/*

 * 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.

 */

import java.util.*;

import com.sun.management.VMOption;

import com.sun.management.VMOption.Origin;

import java.security.AccessController;

/**

 * Flag class is a helper class for constructing a VMOption.

 * It has the static methods for getting the Flag objects, each

 * corresponds to one VMOption.

 *

 */

class Flag {

    private String name;

    private Object value;

    private Origin origin;

    private boolean writeable;

    private boolean external;

    Flag(String name, Object value, boolean writeable,

         boolean external, Origin origin) {

        this.name = name;

        this.value = value == null ? "" : value ;

        this.origin = origin;

        this.writeable = writeable;

        this.external = external;

    }

    Object getValue() {

        return value;

    }

    boolean isWriteable() {

        return writeable;

    }

    boolean isExternal() {

        return external;

    }

    VMOption getVMOption() {

        return new VMOption(name, value.toString(), writeable, origin);

    }

    static Flag getFlag(String name) {

        String[] names = new String[1];

        names[0] = name;

        List<Flag> flags = getFlags(names, 1);

        if (flags.isEmpty()) {

            return null;

        } else {

            // flags should have only one element

            return flags.get(0);

        }

    }

    static List<Flag> getAllFlags() {

        int numFlags = getInternalFlagCount();

        // Get all internal flags with names = null

        return getFlags(null, numFlags);

    }

    private static List<Flag> getFlags(String[] names, int numFlags) {

        Flag[] flags = new Flag[numFlags];

        int count = getFlags(names, flags, numFlags);

        List<Flag> result = new ArrayList<>();

        for (Flag f : flags) {

            if (f != null) {

                result.add(f);

            }

        }

        return result;

    }

    private static native String[] getAllFlagNames();

    // getFlags sets each element in the given flags array

    // with a Flag object only if the name is valid and the

    // type is supported. The flags array may contain null elements.

    private static native int getFlags(String[] names, Flag[] flags, int count);

    private static native int getInternalFlagCount();

    // These set* methods are synchronized on the class object

    // to avoid multiple threads updating the same flag at the same time.

    static synchronized native void setLongValue(String name, long value);

    static synchronized native void setDoubleValue(String name, double value);

    static synchronized native void setBooleanValue(String name, boolean value);

    static synchronized native void setStringValue(String name, String value);

    static {

        AccessController.doPrivileged(

            new java.security.PrivilegedAction<Void>() {

                public Void run() {

                    System.loadLibrary("management");

                    return null;

                }

            });

        initialize();

    }

    private static native void initialize();

}