package com.atlassian.plugin.metadata;
   
   import com.atlassian.plugin.ModuleDescriptor;
   import com.atlassian.plugin.Plugin;
   import com.atlassian.plugin.descriptors.CannotDisable;
   import net.jcip.annotations.Immutable;
   
   import static com.google.common.base.Preconditions.checkNotNull;
   
  /**
   * A default implementation that uses the {@link com.atlassian.plugin.metadata.ClasspathFilePluginMetadata}
   * plugin metadata implementation to resolve the application provided plugin metadata.
   *
   * @since 2.6
   */
  @Immutable
  public final class DefaultPluginMetadataManager implements PluginMetadataManager
  {
      private final PluginMetadata metadata;
  
      /**
       * Production ctor. Loads from the class path.
       */
      public DefaultPluginMetadataManager()
      {
          this(new ClasspathFilePluginMetadata());
      }
  
      /**
       * Test ctor.
       */
      DefaultPluginMetadataManager(final PluginMetadata metadata)
      {
          this.metadata = checkNotNull(metadata, "metadata");
      }
  
      /**
       * <p>A plugin is determined to be non-user if
       * {@link com.atlassian.plugin.Plugin#isBundledPlugin()} is true or if the
       * host application has indicated to the plugins system that a plugin was
       * provided by it.</p>
       *
       * <p><strong>NOTE:</strong> If a user has upgraded a bundled plugin then the
       * decision of whether it is user installed plugin is determined by if the
       * application has indicated to the plugins system that a plugin was
       * provided or not.</p>
       */
      public boolean isUserInstalled(final Plugin plugin)
      {
          checkNotNull(plugin, "plugin");
          // It is user installed if it has not been marked as provided by the
          // application and it was not bundled.
          return !plugin.isBundledPlugin() && !metadata.applicationProvided(plugin);
      }
  
      /**
       * A plugin is determined to be &quot;system&quot; if
       * {@link #isUserInstalled(com.atlassian.plugin.Plugin)} is false.
       */
      public boolean isSystemProvided(Plugin plugin)
      {
          return !isUserInstalled(plugin);
      }
  
      /**
       * A plugin is determined to be optional if the host application has not
       * indicated to the plugins system that it is required or if any of its
       * modules have been flagged as not optional.
       */
      public boolean isOptional(final Plugin plugin)
      {
          checkNotNull(plugin, "plugin");
          // If the application has marked the plugin as required then we know we
          // are required
          if (!optionalAccordingToHostApplication(plugin))
          {
              return false;
          }
  
          // We need to check if any of the plugins modules are not optional
          for (final ModuleDescriptor<?> moduleDescriptor : plugin.getModuleDescriptors())
          {
              if (!optionalAccordingToHostApplication(moduleDescriptor))
              {
                  return false;
              }
          }
          return true;
      }
  
      /**
       * A module is determined to be optional if the host application has not
       * indicated to the plugins system that it is required. If the call to
       * {@code isOptional} with the module descriptor's plugin is {@code false},
       * then this method will also return {@code false}. Also if the module
       * descriptor is annotated with
       * {@link com.atlassian.plugin.descriptors.CannotDisable} then it can not be
       * optional.
       */
     public boolean isOptional(final ModuleDescriptor<?> moduleDescriptor)
     {
         checkNotNull(moduleDescriptor, "moduleDescriptor");
         // It is not optional if the host application has marked it as required
         if (!optionalAccordingToHostApplication(moduleDescriptor))
         {
             return false;
         }
 
         // A module can not be optional if it is marked 
         // by the CannotDisable annotation
         if (!optionalAccordingToModuleDescriptorType(moduleDescriptor))
         {
             return false;
         }
 
         // A module can only be optional if its parent plugin is not declared by
         // the host application as required
         return optionalAccordingToHostApplication(moduleDescriptor.getPlugin());
     }
 
     private boolean optionalAccordingToHostApplication(final Plugin plugin)
     {
         return !metadata.required(plugin);
     }
 
     private boolean optionalAccordingToHostApplication(final ModuleDescriptor<?> moduleDescriptor)
     {
         return !metadata.required(moduleDescriptor);
     }
 
     private boolean optionalAccordingToModuleDescriptorType(final ModuleDescriptor<?> moduleDescriptor)
     {
         return !moduleDescriptor.getClass().isAnnotationPresent(CannotDisable.class);
     }
 }