/*

 * Copyright (c) 2017, 2019, 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.

 */

import java.security.KeyPairGenerator;

import java.security.MessageDigest;

import java.security.NoSuchAlgorithmException;

import java.security.Signature;

import static java.util.Arrays.asList;

/*

 * This class is used for returning some specific JDK information.

 */

public class JdkUtils {

    private enum Alg {

        KEY, SIG, DIGEST;

    }

    static final String M_JAVA_VERSION = "javaVersion";

    static final String M_JAVA_RUNTIME_VERSION = "javaRuntimeVersion";

    static final String M_IS_SUPPORTED_KEYALG = "isSupportedKeyalg";

    static final String M_IS_SUPPORTED_SIGALG = "isSupportedSigalg";

    static final String M_IS_SUPPORTED_DIGESTALG = "isSupportedDigestalg";

    // Returns the JDK build version.

    static String javaVersion() {

        return System.getProperty("java.version");

    }

    // Returns the JDK build runtime version.

    static String javaRuntimeVersion() {

        return System.getProperty("java.runtime.version");

    }

    // Checks if the specified algorithm is supported by the JDK.

    static boolean isSupportedAlg(Alg algType, String algName) {

        try {

            switch (algType) {

            case KEY:

                return KeyPairGenerator.getInstance(algName) != null;

            case SIG:

                return Signature.getInstance(algName) != null;

            case DIGEST:

                return MessageDigest.getInstance(algName) != null;

            }

        } catch (NoSuchAlgorithmException e) { }

        System.out.println(algName + " is not supported yet.");

        return false;

    }

    public static void main(String[] args) {

        if (M_JAVA_VERSION.equals(args[0])) {

            System.out.print(javaVersion());

        } else if (M_JAVA_RUNTIME_VERSION.equals(args[0])) {

            System.out.print(javaRuntimeVersion());

        } else if (M_IS_SUPPORTED_KEYALG.equals(args[0])) {

            System.out.print(isSupportedAlg(Alg.KEY, args[1]));

        } else if (M_IS_SUPPORTED_SIGALG.equals(args[0])) {

            System.out.print(isSupportedAlg(Alg.SIG, args[1]));

        } else if (M_IS_SUPPORTED_DIGESTALG.equals(args[0])) {

            System.out.print(isSupportedAlg(Alg.DIGEST, args[1]));

        } else {

            throw new IllegalArgumentException("invalid: " + asList(args));

        }

    }

}