package com.atlassian.plugin.servlet;
   
   import com.atlassian.plugin.servlet.util.LastModifiedHandler;
   import com.atlassian.plugin.webresource.PluginResourceLocator;
   
   import javax.servlet.http.HttpServletRequest;
   import javax.servlet.http.HttpServletResponse;
   import java.io.IOException;
   import java.net.URLDecoder;
  import java.util.Date;
  import java.util.Map;
  import java.util.TreeMap;
  
  import com.atlassian.plugin.webresource.ResourceUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  
  /**
   * A downloadable plugin resource, as described here: http://confluence.atlassian.com/display/JIRA/Downloadable+plugin+resource
   * It supports the download of single plugin resources as well as batching.
   * <p/>
   *
   * The URL that it parses for a single resource looks like this: <br>
   * <code>{server root}/download/resources/{plugin key}:{module key}/{resource name}</code>
  
   * The URL that it parses for a batch looks like this: <br>
   * <code>{server root}/download/batch/{plugin key}:{module key}/all.css?ieonly=true</code>
   */
  public class PluginResourceDownload implements DownloadStrategy
  {
      private static final Logger log = LoggerFactory.getLogger(PluginResourceDownload.class);
      private String characterEncoding = "UTF-8"; // default to sensible encoding
      private PluginResourceLocator pluginResourceLocator;
      private ContentTypeResolver contentTypeResolver;
  
      public PluginResourceDownload()
      {
      }
  
      public PluginResourceDownload(PluginResourceLocator pluginResourceLocator, ContentTypeResolver contentTypeResolver, String characterEncoding)
      {
          this.characterEncoding = characterEncoding;
          this.pluginResourceLocator = pluginResourceLocator;
          this.contentTypeResolver = contentTypeResolver;
      }
  
      public boolean matches(String urlPath)
      {
          return pluginResourceLocator.matches(urlPath);
      }
  
      public void serveFile(HttpServletRequest request, HttpServletResponse response) throws DownloadException
      {
          try
          {
              // Calculating downloadableResource.isResourceModified can be moderately expensive. Avoiding if possible.
              final Map params = ResourceUtils.getQueryParameters(request);
              final boolean cacheableResource = ResourceUtils.canRequestedResourcesContentBeAssumedConstant(params);
              if (cacheableResource)
              {
                  final LastModifiedHandler lastModifiedHandler = new LastModifiedHandler(new Date(request.getDateHeader("If-Modified-Since")));
                  if (lastModifiedHandler.checkRequest(request, response)) {
                      // 304
                      return;
                  }
              }
  
              String requestUri = URLDecoder.decode(request.getRequestURI(), characterEncoding);
              DownloadableResource downloadableResource = pluginResourceLocator.getDownloadableResource(requestUri, params);
  
              if (downloadableResource == null)
              {
                  log.info("Could not locate resource: " + request.getRequestURI());
                  response.sendError(HttpServletResponse.SC_NOT_FOUND);
                  return;
              }
  
              // Don't try and calculate isResourceModified if it's a cacheable resource - answer is always false.
              if(cacheableResource && !downloadableResource.isResourceModified(request, response))
              {
                  // 304
                  return;
              }
  
              String contentType = getContentType(requestUri, downloadableResource);
              if (contentType != null)
              {
                  response.setContentType(contentType);
              }
  
              downloadableResource.serveResource(request, response);
          }
          catch(IOException e)
          {
              throw new DownloadException(e);
          }
      }
  
     public void setCharacterEncoding(String characterEncoding)
     {
         this.characterEncoding = characterEncoding;
     }
 
     public void setContentTypeResolver(ContentTypeResolver contentTypeResolver)
     {
         this.contentTypeResolver = contentTypeResolver;
     }
 
     public void setPluginResourceLocator(PluginResourceLocator pluginResourceLocator)
     {
         this.pluginResourceLocator = pluginResourceLocator;
     }
 
     /**
      * Gets the content type for the resource. If the downloadable resource does not specify one, look one up
      * using the {@link ContentTypeResolver}.
      */
     private String getContentType(String requestUri, DownloadableResource downloadableResource)
     {
         String contentType = downloadableResource.getContentType();
         if(contentType == null)
         {
             return contentTypeResolver.getContentType(requestUri);
         }
 
         return contentType;
     }
 }