/*

 * 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.  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

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 */

package jdk.internal.module;

import java.lang.module.ModuleDescriptor;

import java.lang.module.ModuleFinder;

import java.lang.module.ModuleReference;

import java.util.HashSet;

import java.util.Set;

/**

 * Defines methods to compute the default set of root modules for the unnamed

 * module.

 */

public final class DefaultRoots {

    private static final String JAVA_SE = "java.se";

    private DefaultRoots() { }

    /**

     * Returns the default set of root modules for the unnamed module computed from

     * the system modules observable with the given module finder.

     */

    static Set<String> compute(ModuleFinder systemModuleFinder, ModuleFinder finder) {

        Set<String> roots = new HashSet<>();

        boolean hasJava = false;

        if (systemModuleFinder.find(JAVA_SE).isPresent()) {

            if (finder == systemModuleFinder || finder.find(JAVA_SE).isPresent()) {

                // java.se is a system module

                hasJava = true;

                roots.add(JAVA_SE);

            }

        }

        for (ModuleReference mref : systemModuleFinder.findAll()) {

            String mn = mref.descriptor().name();

            if (hasJava && mn.startsWith("java.")) {

                // not a root

                continue;

            }

            if (ModuleResolution.doNotResolveByDefault(mref)) {

                // not a root

                continue;

            }

            if ((finder == systemModuleFinder || finder.find(mn).isPresent())) {

                // add as root if exports at least one package to all modules

                ModuleDescriptor descriptor = mref.descriptor();

                for (ModuleDescriptor.Exports e : descriptor.exports()) {

                    if (!e.isQualified()) {

                        roots.add(mn);

                        break;

                    }

                }

            }

        }

        return roots;

    }

    /**

     * Returns the default set of root modules for the unnamed module from the

     * modules observable with the given module finder.

     */

    public static Set<String> compute(ModuleFinder finder) {

        return compute(finder, finder);

    }

}