package com.atlassian.refapp.auth.internal;
   
   import org.apache.commons.lang.StringUtils;
   
   import javax.servlet.http.HttpServletRequest;
   import javax.servlet.http.HttpServletResponse;
   import java.io.IOException;
   
   public class RedirectHelper {
      public static void redirect(HttpServletRequest request, HttpServletResponse response) throws IOException {
          // An empty context path actually means a "/" is needed to work as a relative redirect
          String location = StringUtils.isBlank(request.getContextPath()) ? "/" : request.getContextPath();
  
          String redirParam = request.getParameter("redir");
          if (!StringUtils.isEmpty(redirParam)) {
              if (redirParam.startsWith("http:") || redirParam.startsWith("https:")) {
                  location = redirParam;
              } else {
                  if (!redirParam.startsWith("/")) {
                      location += "/";
                  }
                  location += redirParam;
              }
          }
  
          response.sendRedirect(location);
      }
  
  }