/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you under the Apache License, Version 2.0 (the
    * "License"); you may not use this file except in compliance
    * with the License.  You may obtain a copy of the License at
    *
   *   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   * KIND, either express or implied.  See the License for the
   * specific language governing permissions and limitations
   * under the License.
   */
  package org.apache.maven.plugins.javadoc;
  
  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.net.InetAddress;
  import java.nio.charset.StandardCharsets;
  import java.util.Base64;
  import java.util.Map;
  
  import org.eclipse.jetty.proxy.AsyncProxyServlet;
  import org.eclipse.jetty.proxy.ConnectHandler;
  import org.eclipse.jetty.server.Server;
  import org.eclipse.jetty.server.ServerConnector;
  import org.eclipse.jetty.servlet.ServletContextHandler;
  import org.eclipse.jetty.servlet.ServletHolder;
  
  /**
   * A Proxy server.
   *
   * @author <a href="mailto:vincent.siveton@gmail.com">Vincent Siveton</a>
   * @since 2.6
   */
  class ProxyServer implements AutoCloseable {
      private Server proxyServer;
  
      private ServerConnector serverConnector;
  
      /**
       * @param proxyServlet the wanted auth proxy servlet
       */
      ProxyServer(AuthAsyncProxyServlet proxyServlet) {
          this(null, 0, proxyServlet);
      }
  
      /**
       * @param hostName the server name
       * @param port the server port
       * @param proxyServlet the wanted auth proxy servlet
       */
      ProxyServer(String hostName, int port, AuthAsyncProxyServlet proxyServlet) {
          proxyServer = new Server();
  
          serverConnector = new ServerConnector(proxyServer);
          serverConnector.setHost(InetAddress.getLoopbackAddress().getHostName());
          serverConnector.setReuseAddress(true);
          serverConnector.setPort(0);
  
          proxyServer.addConnector(serverConnector);
  
          // Setup proxy handler to handle CONNECT methods
          ConnectHandler proxy = new ConnectHandler();
          proxyServer.setHandler(proxy);
  
          // Setup proxy servlet
          ServletContextHandler context = new ServletContextHandler(proxy, "/", true, false);
          ServletHolder appServletHolder = new ServletHolder(proxyServlet);
          context.addServlet(appServletHolder, "/*");
      }
  
      /**
       * @return the host name
       */
      public String getHostName() {
          return serverConnector.getHost() == null
                  ? InetAddress.getLoopbackAddress().getHostName()
                  : serverConnector.getHost();
      }
  
      /**
       * @return the host port
       */
      public int getPort() {
          return serverConnector.getLocalPort();
      }
  
      /**
      * @throws Exception if any
      */
     public void start() throws Exception {
         if (proxyServer != null) {
             proxyServer.start();
         }
     }
 
     @Override
     public void close() throws Exception {
         this.stop();
     }
 
     /**
      * @throws Exception if any
      */
     public void stop() throws Exception {
         if (proxyServer != null) {
             proxyServer.stop();
         }
         proxyServer = null;
     }
 
     /**
      * A proxy servlet with authentication support.
      */
     static class AuthAsyncProxyServlet extends AsyncProxyServlet {
         private Map<String, String> authentications;
 
         private long sleepTime = 0;
 
         /**
          * Constructor for non authentication servlet.
          */
         AuthAsyncProxyServlet() {
             super();
         }
 
         /**
          * Constructor for authentication servlet.
          *
          * @param authentications a map of user/password
          */
         AuthAsyncProxyServlet(Map<String, String> authentications) {
             this();
 
             this.authentications = authentications;
         }
 
         /**
          * Constructor for authentication servlet.
          *
          * @param authentications a map of user/password
          * @param sleepTime a positive time to sleep the service thread (for timeout)
          */
         AuthAsyncProxyServlet(Map<String, String> authentications, long sleepTime) {
             this();
             this.authentications = authentications;
             this.sleepTime = sleepTime;
         }
 
         /** {@inheritDoc} */
         @Override
         public void service(ServletRequest req, ServletResponse res) throws ServletException, IOException {
             final HttpServletRequest request = (HttpServletRequest) req;
             final HttpServletResponse response = (HttpServletResponse) res;
 
             if (this.authentications != null && !this.authentications.isEmpty()) {
                 String proxyAuthorization = request.getHeader("Proxy-Authorization");
                 if (proxyAuthorization != null && proxyAuthorization.startsWith("Basic ")) {
                     String proxyAuth = proxyAuthorization.substring("Basic ".length());
                     String authorization = new String(Base64.getDecoder().decode(proxyAuth), StandardCharsets.UTF_8);
 
                     String[] authTokens = authorization.split(":");
                     String user = authTokens[0];
                     String password = authTokens[1];
 
                     if (this.authentications.get(user) == null) {
                         throw new IllegalArgumentException(user + " not found in the map!");
                     }
 
                     if (sleepTime > 0) {
                         try {
                             Thread.sleep(sleepTime);
                         } catch (InterruptedException e) {
                             // nop
                         }
                     }
                     String authPass = this.authentications.get(user);
                     if (password.equals(authPass)) {
                         // could throw exceptions...
                         super.service(req, res);
                         return;
                     }
                 }
 
                 // Proxy-Authenticate Basic realm="CCProxy Authorization"
                 response.addHeader("Proxy-Authenticate", "Basic realm=\"Jetty Proxy Authorization\"");
                 response.setStatus(HttpServletResponse.SC_PROXY_AUTHENTICATION_REQUIRED);
                 return;
             }
 
             super.service(req, res);
         }
     }
 }