browser/src/main/java/org/netbeans/html/presenters/browser/Browser.java - netbeans-html4j - Git at Google

 /**
  * 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.netbeans.html.presenters.browser;

 import org.netbeans.html.presenters.render.Show;
 import java.io.Closeable;
 import java.io.File;
 import java.io.FileNotFoundException;
 import java.io.Flushable;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.io.OutputStream;
 import java.io.Reader;
 import java.io.Writer;
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.net.URL;
 import java.net.URLConnection;
 import java.net.URLDecoder;
 import java.nio.file.Files;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Queue;
 import java.util.UUID;
 import java.util.concurrent.Executor;
 import java.util.concurrent.Executors;
 import java.util.concurrent.ThreadFactory;
 import java.util.function.Supplier;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 import org.netbeans.html.boot.spi.Fn;
 import org.netbeans.html.boot.spi.Fn.Presenter;
 import org.netbeans.html.presenters.spi.ProtoPresenter;
 import org.netbeans.html.presenters.spi.ProtoPresenterBuilder;
 import org.openide.util.lookup.ServiceProvider;

 /** Browser based {@link Presenter}. It starts local server and
  * launches browser that connects to it. Use {@link Browser.Config} to
  * configure the actual browser to be started.
  * <p>
  * To use this presenter specify following dependency:
  * <pre>
  * &lt;dependency&gt;
  *   &lt;groupId&gt;org.netbeans.html.browser&lt;/groupId&gt;
  *   &lt;artifactId&gt;browser&lt;/artifactId&gt;
  *   &lt;version&gt;<a target="blank" href="http://search.maven.org/#search%7Cgav%7C1%7Cg%3A%22com.dukescript.presenters%22%20AND%20a%3A%22browser%22">1.x</a>&lt;/version&gt;
  * &lt;/dependency&gt;
  * </pre>
  */
 @ServiceProvider(service = Presenter.class)
 public final class Browser implements Fn.Presenter, Fn.KeepAlive, Flushable,
 Executor, Closeable {
     static final Logger LOG = Logger.getLogger(Browser.class.getName());
     private final Map<String,Command> SESSIONS = new HashMap<>();
     private final String app;
     private HttpServer server;
     private Runnable onPageLoad;
     private Command current;
     private final Config config;
     private final Supplier<HttpServer<?, ?, ?, ?>> serverProvider;

     /** Default constructor. Reads configuration from properties. The actual browser to
      * be launched can be influenced by value of
      * <code>com.dukescript.presenters.browser</code> property.
      * It can have following values:
      * <ul>
      * <li><b>GTK</b> - use Gtk WebKit implementation. Requires presence of
      *    appropriate native libraries</li>
      * <li><b>AWT</b> - use {@link java.awt.Desktop#browse(java.net.URI)} to
      *    launch a browser</li>
      * <li><b>NONE</b> - just launches the server, useful together with
      *    <code>com.dukescript.presenters.browserPort</code> property that
      *    can specify a fixed port to open the server at
      * </li>
      * <li>any other value is interpreted as a command which is then
      *    launched on a command line with one parameter - the URL to connect to</li>
      * </ul>
      * If the property is not specified the system tries <b>GTK</b> mode first,
      * followed by <b>AWT</b> and then tries to execute <code>xdg-open</code>
      * (default LINUX command to launch a browser from a shell script).
      */
     public Browser() {
         this(new Config());
     }

     /**
      * Browser configured by provided config.
      *
      * @param config the configuration
      */
     public Browser(Config config) {
         this(findCalleeClassName(), config, null);
     }

     Browser(String app, Config config, Supplier<HttpServer<?,?,?, ?>> serverProvider) {
         this.serverProvider = serverProvider != null ? serverProvider : GrizzlyServer::new;
         this.app = app;
         this.config = new Config(config);
     }

     @Override
     public final void execute(final Runnable r) {
         current.execute(r);
     }

     @Override
     public void close() throws IOException {
         if (server != null) {
             server.shutdownNow();
         }
     }

     HttpServer server() {
         return server;
     }

     static HttpServer findServer(Object obj) {
         Command c;
         if (obj instanceof Command) {
             c = (Command) obj;
         } else if (obj instanceof ProtoPresenter) {
             c = ((ProtoPresenter) obj).lookup(Command.class);
         } else {
             throw new IllegalArgumentException("Cannot find server for " + obj);
         }
         return c.browser.server();
     }

     /** Shows URL in a browser.
      * @param page the page to display in the browser
      * @throws IOException if something goes wrong
      */
     void show(URI page) throws IOException {
         String impl = config.getBrowser();
         if ("none".equalsIgnoreCase(impl)) { // NOI18N
             return;
         }
         if (impl != null) {
             Show.show(impl, page);
         } else {
             IOException one, two;
             try {
                 String ui = System.getProperty("os.name").contains("Mac") ?
                     "Cocoa" : "GTK";
                 Show.show(ui, page);
                 return;
             } catch (IOException ex) {
                 one = ex;
             }
             try {
                 Show.show("AWT", page);
                 return;
             } catch (IOException ex) {
                 two = ex;
             }
             try {
                 Show.show(impl, page);
             } catch (IOException ex) {
                 two.initCause(one);
                 ex.initCause(two);
                 throw ex;
             }
         }
     }

     @Override
     public Fn defineFn(String string, String... strings) {
         throw new UnsupportedOperationException();
     }

     @Override
     public void loadScript(Reader reader) throws Exception {
         throw new UnsupportedOperationException();
     }

     @Override
     public Fn defineFn(String string, String[] strings, boolean[] blns) {
         throw new UnsupportedOperationException();
     }

     @Override
     public void flush() throws IOException {
         throw new UnsupportedOperationException();
     }

     private static URI pageURL(String protocol, HttpServer server, final String page) {
         int port = server.getPort();
         try {
             return new URI(protocol + "://localhost:" + port + page);
         } catch (URISyntaxException ex) {
             throw new IllegalStateException(ex);
         }
     }

     @Override
     public final void displayPage(URL page, Runnable onPageLoad) {
         try {
             this.onPageLoad = onPageLoad;
             this.server = serverProvider.get();
             int from = 8080;
             int to = 65535;
             int port = config.getPort();
             if (port != -1) {
                 from = to = port;
             }
             server.init(from, to);

             this.server.addHttpHandler(new RootPage(page), "/");
             server.start();

             show(pageURL("http", server, "/"));
         } catch (IOException ex) {
             Logger.getLogger(Browser.class.getName()).log(Level.SEVERE, null, ex);
         }
     }

     /** Parameters to configure {@link Browser}.
      * Create an instance and pass it
      * to {@link Browser#Browser(org.netbeans.html.presenters.browser.Browser.Config) }
      * constructor.
      */
     public final static class Config {
         String browser;
         Integer port;
         boolean debug;

         /**
          * Default constructor.
          */
         public Config() {
         }

         private Config(Config copy) {
             this.browser = copy.browser;
             this.port = copy.port;
             this.debug = copy.debug;
         }

         /** The command to use when invoking a browser. Possible values:
          * <ul>
          * <li>
          *   <b>GTK</b> - use Gtk WebKit implementation. Requires presence of appropriate native libraries
          * </li>
          * <li>
          *   <b>AWT</b> - use Desktop.browse(java.net.URI) to launch a browser
          * </li>
          * <li>
          *   <b>NONE</b> - just launches the server, useful together with {@link #port(int)} to specify a fixed port to open the server at
          * </li>
          * <li>
          * any other value is interpreted as a command which is then launched on a command line with one parameter - the URL to connect to
          * </li>
          * </ul>
          *
          * @param executable browser to execute
          * @return this instance
          */
         public Config command(String executable) {
             this.browser = executable;
             return this;
         }

         /** The port to start the server at.
          * By default a random port is selected.
          * @param port the port
          * @return this instance
          */
         public Config port(int port) {
             this.port = port;
             return this;
         }

         /** Enable or disable debugging. The default value is taken from a property
          * {@code com.dukescript.presenters.browserDebug}. If the property is
          * not specified, then the default value is {@code false}.
          *
          * @param debug true or false
          * @return this instance
          * @since 1.8
          */
         Config debug(boolean debug) {
             this.debug = debug;
             return this;
         }

         final String getBrowser() {
             if (browser != null) {
                 return browser;
             }
             return System.getProperty("com.dukescript.presenters.browser"); // NOI18N
         }

         final int getPort() {
             if (port != null) {
                 return port;
             }
             String browserPort = System.getProperty("com.dukescript.presenters.browserPort"); // NOI18N
             try {
                 return Integer.parseInt(browserPort);
             } catch (NumberFormatException ex) {
                 return -1;
             }
         }
     }

     static <Response> void cors(HttpServer<?, Response, ?, ?> s, Response r) {
         s.setCharacterEncoding(r, "UTF-8");
         s.addHeader(r, "Access-Control-Allow-Origin", "*");
         s.addHeader(r, "Access-Control-Allow-Credentials", "true");
         s.addHeader(r, "Access-Control-Allow-Headers", "Content-Type");
         s.addHeader(r, "Access-Control-Allow-Methods", "GET, POST, DELETE, PUT");
     }

     private final class RootPage extends HttpServer.Handler {
         private final URL page;

         public RootPage(URL page) {
             this.page = page;
         }

         @Override
         public <Request, Response> void service(HttpServer<Request, Response, ?, ?> server, Request rqst, Response rspns) throws IOException {
             String path = server.getRequestURI(rqst);
             cors(server, rspns);
             if ("/".equals(path) || "index.html".equals(path)) {
                 Reader is;
                 String prefix = "http://" + server.getServerName(rqst) + ":" + server.getServerPort(rqst) + "/";
                 Writer w = server.getWriter(rspns);
                 server.setContentType(rspns, "text/html");
                 final Command cmd = new Command(server, Browser.this, prefix);
                 try {
                     is = new InputStreamReader(page.openStream());
                 } catch (IOException ex) {
                     w.write("<html><body>");
                     w.write("<h1>Browser</h1>");
                     w.write("<pre id='cmd'></pre>");
                     emitScript(w, prefix, cmd.id);
                     w.write("</body></html>");
                     w.close();
                     return;
                 }
                 SESSIONS.put(cmd.id, cmd);
                 int state = 0;
                 for (;;) {
                     int ch = is.read();
                     if (ch == -1) {
                         break;
                     }
                     char lower = Character.toLowerCase((char)ch);
                     switch (state) {
                         case 1000: break;
                         case 0: if (lower == '<') state = 1; break;
                         case 1: if (lower == 'b') state = 2;
                             else if (lower != ' ' && lower != '\n') state = 0;
                             break;
                         case 2: if (lower == 'o') state = 3; else state = 0; break;
                         case 3: if (lower == 'd') state = 4; else state = 0; break;
                         case 4: if (lower == 'y') state = 5; else state = 0; break;
                         case 5: if (lower == '>') state = 500;
                             else if (lower != ' ' && lower != '\n') state = 0;
                             break;
                     }
                     w.write((char)ch);
                     if (state == 500) {
                         emitScript(w, prefix, cmd.id);
                         state = 1000;
                     }
                 }
                 if (state != 1000) {
                     emitScript(w, prefix, cmd.id);
                 }
                 is.close();
                 w.close();
             } else if (path.equals("/command.js")) {
                 String id = server.getParameter(rqst, "id");
                 Command c = SESSIONS.get(id);
                 if (c == null) {
                     server.getWriter(rspns).write("No command for " + id);
                     server.setStatus(rspns, 404);
                     return;
                 }
                 c.service(rqst, rspns);
             } else {
                 if (path.startsWith("/")) {
                     path = path.substring(1);
                 }
                 URL relative = new URL(page, path);
                 InputStream is;
                 URLConnection conn;
                 try {
                     conn = relative.openConnection();
                     is = conn.getInputStream();
                 } catch (FileNotFoundException ex) {
                     server.setStatus(rspns, 404);
                     return;
                 }
                 String found = null;
                 if (relative.getProtocol().equals("file")) {
                     try {
                         File file = new File(relative.toURI());
                         found = Files.probeContentType(file.toPath());
                     } catch (URISyntaxException | IOException ignore) {
                     }
                 } else {
                     found = conn.getContentType();
                 }
                 if (found == null || "content/unknown".equals(found)) {
                     if (path.endsWith(".html")) {
                         found = "text/html";
                     }
                     if (path.endsWith(".js")) {
                         found = "text/javascript";
                     }
                     if (path.endsWith(".css")) {
                         found = "text/css";
                     }
                 }
                 if (found != null) {
                     server.setContentType(rspns, found);
                 }
                 OutputStream out = server.getOutputStream(rspns);
                 for (;;) {
                     int b = is.read();
                     if (b == -1) {
                         break;
                     }
                     out.write(b);
                 }
                 out.close();
                 is.close();
             }
         }

         private void emitScript(Writer w, String prefix, String id) throws IOException {
             w.write("  <script id='exec' type='text/javascript'>");
             w.write("\n"
                     + "function waitForCommand(counter) {\n"
                     + "  try {\n"
                     + "    if (waitForCommand.seenError) {\n"
                     + "      console.warn('Disconnected from " + prefix + "');\n"
                     + "      return;\n"
                     + "    };\n"
                     + "    var request = new XMLHttpRequest();\n");
             if (Browser.this.config.debug) {
                 w.write(""
                     + "    console.log('GET[' + counter + ']....');\n"
                 );
             }
             w.write(""
                     + "    request.open('GET', '" + prefix + "command.js?id=" + id + "', true);\n"
                     + "    request.setRequestHeader('Content-Type', 'text/plain; charset=utf-8');\n"
                     + "    request.onerror = function(ev) {\n"
                     + "      console.warn(ev);\n"
                     + "      waitForCommand.seenError = true;\n"
                     + "    };\n"
                     + "    request.onreadystatechange = function() {\n"
                     + "      if (this.readyState!==4) return;\n"
                     + "      try {\n"
             );
             if (Browser.this.config.debug) {
                 w.write(""
                     + "        console.log('...GET[' + counter + '] got something ' + this.responseText.substring(0,80));\n"
                     + "        var cmd = document.getElementById('cmd');\n"
                     + "        if (cmd) cmd.innerHTML = this.responseText.substring(0,80);\n"
                 );
             }
             w.write(""
                     + "        (0 || eval)(this.responseText);\n"
                     + "      } catch (e) {\n"
                     + "        console.warn(e); \n"
                     + "      } finally {\n"
                     + "        waitForCommand(counter + 1);\n"
                     + "      }\n"
                     + "    };\n"
                     + "    request.send();\n"
                     + "  } catch (e) {\n"
                     + "    console.warn(e);\n"
                     + "    waitForCommand(counter + 1);\n"
                     + "  }\n"
                     + "}\n"
                     + "waitForCommand(1);\n"
             );
             w.write("  </script>\n");
         }
     }

     String createCallbackFn(String prefix, String id) {
         StringBuilder sb = new StringBuilder();
         sb.append("this.toBrwsrSrvr = function(name, a1, a2, a3, a4) {\n"
             + "var url = '").append(prefix).append("command.js?id=").append(id).append("&name=' + name;\n"
             + "var body = 'p0=' + encodeURIComponent(a1);\n"
             + "body += '&p1=' + encodeURIComponent(a2);\n"
             + "body += '&p2=' + encodeURIComponent(a3);\n"
             + "body += '&p3=' + encodeURIComponent(a4);\n"
             + "var request = new XMLHttpRequest();\n"
         );
         if (Browser.this.config.debug) {
             sb.append(""
             + "console.log('PUT ... ' + body.substring(0, 80));\n"
             + "var now = new Date().getTime();\n"
             );
         }
         sb.append(""
             + "request.open('PUT', url, false);\n"
             + "request.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded; charset=utf-8');\n"
             + "request.send(body);\n"
             + "var txt = request.responseText;\n"
         );
         if (Browser.this.config.debug) {
             sb.append(""
             + "var then = new Date().getTime();\n"
             + "if (txt && txt !== 'null') {\n"
             + "  var cmd = document.getElementById('cmd');\n"
             + "  if (cmd) cmd.innerHTML = txt.substring(0,80);\n"
             + "}\n"
             + "console.log('... PUT [' + (then - now) + 'ms]: ' + txt.substring(0, 80));\n"
             );
         }
         sb.append(""
             + "return txt;\n"
             + "};\n"
         );
         return sb.toString();
     }

     private static String findCalleeClassName() {
         StackTraceElement[] frames = new Exception().getStackTrace();
         for (StackTraceElement e : frames) {
             String cn = e.getClassName();
             if (cn.startsWith("com.dukescript.presenters.")) { // NOI18N
                 continue;
             }
             if (cn.startsWith("org.netbeans.html.")) { // NOI18N
                 continue;
             }
             if (cn.startsWith("net.java.html.")) { // NOI18N
                 continue;
             }
             if (cn.startsWith("java.")) { // NOI18N
                 continue;
             }
             if (cn.startsWith("javafx.")) { // NOI18N
                 continue;
             }
             if (cn.startsWith("com.sun.")) { // NOI18N
                 continue;
             }
             return cn;
         }
         return "org.netbeans.html"; // NOI18N
     }

     private static final class Command<Request, Response, Runner> extends Object
     implements Executor {
         private final HttpServer<Request, Response, ?, Runner> server;
         private final Queue<Object> exec;
         private final Browser browser;
         private final String id;
         private final String prefix;
         private Runner RUNNER;
         private Response suspended;
         private boolean initialized;
         private final ProtoPresenter presenter;

         Command(HttpServer<Request, Response, ?, Runner> s, Browser browser, String prefix) {
             this.server = s;
             this.id = UUID.randomUUID().toString();
             this.RUNNER = s.initializeRunner(this.id);
             this.exec = new LinkedList<>();
             this.prefix = prefix;
             this.browser = browser;
             this.presenter = ProtoPresenterBuilder.newBuilder().
                 preparator(this::callbackFn, true).
                 loadJavaScript(this::loadJS, false).
                 app(browser.app).
                 dispatcher(this, true).
                 displayer(this::displayPage).
                 logger(this::log).
                 type("Browser").
                 register(this).
                 build();
         }

         @Override
         public final void execute(final Runnable r) {
             server.runSafe(this.RUNNER, r, this.presenter);
         }

         final synchronized void add(Object obj) {
             if (suspended != null) {
                 Response rqst = suspended;
                 server.resume(rqst, () -> {
                     try (Writer w = server.getWriter(rqst)) {
                         w.write(obj.toString());
                     } catch (IOException ex) {
                         LOG.log(Level.SEVERE, null, ex);
                     }
                 });
                 suspended = null;
                 return;
             }
             exec.add(obj);
         }

         private synchronized Object take(Response rspns) {
             Object o = exec.poll();
             if (o != null) {
                 return o;
             }
             suspended = rspns;
             server.suspend(rspns);
             return null;
         }

         private synchronized boolean initialize(Response rspns) {
             if (!initialized) {
                 initialized = true;
                 suspended = rspns;
                 server.suspend(rspns);
                 execute(browser.onPageLoad);
                 return true;
             }
             return false;
         }

         void service(Request rqst, Response rspns) throws IOException {
             final String methodName = server.getParameter(rqst, "name");
             server.setContentType(rspns, "text/javascript");
             Writer w = server.getWriter(rspns);
             if (methodName == null) {
                 if (initialize(rspns)) {
                     return;
                 }
                 // send new request
                 Object obj = take(rspns);
                 if (obj == null) {
                     LOG.log(Level.FINE, "Suspending response {0}", rspns);
                     return;
                 }
                 final String s = obj.toString();
                 w.write(s);
                 LOG.log(Level.FINE, "Exec global: {0}", s);
             } else {
                 List<String> args = new ArrayList<>();
                 String body = server.getBody(rqst);
                 for (String p : body.split("&")) {
                     args.add(URLDecoder.decode(p.substring(3), "UTF-8"));
                 }
                 String res;
                 try {
                     LOG.log(Level.FINE, "Call {0}", methodName + " with " + args);
                     res = presenter.js2java(methodName,
                         args.get(0), args.get(1), args.get(2), args.get(3)
                     );
                     LOG.log(Level.FINE, "Result: {0}", res);
                 } catch (Exception ex) {
                     res = "error:" + ex.getMessage();
                 }
                 if (res != null) {
                     w.write(res);
                 } else {
                     w.write("null");
                 }
             }
             w.close();
         }

         void callbackFn(ProtoPresenterBuilder.OnPrepared onReady) {
             String sb = this.browser.createCallbackFn(prefix, id);
             add(sb);
             onReady.callbackIsPrepared("toBrwsrSrvr");
         }

         private static Level findLevel(int priority) {
             if (priority >= Level.SEVERE.intValue()) {
                 return Level.SEVERE;
             }
             if (priority >= Level.WARNING.intValue()) {
                 return Level.WARNING;
             }
             if (priority >= Level.INFO.intValue()) {
                 return Level.INFO;
             }
             return Level.FINE;
         }

         void log(int priority, String msg, Object... args) {
             Level level = findLevel(priority);

             if (args.length == 1 && args[0] instanceof Throwable) {
                 LOG.log(level, msg, (Throwable) args[0]);
             } else {
                 LOG.log(level, msg, args);
             }
         }

         final void loadJS(String js) {
             add(js);
         }

         void dispatch(Runnable r) {
             server.runSafe(RUNNER, r, null);
         }


         public void displayPage(URL url, Runnable r) {
             throw new UnsupportedOperationException(url.toString());
         }
     } // end of Command
 }
	/**
	* 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.netbeans.html.presenters.browser;

	import org.netbeans.html.presenters.render.Show;
	import java.io.Closeable;
	import java.io.File;
	import java.io.FileNotFoundException;
	import java.io.Flushable;
	import java.io.IOException;
	import java.io.InputStream;
	import java.io.InputStreamReader;
	import java.io.OutputStream;
	import java.io.Reader;
	import java.io.Writer;
	import java.net.URI;
	import java.net.URISyntaxException;
	import java.net.URL;
	import java.net.URLConnection;
	import java.net.URLDecoder;
	import java.nio.file.Files;
	import java.util.ArrayList;
	import java.util.HashMap;
	import java.util.LinkedList;
	import java.util.List;
	import java.util.Map;
	import java.util.Queue;
	import java.util.UUID;
	import java.util.concurrent.Executor;
	import java.util.concurrent.Executors;
	import java.util.concurrent.ThreadFactory;
	import java.util.function.Supplier;
	import java.util.logging.Level;
	import java.util.logging.Logger;
	import org.netbeans.html.boot.spi.Fn;
	import org.netbeans.html.boot.spi.Fn.Presenter;
	import org.netbeans.html.presenters.spi.ProtoPresenter;
	import org.netbeans.html.presenters.spi.ProtoPresenterBuilder;
	import org.openide.util.lookup.ServiceProvider;

	/** Browser based {@link Presenter}. It starts local server and
	* launches browser that connects to it. Use {@link Browser.Config} to
	* configure the actual browser to be started.
	* <p>
	* To use this presenter specify following dependency:
	* <pre>
	* <dependency>
	* <groupId>org.netbeans.html.browser</groupId>
	* <artifactId>browser</artifactId>
	* <version><a target="blank" href="http://search.maven.org/#search%7Cgav%7C1%7Cg%3A%22com.dukescript.presenters%22%20AND%20a%3A%22browser%22">1.x</a></version>
	* </dependency>
	* </pre>
	*/
	@ServiceProvider(service = Presenter.class)
	public final class Browser implements Fn.Presenter, Fn.KeepAlive, Flushable,
	Executor, Closeable {
	static final Logger LOG = Logger.getLogger(Browser.class.getName());
	private final Map<String,Command> SESSIONS = new HashMap<>();
	private final String app;
	private HttpServer server;
	private Runnable onPageLoad;
	private Command current;
	private final Config config;
	private final Supplier<HttpServer<?, ?, ?, ?>> serverProvider;

	/** Default constructor. Reads configuration from properties. The actual browser to
	* be launched can be influenced by value of
	* <code>com.dukescript.presenters.browser</code> property.
	* It can have following values:
	* <ul>
	* <li><b>GTK</b> - use Gtk WebKit implementation. Requires presence of
	* appropriate native libraries</li>
	* <li><b>AWT</b> - use {@link java.awt.Desktop#browse(java.net.URI)} to
	* launch a browser</li>
	* <li><b>NONE</b> - just launches the server, useful together with
	* <code>com.dukescript.presenters.browserPort</code> property that
	* can specify a fixed port to open the server at
	* </li>
	* <li>any other value is interpreted as a command which is then
	* launched on a command line with one parameter - the URL to connect to</li>
	* </ul>
	* If the property is not specified the system tries <b>GTK</b> mode first,
	* followed by <b>AWT</b> and then tries to execute <code>xdg-open</code>
	* (default LINUX command to launch a browser from a shell script).
	*/
	public Browser() {
	this(new Config());
	}

	/**
	* Browser configured by provided config.
	*
	* @param config the configuration
	*/
	public Browser(Config config) {
	this(findCalleeClassName(), config, null);
	}

	Browser(String app, Config config, Supplier<HttpServer<?,?,?, ?>> serverProvider) {
	this.serverProvider = serverProvider != null ? serverProvider : GrizzlyServer::new;
	this.app = app;
	this.config = new Config(config);
	}

	@Override
	public final void execute(final Runnable r) {
	current.execute(r);
	}

	@Override
	public void close() throws IOException {
	if (server != null) {
	server.shutdownNow();
	}
	}

	HttpServer server() {
	return server;
	}

	static HttpServer findServer(Object obj) {
	Command c;
	if (obj instanceof Command) {
	c = (Command) obj;
	} else if (obj instanceof ProtoPresenter) {
	c = ((ProtoPresenter) obj).lookup(Command.class);
	} else {
	throw new IllegalArgumentException("Cannot find server for " + obj);
	}
	return c.browser.server();
	}

	/** Shows URL in a browser.
	* @param page the page to display in the browser
	* @throws IOException if something goes wrong
	*/
	void show(URI page) throws IOException {
	String impl = config.getBrowser();
	if ("none".equalsIgnoreCase(impl)) { // NOI18N
	return;
	}
	if (impl != null) {
	Show.show(impl, page);
	} else {
	IOException one, two;
	try {
	String ui = System.getProperty("os.name").contains("Mac") ?
	"Cocoa" : "GTK";
	Show.show(ui, page);
	return;
	} catch (IOException ex) {
	one = ex;
	}
	try {
	Show.show("AWT", page);
	return;
	} catch (IOException ex) {
	two = ex;
	}
	try {
	Show.show(impl, page);
	} catch (IOException ex) {
	two.initCause(one);
	ex.initCause(two);
	throw ex;
	}
	}
	}

	@Override
	public Fn defineFn(String string, String... strings) {
	throw new UnsupportedOperationException();
	}

	@Override
	public void loadScript(Reader reader) throws Exception {
	throw new UnsupportedOperationException();
	}

	@Override
	public Fn defineFn(String string, String[] strings, boolean[] blns) {
	throw new UnsupportedOperationException();
	}

	@Override
	public void flush() throws IOException {
	throw new UnsupportedOperationException();
	}

	private static URI pageURL(String protocol, HttpServer server, final String page) {
	int port = server.getPort();
	try {
	return new URI(protocol + "://localhost:" + port + page);
	} catch (URISyntaxException ex) {
	throw new IllegalStateException(ex);
	}
	}

	@Override
	public final void displayPage(URL page, Runnable onPageLoad) {
	try {
	this.onPageLoad = onPageLoad;
	this.server = serverProvider.get();
	int from = 8080;
	int to = 65535;
	int port = config.getPort();
	if (port != -1) {
	from = to = port;
	}
	server.init(from, to);

	this.server.addHttpHandler(new RootPage(page), "/");
	server.start();

	show(pageURL("http", server, "/"));
	} catch (IOException ex) {
	Logger.getLogger(Browser.class.getName()).log(Level.SEVERE, null, ex);
	}
	}

	/** Parameters to configure {@link Browser}.
	* Create an instance and pass it
	* to {@link Browser#Browser(org.netbeans.html.presenters.browser.Browser.Config) }
	* constructor.
	*/
	public final static class Config {
	String browser;
	Integer port;
	boolean debug;

	/**
	* Default constructor.
	*/
	public Config() {
	}

	private Config(Config copy) {
	this.browser = copy.browser;
	this.port = copy.port;
	this.debug = copy.debug;
	}

	/** The command to use when invoking a browser. Possible values:
	* <ul>
	* <li>
	* <b>GTK</b> - use Gtk WebKit implementation. Requires presence of appropriate native libraries
	* </li>
	* <li>
	* <b>AWT</b> - use Desktop.browse(java.net.URI) to launch a browser
	* </li>
	* <li>
	* <b>NONE</b> - just launches the server, useful together with {@link #port(int)} to specify a fixed port to open the server at
	* </li>
	* <li>
	* any other value is interpreted as a command which is then launched on a command line with one parameter - the URL to connect to
	* </li>
	* </ul>
	*
	* @param executable browser to execute
	* @return this instance
	*/
	public Config command(String executable) {
	this.browser = executable;
	return this;
	}

	/** The port to start the server at.
	* By default a random port is selected.
	* @param port the port
	* @return this instance
	*/
	public Config port(int port) {
	this.port = port;
	return this;
	}

	/** Enable or disable debugging. The default value is taken from a property
	* {@code com.dukescript.presenters.browserDebug}. If the property is
	* not specified, then the default value is {@code false}.
	*
	* @param debug true or false
	* @return this instance
	* @since 1.8
	*/
	Config debug(boolean debug) {
	this.debug = debug;
	return this;
	}

	final String getBrowser() {
	if (browser != null) {
	return browser;
	}
	return System.getProperty("com.dukescript.presenters.browser"); // NOI18N
	}

	final int getPort() {
	if (port != null) {
	return port;
	}
	String browserPort = System.getProperty("com.dukescript.presenters.browserPort"); // NOI18N
	try {
	return Integer.parseInt(browserPort);
	} catch (NumberFormatException ex) {
	return -1;
	}
	}
	}

	static <Response> void cors(HttpServer<?, Response, ?, ?> s, Response r) {
	s.setCharacterEncoding(r, "UTF-8");
	s.addHeader(r, "Access-Control-Allow-Origin", "*");
	s.addHeader(r, "Access-Control-Allow-Credentials", "true");
	s.addHeader(r, "Access-Control-Allow-Headers", "Content-Type");
	s.addHeader(r, "Access-Control-Allow-Methods", "GET, POST, DELETE, PUT");
	}

	private final class RootPage extends HttpServer.Handler {
	private final URL page;

	public RootPage(URL page) {
	this.page = page;
	}

	@Override
	public <Request, Response> void service(HttpServer<Request, Response, ?, ?> server, Request rqst, Response rspns) throws IOException {
	String path = server.getRequestURI(rqst);
	cors(server, rspns);
	if ("/".equals(path) \|\| "index.html".equals(path)) {
	Reader is;
	String prefix = "http://" + server.getServerName(rqst) + ":" + server.getServerPort(rqst) + "/";
	Writer w = server.getWriter(rspns);
	server.setContentType(rspns, "text/html");
	final Command cmd = new Command(server, Browser.this, prefix);
	try {
	is = new InputStreamReader(page.openStream());
	} catch (IOException ex) {
	w.write("<html><body>");
	w.write("<h1>Browser</h1>");
	w.write("<pre id='cmd'></pre>");
	emitScript(w, prefix, cmd.id);
	w.write("</body></html>");
	w.close();
	return;
	}
	SESSIONS.put(cmd.id, cmd);
	int state = 0;
	for (;;) {
	int ch = is.read();
	if (ch == -1) {
	break;
	}
	char lower = Character.toLowerCase((char)ch);
	switch (state) {
	case 1000: break;
	case 0: if (lower == '<') state = 1; break;
	case 1: if (lower == 'b') state = 2;
	else if (lower != ' ' && lower != '\n') state = 0;
	break;
	case 2: if (lower == 'o') state = 3; else state = 0; break;
	case 3: if (lower == 'd') state = 4; else state = 0; break;
	case 4: if (lower == 'y') state = 5; else state = 0; break;
	case 5: if (lower == '>') state = 500;
	else if (lower != ' ' && lower != '\n') state = 0;
	break;
	}
	w.write((char)ch);
	if (state == 500) {
	emitScript(w, prefix, cmd.id);
	state = 1000;
	}
	}
	if (state != 1000) {
	emitScript(w, prefix, cmd.id);
	}
	is.close();
	w.close();
	} else if (path.equals("/command.js")) {
	String id = server.getParameter(rqst, "id");
	Command c = SESSIONS.get(id);
	if (c == null) {
	server.getWriter(rspns).write("No command for " + id);
	server.setStatus(rspns, 404);
	return;
	}
	c.service(rqst, rspns);
	} else {
	if (path.startsWith("/")) {
	path = path.substring(1);
	}
	URL relative = new URL(page, path);
	InputStream is;
	URLConnection conn;
	try {
	conn = relative.openConnection();
	is = conn.getInputStream();
	} catch (FileNotFoundException ex) {
	server.setStatus(rspns, 404);
	return;
	}
	String found = null;
	if (relative.getProtocol().equals("file")) {
	try {
	File file = new File(relative.toURI());
	found = Files.probeContentType(file.toPath());
	} catch (URISyntaxException \| IOException ignore) {
	}
	} else {
	found = conn.getContentType();
	}
	if (found == null \|\| "content/unknown".equals(found)) {
	if (path.endsWith(".html")) {
	found = "text/html";
	}
	if (path.endsWith(".js")) {
	found = "text/javascript";
	}
	if (path.endsWith(".css")) {
	found = "text/css";
	}
	}
	if (found != null) {
	server.setContentType(rspns, found);
	}
	OutputStream out = server.getOutputStream(rspns);
	for (;;) {
	int b = is.read();
	if (b == -1) {
	break;
	}
	out.write(b);
	}
	out.close();
	is.close();
	}
	}

	private void emitScript(Writer w, String prefix, String id) throws IOException {
	w.write(" <script id='exec' type='text/javascript'>");
	w.write("\n"
	+ "function waitForCommand(counter) {\n"
	+ " try {\n"
	+ " if (waitForCommand.seenError) {\n"
	+ " console.warn('Disconnected from " + prefix + "');\n"
	+ " return;\n"
	+ " };\n"
	+ " var request = new XMLHttpRequest();\n");
	if (Browser.this.config.debug) {
	w.write(""
	+ " console.log('GET[' + counter + ']....');\n"
	);
	}
	w.write(""
	+ " request.open('GET', '" + prefix + "command.js?id=" + id + "', true);\n"
	+ " request.setRequestHeader('Content-Type', 'text/plain; charset=utf-8');\n"
	+ " request.onerror = function(ev) {\n"
	+ " console.warn(ev);\n"
	+ " waitForCommand.seenError = true;\n"
	+ " };\n"
	+ " request.onreadystatechange = function() {\n"
	+ " if (this.readyState!==4) return;\n"
	+ " try {\n"
	);
	if (Browser.this.config.debug) {
	w.write(""
	+ " console.log('...GET[' + counter + '] got something ' + this.responseText.substring(0,80));\n"
	+ " var cmd = document.getElementById('cmd');\n"
	+ " if (cmd) cmd.innerHTML = this.responseText.substring(0,80);\n"
	);
	}
	w.write(""
	+ " (0 \|\| eval)(this.responseText);\n"
	+ " } catch (e) {\n"
	+ " console.warn(e); \n"
	+ " } finally {\n"
	+ " waitForCommand(counter + 1);\n"
	+ " }\n"
	+ " };\n"
	+ " request.send();\n"
	+ " } catch (e) {\n"
	+ " console.warn(e);\n"
	+ " waitForCommand(counter + 1);\n"
	+ " }\n"
	+ "}\n"
	+ "waitForCommand(1);\n"
	);
	w.write(" </script>\n");
	}
	}

	String createCallbackFn(String prefix, String id) {
	StringBuilder sb = new StringBuilder();
	sb.append("this.toBrwsrSrvr = function(name, a1, a2, a3, a4) {\n"
	+ "var url = '").append(prefix).append("command.js?id=").append(id).append("&name=' + name;\n"
	+ "var body = 'p0=' + encodeURIComponent(a1);\n"
	+ "body += '&p1=' + encodeURIComponent(a2);\n"
	+ "body += '&p2=' + encodeURIComponent(a3);\n"
	+ "body += '&p3=' + encodeURIComponent(a4);\n"
	+ "var request = new XMLHttpRequest();\n"
	);
	if (Browser.this.config.debug) {
	sb.append(""
	+ "console.log('PUT ... ' + body.substring(0, 80));\n"
	+ "var now = new Date().getTime();\n"
	);
	}
	sb.append(""
	+ "request.open('PUT', url, false);\n"
	+ "request.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded; charset=utf-8');\n"
	+ "request.send(body);\n"
	+ "var txt = request.responseText;\n"
	);
	if (Browser.this.config.debug) {
	sb.append(""
	+ "var then = new Date().getTime();\n"
	+ "if (txt && txt !== 'null') {\n"
	+ " var cmd = document.getElementById('cmd');\n"
	+ " if (cmd) cmd.innerHTML = txt.substring(0,80);\n"
	+ "}\n"
	+ "console.log('... PUT [' + (then - now) + 'ms]: ' + txt.substring(0, 80));\n"
	);
	}
	sb.append(""
	+ "return txt;\n"
	+ "};\n"
	);
	return sb.toString();
	}

	private static String findCalleeClassName() {
	StackTraceElement[] frames = new Exception().getStackTrace();
	for (StackTraceElement e : frames) {
	String cn = e.getClassName();
	if (cn.startsWith("com.dukescript.presenters.")) { // NOI18N
	continue;
	}
	if (cn.startsWith("org.netbeans.html.")) { // NOI18N
	continue;
	}
	if (cn.startsWith("net.java.html.")) { // NOI18N
	continue;
	}
	if (cn.startsWith("java.")) { // NOI18N
	continue;
	}
	if (cn.startsWith("javafx.")) { // NOI18N
	continue;
	}
	if (cn.startsWith("com.sun.")) { // NOI18N
	continue;
	}
	return cn;
	}
	return "org.netbeans.html"; // NOI18N
	}

	private static final class Command<Request, Response, Runner> extends Object
	implements Executor {
	private final HttpServer<Request, Response, ?, Runner> server;
	private final Queue<Object> exec;
	private final Browser browser;
	private final String id;
	private final String prefix;
	private Runner RUNNER;
	private Response suspended;
	private boolean initialized;
	private final ProtoPresenter presenter;

	Command(HttpServer<Request, Response, ?, Runner> s, Browser browser, String prefix) {
	this.server = s;
	this.id = UUID.randomUUID().toString();
	this.RUNNER = s.initializeRunner(this.id);
	this.exec = new LinkedList<>();
	this.prefix = prefix;
	this.browser = browser;
	this.presenter = ProtoPresenterBuilder.newBuilder().
	preparator(this::callbackFn, true).
	loadJavaScript(this::loadJS, false).
	app(browser.app).
	dispatcher(this, true).
	displayer(this::displayPage).
	logger(this::log).
	type("Browser").
	register(this).
	build();
	}

	@Override
	public final void execute(final Runnable r) {
	server.runSafe(this.RUNNER, r, this.presenter);
	}

	final synchronized void add(Object obj) {
	if (suspended != null) {
	Response rqst = suspended;
	server.resume(rqst, () -> {
	try (Writer w = server.getWriter(rqst)) {
	w.write(obj.toString());
	} catch (IOException ex) {
	LOG.log(Level.SEVERE, null, ex);
	}
	});
	suspended = null;
	return;
	}
	exec.add(obj);
	}

	private synchronized Object take(Response rspns) {
	Object o = exec.poll();
	if (o != null) {
	return o;
	}
	suspended = rspns;
	server.suspend(rspns);
	return null;
	}

	private synchronized boolean initialize(Response rspns) {
	if (!initialized) {
	initialized = true;
	suspended = rspns;
	server.suspend(rspns);
	execute(browser.onPageLoad);
	return true;
	}
	return false;
	}

	void service(Request rqst, Response rspns) throws IOException {
	final String methodName = server.getParameter(rqst, "name");
	server.setContentType(rspns, "text/javascript");
	Writer w = server.getWriter(rspns);
	if (methodName == null) {
	if (initialize(rspns)) {
	return;
	}
	// send new request
	Object obj = take(rspns);
	if (obj == null) {
	LOG.log(Level.FINE, "Suspending response {0}", rspns);
	return;
	}
	final String s = obj.toString();
	w.write(s);
	LOG.log(Level.FINE, "Exec global: {0}", s);
	} else {
	List<String> args = new ArrayList<>();
	String body = server.getBody(rqst);
	for (String p : body.split("&")) {
	args.add(URLDecoder.decode(p.substring(3), "UTF-8"));
	}
	String res;
	try {
	LOG.log(Level.FINE, "Call {0}", methodName + " with " + args);
	res = presenter.js2java(methodName,
	args.get(0), args.get(1), args.get(2), args.get(3)
	);
	LOG.log(Level.FINE, "Result: {0}", res);
	} catch (Exception ex) {
	res = "error:" + ex.getMessage();
	}
	if (res != null) {
	w.write(res);
	} else {
	w.write("null");
	}
	}
	w.close();
	}

	void callbackFn(ProtoPresenterBuilder.OnPrepared onReady) {
	String sb = this.browser.createCallbackFn(prefix, id);
	add(sb);
	onReady.callbackIsPrepared("toBrwsrSrvr");
	}

	private static Level findLevel(int priority) {
	if (priority >= Level.SEVERE.intValue()) {
	return Level.SEVERE;
	}
	if (priority >= Level.WARNING.intValue()) {
	return Level.WARNING;
	}
	if (priority >= Level.INFO.intValue()) {
	return Level.INFO;
	}
	return Level.FINE;
	}

	void log(int priority, String msg, Object... args) {
	Level level = findLevel(priority);

	if (args.length == 1 && args[0] instanceof Throwable) {
	LOG.log(level, msg, (Throwable) args[0]);
	} else {
	LOG.log(level, msg, args);
	}
	}

	final void loadJS(String js) {
	add(js);
	}

	void dispatch(Runnable r) {
	server.runSafe(RUNNER, r, null);
	}


	public void displayPage(URL url, Runnable r) {
	throw new UnsupportedOperationException(url.toString());
	}
	} // end of Command
	}