/*
 *  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
 *
 *      https://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.
 */

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintStream;
import java.io.UnsupportedEncodingException;
import java.net.ServerSocket;
import java.net.Socket;
import java.nio.charset.StandardCharsets;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Enumeration;
import java.util.Vector;

public class SimpleApplication implements Runnable {

    private ServerSocket server=null;
    private Thread thread=null;
    private volatile boolean stopping=false;
    private String directory=null;
    private final Vector<Handler> handlers;

    public static native void toto();

    public SimpleApplication()
    {
        super();
        System.err.println("SimpleApplication: instance "+this.hashCode()+
                           " created");
        this.handlers = new Vector<>();
    }

    @Override
    protected void finalize() {
        System.err.println("SimpleApplication: instance "+this.hashCode()+
                           " garbage collected");
    }

    /**
     * Main method
     *
     * @param args Optional port and directory configuration
     * @throws Exception If the daemon cannot be set up
     */
    public static void main(String[] args) throws Exception {
        SimpleApplication app = new SimpleApplication();
        System.err.println("SimpleApplication: instance " + app.hashCode()+
                           " init " + args.length);
        int port=1200;
        for (int i = 0; i < args.length; i++) {
            System.err.println("SimpleApplication: arg " + i +
                    " = " + args[i]);

        }
        if (args.length > 0 && !args[0].isEmpty())
            port=Integer.parseInt(args[0]);
        if (args.length > 1)
            app.directory = args[1];
        else
            app.directory="/tmp";

        // Dump a message
        System.err.println("SimpleApplication: loading on port "+port);
        Runtime.getRuntime().addShutdownHook(new ShutdownHook(app));
        // Set up this simple daemon
        app.server = new ServerSocket(port);
        app.thread = new Thread(app);
        app.start();
    }

    public void start()
    {
        // Dump a message
        System.err.println("SimpleApplication: starting");

        // Start
        this.thread.start();
    }

    public void stop()
        throws IOException, InterruptedException
    {
        // Dump a message
        System.err.println("SimpleApplication: stopping");

        // Close the ServerSocket. This will make our thread to terminate
        this.stopping=true;
        this.server.close();

        // Wait for the main thread to exit and dump a message
        this.thread.join(5000);
        System.err.println("SimpleApplication: stopped");
    }

    public void destroy()
    {
        System.err.println("SimpleApplication: instance "+this.hashCode()+
                           " destroy");
    }

    @Override
    public void run()
    {
        int number=0;

        System.err.println("SimpleApplication: started acceptor loop");
        try {
            while (!this.stopping) {
                Socket socket = this.server.accept();
                Handler handler = new Handler(socket, this);
                handler.setConnectionNumber(number++);
                handler.setDirectoryName(this.directory);
                new Thread(handler).start();
            }
        } catch (IOException e) {
            // Don't dump any error message if we are stopping. A IOException
            // is generated when the ServerSocket is closed in stop()
            if (!this.stopping) e.printStackTrace(System.err);
        }

        // Terminate all handlers that at this point are still open
        Enumeration<Handler> openhandlers = this.handlers.elements();
        while (openhandlers.hasMoreElements()) {
            Handler handler = openhandlers.nextElement();
            System.err.println("SimpleApplication: dropping connection "+
                               handler.getConnectionNumber());
            handler.close();
        }

        System.err.println("SimpleApplication: exiting acceptor loop");
    }

    protected void addHandler(Handler handler) {
        synchronized (handler) {
            this.handlers.add(handler);
        }
    }

    protected void removeHandler(Handler handler) {
        synchronized (handler) {
            this.handlers.remove(handler);
        }
    }

    public static class ShutdownHook extends Thread
    {
        private final SimpleApplication instance;

        public ShutdownHook(SimpleApplication instance)
        {
            this.instance = instance;
        }
        @Override
        public void run()
        {
            System.out.println("Shutting down");
            try {
                instance.stop();
            }
            catch (Exception e) {
                e.printStackTrace(System.err);
            }
        }
    }

    public static class Handler implements Runnable {

        private final SimpleApplication parent;
        private String directory=null; // Only set before thread is started
        private final Socket socket;
        private int number=0; // Only set before thread is started

        public Handler(Socket s, SimpleApplication p) {
            super();
            this.socket=s;
            this.parent=p;
        }

        @Override
        public void run() {
            this.parent.addHandler(this);
            System.err.println("SimpleApplication: connection " + this.number + " opened from " + this.socket.getInetAddress());
            try {
                InputStream in = this.socket.getInputStream();
                OutputStream out = this.socket.getOutputStream();
                handle(in, out);
                this.socket.close();
            } catch (IOException e) {
                e.printStackTrace(System.err);
            }
            System.err.println("SimpleApplication: connection " + this.number + " closed");
            this.parent.removeHandler(this);
        }

        public void close() {
            try {
                this.socket.close();
            } catch (IOException e) {
                e.printStackTrace(System.err);
            }
        }

        public void setConnectionNumber(int number) {
            this.number=number;
        }

        public int getConnectionNumber() {
            return(this.number);
        }

        public void setDirectoryName(String directory) {
            this.directory=directory;
        }

        public String getDirectoryName() {
            return(this.directory);
        }

        public void createFile(String name) throws IOException {
            OutputStream file = new FileOutputStream(name, true);
            PrintStream out = new PrintStream(file);
            SimpleDateFormat fmt = new SimpleDateFormat();

            out.println(fmt.format(new Date()));
            out.close();
            file.close();
        }

        public void createDir(String name)
        throws IOException {
            File file = new File(name);
            boolean ok = file.mkdirs();
            if (!ok)
                throw new IOException("mkdirs for "+name+" failed");
            createFile(name);
        }

        public void handle(InputStream in, OutputStream os) {
            PrintStream out = null;
            try {
                out = new PrintStream(os, true, StandardCharsets.US_ASCII.name());
            } catch (UnsupportedEncodingException ex) {
                out = new PrintStream(os, true);
            }

            while (true) {
                try {
                    // If we don't have data in the System InputStream, we want
                    // to ask to the user for an option.
                    if (in.available() == 0) {
                        out.println();
                        out.println("Please select one of the following:");
                        out.println("    1) Shutdown");
                        out.println("    2) Create a file");
                        out.println("    3) Disconnect");
                        out.println("    4) Cause a core of the JVM");
                        out.println("    5) Create a directory");
                        out.print("Your choice: ");
                    }

                    // Read an option from the client
                    int x = in.read();

                    switch (x) {
                    // If the socket was closed, we simply return
                    case -1:
                        return;

                    // Attempt to shutdown
                    case '1':
                        out.println("Attempting a shutdown...");
                        try {
                            System.exit(0);
                        } catch (IllegalStateException e) {
                            out.println();
                            out.println("Can't shutdown now");
                            e.printStackTrace(out);
                        }
                        break;

                    // Create a file
                    case '2':
                        String name = this.getDirectoryName() + "/SimpleApplication." + this.getConnectionNumber() + ".tmp";
                        try {
                            this.createFile(name);
                            out.println("File '" + name + "' created");
                        } catch (IOException e) {
                            e.printStackTrace(out);
                        }
                        break;

                    // Disconnect
                    case '3':
                        out.println("Disconnecting...");
                        return;

                    // Crash JVM in a native call: It need an so file ;-)
                    case '4':
                        System.load(System.getProperty("native.library", "./Native.so"));
                        toto();
                        break;

                    // Create a directory (PR 30177 with 1.4.x and 1.5.0
                    case '5':
                        String name1 = this.getDirectoryName() + "/a/b/c/d/e/SimpleApplication." + this.getConnectionNumber() + ".tmp";
                        try {
                            this.createDir(name1);
                            out.println("File '" + name1 + "' created");
                        } catch (IOException e) {
                            e.printStackTrace(out);
                        }
                        break;

                    // Discard any carriage return / newline characters
                    case '\r':
                    case '\n':
                        break;

                    // We got something that we weren't supposed to get
                    default:
                        out.println("Unknown option '" + (char) x + "'");
                        break;

                    }

                    // If we get an IOException we return (disconnect)
                } catch (IOException e) {
                    System.err.println("SimpleApplication: IOException in connection " + this.getConnectionNumber());
                    return;
                }
            }
        }
    }
}