper(Map<String, ClassLoader> map) {

            this.map = map; // defensive copy not needed

        }

        @Override

        public ClassLoader apply(String name) {

            return map.get(name);

        }

    }

    /**

     * Returns the names of the modules defined to the boot loader.

     */

    public static Set<String> bootModules() {

        // The list of boot modules generated at build time.

        String[] BOOT_MODULES = new String[] { "@@BOOT_MODULE_NAMES@@" };

        Set<String> bootModules = new HashSet<>(BOOT_MODULES.length);

        for (String mn : BOOT_MODULES) {

            bootModules.add(mn);

        }

        return bootModules;

    }

    /**

     * Returns the names of the modules defined to the platform loader.

     */

    public static Set<String> platformModules() {

        // The list of platform modules generated at build time.

        String[] PLATFORM_MODULES = new String[] { "@@PLATFORM_MODULE_NAMES@@" };

        Set<String> platformModules = new HashSet<>(PLATFORM_MODULES.length);

        for (String mn : PLATFORM_MODULES) {

            platformModules.add(mn);

        }

        return platformModules;

    }

    /**

     * Returns the function to map modules in the given configuration to the

     * built-in class loaders.

     */

    static Function<String, ClassLoader> mappingFunction(Configuration cf) {

        Set<String> bootModules = bootModules();

        Set<String> platformModules = platformModules();

        ClassLoader platformClassLoader = ClassLoaders.platformClassLoader();

        ClassLoader appClassLoader = ClassLoaders.appClassLoader();

        Map<String, ClassLoader> map = new HashMap<>();

        for (ResolvedModule resolvedModule : cf.modules()) {

            String mn = resolvedModule.name();

            if (!bootModules.contains(mn)) {

                if (platformModules.contains(mn)) {

                    map.put(mn, platformClassLoader);

                } else {

                    map.put(mn, appClassLoader);

                }

            }

        }

        return new Mapper(map);

    }

}