/*
    * Copyright 2006-2013 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.core.repository.dao;
  
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.Comparator;
  import java.util.List;
  import java.util.Set;
  import java.util.concurrent.CopyOnWriteArraySet;
  import java.util.concurrent.atomic.AtomicLong;
  
  import org.springframework.batch.core.JobExecution;
  import org.springframework.batch.core.JobInstance;
  import org.springframework.batch.core.JobParameters;
  import org.springframework.util.Assert;
  
  /**
   * In-memory implementation of {@link JobInstanceDao}.
   */
  public class MapJobInstanceDao implements JobInstanceDao {
  
  	// JDK6 Make a ConcurrentSkipListSet: tends to add on end
  	private final Set<JobInstance> jobInstances = new CopyOnWriteArraySet<JobInstance>();
  
  	private final AtomicLong currentId = new AtomicLong(0L);
  
  	public void clear() {
  		jobInstances.clear();
  	}
  
  	@Override
  	public JobInstance createJobInstance(String jobName, JobParameters jobParameters) {
  
  		Assert.state(getJobInstance(jobName, jobParameters) == null, "JobInstance must not already exist");
  
  		JobInstance jobInstance = new JobInstance(currentId.getAndIncrement(), jobParameters, jobName);
  		jobInstance.incrementVersion();
  		jobInstances.add(jobInstance);
  
  		return jobInstance;
  	}
  
  	@Override
  	public JobInstance getJobInstance(String jobName, JobParameters jobParameters) {
  
  		for (JobInstance instance : jobInstances) {
  			if (instance.getJobName().equals(jobName) && instance.getJobParameters().equals(jobParameters)) {
  				return instance;
  			}
  		}
  		return null;
  
  	}
  
  	@Override
  	public JobInstance getJobInstance(Long instanceId) {
  		for (JobInstance instance : jobInstances) {
  			if (instance.getId().equals(instanceId)) {
  				return instance;
  			}
  		}
  		return null;
  	}
  
  	@Override
  	public List<String> getJobNames() {
  		List<String> result = new ArrayList<String>();
  		for (JobInstance instance : jobInstances) {
  			result.add(instance.getJobName());
  		}
  		Collections.sort(result);
  		return result;
  	}
  
  	@Override
  	public List<JobInstance> getJobInstances(String jobName, int start, int count) {
  		List<JobInstance> result = new ArrayList<JobInstance>();
  		for (JobInstance instance : jobInstances) {
  			if (instance.getJobName().equals(jobName)) {
  				result.add(instance);
  			}
  		}
  		Collections.sort(result, new Comparator<JobInstance>() {
  			// sort by ID descending
 			@Override
 			public int compare(JobInstance o1, JobInstance o2) {
 				return Long.signum(o2.getId() - o1.getId());
 			}
 		});
 
 		int startIndex = Math.min(start, result.size());
 		int endIndex = Math.min(start + count, result.size());
 		return result.subList(startIndex, endIndex);
 	}
 
 	@Override
 	public JobInstance getJobInstance(JobExecution jobExecution) {
 		return jobExecution.getJobInstance();
 	}
 
 }