/**
    * This file Copyright (c) 2009-2018 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.imaging;
  
  import info.magnolia.context.MgnlContext;
  import info.magnolia.imaging.util.PathSplitter;
  import info.magnolia.init.MagnoliaConfigurationProperties;
  import info.magnolia.objectfactory.Components;
  
  import java.io.IOException;
  import java.io.OutputStream;
  import java.util.concurrent.ExecutorService;
  import java.util.concurrent.Executors;
  
  import javax.inject.Inject;
  import javax.inject.Provider;
  import javax.servlet.AsyncContext;
  import javax.servlet.ServletException;
  import javax.servlet.ServletResponse;
  import javax.servlet.http.HttpServlet;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import com.google.common.net.MediaType;
  
  /**
   * Servlet responsible for the actual generation of the images.
   */
  public class ImagingServlet extends HttpServlet {
      private static final Logger log = LoggerFactory.getLogger(ImagingServlet.class);
      private final Imaging imaging;
      private final Provider<ImagingModule> imagingModuleProvider;
      private ExecutorService workers;
  
  
      @Inject
      public ImagingServlet(Imaging imaging, Provider<ImagingModule> imagingModuleProvider, MagnoliaConfigurationProperties mcp) {
          this.imaging = imaging;
          this.imagingModuleProvider = imagingModuleProvider;
          int workersCount = 4;
          if (mcp.hasProperty("imaging.workers.count")) {
              try {
                  workersCount = Integer.parseInt(mcp.getProperty("imaging.workers.count"));
              } catch (NumberFormatException e) {
                  log.error("Failed to parse the number of imaging workers, falling back to 4");
              }
          }
          this.workers = Executors.newFixedThreadPool(workersCount);
      }
  
      /**
       * @deprecated since 3.4.3 - use {@link #ImagingServlet(Imaging, Provider, MagnoliaConfigurationProperties)} instead.
       */
      @Deprecated
      public ImagingServlet(Imaging imaging, Provider<ImagingModule> imagingModuleProvider) {
          this(imaging, imagingModuleProvider, Components.getComponent(MagnoliaConfigurationProperties.class));
      }
  
      /**
       * @deprecated Since Imaging 3.3 (Magnolia 5.5), use {@link ImagingServlet(Imaging)}.
       */
      @Deprecated
      public ImagingServlet(final ImagingModule imagingModule) {
          this.imaging = Components.getComponent(Imaging.class);
          this.imagingModuleProvider = new Provider<ImagingModule>() {
             @Override
             public ImagingModule get() {
                 return Components.getComponent(ImagingModule.class);
             }
         };
     }
 
 
     @Override
     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
         AsyncContext asyncContext = request.startAsync();
         log.debug("Requesting {}", request.getRequestURI());
         workers.submit(() -> {
             MgnlContext.doInSystemContext(new MgnlContext.VoidOp() {
 
                 @Override
                 public void doExec() {
                     try {
                         String generatorName = getImageGeneratorName(request);
                         imaging.generate(generatorName, request, new ServletImageResponse(asyncContext.getResponse()));
                         log.debug("Generated image for {}", request.getRequestURI());
                         asyncContext.getResponse().flushBuffer();
                     } catch (IllegalArgumentException | ImagingRuntimeException | ImagingException e) {
                         log.warn("Because of incorrect arguments the image couldn't be found", e);
                         sendError(asyncContext, HttpServletResponse.SC_NOT_FOUND, "");
                     } catch (IOException e) {
                         // only log at debug level
                         // tomcat usually throws a ClientAbortException anytime the user stop loading the page
                         log.debug("Unable to spool resource due to a {} exception", e.getClass().getName());
                         if (!asyncContext.getResponse().isCommitted()) {
                             sendError(asyncContext, HttpServletResponse.SC_INTERNAL_SERVER_ERROR, "");
                         }
                     } finally {
                         asyncContext.complete();
                     }
                 }
             });
 
         });
     }
 
 
     private void sendError(AsyncContext asyncContext, int statusCode, String message) {
         if(asyncContext.getResponse() instanceof HttpServletResponse)
             try {
                 ((HttpServletResponse) asyncContext.getResponse()).sendError(statusCode, message);
             } catch (IOException e) {
                 e.printStackTrace();
             }
     }
 
     /**
      * Determines the ImageGenerator to use, using the first path element of the
      * pathInfo.
      */
     protected String getImageGeneratorName(HttpServletRequest request) {
         final String pathInfo = request.getPathInfo();
         return new PathSplitter(pathInfo).skipTo(0);
     }
 
     protected ImageGenerator getGenerator(String generatorName) {
         final ImagingModule module = getImagingModule();
         return module.getGenerators().get(generatorName);
     }
 
     protected ImagingModule getImagingModule() {
         return imagingModuleProvider.get();
     }
 
     private static class ServletImageResponse implements ImageResponse {
         private final ServletResponse response;
 
         public ServletImageResponse(ServletResponse response) {
             this.response = response;
         }
 
         @Override
         public void setMediaType(MediaType mediaType) throws IOException {
             response.setContentType(mediaType.toString());
         }
 
         @Override
         public OutputStream getOutputStream() throws IOException {
             return response.getOutputStream();
         }
     }
 }