/*
    * Copyright 2012-2013 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.configuration.support;
  
  import java.util.Collection;
  import java.util.HashMap;
  import java.util.Map;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentMap;
  
  import org.springframework.batch.core.Step;
  import org.springframework.batch.core.configuration.DuplicateJobException;
  import org.springframework.batch.core.configuration.StepRegistry;
  import org.springframework.batch.core.launch.NoSuchJobException;
  import org.springframework.batch.core.step.NoSuchStepException;
  import org.springframework.util.Assert;
  
  /**
   * Simple map-based implementation of {@link StepRegistry}. Access to the map is
   * synchronized, guarded by an internal lock.
   *
   * @author Sebastien Gerard
   * @author Stephane Nicoll
   */
  public class MapStepRegistry implements StepRegistry {
  
  	private final ConcurrentMap<String, Map<String, Step>> map = new ConcurrentHashMap<String, Map<String, Step>>();
  
  	@Override
  	public void register(String jobName, Collection<Step> steps) throws DuplicateJobException {
  		Assert.notNull(jobName, "The job name cannot be null.");
  		Assert.notNull(steps, "The job steps cannot be null.");
  
  
  		final Map<String, Step> jobSteps = new HashMap<String, Step>();
  		for (Step step : steps) {
  			jobSteps.put(step.getName(), step);
  		}
  		final Object previousValue = map.putIfAbsent(jobName, jobSteps);
  		if (previousValue != null) {
  			throw new DuplicateJobException("A job configuration with this name [" + jobName
  					+ "] was already registered");
  		}
  	}
  
  	@Override
  	public void unregisterStepsFromJob(String jobName) {
  		Assert.notNull(jobName, "Job configuration must have a name.");
  		map.remove(jobName);
  	}
  
  	@Override
  	public Step getStep(String jobName, String stepName) throws NoSuchJobException {
  		Assert.notNull(jobName, "The job name cannot be null.");
  		Assert.notNull(stepName, "The step name cannot be null.");
  		if (!map.containsKey(jobName)) {
  			throw new NoSuchJobException("No job configuration with the name [" + jobName + "] was registered");
  		} else {
  			final Map<String, Step> jobSteps = map.get(jobName);
  			if (jobSteps.containsKey(stepName)) {
  				return jobSteps.get(stepName);
  			} else {
  				throw new NoSuchStepException("The step called [" + stepName + "] does not exist in the job [" +
  						jobName + "]");
  			}
  		}
  	}
  
  }