package fr.ifremer.quadrige2.core.service;
   
   /*-
    * #%L
    * Quadrige2 Core :: Quadrige2 Core Shared
    * $Id:$
    * $HeadURL:$
    * %%
    * Copyright (C) 2017 Ifremer
   * %%
   * This program is free software: you can redistribute it and/or modify
   * it under the terms of the GNU Affero General Public License as published by
   * the Free Software Foundation, either version 3 of the License, or
   * (at your option) any later version.
   * 
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   * 
   * You should have received a copy of the GNU Affero General Public License
   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
   * #L%
   */
  
  import fr.ifremer.quadrige2.core.security.SecurityContext;
  import fr.ifremer.quadrige2.core.service.technical.CacheService;
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.springframework.beans.factory.access.BeanFactoryLocator;
  import org.springframework.beans.factory.access.BeanFactoryReference;
  import org.springframework.context.ApplicationContext;
  import org.springframework.context.access.ContextSingletonBeanFactoryLocator;
  import org.springframework.context.support.AbstractApplicationContext;
  
  import java.io.Closeable;
  import java.io.IOException;
  
  /**
   * Locates and provides all available application services.
   */
  public class ServiceLocator implements Closeable {
  
      /* Logger */
      private static final Log log = LogFactory.getLog(ServiceLocator.class);
  
      /**
       * The default bean reference factory location.
       */
      private static final String DEFAULT_BEAN_REFERENCE_LOCATION = "beanRefFactory.xml";
  
      /**
       * The default bean reference factory ID.
       */
      private static final String DEFAULT_BEAN_REFERENCE_ID = "beanRefFactory";
  
      /**
       * The shared instance of this ServiceLocator.
       */
      private static ServiceLocator instance = new ServiceLocator();
  
      /**
       * Indicates if the spring context is open or not.
       */
      private boolean open = false;
  
      /**
       * <p>Constructor for ServiceLocator.</p>
       */
      protected ServiceLocator() {
          // shouldn't be instantiated
          init(null, null);
      }
  
      /**
       * <p>Constructor for ServiceLocator.</p>
       *
       * @param beanFactoryReferenceLocation a {@link java.lang.String} object.
       * @param beanRefFactoryReferenceId    a {@link java.lang.String} object.
       */
      protected ServiceLocator(String beanFactoryReferenceLocation,
                               String beanRefFactoryReferenceId) {
          init(beanFactoryReferenceLocation, beanRefFactoryReferenceId);
      }
  
      /**
       * replace the default shared instance of this Class
       *
       * @param newInstance the new shared service locator instance.
       */
      public static void setInstance(ServiceLocator newInstance) {
          instance = newInstance;
      }
  
      /**
       * Gets the shared instance of this Class
       *
       * @return the shared service locator instance.
       */
     public static ServiceLocator instance() {
         return instance;
     }
 
     /**
      * The bean factory reference instance.
      */
     private BeanFactoryReference beanFactoryReference;
 
     /**
      * The bean factory reference location.
      */
     private String beanFactoryReferenceLocation;
 
     /**
      * The bean factory reference id.
      */
     private String beanRefFactoryReferenceId;
 
     /**
      * <p>initQuadrige2Default.</p>
      */
     public static void initQuadrige2Default() {
         instance.init(null, null);
         ServiceLocator.setInstance(instance);
     }
 
     /**
      * Initializes the Spring application context from the given <code>beanFactoryReferenceLocation</code>. If <code>null</code> is
      * specified for the <code>beanFactoryReferenceLocation</code> then the
      * default application context will be used.
      *
      * @param beanFactoryReferenceLocation the location of the beanRefFactory reference.
      * @param beanRefFactoryReferenceId    a {@link java.lang.String} object.
      */
     public synchronized void init(String beanFactoryReferenceLocation,
                                   String beanRefFactoryReferenceId) {
         // Log if default values are overrided
         if (log.isDebugEnabled() && beanFactoryReferenceLocation != null && beanRefFactoryReferenceId != null) {
             log.debug(String.format("Initializing ServiceLocator to use Spring bean factory [%s] at: %s", beanRefFactoryReferenceId,
                     beanFactoryReferenceLocation));
         }
 
         this.beanFactoryReferenceLocation =
                 beanFactoryReferenceLocation == null ?
                         DEFAULT_BEAN_REFERENCE_LOCATION :
                         beanFactoryReferenceLocation;
         this.beanRefFactoryReferenceId = beanRefFactoryReferenceId == null ?
                 DEFAULT_BEAN_REFERENCE_ID :
                 beanRefFactoryReferenceId;
         this.beanFactoryReference = null;
     }
 
     /**
      * Initializes the Spring application context from the given <code>beanFactoryReferenceLocation</code>. If <code>null</code> is
      * specified for the <code>beanFactoryReferenceLocation</code> then the
      * default application context will be used.
      *
      * @param beanFactoryReferenceLocation the location of the beanRefFactory reference.
      */
     public synchronized void init(String beanFactoryReferenceLocation) {
         this.beanFactoryReferenceLocation = beanFactoryReferenceLocation == null ?
                 DEFAULT_BEAN_REFERENCE_LOCATION :
                 beanFactoryReferenceLocation;
         this.beanFactoryReference = null;
     }
 
     /**
      * Shuts down the ServiceLocator and releases any used resources.
      */
     public synchronized void shutdown() {
         // Do not try to close if not already opened
         if (!open) {
             return;
         }
         if (log.isDebugEnabled()) {
             log.debug("Close Spring application context");
         }
 
         ((AbstractApplicationContext) getContext()).close();
         if (beanFactoryReference != null) {
             beanFactoryReference.release();
             beanFactoryReference = null;
         }
         open = false;
     }
 
     /**
      * Get a service.
      *
      * @param name        name of the service (i.e name of the srping bean)
      * @param serviceType type of service
      * @param <S>         type of the service
      * @return the instanciated service
      */
     public <S> S getService(String name, Class<S> serviceType) {
         return getContext().getBean(name, serviceType);
     }
 
     /**
      * Gets an instance of {@link fr.ifremer.quadrige2.core.service.technical.CacheService}.
      *
      * @return a {@link fr.ifremer.quadrige2.core.service.technical.CacheService} object.
      */
     public final CacheService getCacheService() {
         return getService("cacheService", CacheService.class);
     }
 
     /**
      * <p>isOpen.</p>
      *
      * @return {@code true} if spring context is open, {@code false} otherwise.
      * @since 3.5.2
      */
     public boolean isOpen() {
         return open;
     }
 
     /**
      * Gets the Spring ApplicationContext.
      *
      * @return a {@link org.springframework.context.ApplicationContext} object.
      */
     protected synchronized ApplicationContext getContext() {
         if (beanFactoryReference == null) {
             if (log.isDebugEnabled() && beanFactoryReferenceLocation != null && beanRefFactoryReferenceId != null) {
                 log.debug(String.format("Starting Spring application context using bean factory [%s] from file: %s", beanRefFactoryReferenceId,
                         beanFactoryReferenceLocation));
             }
             BeanFactoryLocator beanFactoryLocator =
                     ContextSingletonBeanFactoryLocator.getInstance(
                             beanFactoryReferenceLocation);
             beanFactoryReference = beanFactoryLocator
                     .useBeanFactory(beanRefFactoryReferenceId);
 
             open = true;
         }
         return (ApplicationContext) beanFactoryReference.getFactory();
     }
 
     /**
      * {@inheritDoc}
      */
     @Override
     public void close() throws IOException {
         shutdown();
     }
 
     /**
      * <p>getDatabaseSchemaService.</p>
      *
      * @return a {@link fr.ifremer.quadrige2.core.service.DatabaseSchemaService} object.
      */
     public DatabaseSchemaService getDatabaseSchemaService() {
         return getService("databaseSchemaService", DatabaseSchemaService.class);
     }
 
     /**
      * <p>getSecurityContext.</p>
      *
      * @return a {@link fr.ifremer.quadrige2.core.security.SecurityContext} object.
      */
     public SecurityContext getSecurityContext() {
         return getService("securityContext", SecurityContext.class);
     }
 
 }