package com.atlassian.asap.core.server;
   
   import com.atlassian.asap.api.server.http.RequestAuthenticator;
   import com.atlassian.asap.core.server.filter.AbstractRequestAuthenticationFilter;
   import com.atlassian.asap.core.server.filter.WhitelistRequestAuthorizationFilter;
   import com.atlassian.asap.core.server.http.RequestAuthenticatorImpl;
   import com.atlassian.asap.core.validator.JwtValidator;
   import com.atlassian.asap.core.validator.JwtValidatorImpl;
   import com.google.common.collect.ImmutableSet;
  import com.sun.grizzly.http.SelectorThread;
  import com.sun.grizzly.http.servlet.ServletAdapter;
  import com.sun.jersey.api.container.grizzly.GrizzlyServerFactory;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import javax.servlet.Filter;
  import javax.servlet.FilterConfig;
  import javax.servlet.ServletException;
  import javax.servlet.http.HttpServlet;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  import java.io.IOException;
  import java.net.URI;
  import java.util.Collections;
  import java.util.Set;
  
  /**
   * A simple server for demonstration purposes. Only accepts valid requests from some issuers and subjects.
   */
  public class SimpleServer {
      private static Logger logger = LoggerFactory.getLogger(SimpleServer.class);
  
      private final int port;
  
      private final String publicKeyBaseUrl;
      private final String audience;
      private final Set<String> authorizedSubjects;
      private final Set<String> authorizedIssuers;
  
      private SelectorThread thread;
  
      public SimpleServer(int port, String publicKeyBaseUrl, String audience,
                          Set<String> authorizedSubjects, Set<String> authorizedIssuers) {
          this.port = port;
          this.publicKeyBaseUrl = publicKeyBaseUrl;
          this.audience = audience;
          this.authorizedIssuers = ImmutableSet.copyOf(authorizedIssuers);
          this.authorizedSubjects = ImmutableSet.copyOf(authorizedSubjects);
      }
  
      public URI getUrl() {
          return URI.create("http://localhost:" + port);
      }
  
      /**
       * Start the server.
       *
       * @throws Exception if the server fails to start
       */
      public void start() throws Exception {
          ServletAdapter servletAdapter = new ServletAdapter();
  
          servletAdapter.setServletInstance(new HelloWorldServlet());
  
          servletAdapter.addFilter(
                  newAuthenticationFilter(),
                  "authenticationFilter",
                  Collections.emptyMap()
          );
          servletAdapter.addFilter(
                  newAuthorizationFilter(),
                  "authorizationFilter",
                  Collections.emptyMap()
          );
  
          thread = GrizzlyServerFactory.create(getUrl(), servletAdapter);
      }
  
      /**
       * Stop the server.
       */
      public void stop() {
          thread.stopEndpoint();
      }
  
      private Filter newAuthenticationFilter() {
          JwtValidator jwtValidator = JwtValidatorImpl.createDefault(audience, publicKeyBaseUrl);
          final RequestAuthenticator requestAuthenticator = new RequestAuthenticatorImpl(jwtValidator);
          return new AbstractRequestAuthenticationFilter() {
              @Override
              protected RequestAuthenticator getRequestAuthenticator(FilterConfig filterConfig) {
                  return requestAuthenticator;
              }
          };
      }
  
      private Filter newAuthorizationFilter() {
          return new WhitelistRequestAuthorizationFilter(authorizedSubjects, authorizedIssuers);
      }
 
     private static class HelloWorldServlet extends HttpServlet {
         private static final long serialVersionUID = -134479483378982999L;
 
         @Override
         protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
             doGet(req, resp);
         }
 
         @Override
         protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
             logger.info("Successfully authenticated request!");
             resp.getWriter().println("Hello World!");
         }
     }
 }