package com.atlassian.johnson.config;
   
   import com.atlassian.johnson.event.*;
   import com.atlassian.johnson.setup.ContainerFactory;
   import com.atlassian.johnson.setup.DefaultContainerFactory;
   import com.atlassian.johnson.setup.DefaultSetupConfig;
   import com.atlassian.johnson.setup.SetupConfig;
   
   import java.util.Collections;
  import java.util.List;
  import java.util.Map;
  
  /**
   * A default implementation of {@link JohnsonConfig} which may be used as a failsafe when no other configuration is
   * available.
   * <p/>
   * All URIs are {@link #isIgnoredPath(String) ignored} by this implementation. All collection-returning properties are
   * implemented to return empty, immutable collections. All other methods generally return {@code null}, except for:
   * <ul>
   *     <li>{@link SetupConfig} is provided by {@link DefaultSetupConfig}</li>
   *     <li>{@link ContainerFactory} is provided by {@link DefaultContainerFactory}</li>
   * </ul>
   * This class cannot be instantiated. A single, immutable instance is available via {@link #getInstance()}.
   *
   * @since 2.0
   */
  public final class DefaultJohnsonConfig implements JohnsonConfig
  {
      private static final DefaultJohnsonConfig instance = new DefaultJohnsonConfig();
  
      private final ContainerFactory containerFactory;
      private final SetupConfig setupConfig;
  
      private DefaultJohnsonConfig()
      {
          containerFactory = new DefaultContainerFactory();
          setupConfig = new DefaultSetupConfig();
      }
  
      /**
       * Retrieves the immutable singleton instance of the default configuration.
       * 
       * @return the default configuration singleton
       */
      public static JohnsonConfig getInstance()
      {
          return instance;
      }
  
      /**
       * Always empty but non-{@code null}.
       * 
       * @return an empty list
       */
      @Override
      public List<ApplicationEventCheck> getApplicationEventChecks()
      {
          return Collections.emptyList();
      }
  
      /**
       * Always an instance of {@link DefaultContainerFactory}.
       * 
       * @return a default container factory
       */
      @Override
      public ContainerFactory getContainerFactory()
      {
          return containerFactory;
      }
  
      /**
       * Always {@code null}.
       * 
       * @return {@code null}
       */
      @Override
      public String getErrorPath()
      {
          return null;
      }
  
      /**
       * Always {@code null}.
       * 
       * @param id ignored
       * @return {@code null}
       */
      @Override
      public EventCheck getEventCheck(int id)
      {
          return null;
      }
  
      /**
       * Always empty but non-{@code null}.
       * 
       * @return an empty list
       */
     @Override
     public List<EventCheck> getEventChecks()
     {
         return Collections.emptyList();
     }
 
     /**
      * Always {@code null}.
      * 
      * @param level ignored
      * @return {@code null}
      */
     @Override
     public EventLevel getEventLevel(String level)
     {
         return null;
     }
 
     /**
      * Always {@code null}.
      *
      * @param type ignored
      * @return {@code null}
      */
     @Override
     public EventType getEventType(String type)
     {
         return null;
     }
 
     /**
      * Always empty but non-{@code null}.
      * 
      * @return an empty list
      */
     @Override
     public List<String> getIgnorePaths()
     {
         return Collections.emptyList();
     }
 
     /**
      * Always empty but non-{@code null}.
      * 
      * @return an empty map
      */
     @Override
     public Map<String, String> getParams()
     {
         return Collections.emptyMap();
     }
 
     /**
      * Always empty but non-{@code null}.
      * 
      * @return an empty list
      */
     @Override
     public List<RequestEventCheck> getRequestEventChecks()
     {
         return Collections.emptyList();
     }
 
     /**
      * Always an instance of {@link DefaultSetupConfig}.
      */
     @Override
     public SetupConfig getSetupConfig()
     {
         return setupConfig;
     }
 
     /**
      * Always {@code null}.
      *
      * @return {@code null}
      */
     @Override
     public String getSetupPath()
     {
         return null;
     }
 
     /**
      * Always {@code true}. This has the net effect of disabling Johnson, because all URIs included for filtering will
      * be ignored and events will not be processed for them.
      *
      * @param uri ignored
      * @return {@code true}
      */
     @Override
     public boolean isIgnoredPath(String uri)
     {
         return true;
     }
 }