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package org.apache.juneau.microservice.jetty;

import static org.apache.juneau.internal.SystemUtils.*;

import java.io.*;
import java.net.*;
import java.util.*;
import java.util.logging.*;

import javax.servlet.*;

import org.apache.juneau.*;
import org.apache.juneau.config.*;
import org.apache.juneau.internal.*;
import org.apache.juneau.microservice.*;
import org.apache.juneau.rest.*;
import org.apache.juneau.svl.*;
import org.apache.juneau.utils.*;
import org.eclipse.jetty.server.*;
import org.eclipse.jetty.server.Handler;
import org.eclipse.jetty.server.handler.*;
import org.eclipse.jetty.servlet.*;

/**
 * Entry point for Juneau microservice that implements a REST interface using Jetty on a single port.
 *
 * <h5 class='topic'>Jetty Server Details</h5>
 *
 * The Jetty server is created by the {@link #createServer()} method and started with the {@link #startServer()} method.
 * These methods can be overridden to provided customized behavior.
 *
 * <h5 class='topic'>Defining REST Resources</h5>
 *
 * Top-level REST resources are defined in the <code>jetty.xml</code> file as normal servlets.
 */
public class JettyMicroservice extends Microservice {

   private static volatile JettyMicroservice INSTANCE;

   private static void setInstance(JettyMicroservice m) {
      synchronized(JettyMicroservice.class) {
         INSTANCE = m;
      }
   }

   /**
    * Returns the Microservice instance.
    * <p>
    * This method only works if there's only one Microservice instance in a JVM.
    * Otherwise, it's just overwritten by the last instantiated microservice.
    *
    * @return The Microservice instance, or <jk>null</jk> if there isn't one.
    */
   public static JettyMicroservice getInstance() {
      synchronized(JettyMicroservice.class) {
         return INSTANCE;
      }
   }

   /**
    * Entry-point method.
    *
    * @param args Command line arguments.
    * @throws Exception
    */
   public static void main(String[] args) throws Exception {
      JettyMicroservice
         .create()
         .args(args)
         .build()
         .start()
         .startConsole()
         .join();
   }

   final MessageBundle messages = MessageBundle.create(JettyMicroservice.class);

   //-----------------------------------------------------------------------------------------------------------------
   // Properties set in constructor
   //-----------------------------------------------------------------------------------------------------------------
   private final JettyMicroserviceBuilder builder;
   final JettyMicroserviceListener listener;
   private final JettyServerFactory factory;

   //-----------------------------------------------------------------------------------------------------------------
   // Properties set in constructor
   //-----------------------------------------------------------------------------------------------------------------
   volatile Server server;

   /**
    * Creates a new microservice builder.
    *
    * @return A new microservice builder.
    */
   public static JettyMicroserviceBuilder create() {
      return new JettyMicroserviceBuilder();
   }

   /**
    * Constructor.
    *
    * @param builder The constructor arguments.
    * @throws Exception
    */
   protected JettyMicroservice(JettyMicroserviceBuilder builder) throws Exception {
      super(builder);
      setInstance(this);
      this.builder = builder.copy();
      this.listener = builder.listener != null ? builder.listener : new BasicJettyMicroserviceListener();
      this.factory = builder.factory != null ? builder.factory : new BasicJettyServerFactory();
   }

   //-----------------------------------------------------------------------------------------------------------------
   // Methods implemented on Microservice API
   //-----------------------------------------------------------------------------------------------------------------

   @Override /* Microservice */
   public JettyMicroservice init() throws Exception {
      super.init();
      return this;
   }

   @Override /* Microservice */
   public JettyMicroservice startConsole() throws Exception {
      super.startConsole();
      return this;
   }

   @Override /* Microservice */
   public JettyMicroservice stopConsole() throws Exception {
      super.stopConsole();
      return this;
   }

   @Override /* Microservice */
   public synchronized JettyMicroservice start() throws Exception {
      super.start();
      createServer();
      startServer();
      return this;
   }

   @Override /* Microservice */
   public JettyMicroservice join() throws Exception {
      server.join();
      return this;
   }

   @Override /* Microservice */
   public synchronized JettyMicroservice stop() throws Exception {
      final Logger logger = getLogger();
      final MessageBundle mb2 = messages;
      Thread t = new Thread("JettyMicroserviceStop") {
         @Override /* Thread */
         public void run() {
            try {
               if (server == null || server.isStopping() || server.isStopped())
                  return;
               listener.onStopServer(JettyMicroservice.this);
               out(mb2, "StoppingServer");
               server.stop();
               out(mb2, "ServerStopped");
               listener.onPostStopServer(JettyMicroservice.this);
            } catch (Exception e) {
               logger.log(Level.WARNING, e.getLocalizedMessage(), e);
            }
         }
      };
      t.start();
      try {
         t.join();
      } catch (InterruptedException e) {
         e.printStackTrace();
      }
      super.stop();

      return this;
   }


   //-----------------------------------------------------------------------------------------------------------------
   // JettyMicroservice API methods.
   //-----------------------------------------------------------------------------------------------------------------

   /**
    * Returns the port that this microservice started up on.
    * <p>
    * The value is determined by looking at the <code>Server/Connectors[ServerConnector]/port</code> value in the
    * Jetty configuration.
    *
    * @return The port that this microservice started up on.
    */
   public int getPort() {
      for (Connector c : getServer().getConnectors())
         if (c instanceof ServerConnector)
            return ((ServerConnector)c).getPort();
      throw new RuntimeException("Could not locate ServerConnector in Jetty server.");
   }

   /**
    * Returns the context path that this microservice is using.
    * <p>
    * The value is determined by looking at the <code>Server/Handlers[ServletContextHandler]/contextPath</code> value
    * in the Jetty configuration.
    *
    * @return The context path that this microservice is using.
    */
   public String getContextPath() {
      for (Handler h : getServer().getHandlers()) {
         if (h instanceof HandlerCollection)
            for (Handler h2 : ((HandlerCollection)h).getChildHandlers())
               if (h2 instanceof ServletContextHandler)
                  return ((ServletContextHandler)h2).getContextPath();
         if (h instanceof ServletContextHandler)
            return ((ServletContextHandler)h).getContextPath();
      }
      throw new RuntimeException("Could not locate ServletContextHandler in Jetty server.");
   }

   /**
    * Returns whether this microservice is using <js>"http"</js> or <js>"https"</js>.
    * <p>
    * The value is determined by looking for the existence of an SSL Connection Factorie by looking for the
    * <code>Server/Connectors[ServerConnector]/ConnectionFactories[SslConnectionFactory]</code> value in the Jetty
    * configuration.
    *
    * @return Whether this microservice is using <js>"http"</js> or <js>"https"</js>.
    */
   public String getProtocol() {
      for (Connector c : getServer().getConnectors())
         if (c instanceof ServerConnector)
            for (ConnectionFactory cf : ((ServerConnector)c).getConnectionFactories())
               if (cf instanceof SslConnectionFactory)
                  return "https";
      return "http";
   }

   /**
    * Returns the hostname of this microservice.
    * <p>
    * Simply uses <code>InetAddress.getLocalHost().getHostName()</code>.
    *
    * @return The hostname of this microservice.
    */
   public String getHostName() {
      String hostname = "localhost";
      try {
         hostname = InetAddress.getLocalHost().getHostName();
      } catch (UnknownHostException e) {}
      return hostname;
   }

   /**
    * Returns the URI where this microservice is listening on.
    *
    * @return The URI where this microservice is listening on.
    */
   public URI getURI() {
      String cp = getContextPath();
      try {
         return new URI(getProtocol(), null, getHostName(), getPort(), "/".equals(cp) ? null : cp, null, null);
      } catch (URISyntaxException e) {
         throw new RuntimeException(e);
      }
   }

   /**
    * Method used to create (but not start) an instance of a Jetty server.
    *
    * <p>
    * Subclasses can override this method to customize the Jetty server before it is started.
    *
    * <p>
    * The default implementation is configured by the following values in the config file
    * if a jetty.xml is not specified via a <code>REST/jettyXml</code> setting:
    * <p class='bcode w800'>
    *    <cc>#================================================================================
    *    # Jetty settings
    *    #================================================================================</cc>
    *    <cs>[Jetty]</cs>
    *
    *    <cc># Path of the jetty.xml file used to configure the Jetty server.</cc>
    *    <ck>config</ck> = jetty.xml
    *
    *    <cc># Resolve Juneau variables in the jetty.xml file.</cc>
    *    <ck>resolveVars</ck> = true
    *
    *    <cc># Port to use for the jetty server.
    *    # You can specify multiple ports.  The first available will be used.  '0' indicates to try a random port.
    *    # The resulting available port gets set as the system property "availablePort" which can be referenced in the
    *    # jetty.xml file as "$S{availablePort}" (assuming resolveVars is enabled).</cc>
    *    <ck>port</ck> = 10000,0,0,0
    * </p>
    *
    * @return The newly-created server.
    * @throws Exception
    */
   public Server createServer() throws Exception {
      listener.onCreateServer(this);

      Config cf = getConfig();
      ObjectMap mf = getManifest();
      VarResolver vr = getVarResolver();

      int[] ports = ObjectUtils.firstNonNull(builder.ports, cf.getObjectWithDefault("Jetty/port", mf.getWithDefault("Jetty-Port", new int[]{8000}, int[].class), int[].class));
      int availablePort = findOpenPort(ports);
      setProperty("availablePort", availablePort, false);

      String jettyXml = builder.jettyXml;
      String jettyConfig = cf.getString("Jetty/config", mf.getString("Jetty-Config", "jetty.xml"));
      boolean resolveVars = ObjectUtils.firstNonNull(builder.jettyXmlResolveVars, cf.getBoolean("Jetty/resolveVars"));

      if (jettyXml == null)
         jettyXml = IOUtils.loadSystemResourceAsString("jetty.xml", ".", "files");
      if (jettyXml == null)
         throw new FormattedRuntimeException("jetty.xml file ''{0}'' was not found on the file system or classpath.", jettyConfig);

      if (resolveVars)
         jettyXml = vr.resolve(jettyXml);

      getLogger().info(jettyXml);

      server = factory.create(jettyXml);

      for (String s : cf.getStringArray("Jetty/servlets", new String[0])) {
         Class<?> c = Class.forName(s);
         if (ClassUtils.isParentClass(RestServlet.class, c)) {
            RestServlet rs = (RestServlet)c.newInstance();
            addServlet(rs, rs.getPath());
         } else {
            throw new FormattedRuntimeException("Invalid servlet specified in Jetty/servlets.  Must be a subclass of RestServlet.", s);
         }
      }

      for (Map.Entry<String,Object> e : cf.getObjectMap("Jetty/servletMap", ObjectMap.EMPTY_MAP).entrySet()) {
         Class<?> c = Class.forName(e.getValue().toString());
         if (ClassUtils.isParentClass(Servlet.class, c)) {
            Servlet rs = (Servlet)c.newInstance();
            addServlet(rs, e.getKey());
         } else {
            throw new FormattedRuntimeException("Invalid servlet specified in Jetty/servletMap.  Must be a subclass of Servlet.", e.getValue());
         }
      }

      for (Map.Entry<String,Object> e : cf.getObjectMap("Jetty/servletAttributes", ObjectMap.EMPTY_MAP).entrySet())
         addServletAttribute(e.getKey(), e.getValue());

      for (Map.Entry<String,Servlet> e : builder.servlets.entrySet())
         addServlet(e.getValue(), e.getKey());

      for (Map.Entry<String,Object> e : builder.servletAttributes.entrySet())
         addServletAttribute(e.getKey(), e.getValue());

      setProperty("juneau.serverPort", availablePort, false);

      return server;
   }

   /**
    * Calls {@link Server#destroy()} on the underlying Jetty server if it exists.
    *
    * @throws Exception
    */
   public void destroyServer() throws Exception {
      if (server != null)
         server.destroy();
      server = null;
   }

   /**
    * Adds an arbitrary servlet to this microservice.
    *
    * @param servlet The servlet instance.
    * @param pathSpec The context path of the servlet.
    * @return This object (for method chaining).
    * @throws RuntimeException if {@link #createServer()} has not previously been called.
    */
   public JettyMicroservice addServlet(Servlet servlet, String pathSpec) {
      ServletHolder sh = new ServletHolder(servlet);
      getServletContextHandler().addServlet(sh, pathSpec);
      return this;
   }

   /**
    * Finds and returns the servlet context handler define in the Jetty container.
    *
    * @return The servlet context handler.
    * @throws RuntimeException if context handler is not defined.
    */
   protected ServletContextHandler getServletContextHandler() {
      for (Handler h : getServer().getHandlers()) {
         ServletContextHandler sch = getServletContextHandler(h);
         if (sch != null)
            return sch;
      }
      throw new RuntimeException("Servlet context handler not found in jetty server.");
   }

   /**
    * Adds a servlet attribute to the Jetty server.
    *
    * @param name The server attribute name.
    * @param value The context path of the servlet.
    * @return This object (for method chaining).
    * @throws RuntimeException if {@link #createServer()} has not previously been called.
    */
   public JettyMicroservice addServletAttribute(String name, Object value) {
      getServer().setAttribute(name, value);
      return this;
   }

   /**
    * Returns the underlying Jetty server.
    *
    * @return The underlying Jetty server, or <jk>null</jk> if {@link #createServer()} has not yet been called.
    */
   public Server getServer() {
      if (server == null)
         throw new RuntimeException("Server not found.  createServer() must be called first.");
      return server;
   }

   /**
    * Method used to start the Jetty server created by {@link #createServer()}.
    *
    * <p>
    * Subclasses can override this method to customize server startup.
    *
    * @return The port that this server started on.
    * @throws Exception
    */
   protected int startServer() throws Exception {
      listener.onStartServer(this);
      server.start();
      out(messages, "ServerStarted", getPort());
      listener.onPostStartServer(this);
      return getPort();
   }

   //-----------------------------------------------------------------------------------------------------------------
   // Utility methods.
   //-----------------------------------------------------------------------------------------------------------------

   private static ServletContextHandler getServletContextHandler(Handler h) {
      if (h instanceof ServletContextHandler)
         return (ServletContextHandler)h;
      if (h instanceof HandlerCollection) {
         for (Handler h2 : ((HandlerCollection)h).getHandlers()) {
            ServletContextHandler sch = getServletContextHandler(h2);
            if (sch != null)
               return sch;
         }
      }
      return null;
   }

   private static int findOpenPort(int[] ports) {
      for (int port : ports) {
         // If port is 0, try a random port between ports[0] and 32767.
         if (port == 0)
            port = new Random().nextInt(32767 - ports[0] + 1) + ports[0];
         try (ServerSocket ss = new ServerSocket(port)) {
            return port;
         } catch (IOException e) {}
      }
      return 0;
   }
}