/*
 * 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.felix.gogo.jline.telnet;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintStream;
import java.util.List;

import org.apache.felix.gogo.jline.Shell;
import org.apache.felix.gogo.jline.Shell.Context;
import org.apache.felix.service.command.CommandProcessor;
import org.apache.felix.service.command.CommandSession;
import org.jline.builtins.Options;
import org.jline.terminal.Size;
import org.jline.terminal.Terminal;
import org.jline.terminal.Terminal.Signal;
import org.jline.terminal.TerminalBuilder;

/*
 * a very simple Telnet server.
 * real remote access should be via ssh.
 */
public class Telnet {
    public static final String[] functions = {"telnetd"};

    private static final int defaultPort = 2019;
    private final CommandProcessor processor;
    private PortListener portListener;
    private int port;
    private String ip;

    public Telnet(CommandProcessor procesor) {
        this.processor = procesor;
    }

    public void telnetd(CommandSession session, String[] argv) throws IOException {
        final String[] usage = {"telnetd - start simple telnet server",
                "Usage: telnetd [-i ip] [-p port] start | stop | status",
                "  -i --ip=INTERFACE        listen interface (default=127.0.0.1)",
                "  -p --port=PORT           listen port (default=" + defaultPort + ")",
                "  -? --help                show help"};

        Options opt = Options.compile(usage).parse(argv);
        List<String> args = opt.args();

        if (opt.isSet("help") || args.isEmpty()) {
            opt.usage(System.err);
            return;
        }

        String command = args.get(0);

        if ("start".equals(command)) {
            if (portListener != null) {
                throw new IllegalStateException("telnetd is already running on port " + port);
            }
            ip = opt.get("ip");
            port = opt.getNumber("port");
            start(session);
            status();
        } else if ("stop".equals(command)) {
            if (portListener == null) {
                throw new IllegalStateException("telnetd is not running.");
            }
            stop();
        } else if ("status".equals(command)) {
            status();
        } else {
            throw opt.usageError("bad command: " + command);
        }
    }

    private void status() {
        if (portListener != null) {
            System.out.println("telnetd is running on " + ip + ":" + port);
        } else {
            System.out.println("telnetd is not running.");
        }
    }

    private void start(CommandSession session) {
        ConnectionManager connectionManager = new ConnectionManager(1000, 5 * 60 * 1000, 5 * 60 * 1000, 60 * 1000, null, null, false) {
            @Override
            protected Connection createConnection(ThreadGroup threadGroup, ConnectionData newCD) {
                return new Connection(threadGroup, newCD) {
                    TelnetIO telnetIO;

                    @Override
                    protected void doRun() throws Exception {
                        telnetIO = new TelnetIO();
                        telnetIO.setConnection(this);
                        telnetIO.initIO();

                        InputStream in = new InputStream() {
                            @Override
                            public int read() throws IOException {
                                return telnetIO.read();
                            }
                            @Override
                            public int read(byte[] b, int off, int len) throws IOException {
                                int r = read();
                                if (r >= 0) {
                                    b[off] = (byte) r;
                                    return 1;
                                } else {
                                    return -1;
                                }
                            }
                        };
                        PrintStream out = new PrintStream(new OutputStream() {
                            @Override
                            public void write(int b) throws IOException {
                                telnetIO.write(b);
                            }
                            @Override
                            public void flush() throws IOException {
                                telnetIO.flush();
                            }
                        });
                        Terminal terminal = TerminalBuilder.builder()
                                .type(getConnectionData().getNegotiatedTerminalType().toLowerCase())
                                .streams(in, out)
                                .system(false)
                                .name("telnet")
                                .build();
                        terminal.setSize(new Size(getConnectionData().getTerminalColumns(), getConnectionData().getTerminalRows()));
                        terminal.setAttributes(Shell.getTerminal(session).getAttributes());
                        addConnectionListener(new ConnectionListener() {
                            @Override
                            public void connectionIdle(ConnectionEvent ce) {
                            }

                            @Override
                            public void connectionTimedOut(ConnectionEvent ce) {
                            }

                            @Override
                            public void connectionLogoutRequest(ConnectionEvent ce) {
                            }

                            @Override
                            public void connectionSentBreak(ConnectionEvent ce) {
                            }

                            @Override
                            public void connectionTerminalGeometryChanged(ConnectionEvent ce) {
                                terminal.setSize(new Size(getConnectionData().getTerminalColumns(), getConnectionData().getTerminalRows()));
                                terminal.raise(Signal.WINCH);
                            }
                        });
                        PrintStream pout = new PrintStream(terminal.output());
                        CommandSession session = processor.createSession(terminal.input(), pout, pout);
                        session.put(Shell.VAR_TERMINAL, terminal);
                        Context context = new Context() {
                            @Override
                            public String getProperty(String name) {
                                return System.getProperty(name);
                            }
                            @Override
                            public void exit() {
                                close();
                            }
                        };
                        new Shell(context, processor).gosh(session, new String[]{"--login"});
                    }

                    @Override
                    protected void doClose() {
                        telnetIO.closeOutput();
                        telnetIO.closeInput();
                    }
                };
            }
        };
        portListener = new PortListener("gogo", port, 10);
        portListener.setConnectionManager(connectionManager);
        portListener.start();
    }

    private void stop() {
        portListener.stop();
        portListener = null;
    }

}