/*
 * @(#)StringMonitor.java	4.41 04/05/18
 *
 * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package javax.management.monitor;


// java imports
//
import java.util.Date;
import java.util.Timer;
import java.util.TimerTask;

// jmx imports
//
import javax.management.ObjectName;
import javax.management.MBeanNotificationInfo;
import javax.management.AttributeNotFoundException;
import javax.management.InstanceNotFoundException;
import javax.management.MBeanException;
import javax.management.ReflectionException;

/**
 * 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>
 *
 * @version     4.41     05/18/04
 * @author      Sun Microsystems, Inc
 *
 * @since 1.5
 */
public class StringMonitor extends Monitor implements StringMonitorMBean {


    // TRACES & DEBUG
    //---------------

    String makeDebugTag() {
        return "StringMonitor";
    }

    /*
     * ------------------------------------------
     *  PRIVATE VARIABLES
     * ------------------------------------------
     */

    private final static String[] types  = {
	    MonitorNotification.RUNTIME_ERROR,
	    MonitorNotification.OBSERVED_OBJECT_ERROR,
	    MonitorNotification.OBSERVED_ATTRIBUTE_ERROR,
	    MonitorNotification.OBSERVED_ATTRIBUTE_TYPE_ERROR,
	    MonitorNotification.STRING_TO_COMPARE_VALUE_MATCHED,
	    MonitorNotification.STRING_TO_COMPARE_VALUE_DIFFERED};
    private final static MBeanNotificationInfo[] notifsInfo = {
	    new MBeanNotificationInfo(types,
		"javax.management.monitor.MonitorNotification",
		"Notifications sent by the StringMonitor MBean")};

    /**
     * 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;

    /**
     * Derived gauges.
     * <BR>Each element in this array corresponds to an observed object
     * in the list.
     */
    private String derivedGauge[] = new String[capacityIncrement];

    /**
     * Derived gauge timestamps.
     * <BR>Each element in this array corresponds to an observed object
     * in the list.
     */
    private long derivedGaugeTimestamp[] = new long[capacityIncrement];

    /**
     * This attribute is used to handle the matching/differing mechanism.
     * <BR>Each element in this array corresponds to an observed object
     * in the list.
     */
    private int status[] = new int[capacityIncrement];

    // 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;

    /**
     * Timer.
     */
    private transient Timer timer = null;


    /*
     * ------------------------------------------
     *  CONSTRUCTORS
     * ------------------------------------------
     */

    /**
     * Default constructor.
     */
    public StringMonitor() {
	dbgTag = makeDebugTag();
    }

    /*
     * ------------------------------------------
     *  PUBLIC METHODS
     * ------------------------------------------
     */

    /**
     * Starts the string monitor.
     */
    public synchronized void start() {

        if (isTraceOn()) {
            trace("start", "start the string monitor");
        }

	if (isActive) {
	    if (isTraceOn()) {
		trace("start", "the string monitor is already activated");
	    }

	    return;
	}

	isActive = true;

	// Reset values.
	//
	for (int i = 0; i < elementCount; i++) {
	    status[i] = MATCHING_OR_DIFFERING;
	}

	// Start the AlarmClock.
	//
	timer = new Timer();
	timer.schedule(new StringAlarmClock(this),
		       getGranularityPeriod(), getGranularityPeriod());
    }

    /**
     * Stops the string monitor.
     */
    /* This method is not synchronized, because if it were there could
       be a deadlock with a thread that attempted to get the lock on
       the monitor before being interrupted or noticing that it had
       been interrupted.  */
    public void stop() {

        if (isTraceOn()) {
            trace("stop", "stop the string monitor");
        }

        synchronized(this) {
	    if (!isActive) {
		if (isTraceOn()) {
		    trace("stop", "the string monitor is already deactivated");
		}

		return;
	    }

            isActive = false;

            // Stop the AlarmClock.
            //
            if (timer != null) {
		timer.cancel();
		timer = null;
            }
	}
    }

    // GETTERS AND SETTERS
    //--------------------

    /**
     * Sets the granularity period (in milliseconds).
     * <BR>The default value of the granularity period is 10 seconds.
     *
     * @param period The granularity period value.
     * @exception java.lang.IllegalArgumentException The granularity
     * period is less than or equal to zero.
     *
     * @see Monitor#setGranularityPeriod(long)
     */
    public synchronized void setGranularityPeriod(long period)
	    throws IllegalArgumentException {
        super.setGranularityPeriod(period);

        // Reschedule timer task if timer is already running
        //
	if (isActive) {
	    timer.cancel();
	    timer = new Timer();
	    timer.schedule(new StringAlarmClock(this),
			   getGranularityPeriod(), getGranularityPeriod());
	}
    }

    /**
     * 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.
     *
     * @since.unbundled JMX 1.2
     */
    public synchronized String getDerivedGauge(ObjectName object) {
        int index = indexOf(object);
        if (index != -1)
            return derivedGauge[index];
        else
            return null;
    }

    /**
     * Gets the derived gauge timestamp 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
     * timestamp is required.
     *
     * @return The derived gauge timestamp of the specified object.
     *
     * @since.unbundled JMX 1.2
     */
    public synchronized long getDerivedGaugeTimeStamp(ObjectName object) {
        int index = indexOf(object);
        if (index != -1)
            return derivedGaugeTimestamp[index];
        else
            return 0;
    }

    /**
     * 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)}
     */
    public synchronized String getDerivedGauge() {
        return derivedGauge[0];
    }

    /**
     * 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() {
        return derivedGaugeTimestamp[0];
    }

    /**
     * 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 java.lang.IllegalArgumentException The specified
     *        string to compare is null.
     *
     * @see #getStringToCompare
     */
    public synchronized void setStringToCompare(String value)
	    throws java.lang.IllegalArgumentException {

        if (value == null) {
	    throw new IllegalArgumentException("Null string to compare");
        }

        stringToCompare = value;

        // Reset values.
        //
        for (int i = 0; i < elementCount; i++) {
          status[i] = 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) {
        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) {
        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.
     */
    public MBeanNotificationInfo[] getNotificationInfo() {
        return notifsInfo;
    }

    /*
     * ------------------------------------------
     *  PRIVATE METHODS
     * ------------------------------------------
     */

    /**
     * Updates the derived gauge and the derived gauge timestamp attributes
     * of the observed object at the specified index.
     *
     * @param scanString The value of the observed attribute.
     * @param index The index of the observed object.
     */
    private synchronized void updateDerivedGauge(Object scanString,
						 int index) {
        derivedGaugeTimestamp[index] = System.currentTimeMillis();
        derivedGauge[index] = (String)scanString;
    }

    /**
     * Updates the notification attributes of the observed object at the
     * specified index and notifies the listeners only once if the
     * notifyMatch/notifyDiffer flag is set to <CODE>true</CODE>.
     * @param index The index of the observed object.
     */
    private void updateNotifications(int index) {
	boolean sendNotify = false;
	String type = null;
	long timeStamp = 0;
	String msg = null;
	Object derGauge = null;
	Object trigger = null;

	synchronized(this) {
	    // Send matching notification if notifyMatch is true.
	    // Send differing notification if notifyDiffer is true.
	    //
	    if (status[index] == MATCHING_OR_DIFFERING) {
		if (derivedGauge[index].equals(stringToCompare)) {
		    if (notifyMatch) {
			sendNotify = true;
			type =
			    MonitorNotification.STRING_TO_COMPARE_VALUE_MATCHED;
			timeStamp = derivedGaugeTimestamp[index];
			msg = "";
			derGauge = derivedGauge[index];
			trigger = stringToCompare;
		    }

		    status[index] = DIFFERING;
		} else {
		    if (notifyDiffer) {
			sendNotify = true;
			type =
			    MonitorNotification.STRING_TO_COMPARE_VALUE_DIFFERED;
			timeStamp = derivedGaugeTimestamp[index];
			msg = "";
			derGauge = derivedGauge[index];
			trigger = stringToCompare;
		    }
		    status[index] = MATCHING;
		}
	    } else {
		if (status[index] == MATCHING) {
		    if (derivedGauge[index].equals(stringToCompare)) {
			if (notifyMatch) {
			    sendNotify = true;
			    type =
				MonitorNotification.STRING_TO_COMPARE_VALUE_MATCHED;
			    timeStamp = derivedGaugeTimestamp[index];
			    msg = "";
			    derGauge = derivedGauge[index];
			    trigger = stringToCompare;

			}
			status[index] = DIFFERING;
		    }
		} else if (status[index] == DIFFERING) {
		    if (!derivedGauge[index].equals(stringToCompare)) {
			if (notifyDiffer) {
			    sendNotify = true;
			    type =
				MonitorNotification.STRING_TO_COMPARE_VALUE_DIFFERED;
			    timeStamp = derivedGaugeTimestamp[index];
			    msg = "";
			    derGauge = derivedGauge[index];
			    trigger = stringToCompare;
			}
			status[index] = MATCHING;
		    }
		}
	    }
	}

	if (sendNotify) {
	    sendNotification(type, timeStamp, msg, derGauge, trigger, index);
	}
    }

    /*
     * ------------------------------------------
     *  PACKAGE METHODS
     * ------------------------------------------
     */

    /**
     * This method is called by the string monitor each time
     * the granularity period has been exceeded.
     * @param index The index of the observed object.
     */
    void notifyAlarmClock(int index) {
	boolean sendNotify = false;
	String type = null;
	long timeStamp = 0;
	String msg = null;
	Object derGauge = null;
	Object trigger = null;

        Object  scan_string = null;
        String  notif_type = null;

	synchronized(this) {
	    if (!isActive)
		return;

	    // Check if the observed object and observed attribute are valid.
	    //

	    // Check that neither the observed object nor the observed
	    // attribute are null.  If the observed object or observed
	    // attribute is null, this means that the monitor started
	    // before a complete initialization and nothing is done.
	    //
	    if ((getObservedObject(index) == null) ||
		(getObservedAttribute() == null))
		return;

	    // Check that the observed object is registered in the
	    // MBean server and that the observed attribute belongs to
	    // the observed object.
	    //
	    try {
		scan_string = server.getAttribute(getObservedObject(index),
						  getObservedAttribute());
		if (scan_string == null)
		    return;
	    } catch (NullPointerException np_ex) {
		if (alreadyNotified(index, RUNTIME_ERROR_NOTIFIED))
		    return;
		else {
		    notif_type = MonitorNotification.RUNTIME_ERROR;
		    setAlreadyNotified(index, RUNTIME_ERROR_NOTIFIED);
		    msg =
			"The string monitor must be registered in " +
			"the MBean server.";
		}
	    } catch (InstanceNotFoundException inf_ex) {
		if (alreadyNotified(index, OBSERVED_OBJECT_ERROR_NOTIFIED))
		    return;
		else {
		    notif_type = MonitorNotification.OBSERVED_OBJECT_ERROR;
		    setAlreadyNotified(index, OBSERVED_OBJECT_ERROR_NOTIFIED);
		    msg =
			"The observed object must be registered in " +
			"the MBean server.";
		}
	    } catch (AttributeNotFoundException anf_ex) {
		if (alreadyNotified(index, OBSERVED_ATTRIBUTE_ERROR_NOTIFIED))
		    return;
		else {
		    notif_type = MonitorNotification.OBSERVED_ATTRIBUTE_ERROR;
		    setAlreadyNotified(index,
				       OBSERVED_ATTRIBUTE_ERROR_NOTIFIED);
		    msg =
			"The observed attribute must be accessible in " +
			"the observed object.";
		}
	    } catch (MBeanException mb_ex) {
		if (alreadyNotified(index, RUNTIME_ERROR_NOTIFIED))
		    return;
		else {
		    notif_type = MonitorNotification.RUNTIME_ERROR;
		    setAlreadyNotified(index, RUNTIME_ERROR_NOTIFIED);
		    msg = mb_ex.getMessage();
		}
	    } catch (ReflectionException ref_ex) {
		if (alreadyNotified(index, OBSERVED_ATTRIBUTE_ERROR_NOTIFIED))
		    return;
		else {
		    notif_type = MonitorNotification.OBSERVED_ATTRIBUTE_ERROR;
		    setAlreadyNotified(index, OBSERVED_ATTRIBUTE_ERROR_NOTIFIED);
		    msg = ref_ex.getMessage();
		}
	    }

	    if (msg == null) {
		// Check that the observed attribute is of type "String".
		//
		if (!(scan_string instanceof String)) {
		    if (alreadyNotified(index,
					OBSERVED_ATTRIBUTE_TYPE_ERROR_NOTIFIED))
			return;
		    else {
			notif_type =
			    MonitorNotification.OBSERVED_ATTRIBUTE_TYPE_ERROR;
			setAlreadyNotified(index,
					   OBSERVED_ATTRIBUTE_TYPE_ERROR_NOTIFIED);
			msg =
			    "The observed attribute type must be " +
			    "a string type.";
		    }
		}
	    }

	    if (msg == null) {

		// Clear all already notified flags.
		//
		resetAllAlreadyNotified(index);

		// Update the derived gauge attributes.
		//
		updateDerivedGauge(scan_string, index);

		// Notify the listeners.
		//
		updateNotifications(index);

	    } else {

		// msg != null, will send the monitor error notification.

		timeStamp = derivedGaugeTimestamp[index];
                derGauge = derivedGauge[index];

		// Reset values.
		//
		status[index] = MATCHING_OR_DIFFERING;
	    }
	}

	if (msg != null) {
	    sendNotification(type, timeStamp, msg, derGauge, null, index);
	}
    }

    /**
     * This method is called when adding a new observed object in the vector.
     * It updates all the string specific arrays.
     * @param index The index of the observed object.
     */
    synchronized void insertSpecificElementAt(int index) {
        // Update derivedGauge, derivedGaugeTimestamp, and status arrays.
        //

	if (index != elementCount)
	    throw new Error("Internal error: index != elementCount");

	if (elementCount >= derivedGauge.length) {
	    derivedGauge = expandArray(derivedGauge);
	    derivedGaugeTimestamp = expandArray(derivedGaugeTimestamp);
	    status = expandArray(status);
	}

	derivedGauge[index] = "";
	derivedGaugeTimestamp[index] = System.currentTimeMillis();
	status[index] = MATCHING_OR_DIFFERING;
    }

    /**
     * This method is called when removing an observed object from the vector.
     * It updates all the string specific arrays.
     * @param index The index of the observed object.
     */
    synchronized void removeSpecificElementAt(int index) {
	if (index < 0 || index >= elementCount)
	    return;

        // Update derivedGauge, derivedGaugeTimestamp, and status arrays.
        //
        removeElementAt(derivedGauge, index);
        removeElementAt(derivedGaugeTimestamp, index);
        removeElementAt(status, index);
    }

    /**
     * StringAlarmClock inner class:
     * This class provides a simple implementation of an alarm clock MBean.
     * The aim of this MBean is to set up an alarm which wakes up the
     * string monitor every granularity period.
     */

    private static class StringAlarmClock extends TimerTask {

	StringMonitor listener = null;

	/*
	 * ------------------------------------------
	 *  CONSTRUCTORS
	 * ------------------------------------------
	 */

	public StringAlarmClock(StringMonitor listener) {
	    this.listener = listener;
	}

	/*
	 * ------------------------------------------
	 *  PUBLIC METHODS
	 * ------------------------------------------
	 */

	/**
	 * This method is called by the StringAlarmClock thread when
	 * it is started.
	 */
	public void run() {
	    if (listener.isActive) {
		for (int i = 0; i < listener.elementCount; i++) {
		    listener.notifyAlarmClock(i);
		}
	    }
	}
    }
}