/**
    * This file Copyright (c) 2013-2016 Magnolia International
    * Ltd.  (http://www.magnolia-cms.com). All rights reserved.
    *
    *
    * This file is dual-licensed under both the Magnolia
    * Network Agreement and the GNU General Public License.
    * You may elect to use one or the other of these licenses.
    *
   * This file is distributed in the hope that it will be
   * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
   * implied warranty of MERCHANTABILITY or FITNESS FOR A
   * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
   * Redistribution, except as permitted by whichever of the GPL
   * or MNA you select, is prohibited.
   *
   * 1. For the GPL license (GPL), you can redistribute and/or
   * modify this file under the terms of the GNU General
   * Public License, Version 3, as published by the Free Software
   * Foundation.  You should have received a copy of the GNU
   * General Public License, Version 3 along with this program;
   * if not, write to the Free Software Foundation, Inc., 51
   * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * 2. For the Magnolia Network Agreement (MNA), this file
   * and the accompanying materials are made available under the
   * terms of the MNA which accompanies this distribution, and
   * is available at http://www.magnolia-cms.com/mna.html
   *
   * Any modifications to this file must keep this entire header
   * intact.
   *
   */
  package info.magnolia.rest.tools;
  
  import info.magnolia.cms.util.CustomServletConfig;
  import info.magnolia.context.MgnlContext;
  import info.magnolia.event.EventBus;
  import info.magnolia.event.SystemEventBus;
  import info.magnolia.rest.RestDispatcherServlet;
  import info.magnolia.rest.RestIntegrationModule;
  import info.magnolia.rest.registry.ConfiguredEndpointDefinition;
  import info.magnolia.rest.registry.EndpointDefinitionRegistry;
  import info.magnolia.rest.registry.EndpointDefinitionRegistryEvent;
  
  import java.io.IOException;
  import java.util.HashMap;
  
  import javax.inject.Inject;
  import javax.inject.Named;
  import javax.servlet.ServletConfig;
  import javax.servlet.ServletException;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  import io.swagger.jaxrs.config.DefaultJaxrsConfig;
  import io.swagger.jaxrs.listing.ApiListingResource;
  
  /**
   * API-aware dispatcher of the rest requests to the dynamically registered endpoints.
   *
   * Additional providers needed for the API documentation are loaded in {@link info.magnolia.rest.RestDispatcherServlet}.
   * More providers can be loaded by adding them to the configuration of {@link info.magnolia.rest.RestIntegrationModule}.
   */
  public class SwaggerRestDispatcherServlet extends RestDispatcherServlet {
  
      private final static String PARAMETER_API_VERSION = "api.version";
      private final static String PARAMETER_API_BASEPATH = "swagger.api.basepath";
      private static final String ENDPOINT_NAME = "api-listing-resource-json";
      /**
       * Key of object in servlet context where swagger caches data.
       */
      static final String SWAGGER = "swagger";
  
      private final RestToolsModule restToolsModule;
      private DefaultJaxrsConfig config;
      /**
       * Indicates that endpoint definitions have changed. Swagger caches some information in the servlet context
       * (see {@link ApiListingResource}), which we can only access (and flush) during a request. However, since notifications
       * about changed endpoint definitions arrive independently of requests, we use this flag to keep track of 'staleness'
       * and flush on the next request we encounter.
       */
      private boolean swaggerCacheIsStale = false;
  
      @Inject
      public SwaggerRestDispatcherServlet(final RestIntegrationModule restIntegrationModule, final EndpointDefinitionRegistry endpointDefinitionRegistry, @Named(SystemEventBus.NAME) EventBus systemEventBus, final RestToolsModule restToolsModule) {
          super(restIntegrationModule, endpointDefinitionRegistry, systemEventBus);
          this.restToolsModule = restToolsModule;
      }
  
      @Override
      public void init(ServletConfig servletConfig) throws ServletException {
          super.init(servletConfig);
  
          initApiListing();
  
          config = new DefaultJaxrsConfig();
          HashMap<String, String> initParameters = new HashMap<String, String>();
          initParameters.put(PARAMETER_API_VERSION, restToolsModule.getApiVersion());
         initParameters.put(PARAMETER_API_BASEPATH, restToolsModule.getApiBasepath());
         config.init(new CustomServletConfig("DefaultJaxrsConfig", super.getServletContext(), initParameters));
     }
 
     private void initApiListing() {
         // Register API listing resource
         ConfiguredEndpointDefinition endpointDefinition = new ConfiguredEndpointDefinition();
         endpointDefinition.setImplementationClass(ApiListingResource.class);
         endpointDefinition.setName(ENDPOINT_NAME);
         super.registerEndpoint(endpointDefinition);
     }
 
     /**
      * Refresh doc listings after changes in endpoint config.
      * In particular, un- and re-register the doc endpoint to create new instances in order to get rid of internal cachings,
      * like in {@link ApiListingResource}. Then set a flag to flush additional cached data in servlet context on next opportunity.
      */
     private void refreshApiListing() {
         unregisterEndpoint(ENDPOINT_NAME);
         initApiListing();
         swaggerCacheIsStale = true;
     }
 
     @Override
     protected void service(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) throws ServletException, IOException {
         // Swagger caches data in context -> hack it away. Sometimes you gotta turn your swag off.
         if (swaggerCacheIsStale) {
             MgnlContext.getWebContext().getServletContext().removeAttribute(SWAGGER);
             swaggerCacheIsStale = false;
         }
 
         super.service(httpServletRequest, httpServletResponse);
     }
 
     @Override
     public void destroy() {
         unregisterEndpoint(ENDPOINT_NAME);
         super.destroy();
         if (config != null) {
             config.destroy();
         }
     }
 
     @Override
     public void onEndpointRegistered(EndpointDefinitionRegistryEvent event) {
         super.onEndpointRegistered(event);
         refreshApiListing();
     }
 
     @Override
     public void onEndpointReregistered(EndpointDefinitionRegistryEvent event) {
         super.onEndpointReregistered(event);
         refreshApiListing();
     }
 
     @Override
     public void onEndpointUnregistered(EndpointDefinitionRegistryEvent event) {
         super.onEndpointUnregistered(event);
         refreshApiListing();
     }
 }