content: /*
   * 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.kafka.trogdor.rest;
  
  import org.apache.kafka.common.utils.ThreadUtils;
  import org.apache.kafka.trogdor.common.JsonUtil;
  
  import com.fasterxml.jackson.core.type.TypeReference;
  import com.fasterxml.jackson.jakarta.rs.json.JacksonJsonProvider;
  
  import org.eclipse.jetty.ee10.servlet.ServletContextHandler;
  import org.eclipse.jetty.ee10.servlet.ServletHolder;
  import org.eclipse.jetty.server.Connector;
  import org.eclipse.jetty.server.CustomRequestLog;
  import org.eclipse.jetty.server.Handler;
  import org.eclipse.jetty.server.Server;
  import org.eclipse.jetty.server.ServerConnector;
  import org.eclipse.jetty.server.Slf4jRequestLogWriter;
  import org.eclipse.jetty.server.handler.ContextHandlerCollection;
  import org.eclipse.jetty.server.handler.DefaultHandler;
  import org.eclipse.jetty.server.handler.StatisticsHandler;
  import org.glassfish.jersey.server.ResourceConfig;
  import org.glassfish.jersey.servlet.ServletContainer;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.net.HttpURLConnection;
  import java.net.URL;
  import java.nio.charset.StandardCharsets;
  import java.util.concurrent.Callable;
  import java.util.concurrent.Executors;
  import java.util.concurrent.ScheduledExecutorService;
  import java.util.concurrent.TimeUnit;
  
  /**
   * Embedded server for the REST API that provides the control plane for Trogdor.
   */
  public class JsonRestServer {
      private static final Logger log = LoggerFactory.getLogger(JsonRestServer.class);
  
      private static final long GRACEFUL_SHUTDOWN_TIMEOUT_MS = 10 * 1000;
  
      private final ScheduledExecutorService shutdownExecutor;
  
      private final Server jettyServer;
  
      private final ServerConnector connector;
  
      /**
       * Create a REST server for this herder using the specified configs.
       *
       * @param port              The port number to use for the REST server, or
       *                          0 to use a random port.
       */
      public JsonRestServer(int port) {
          this.shutdownExecutor = Executors.newSingleThreadScheduledExecutor(
              ThreadUtils.createThreadFactory("JsonRestServerCleanupExecutor", false));
          this.jettyServer = new Server();
          this.connector = new ServerConnector(jettyServer);
          if (port > 0) {
              connector.setPort(port);
          }
          jettyServer.setConnectors(new Connector[]{connector});
      }
  
      /**
       * Start the JsonRestServer.
       *
       * @param resources         The path handling resources to register.
       */
      public void start(Object... resources) {
          log.info("Starting REST server");
          ResourceConfig resourceConfig = new ResourceConfig();
          resourceConfig.register(new JacksonJsonProvider(JsonUtil.JSON_SERDE));
          for (Object resource : resources) {
              resourceConfig.register(resource);
              log.info("Registered resource {}", resource);
          }
          resourceConfig.register(RestExceptionMapper.class);
          ServletContainer servletContainer = new ServletContainer(resourceConfig);
          ServletHolder servletHolder = new ServletHolder(servletContainer);
          ServletContextHandler context = new ServletContextHandler(ServletContextHandler.SESSIONS);
          context.setContextPath("/");
          context.addServlet(servletHolder, "/*");
  
          Slf4jRequestLogWriter slf4jRequestLogWriter = new Slf4jRequestLogWriter();
          slf4jRequestLogWriter.setLoggerName(JsonRestServer.class.getCanonicalName());
          CustomRequestLog requestLog = new CustomRequestLog(slf4jRequestLogWriter, CustomRequestLog.EXTENDED_NCSA_FORMAT + " %{ms}T");
          jettyServer.setRequestLog(requestLog);
  
          ContextHandlerCollection handlers = new ContextHandlerCollection();
          handlers.setHandlers(new Handler[]{context, new DefaultHandler()});
          StatisticsHandler statsHandler = new StatisticsHandler();
          statsHandler.setHandler(handlers);
          jettyServer.setHandler(statsHandler);
          /* Needed for graceful shutdown as per `setStopTimeout` documentation */
          jettyServer.setStopTimeout(GRACEFUL_SHUTDOWN_TIMEOUT_MS);
          jettyServer.setStopAtShutdown(true);
  
          try {
              jettyServer.start();
          } catch (Exception e) {
              throw new RuntimeException("Unable to start REST server", e);
          }
          log.info("REST server listening at " + jettyServer.getURI());
      }
  
      public int port() {
          return connector.getLocalPort();
      }
  
      /**
       * Initiate shutdown, but do not wait for it to complete.
       */
      public void beginShutdown() {
          if (!shutdownExecutor.isShutdown()) {
              shutdownExecutor.submit((Callable<Void>) () -> {
                  try {
                      log.info("Stopping REST server");
                      jettyServer.stop();
                      jettyServer.join();
                      log.info("REST server stopped");
                  } catch (Exception e) {
                      log.error("Unable to stop REST server", e);
                  } finally {
                      try {
                          jettyServer.destroy();
                      } catch (Exception e) {
                          log.error("Unable to destroy REST server", e);
                      }
                      shutdownExecutor.shutdown();
                  }
                  return null;
              });
          }
      }
  
      /**
       * Wait for shutdown to complete.  May be called prior to beginShutdown.
       */
      public void waitForShutdown() throws InterruptedException {
          while (!shutdownExecutor.isShutdown()) {
              shutdownExecutor.awaitTermination(1, TimeUnit.DAYS);
          }
      }
  
      /**
       * Make an HTTP request.
       *
       * @param logger            The logger to use.
       * @param url               HTTP connection will be established with this url.
       * @param method            HTTP method ("GET", "POST", "PUT", etc.)
       * @param requestBodyData   Object to serialize as JSON and send in the request body.
       * @param responseFormat    Expected format of the response to the HTTP request.
       * @param <T>               The type of the deserialized response to the HTTP request.
       * @return The deserialized response to the HTTP request, or null if no data is expected.
       */
      public static <T> HttpResponse<T> httpRequest(Logger logger, String url, String method,
              Object requestBodyData, TypeReference<T> responseFormat) throws IOException {
          HttpURLConnection connection = null;
          try {
              String serializedBody = requestBodyData == null ? null :
                  JsonUtil.JSON_SERDE.writeValueAsString(requestBodyData);
              logger.debug("Sending {} with input {} to {}", method, serializedBody, url);
              connection = (HttpURLConnection) new URL(url).openConnection();
              connection.setRequestMethod(method);
              connection.setRequestProperty("User-Agent", "kafka");
              connection.setRequestProperty("Accept", "application/json");
  
              // connection.getResponseCode() implicitly calls getInputStream, so always set
              // this to true.
              connection.setDoInput(true);
  
              connection.setUseCaches(false);
  
              if (requestBodyData != null) {
                  connection.setRequestProperty("Content-Type", "application/json");
                  connection.setDoOutput(true);
  
                  OutputStream os = connection.getOutputStream();
                  os.write(serializedBody.getBytes(StandardCharsets.UTF_8));
                  os.flush();
                  os.close();
              }
  
              int responseCode = connection.getResponseCode();
              if (responseCode == HttpURLConnection.HTTP_NO_CONTENT) {
                  return new HttpResponse<>(null, new ErrorResponse(responseCode, connection.getResponseMessage()));
              } else if ((responseCode >= 200) && (responseCode < 300)) {
                  InputStream is = connection.getInputStream();
                  T result = JsonUtil.JSON_SERDE.readValue(is, responseFormat);
                  is.close();
                  return new HttpResponse<>(result, null);
              } else {
                  // If the resposne code was not in the 200s, we assume that this is an error
                  // response.
                  InputStream es = connection.getErrorStream();
                  if (es == null) {
                      // Handle the case where HttpURLConnection#getErrorStream returns null.
                      return new HttpResponse<>(null, new ErrorResponse(responseCode, ""));
                  }
                  // Try to read the error response JSON.
                  ErrorResponse error = JsonUtil.JSON_SERDE.readValue(es, ErrorResponse.class);
                  es.close();
                  return new HttpResponse<>(null, error);
              }
          } finally {
              if (connection != null) {
                  connection.disconnect();
              }
          }
      }
  
      /**
       * Make an HTTP request with retries.
       *
       * @param url               HTTP connection will be established with this url.
       * @param method            HTTP method ("GET", "POST", "PUT", etc.)
       * @param requestBodyData   Object to serialize as JSON and send in the request body.
       * @param responseFormat    Expected format of the response to the HTTP request.
       * @param <T>               The type of the deserialized response to the HTTP request.
       * @return The deserialized response to the HTTP request, or null if no data is expected.
       */
      public static <T> HttpResponse<T> httpRequest(String url, String method, Object requestBodyData,
                                                    TypeReference<T> responseFormat, int maxTries)
              throws IOException, InterruptedException {
          return httpRequest(log, url, method, requestBodyData, responseFormat, maxTries);
      }
  
      /**
       * Make an HTTP request with retries.
       *
       * @param logger            The logger to use.
       * @param url               HTTP connection will be established with this url.
       * @param method            HTTP method ("GET", "POST", "PUT", etc.)
       * @param requestBodyData   Object to serialize as JSON and send in the request body.
       * @param responseFormat    Expected format of the response to the HTTP request.
       * @param <T>               The type of the deserialized response to the HTTP request.
       * @return The deserialized response to the HTTP request, or null if no data is expected.
       */
      public static <T> HttpResponse<T> httpRequest(Logger logger, String url, String method,
              Object requestBodyData, TypeReference<T> responseFormat, int maxTries)
              throws IOException, InterruptedException {
          IOException exc = null;
          for (int tries = 0; tries < maxTries; tries++) {
              if (tries > 0) {
                  Thread.sleep(tries > 1 ? 10 : 2);
              }
              try {
                  return httpRequest(logger, url, method, requestBodyData, responseFormat);
              } catch (IOException e) {
                  logger.info("{} {}: error: {}", method, url, e.getMessage());
                  exc = e;
              }
          }
          throw exc;
      }
  
      public static class HttpResponse<T> {
          private final T body;
          private final ErrorResponse error;
  
          HttpResponse(T body, ErrorResponse error) {
              this.body = body;
              this.error = error;
          }
  
          public T body() throws Exception {
              if (error != null) {
                  throw RestExceptionMapper.toException(error.code(), error.message());
              }
              return body;
          }
  
          public ErrorResponse error() {
              return error;
          }
      }
  }
  