package com.atlassian.johnson.filters;
   
   import com.atlassian.johnson.Johnson;
   import com.atlassian.johnson.JohnsonEventContainer;
   import com.atlassian.johnson.config.JohnsonConfig;
   import com.atlassian.johnson.event.Event;
   import com.atlassian.johnson.event.RequestEventCheck;
   import com.atlassian.johnson.setup.SetupConfig;
   import org.apache.commons.lang.StringUtils;
  
  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;
  import java.util.Collection;
  
  /**
   * Base class for handling error cases where the application is unavailable to handle normal requests.
   */
  public abstract class AbstractJohnsonFilter implements Filter {
  
      protected static final String TEXT_XML_UTF8_CONTENT_TYPE = "text/xml;charset=utf-8";
  
      protected FilterConfig filterConfig;
      protected JohnsonConfig config;
  
      /**
       * This filter checks to see if there are any application consistency errors before any pages are accessed. If there are errors then a redirect to the errors page is made
       */
      public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
          String alreadyFilteredKey = getClass().getName() + "_already_filtered";
          if (servletRequest.getAttribute(alreadyFilteredKey) != null) {
              filterChain.doFilter(servletRequest, servletResponse);
              return;
          } else {
              servletRequest.setAttribute(alreadyFilteredKey, Boolean.TRUE);
          }
  
          HttpServletRequest request = (HttpServletRequest) servletRequest;
          HttpServletResponse response = (HttpServletResponse) servletResponse;
  
          //get the URI of this request
          String servletPath = getServletPath(request);
  
          //Get the container for this context and run all of the configured request event checks
          JohnsonEventContainer appEventContainer = getContainerAndRunEventChecks(request);
  
          SetupConfig setup = config.getSetupConfig();
  
          //if there are application consistency events then redirect to the errors page
          boolean ignoreUri = ignoreURI(servletPath);
          if (appEventContainer.hasEvents() && !ignoreUri) {
              handleError(appEventContainer, request, response);
          }
          //if application is not setup then send to the Setup Page
          else if (!ignoreUri && !setup.isSetup() && !setup.isSetupPage(servletPath)) {
              handleNotSetup(request, response);
          } else {
              filterChain.doFilter(servletRequest, servletResponse);
          }
      }
  
      public void destroy() {
      }
  
      public void init(FilterConfig filterConfig) {
          this.filterConfig = filterConfig;
  
          config = Johnson.getConfig();
      }
  
      protected JohnsonEventContainer getContainerAndRunEventChecks(HttpServletRequest req) {
          //Get the container for this context
          JohnsonEventContainer appEventContainer = Johnson.getEventContainer(filterConfig.getServletContext());
          // run all of the configured request event checks
          for (RequestEventCheck requestEventCheck : config.getRequestEventChecks()) {
              requestEventCheck.check(appEventContainer, req);
          }
          return appEventContainer;
      }
  
      /**
       * Retrieves the current request servlet path. Deals with differences between servlet specs (2.2 vs 2.3+)
       * <p>
       * Taken from the Webwork RequestUtils class
       *
       * @param request the request
       * @return the servlet path
       */
      protected static String getServletPath(HttpServletRequest request) {
          String servletPath = request.getServletPath();
          if (StringUtils.isNotEmpty(servletPath)) {
              return servletPath;
          }
 
         String requestUri = request.getRequestURI();
         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);
     }
 
     protected String getStringForEvents(Collection<Event> events) {
         StringBuilder message = new StringBuilder();
         for (Event event : events) {
             if (message.length() > 0) {
                 message.append("\n");
             }
             message.append(event.getDesc());
         }
         return message.toString();
     }
 
     /**
      * Handles the given request for error cases when there is a Johnson {@link com.atlassian.johnson.event.Event} which
      * stops normal application functioning.
      *
      * @param appEventContainer the JohnsonEventContainer that contains the events.
      * @param servletRequest    the request being directed to the error.
      * @param servletResponse   the response.
      * @throws IOException when the error cannot be handled.
      */
     protected abstract void handleError(JohnsonEventContainer appEventContainer, HttpServletRequest servletRequest, HttpServletResponse servletResponse) throws IOException;
 
     /**
      * Handles the given request for cases when the application is not yet setup which
      * stops normal application functioning.
      *
      * @param servletRequest  the request being directed to the error.
      * @param servletResponse the response.
      * @throws IOException when the error cannot be handled.
      */
     protected abstract void handleNotSetup(HttpServletRequest servletRequest, HttpServletResponse servletResponse) throws IOException;
 
     protected boolean ignoreURI(String uri) {
         return uri.equalsIgnoreCase(config.getErrorPath()) || config.isIgnoredPath(uri);
     }
 }