/**
 * 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.knox.gateway.websockets;

import static org.hamcrest.CoreMatchers.is;
import static org.hamcrest.MatcherAssert.assertThat;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.net.URI;
import java.net.URL;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.TimeUnit;

import javax.websocket.ContainerProvider;
import javax.websocket.Session;
import javax.websocket.WebSocketContainer;

import org.apache.commons.io.FileUtils;
import org.apache.knox.gateway.config.GatewayConfig;
import org.apache.knox.gateway.config.impl.GatewayConfigImpl;
import org.apache.knox.gateway.deploy.DeploymentFactory;
import org.apache.knox.gateway.services.DefaultGatewayServices;
import org.apache.knox.gateway.services.GatewayServices;
import org.apache.knox.gateway.services.ServiceLifecycleException;
import org.apache.knox.gateway.services.topology.TopologyService;
import org.apache.knox.gateway.topology.TopologyEvent;
import org.apache.knox.gateway.topology.TopologyListener;
import org.apache.knox.test.TestUtils;
import org.easymock.EasyMock;
import org.eclipse.jetty.server.Server;
import org.eclipse.jetty.server.ServerConnector;
import org.eclipse.jetty.server.handler.ContextHandler;
import org.eclipse.jetty.server.handler.HandlerCollection;
import org.junit.AfterClass;
import org.junit.BeforeClass;
import org.junit.Test;

import com.mycila.xmltool.XMLDoc;
import com.mycila.xmltool.XMLTag;

/**
 * A basic test that attempts to proxy websocket connections through Knox
 * gateway.
 * <p>
 * The way the test is set up is as follows: <br/>
 * <ul>
 * <li>A Mock Websocket server is setup which simply echos the responses sent by
 * client.
 * <li>Knox Gateway is set up with websocket handler
 * {@link GatewayWebsocketHandler} that can proxy the requests.
 * <li>Appropriate Topology and service definition files are set up with the
 * address of the Websocket server.
 * <li>A mock client is setup to connect to gateway.
 * </ul>
 * 
 * The test is to confirm whether the message is sent all the way to the backend
 * Websocket server through Knox and back.
 * 
 * 
 * @since 0.10
 */
public class WebsocketEchoTest {

  /**
   * Simulate backend websocket
   */
  private static Server backendServer;
  /**
   * URI for backend websocket server
   */
  private static URI backendServerUri;

  /**
   * Mock Gateway server
   */
  private static Server gatewayServer;

  /**
   * Mock gateway config
   */
  private static GatewayConfig gatewayConfig;

  private static GatewayServices services;

  /**
   * URI for gateway server
   */
  private static URI serverUri;

  private static File topoDir;

  public WebsocketEchoTest() {
    super();
  }

  @BeforeClass
  public static void startServers() throws Exception {

    startWebsocketServer();
    startGatewayServer();

  }

  @AfterClass
  public static void stopServers() {
    try {
      gatewayServer.stop();
      backendServer.stop();
    } catch (final Exception e) {
      e.printStackTrace(System.err);
    }

    /* Cleanup the created files */
    FileUtils.deleteQuietly(topoDir);

  }

  /**
   * Test direct connection to websocket server without gateway
   * 
   * @throws Exception
   */
  @Test
  public void testDirectEcho() throws Exception {

    WebSocketContainer container = ContainerProvider.getWebSocketContainer();
    WebsocketClient client = new WebsocketClient();

    Session session = container.connectToServer(client, backendServerUri);

    session.getBasicRemote().sendText("Echo");
    client.messageQueue.awaitMessages(1, 1000, TimeUnit.MILLISECONDS);

  }

  /**
   * Test websocket proxying through gateway.
   * 
   * @throws Exception
   */
  @Test
  public void testGatewayEcho() throws Exception {
    WebSocketContainer container = ContainerProvider.getWebSocketContainer();

    WebsocketClient client = new WebsocketClient();
    Session session = container.connectToServer(client,
        new URI(serverUri.toString() + "gateway/websocket/ws"));

    session.getBasicRemote().sendText("Echo");
    client.messageQueue.awaitMessages(1, 1000, TimeUnit.MILLISECONDS);

    assertThat(client.messageQueue.get(0), is("Echo"));

  }

  /**
   * Test websocket rewrite rules proxying through gateway.
   *
   * @throws Exception
   */
  @Test
  public void testGatewayRewriteEcho() throws Exception {
    WebSocketContainer container = ContainerProvider.getWebSocketContainer();

    WebsocketClient client = new WebsocketClient();
    Session session = container.connectToServer(client,
            new URI(serverUri.toString() + "gateway/websocket/123foo456bar/channels"));

    session.getBasicRemote().sendText("Echo");
    client.messageQueue.awaitMessages(1, 1000, TimeUnit.MILLISECONDS);

    assertThat(client.messageQueue.get(0), is("Echo"));

  }

  /**
   * Start Mock Websocket server that acts as backend.
   * 
   * @throws Exception
   */
  private static void startWebsocketServer() throws Exception {

    backendServer = new Server();
    ServerConnector connector = new ServerConnector(backendServer);
    backendServer.addConnector(connector);

    final WebsocketEchoHandler handler = new WebsocketEchoHandler();

    ContextHandler context = new ContextHandler();
    context.setContextPath("/");
    context.setHandler(handler);
    backendServer.setHandler(context);

    // Start Server
    backendServer.start();

    String host = connector.getHost();
    if (host == null) {
      host = "localhost";
    }
    int port = connector.getLocalPort();
    backendServerUri = new URI(String.format("ws://%s:%d/ws", host, port));

  }

  /**
   * Start Gateway Server.
   * 
   * @throws Exception
   */
  private static void startGatewayServer() throws Exception {
    gatewayServer = new Server();
    final ServerConnector connector = new ServerConnector(gatewayServer);
    gatewayServer.addConnector(connector);

    /* workaround so we can add our handler later at runtime */
    HandlerCollection handlers = new HandlerCollection(true);

    /* add some initial handlers */
    ContextHandler context = new ContextHandler();
    context.setContextPath("/");
    handlers.addHandler(context);

    gatewayServer.setHandler(handlers);

    // Start Server
    gatewayServer.start();

    String host = connector.getHost();
    if (host == null) {
      host = "localhost";
    }
    int port = connector.getLocalPort();
    serverUri = new URI(String.format("ws://%s:%d/", host, port));

    /* Setup websocket handler */
    setupGatewayConfig(backendServerUri.toString());

    final GatewayWebsocketHandler gatewayWebsocketHandler = new GatewayWebsocketHandler(
        gatewayConfig, services);
    handlers.addHandler(gatewayWebsocketHandler);
    gatewayWebsocketHandler.start();
  }

  /**
   * Initialize the configs and components required for this test.
   * 
   * @param backend
   * @throws IOException
   */
  private static void setupGatewayConfig(final String backend)
      throws IOException {
    services = new DefaultGatewayServices();

    topoDir = createDir();
    URL serviceUrl = ClassLoader.getSystemResource("websocket-services");

    final File descriptor = new File(topoDir, "websocket.xml");
    final FileOutputStream stream = new FileOutputStream(descriptor);
    createKnoxTopology(backend).toStream(stream);
    stream.close();

    final TestTopologyListener topoListener = new TestTopologyListener();

    final Map<String, String> options = new HashMap<>();
    options.put("persist-master", "false");
    options.put("master", "password");

    gatewayConfig = EasyMock.createNiceMock(GatewayConfig.class);
    EasyMock.expect(gatewayConfig.getGatewayTopologyDir())
        .andReturn(topoDir.toString()).anyTimes();

    EasyMock.expect(gatewayConfig.getGatewayProvidersConfigDir())
            .andReturn(topoDir.getAbsolutePath() + "/shared-providers").anyTimes();

    EasyMock.expect(gatewayConfig.getGatewayDescriptorsDir())
            .andReturn(topoDir.getAbsolutePath() + "/descriptors").anyTimes();

    EasyMock.expect(gatewayConfig.getGatewayServicesDir())
        .andReturn(serviceUrl.getFile()).anyTimes();

    EasyMock.expect(gatewayConfig.getEphemeralDHKeySize()).andReturn("2048")
        .anyTimes();

    EasyMock.expect(gatewayConfig.getGatewaySecurityDir())
        .andReturn(topoDir.toString()).anyTimes();

    /* Websocket configs */
    EasyMock.expect(gatewayConfig.isWebsocketEnabled()).andReturn(true)
        .anyTimes();

    EasyMock.expect(gatewayConfig.getWebsocketMaxTextMessageSize())
        .andReturn(GatewayConfigImpl.DEFAULT_WEBSOCKET_MAX_TEXT_MESSAGE_SIZE)
        .anyTimes();

    EasyMock.expect(gatewayConfig.getWebsocketMaxBinaryMessageSize())
        .andReturn(GatewayConfigImpl.DEFAULT_WEBSOCKET_MAX_BINARY_MESSAGE_SIZE)
        .anyTimes();

    EasyMock.expect(gatewayConfig.getWebsocketMaxTextMessageBufferSize())
        .andReturn(
            GatewayConfigImpl.DEFAULT_WEBSOCKET_MAX_TEXT_MESSAGE_BUFFER_SIZE)
        .anyTimes();

    EasyMock.expect(gatewayConfig.getWebsocketMaxBinaryMessageBufferSize())
        .andReturn(
            GatewayConfigImpl.DEFAULT_WEBSOCKET_MAX_BINARY_MESSAGE_BUFFER_SIZE)
        .anyTimes();

    EasyMock.expect(gatewayConfig.getWebsocketInputBufferSize())
        .andReturn(GatewayConfigImpl.DEFAULT_WEBSOCKET_INPUT_BUFFER_SIZE)
        .anyTimes();

    EasyMock.expect(gatewayConfig.getWebsocketAsyncWriteTimeout())
        .andReturn(GatewayConfigImpl.DEFAULT_WEBSOCKET_ASYNC_WRITE_TIMEOUT)
        .anyTimes();

    EasyMock.expect(gatewayConfig.getWebsocketIdleTimeout())
        .andReturn(GatewayConfigImpl.DEFAULT_WEBSOCKET_IDLE_TIMEOUT).anyTimes();

    EasyMock.expect(gatewayConfig.getRemoteRegistryConfigurationNames())
            .andReturn(Collections.emptyList())
            .anyTimes();

    EasyMock.replay(gatewayConfig);

    try {
      services.init(gatewayConfig, options);
    } catch (ServiceLifecycleException e) {
      e.printStackTrace();
    }

    DeploymentFactory.setGatewayServices(services);
    final TopologyService monitor = services
        .getService(GatewayServices.TOPOLOGY_SERVICE);
    monitor.addTopologyChangeListener(topoListener);
    monitor.reloadTopologies();

  }

  private static File createDir() throws IOException {
    return TestUtils
        .createTempDir(WebsocketEchoTest.class.getSimpleName() + "-");
  }

  private static XMLTag createKnoxTopology(final String backend) {
    XMLTag xml = XMLDoc.newDocument(true).addRoot("topology").addTag("service")
        .addTag("role").addText("WEBSOCKET").addTag("url").addText(backend)
        .gotoParent().gotoRoot();
    // System.out.println( "GATEWAY=" + xml.toString() );
    return xml;
  }

  private static class TestTopologyListener implements TopologyListener {

    public ArrayList<List<TopologyEvent>> events = new ArrayList<List<TopologyEvent>>();

    @Override
    public void handleTopologyEvent(List<TopologyEvent> events) {
      this.events.add(events);

      synchronized (this) {
        for (TopologyEvent event : events) {
          if (!event.getType().equals(TopologyEvent.Type.DELETED)) {

            /* for this test we only care about this part */
            DeploymentFactory.createDeployment(gatewayConfig,
                event.getTopology());

          }
        }

      }

    }

  }
}
