/*

 * Copyright (c) 1999, 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 javax.management.monitor;

import static com.sun.jmx.defaults.JmxProperties.MONITOR_LOGGER;

import java.lang.System.Logger.Level;

import javax.management.ObjectName;

import javax.management.MBeanNotificationInfo;

import static javax.management.monitor.MonitorNotification.*;

/**

 * Defines a monitor MBean designed to observe the values of a string

 * attribute.

 * <P>

 * A string monitor sends notifications as follows:

 * <UL>

 * <LI> if the attribute value matches the string to compare value,

 *      a {@link MonitorNotification#STRING_TO_COMPARE_VALUE_MATCHED

 *      match notification} is sent.

 *      The notify match flag must be set to <CODE>true</CODE>.

 *      <BR>Subsequent matchings of the string to compare values do not

 *      cause further notifications unless

 *      the attribute value differs from the string to compare value.

 * <LI> if the attribute value differs from the string to compare value,

 *      a {@link MonitorNotification#STRING_TO_COMPARE_VALUE_DIFFERED

 *      differ notification} is sent.

 *      The notify differ flag must be set to <CODE>true</CODE>.

 *      <BR>Subsequent differences from the string to compare value do

 *      not cause further notifications unless

 *      the attribute value matches the string to compare value.

 * </UL>

 *

 *

 * @since 1.5

 */

public class StringMonitor extends Monitor implements StringMonitorMBean {

    /*

     * ------------------------------------------

     *  PACKAGE CLASSES

     * ------------------------------------------

     */

    static class StringMonitorObservedObject extends ObservedObject {

        public StringMonitorObservedObject(ObjectName observedObject) {

            super(observedObject);

        }

        public final synchronized int getStatus() {

            return status;

        }

        public final synchronized void setStatus(int status) {

            this.status = status;

        }

        private int status;

    }

    /*

     * ------------------------------------------

     *  PRIVATE VARIABLES

     * ------------------------------------------

     */

    /**

     * String to compare with the observed attribute.

     * <BR>The default value is an empty character sequence.

     */

    private String stringToCompare = "";

    /**

     * Flag indicating if the string monitor notifies when matching

     * the string to compare.

     * <BR>The default value is set to <CODE>false</CODE>.

     */

    private boolean notifyMatch = false;

    /**

     * Flag indicating if the string monitor notifies when differing

     * from the string to compare.

     * <BR>The default value is set to <CODE>false</CODE>.

     */

    private boolean notifyDiffer = false;

    private static final String[] types = {

        RUNTIME_ERROR,

        OBSERVED_OBJECT_ERROR,

        OBSERVED_ATTRIBUTE_ERROR,

        OBSERVED_ATTRIBUTE_TYPE_ERROR,

        STRING_TO_COMPARE_VALUE_MATCHED,

        STRING_TO_COMPARE_VALUE_DIFFERED

    };

    private static final MBeanNotificationInfo[] notifsInfo = {

        new MBeanNotificationInfo(

            types,

            "javax.management.monitor.MonitorNotification",

            "Notifications sent by the StringMonitor MBean")

    };

    // Flags needed to implement the matching/differing mechanism.

    //

    private static final int MATCHING                   = 0;

    private static final int DIFFERING                  = 1;

    private static final int MATCHING_OR_DIFFERING      = 2;

    /*

     * ------------------------------------------

     *  CONSTRUCTORS

     * ------------------------------------------

     */

    /**

     * Default constructor.

     */

    public StringMonitor() {

    }

    /*

     * ------------------------------------------

     *  PUBLIC METHODS

     * ------------------------------------------

     */

    /**

     * Starts the string monitor.

     */

    public synchronized void start() {

        if (isActive()) {

            MONITOR_LOGGER.log(Level.TRACE, "the monitor is already active");

            return;

        }

        // Reset values.

        //

        for (ObservedObject o : observedObjects) {

            final StringMonitorObservedObject smo =

                (StringMonitorObservedObject) o;

            smo.setStatus(MATCHING_OR_DIFFERING);

        }

        doStart();

    }

    /**

     * Stops the string monitor.

     */

    public synchronized void stop() {

        doStop();

    }

    // GETTERS AND SETTERS

    //--------------------

    /**

     * Gets the derived gauge of the specified object, if this object is

     * contained in the set of observed MBeans, or <code>null</code> otherwise.

     *

     * @param object the name of the MBean whose derived gauge is required.

     *

     * @return The derived gauge of the specified object.

     *

     */

    @Override

    public synchronized String getDerivedGauge(ObjectName object) {

        return (String) super.getDerivedGauge(object);

    }

    /**

     * Gets the derived gauge timestamp of the specified object, if

     * this object is contained in the set of observed MBeans, or

     * <code>0</code> otherwise.

     *

     * @param object the name of the object whose derived gauge

     * timestamp is to be returned.

     *

     * @return The derived gauge timestamp of the specified object.

     *

     */

    @Override

    public synchronized long getDerivedGaugeTimeStamp(ObjectName object) {

        return super.getDerivedGaugeTimeStamp(object);

    }

    /**

     * Returns the derived gauge of the first object in the set of

     * observed MBeans.

     *

     * @return The derived gauge.

     *

     * @deprecated As of JMX 1.2, replaced by

     * {@link #getDerivedGauge(ObjectName)}

     */

    @Deprecated

    public synchronized String getDerivedGauge() {

        if (observedObjects.isEmpty()) {

            return null;

        } else {

            return (String) observedObjects.get(0).getDerivedGauge();

        }

    }

    /**

     * Gets the derived gauge timestamp of the first object in the set

     * of observed MBeans.

     *

     * @return The derived gauge timestamp.

     *

     * @deprecated As of JMX 1.2, replaced by

     * {@link #getDerivedGaugeTimeStamp(ObjectName)}

     */

    @Deprecated

    public synchronized long getDerivedGaugeTimeStamp() {

        if (observedObjects.isEmpty()) {

            return 0;

        } else {

            return observedObjects.get(0).getDerivedGaugeTimeStamp();

        }

    }

    /**

     * Gets the string to compare with the observed attribute common

     * to all observed MBeans.

     *

     * @return The string value.

     *

     * @see #setStringToCompare

     */

    public synchronized String getStringToCompare() {

        return stringToCompare;

    }

    /**

     * Sets the string to compare with the observed attribute common

     * to all observed MBeans.

     *

     * @param value The string value.

     *

     * @exception IllegalArgumentException The specified

     * string to compare is null.

     *

     * @see #getStringToCompare

     */

    public synchronized void setStringToCompare(String value)

        throws IllegalArgumentException {

        if (value == null) {

            throw new IllegalArgumentException("Null string to compare");

        }

        if (stringToCompare.equals(value))

            return;

        stringToCompare = value;

        // Reset values.

        //

        for (ObservedObject o : observedObjects) {

            final StringMonitorObservedObject smo =

                (StringMonitorObservedObject) o;

            smo.setStatus(MATCHING_OR_DIFFERING);

        }

    }

    /**

     * Gets the matching notification's on/off switch value common to

     * all observed MBeans.

     *

     * @return <CODE>true</CODE> if the string monitor notifies when

     * matching the string to compare, <CODE>false</CODE> otherwise.

     *

     * @see #setNotifyMatch

     */

    public synchronized boolean getNotifyMatch() {

        return notifyMatch;

    }

    /**

     * Sets the matching notification's on/off switch value common to

     * all observed MBeans.

     *

     * @param value The matching notification's on/off switch value.

     *

     * @see #getNotifyMatch

     */

    public synchronized void setNotifyMatch(boolean value) {

        if (notifyMatch == value)

            return;

        notifyMatch = value;

    }

    /**

     * Gets the differing notification's on/off switch value common to

     * all observed MBeans.

     *

     * @return <CODE>true</CODE> if the string monitor notifies when

     * differing from the string to compare, <CODE>false</CODE> otherwise.

     *

     * @see #setNotifyDiffer

     */

    public synchronized boolean getNotifyDiffer() {

        return notifyDiffer;

    }

    /**

     * Sets the differing notification's on/off switch value common to

     * all observed MBeans.

     *

     * @param value The differing notification's on/off switch value.

     *

     * @see #getNotifyDiffer

     */

    public synchronized void setNotifyDiffer(boolean value) {

        if (notifyDiffer == value)

            return;

        notifyDiffer = value;

    }

    /**

     * Returns a <CODE>NotificationInfo</CODE> object containing the name of

     * the Java class of the notification and the notification types sent by

     * the string monitor.

     */

    @Override

    public MBeanNotificationInfo[] getNotificationInfo() {

        return notifsInfo.clone();

    }

    /*

     * ------------------------------------------

     *  PACKAGE METHODS

     * ------------------------------------------

     */

    /**

     * Factory method for ObservedObject creation.

     *

     * @since 1.6

     */

    @Override

    ObservedObject createObservedObject(ObjectName object) {

        final StringMonitorObservedObject smo =

            new StringMonitorObservedObject(object);

        smo.setStatus(MATCHING_OR_DIFFERING);

        return smo;

    }

    /**

     * Check that the type of the supplied observed attribute

     * value is one of the value types supported by this monitor.

     */

    @Override

    synchronized boolean isComparableTypeValid(ObjectName object,

                                               String attribute,

                                               Comparable<?> value) {

        // Check that the observed attribute is of type "String".

        //

        if (value instanceof String) {

            return true;

        }

        return false;

    }

    @Override

    synchronized void onErrorNotification(MonitorNotification notification) {

        final StringMonitorObservedObject o = (StringMonitorObservedObject)

            getObservedObject(notification.getObservedObject());

        if (o == null)

            return;

        // Reset values.

        //

        o.setStatus(MATCHING_OR_DIFFERING);

    }

    @Override

    synchronized MonitorNotification buildAlarmNotification(

                                               ObjectName object,

                                               String attribute,

                                               Comparable<?> value) {

        String type = null;

        String msg = null;

        Object trigger = null;

        final StringMonitorObservedObject o =

            (StringMonitorObservedObject) getObservedObject(object);

        if (o == null)

            return null;

        // Send matching notification if notifyMatch is true.

        // Send differing notification if notifyDiffer is true.

        //

        if (o.getStatus() == MATCHING_OR_DIFFERING) {

            if (o.getDerivedGauge().equals(stringToCompare)) {

                if (notifyMatch) {

                    type = STRING_TO_COMPARE_VALUE_MATCHED;

                    msg = "";

                    trigger = stringToCompare;

                }

                o.setStatus(DIFFERING);

            } else {

                if (notifyDiffer) {

                    type = STRING_TO_COMPARE_VALUE_DIFFERED;

                    msg = "";

                    trigger = stringToCompare;

                }

                o.setStatus(MATCHING);

            }

        } else {

            if (o.getStatus() == MATCHING) {

                if (o.getDerivedGauge().equals(stringToCompare)) {

                    if (notifyMatch) {

                        type = STRING_TO_COMPARE_VALUE_MATCHED;

                        msg = "";

                        trigger = stringToCompare;

                    }

                    o.setStatus(DIFFERING);

                }

            } else if (o.getStatus() == DIFFERING) {

                if (!o.getDerivedGauge().equals(stringToCompare)) {

                    if (notifyDiffer) {

                        type = STRING_TO_COMPARE_VALUE_DIFFERED;

                        msg = "";

                        trigger = stringToCompare;

                    }

                    o.setStatus(MATCHING);

                }

            }

        }

        return new MonitorNotification(type,

                                       this,

                                       0,

                                       0,

                                       msg,

                                       null,

                                       null,

                                       null,

                                       trigger);

    }

}