/*
 * Copyright 2002-2011 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.scheduling.quartz;

import java.lang.reflect.Method;

import org.quartz.Job;
import org.quartz.Scheduler;
import org.quartz.SchedulerException;
import org.quartz.spi.JobFactory;
import org.quartz.spi.TriggerFiredBundle;

import org.springframework.util.ReflectionUtils;

/**
 * JobFactory implementation that supports {@link java.lang.Runnable}
 * objects as well as standard Quartz {@link org.quartz.Job} instances.
 *
 * <p>Compatible with Quartz 1.5+ as well as Quartz 2.0/2.1, as of Spring 3.1.
 *
 * @author Juergen Hoeller
 * @since 2.0
 * @see DelegatingJob
 * @see #adaptJob(Object)
 */
public class AdaptableJobFactory implements JobFactory {

	/**
	 * Quartz 2.0 version of newJob: simply delegates to old newJob variant.
	 * @see #newJob(org.quartz.spi.TriggerFiredBundle)
	 */
	public Job newJob(TriggerFiredBundle bundle, Scheduler scheduler) throws SchedulerException {
		return newJob(bundle);
	}

	/**
	 * Quartz 1.x version of newJob: contains actual implementation code.
	 */
	public Job newJob(TriggerFiredBundle bundle) throws SchedulerException {
		try {
			Object jobObject = createJobInstance(bundle);
			return adaptJob(jobObject);
		}
		catch (Exception ex) {
			throw new SchedulerException("Job instantiation failed", ex);
		}
	}

	/**
	 * Create an instance of the specified job class.
	 * <p>Can be overridden to post-process the job instance.
	 * @param bundle the TriggerFiredBundle from which the JobDetail
	 * and other info relating to the trigger firing can be obtained
	 * @return the job instance
	 * @throws Exception if job instantiation failed
	 */
	protected Object createJobInstance(TriggerFiredBundle bundle) throws Exception {
		// Reflectively adapting to differences between Quartz 1.x and Quartz 2.0...
		Method getJobDetail = bundle.getClass().getMethod("getJobDetail");
		Object jobDetail = ReflectionUtils.invokeMethod(getJobDetail, bundle);
		Method getJobClass = jobDetail.getClass().getMethod("getJobClass");
		Class jobClass = (Class) ReflectionUtils.invokeMethod(getJobClass, jobDetail);
		return jobClass.newInstance();
	}

	/**
	 * Adapt the given job object to the Quartz Job interface.
	 * <p>The default implementation supports straight Quartz Jobs
	 * as well as Runnables, which get wrapped in a DelegatingJob.
	 * @param jobObject the original instance of the specified job class
	 * @return the adapted Quartz Job instance
	 * @throws Exception if the given job could not be adapted
	 * @see DelegatingJob
	 */
	protected Job adaptJob(Object jobObject) throws Exception {
		if (jobObject instanceof Job) {
			return (Job) jobObject;
		}
		else if (jobObject instanceof Runnable) {
			return new DelegatingJob((Runnable) jobObject);
		}
		else {
			throw new IllegalArgumentException("Unable to execute job class [" + jobObject.getClass().getName() +
					"]: only [org.quartz.Job] and [java.lang.Runnable] supported.");
		}
	}

}
