/*
    * Copyright 2006-2010 the original author or authors.
    *
    * 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 org.springframework.batch.admin.jmx;
  
  import javax.management.ObjectName;
  import javax.management.monitor.GaugeMonitor;
  import javax.management.monitor.MonitorMBean;
  
  import org.springframework.beans.factory.FactoryBean;
  import org.springframework.beans.factory.InitializingBean;
  import org.springframework.util.Assert;
  
  /**
   * Monitors executions of a given step and sends JMX notifications if it takes
   * too long. The monitor is a {@link MonitorMBean} so it can be automatically
   * exposed to an existing MBeanServer using Spring JMX. JMX clients subscribe to
   * notifications and receive them whenever the thresholds are crossed.
   * 
   * @author Dave Syer
   * 
   */
  public class StepExecutionServiceLevelMonitor implements FactoryBean<GaugeMonitor>, InitializingBean {
  
  	private String defaultDomain = BatchMBeanExporter.DEFAULT_DOMAIN;
  
  	private String stepName;
  
  	private String jobName;
  
  	private int upperThreshold = 0;
  
  	private int lowerThreshold = 0;
  
  	private boolean autoStart = true;
  
  	private String observedAttribute = "LatestDuration";
  
  	/**
  	 * The name of the attribute to monitor on the step. Defaults to
  	 * <code>LatestDuration</code>. This can be changed at runtime, but note
  	 * that if the type of the observed metric changes (e.g. from double to
  	 * integer) then the thresholds will also have to be changed so their type
  	 * matches.
  	 * 
  	 * @param observedAttribute the observed attribute to set
  	 */
  	public void setObservedAttribute(String observedAttribute) {
  		this.observedAttribute = observedAttribute;
  	}
  
  	/**
  	 * Should the monitor start immediately or wait to be started manually?
  	 * 
  	 * @param autoStart the auto start flag to set
  	 */
  	public void setAutoStart(boolean autoStart) {
  		this.autoStart = autoStart;
  	}
  
  	/**
  	 * The domain name to use in constructing object names for the monitored
  	 * step. Default to <code>org.springframework.batch</code> (same as
  	 * {@link BatchMBeanExporter}).
  	 * 
  	 * @param defaultDomain the default domain to set
  	 */
  	public void setDefaultDomain(String defaultDomain) {
  		this.defaultDomain = defaultDomain;
  	}
  
  	/**
  	 * @param stepName the stepName to set
  	 */
  	public void setStepName(String stepName) {
  		this.stepName = stepName;
  	}
  
  	/**
  	 * @param jobName the jobName to set
  	 */
  	public void setJobName(String jobName) {
  		this.jobName = jobName;
  	}
  
  	/**
  	 * Upper threshold for observed attribute. Mandatory with no default.
 	 * 
 	 * @param upperThreshold the upper threshold to set
 	 */
 	public void setUpperThreshold(int upperThreshold) {
 		this.upperThreshold = upperThreshold;
 	}
 
 	/**
 	 * Optional lower threshold. Defaults to 80% of the upper threshold.
 	 * 
 	 * @param lowerThreshold the lower threshold to set
 	 */
 	public void setLowerThreshold(int lowerThreshold) {
 		this.lowerThreshold = lowerThreshold;
 	}
 
 	public GaugeMonitor getObject() throws Exception {
 		GaugeMonitor monitor = new GaugeMonitor();
 		monitor.setNotifyHigh(true);
 		monitor.addObservedObject(new ObjectName(String.format("%s:type=JobExecution,name=%s,step=%s", defaultDomain,
 				jobName, stepName)));
 		monitor.setObservedAttribute(observedAttribute);
 		if (observedAttribute.endsWith("Duration")) {
 			monitor.setThresholds(new Double(upperThreshold), new Double(lowerThreshold));
 		}
 		else {
 			monitor.setThresholds(new Integer(upperThreshold), new Integer(lowerThreshold));
 		}
 		if (autoStart) {
 			monitor.start();
 		}
 		return monitor;
 	}
 
 	public Class<?> getObjectType() {
 		return GaugeMonitor.class;
 	}
 
 	public boolean isSingleton() {
 		return true;
 	}
 
 	public void afterPropertiesSet() throws Exception {
 		Assert.state(jobName != null, "A Job name must be provided");
 		Assert.state(stepName != null, "A Step name must be provided");
 		Assert.state(upperThreshold > 0, "A threshold must be provided");
 		Assert.state(lowerThreshold < upperThreshold, "A threshold must be provided");
 		if (lowerThreshold == 0) {
 			lowerThreshold = upperThreshold * 8 / 10;
 		}
 	}
 
 }