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/*
 *      Copyright 2005 stat4j.org
 *
 *   Licensed under the Apache License, Version 2.0 (the "License");
 *   you may not use this file except in compliance with the License.
 *      You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 *   Unless required by applicable law or agreed to in writing, software
 *   distributed under the License is distributed on an "AS IS" BASIS,
 *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *   See the License for the specific language governing permissions and
 *   limitations under the License.
 */
package net.sourceforge.stat4j;

import java.util.Properties;

import net.sourceforge.stat4j.util.Log;

/**
 * Name: Alert.java Date: Sep 6, 2004 Description:
 * 
 * Simple threshold based alert.
 * 
 * This class represents a pre-configured alert for a statistic.
 * 
 * The alert will be evaluated every time the statistic is updated. (alert
 * suppresion is not supported in this version)
 * 
 * If the alert fires (either WARN or CRITICAL) then an alert message will be
 * sent to the nominated log4j category (console,email,NT event log etc)
 * 
 * @see Threashold
 * 
 * @author Lara D'Abreo
 * @author Jakub Holy
 */
public final class Alert {

        protected String name;
        protected String statisticName;
        protected String category;
        protected String description;
        protected Threshold warn;
        protected Threshold critical;
    
    protected long lastAlertedMs;
    private long quietPeriodMs = 1000 * 60 * 10; // 10 min
    private boolean lastAlertCritical = false;

    public void init(String name, Properties properties) {
                this.name = name;

                statisticName = properties.getProperty("statistic");

                description = properties.getProperty("description");
                if (description == null) {
                        description = name;
                }
                // init category
                category = (String) properties.get("category");
                if (category == null) {
                        category = "alerts";
                }

                // init warn
                String str = (String) properties.get("warn");
                if (str != null) {
                        warn = Threshold.toThreshold(str);
                }

                // init critical
                str = (String) properties.get("critical");
                if (str != null) {
                        critical = Threshold.toThreshold(str);
                }

        str = (String) properties.getProperty("quietperiod");
        if (str != null) {
            quietPeriodMs = Long.parseLong(str);
        }

        }

        public boolean evaluateAlert(double value) {
        boolean triggered = false;
                if (isTriggered(critical, value, true)) {
            triggered = true;
            lastAlertCritical = true;
                        Log.error(
                                category,
                                "CRITICAL Alert "
                                        + description
                                        + " rule "
                                        + critical
                                        + " value "
                                        + value);
                } else if (isTriggered(warn, value, false)) {
            triggered = true;
            lastAlertCritical = false;
                        Log.error(
                                category,
                                "WARN Alert "
                                        + description
                                        + " rule "
                                        + warn
                                        + " value "
                                        + value);
                }

        if (triggered) {
            lastAlertedMs = System.currentTimeMillis();
        }

        return triggered;

    }

        boolean isTriggered(Threshold t, double value, boolean critical) {
                if (t == null) return false;

        boolean inQuietPeriod = (System.currentTimeMillis() - lastAlertedMs) <= quietPeriodMs;
        boolean newCritical = critical && !lastAlertCritical;
        boolean ignoreEvent = inQuietPeriod && !newCritical;

        boolean result = !ignoreEvent && t.isTriggered(value);

        //System.out.println("Alert.isTriggered: quiet=" + inQuietPeriod + ", result=" + result + ", last alert at " + lastAlertedMs);

        return result;
        }

        /**
         * @return
         */
        public String getName() {
                return name;
        }

        /**
         * @return
         */
        public String getStatisticName() {
                return statisticName;
        }

}