package com.atlassian.plugin.servlet.filter;
   
   import com.atlassian.plugin.servlet.ServletModuleManager;
   import com.atlassian.plugin.servlet.util.ServletContextServletModuleManagerAccessor;
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   import javax.servlet.Filter;
   import javax.servlet.FilterChain;
  import javax.servlet.FilterConfig;
  import javax.servlet.ServletException;
  import javax.servlet.ServletRequest;
  import javax.servlet.ServletResponse;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  import java.io.IOException;
  
  /**
   * Applications need to create a concrete subclass of this for use in their filter stack. This filters responsiblity
   * is to retrieve the filters to be applied to the request from the {@link ServletModuleManager} and build a
   * {@link FilterChain} from them. Once all the filters in the chain have been applied to the request, this filter
   * returns control to the main chain.
   * <p>
   * There is one init parameters that must be configured for this filter, the "location" parameter. It can be one of
   * "top", "middle" or "bottom". A filter with a "top" location must appear before the filter with a "middle" location
   * which must appear before a filter with a "bottom" location. Where any other application filters lie in the filter
   * stack is completely up to the application.
   *
   * @since 2.1.0
   */
  public class ServletFilterModuleContainerFilter implements Filter {
      private static final Logger log = LoggerFactory.getLogger(ServletFilterModuleContainerFilter.class);
  
      private FilterConfig filterConfig;
      private FilterLocation location;
  
      public void init(FilterConfig filterConfig) throws ServletException {
          this.filterConfig = filterConfig;
          location = FilterLocation.parse(filterConfig.getInitParameter("location"));
      }
  
      public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
          doFilter((HttpServletRequest) request, (HttpServletResponse) response, chain);
      }
  
      void doFilter(HttpServletRequest request, HttpServletResponse response, final FilterChain chain) throws IOException, ServletException {
          if (getServletModuleManager() == null) {
              log.info("Could not get ServletModuleManager. Skipping filter plugins.");
              chain.doFilter(request, response);
              return;
          }
  
          final Iterable<Filter> filters = getServletModuleManager().getFilters(location, getUri(request), filterConfig, request.getDispatcherType());
          FilterChain pluginFilterChain = new IteratingFilterChain(filters.iterator(), chain);
          pluginFilterChain.doFilter(request, response);
      }
  
      public void destroy() {
      }
  
      /**
       * Retrieve the DefaultServletModuleManager from your container framework. Uses the {@link com.atlassian.plugin.servlet.util.ServletContextServletModuleManagerAccessor}
       * by default.
       */
      protected ServletModuleManager getServletModuleManager() {
          return ServletContextServletModuleManagerAccessor.getServletModuleManager(filterConfig.getServletContext());
      }
  
      protected final FilterConfig getFilterConfig() {
          return filterConfig;
      }
  
      protected final FilterLocation getFilterLocation() {
          return location;
      }
  
      /**
       * Gets the uri from the request. Copied from Struts 2.1.0.
       *
       * @param request The request
       * @return The uri
       */
      private static String getUri(HttpServletRequest request) {
          // handle http dispatcher includes.
          String uri = (String) request
                  .getAttribute("javax.servlet.include.servlet_path");
          if (uri != null) {
              return uri;
          }
  
          uri = getServletPath(request);
          if (uri != null && !"".equals(uri)) {
              return uri;
          }
  
          uri = request.getRequestURI();
          return uri.substring(request.getContextPath().length());
      }
  
     /**
      * Retrieves the current request servlet path.
      * Deals with differences between servlet specs (2.2 vs 2.3+).
      * Copied from Struts 2.1.0.
      *
      * @param request the request
      * @return the servlet path
      */
     private static String getServletPath(HttpServletRequest request) {
         String servletPath = request.getServletPath();
 
         String requestUri = request.getRequestURI();
         // Detecting other characters that the servlet container cut off (like anything after ';')
         if (requestUri != null && servletPath != null && !requestUri.endsWith(servletPath)) {
             int pos = requestUri.indexOf(servletPath);
             if (pos > -1) {
                 servletPath = requestUri.substring(requestUri.indexOf(servletPath));
             }
         }
 
         if (null != servletPath && !"".equals(servletPath)) {
             return servletPath;
         }
 
         int startIndex = request.getContextPath().equals("") ? 0 : request.getContextPath().length();
         int endIndex = request.getPathInfo() == null ? requestUri.length() : requestUri.lastIndexOf(request.getPathInfo());
 
         if (startIndex > endIndex) { // this should not happen
             endIndex = startIndex;
         }
 
         return requestUri.substring(startIndex, endIndex);
     }
 }