/**
    * Copyright 2010-2014 The Kuali Foundation
    *
    * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php
    *
   * 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.kuali.common.util.serviceloader;
  
  import static com.google.common.base.Preconditions.checkState;
  
  import java.util.Iterator;
  import java.util.List;
  import java.util.ServiceLoader;
  
  import com.google.common.collect.Lists;
  
  public class ServiceProvider {
  
  	/**
  	 * Return the first service located by ServiceLoader
  	 * 
  	 * @throws IllegalStateException
  	 *             If no service can be found
  	 */
  	public static <T> T getFirst(Class<T> type) {
  		return getFirst(type, Thread.currentThread().getContextClassLoader());
  	}
  
  	/**
  	 * Return the first service located by ServiceLoader
  	 * 
  	 * @throws IllegalStateException
  	 *             If no service can be found
  	 */
  	public static <T> T getFirst(Class<T> type, ClassLoader classLoader) {
  		ServiceLoader<T> loader = ServiceLoader.load(type, classLoader);
  		Iterator<T> itr = loader.iterator();
  		checkState(itr.hasNext(), "ServiceLoader could not find a service for type [%s]", type.getCanonicalName());
  		return itr.next();
  	}
  
  	/**
  	 * Return all service implementations located by ServiceLoader
  	 */
  	public static <T> List<T> getAll(Class<T> type) {
  		return getAll(type, Thread.currentThread().getContextClassLoader());
  	}
  
  	/**
  	 * Return all service implementations located by ServiceLoader
  	 */
  	public static <T> List<T> getAll(Class<T> type, ClassLoader classLoader) {
  		ServiceLoader<T> loader = ServiceLoader.load(type);
  		Iterator<T> itr = loader.iterator();
  		List<T> list = Lists.newArrayList();
  		while (itr.hasNext()) {
  			list.add(itr.next());
  		}
  		return list;
  	}
  
  }