// Autor: Antonín Daněk

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;
import java.util.Random;


public class server
{
public int PORT=3555;

public server(String port){

    PORT=Integer.valueOf(port);
    Service s = new Service();
    s.start();

    try{
    System.out.println("Will try to start server on port: " + PORT);
    ServerSocket ss = new ServerSocket(PORT);
    System.out.println("Server started on port: " + PORT);

    while (true) {

        System.out.println("Waiting for the client");
        Socket sck = ss.accept();
        if(s.add(new BufferedReader(new InputStreamReader(sck.getInputStream())),
                new PrintWriter(sck.getOutputStream(), true))){

                    } else System.out.println("too many connections");

           /* try{
            Thread.sleep(10);
            }
            catch(InterruptedException e){
            e.printStackTrace();
            } */

     }

    } catch (IOException ex) {
    System.err.print("Server creation failed on port " + PORT);
    }

    }



	public static void main(String [] args)
	{
            if(args.length!=1) System.out.println("Usage: server <PORT>");
            else new server(args[0]);

	}

}

// It provides services for the clients, respondes to their requests
class Service implements Runnable{

    Random rnd = new Random();

    public static final int MAX_CONNECTION=20;
    int clientCount=0;

    private Thread th=null;

    ArrayList<BufferedReader> br = new ArrayList<BufferedReader>();
    ArrayList<PrintWriter> pw = new ArrayList<PrintWriter>();
    ArrayList<RobotState> rs = new ArrayList<RobotState>();

    public Service() {

    }

    // adds new client to the array lists, if number of connections is not over limit
    boolean add(BufferedReader b, PrintWriter p){

        if(clientCount < MAX_CONNECTION){

            br.add(b);
            pw.add(p);
            rs.add(new RobotState());

            // sends "welcome message" to the client
                 pw.get(clientCount).print("220 Ahoj, tady je robot. Oslovuj mne "+ rs.get(clientCount).robotsName +"." + "\r\n");
                 pw.get(clientCount).flush();

                System.out.println("Client " + clientCount +" connected");

           clientCount++;

            return true;

        } else return false;

    }

    public void start(){
    th = new Thread(this);
    th.start();
    }

    @Override
    public void run(){

int commandType;

// server never ends
while(true){

    //System.out.println("Number of actually connected clients: "+ clientCount);

    // This got to be here, otherwise its not working on FEL servers. I guess, there is some
    // code optimalization and because clientCount is zero in the begining, it seems to optimizer as
    // useless cycle
    System.out.print("");

    // go throuhgt the array of clients and responde to their request / close their connections
    for (int i = 0; i < clientCount; i++) {

    waitForData(i);

    if(rs.get(i).dataReady) {

        rs.get(i).dataReady=false;

    commandType = getTypeOfCommand(i);

    if(commandType==-1) {
        System.out.println("Client " + i + " sent: " + rs.get(i).fromClient);
        System.out.println("Response to client " + i + ": 500 NEZNAMY PRIKAZ");

        pw.get(i).print("500 NEZNAMY PRIKAZ" +"\r\n");
        pw.get(i).flush();
    }

    if(commandType==1) { step(i); }
    if(commandType==2) { left(i); }
    if(commandType==3) { pickUp(i); }
    if(commandType==4) { repair(i); }

    }
    }
    }
}

    // tries to repair the robot and sends message
    void repair(int i) {
        int clWantsToRepair = Integer.parseInt(rs.get(i).fromClient.split(" ")[1]);

        if(clWantsToRepair>0 && clWantsToRepair<10) {

        // does client want to repair the part which is broken?
        if(clWantsToRepair==rs.get(i).broken) {

        System.out.println("Client " + i + " sent: " + rs.get(i).fromClient);
        System.out.println("Response to client " + i + ": 250 OK ("+rs.get(i).positionX+","+rs.get(i).positionY+")");

            rs.get(i).broken=0;
            pw.get(i).print("250 OK ("+rs.get(i).positionX+","+rs.get(i).positionY+")" + "\r\n");
            pw.get(i).flush();


        } else {
        System.out.println("Client " + i + " sent: " + rs.get(i).fromClient);
        System.out.println("Response to client " + i + ": 571 NENI PORUCHA");

            pw.get(i).print("571 NENI PORUCHA" + "\r\n");
            pw.get(i).flush();

           remove(i);
        } } else {
         // client is trying to repair blok, which doesn't exist

        System.out.println("Client " + i + " sent: " + rs.get(i).fromClient);
        System.out.println("Response to client " + i + ": 500 NEZNAMY PRIKAZ");

            pw.get(i).print("500 NEZNAMY PRIKAZ" + "\r\n");
            pw.get(i).flush();


        }

    }

    // end the connection with particular client and removes him from array list
    void remove(int i) {

        System.out.println("Closing connection with client: " + i);

            pw.get(i).close();
            try{
            br.get(i).close();
            } catch(IOException e) {
                System.out.println("Closeing connection with client " + i + " failed.");
            }

            pw.remove(i);
            br.remove(i);
            rs.remove(i);

            clientCount--;

    }

    // tries to pick up the secret and sends message
    void pickUp(int i){

        //Is the robot on the field with the secret?
        if(rs.get(i).positionX==0 && rs.get(i).positionY==0) {
            pw.get(i).print("221 USPECH " + rs.get(i).SECRET + "\r\n");

        System.out.println("Client " + i + " sent: " + rs.get(i).fromClient);
        System.out.println("Response to client " + i + ": 221 USPECH " + rs.get(i).SECRET);
        } else {

            pw.get(i).print("550 NELZE ZVEDNOUT ZNACKU" + "\r\n");

        System.out.println("Client " + i + " sent: " + rs.get(i).fromClient);
        System.out.println("Response to client " + i + ": 550 NELZE ZVEDNOUT ZNACKU");
        }

            pw.get(i).flush();

            remove(i);

    }

    // makes one step and sends message
    void step(int i){

        // when client tries to make step when robot is broken
        if(rs.get(i).broken!=0) {
            pw.get(i).print("572 ROBOT SE ROZPADL" + "\r\n");
            pw.get(i).flush();

        System.out.println("Client " + i + " sent: " + rs.get(i).fromClient);
        System.out.println("Response to client " + i + ": 572 ROBOT SE ROZPADL");

            remove(i);
            return;
        }

        // radomly generated failures of robot
        if(rs.get(i).stepsWithoutDefect>0 && (rnd.nextBoolean() || rs.get(i).stepsWithoutDefect==10)) {
            rs.get(i).broken=rnd.nextInt(10); if(rs.get(i).broken==0) rs.get(i).broken++;
            pw.get(i).print("570 PORUCHA BLOK " + rs.get(i).broken + "\r\n");
            pw.get(i).flush();

        System.out.println("Client " + i + " sent: " + rs.get(i).fromClient);
        System.out.println("Response to client " + i + ": 570 PORUCHA BLOK " + rs.get(i).broken);

            rs.get(i).stepsWithoutDefect=0;

            return;
        }

        // robot is fine, make step in right direction
        if(rs.get(i).rotation==0) rs.get(i).positionY+=1; // up
        if(rs.get(i).rotation==1) rs.get(i).positionX+=1; // right
        if(rs.get(i).rotation==2) rs.get(i).positionY-=1; // down
        if(rs.get(i).rotation==3) rs.get(i).positionX-=1; // left

        // was the step in the field?
        if(rs.get(i).positionY>=-17 && rs.get(i).positionY<=17 && rs.get(i).positionX>=-17 && rs.get(i).positionX<=17){

            pw.get(i).print("250 OK ("+rs.get(i).positionX+","+rs.get(i).positionY+")" + "\r\n");
            pw.get(i).flush();

        System.out.println("Client " + i + " sent: " + rs.get(i).fromClient);
        System.out.println("Response to client " + i + ": 250 OK ("+rs.get(i).positionX+","+rs.get(i).positionY+")");

            rs.get(i).stepsWithoutDefect++;

        } else {

               pw.get(i).print("530 HAVARIE" + "\r\n");
               pw.get(i).flush();

        System.out.println("Client " + i + " sent: " + rs.get(i).fromClient);
        System.out.println("Response to client " + i + ": 530 HAVARIE");

               remove(i);

        }

    }

    // makes turn to the left and sends message
    void left(int i){

        rs.get(i).rotation--;
        if(rs.get(i).rotation<0) rs.get(i).rotation=3;
        pw.get(i).print("250 OK ("+rs.get(i).positionX+","+rs.get(i).positionY+")" + "\r\n");
        pw.get(i).flush();

        System.out.println("Client " + i + " sent: " + rs.get(i).fromClient);
        System.out.println("Response to client " + i + ": 250 OK ("+rs.get(i).positionX+","+rs.get(i).positionY+")");

    }

    // waits for data from client and save it into member fromClient
    void waitForData(int i){

        // System.out.println("Waiting for data from client: "+ i);

        int fs=-1;
        rs.get(i).fromClient="";

        try{

            /* try{
            Thread.sleep(10);
            }
            catch(InterruptedException e){
            e.printStackTrace();
            } */

            if(br.get(i).ready()) {
                rs.get(i).dataReady=true;
            }
            else {

               // System.out.println("Client " + i + "wasn't ready. Let's continue to other client.");
                return;

            }

            boolean CR=false,LF=false;
                // client sent data, lets recieve it
                    while (true){

                    fs = br.get(i).read();

                    if(CR || fs==13) CR=true;
                    if(CR && fs==10) LF=true;
                    else if (fs!=13) CR=false;

                   // System.out.print(fs + " ");


                    if(rs.get(i).fromClient.length()<(rs.get(i).robotsName.length()+50)) {
                        rs.get(i).fromClient+=(char)fs;
                    }

                    //finishing tag arrived
                     if(LF) {
                     if(rs.get(i).fromClient.length()<(rs.get(i).robotsName.length()+50)) {} else {
                        // client sent me some freaky long string
                        pw.get(i).print("500 NEZNAMY PRIKAZ" + "\r\n");
                        pw.get(i).flush();
                        System.out.println("Client " + i + " is probably hacker! He sent: " + rs.get(i).fromClient);
                        System.out.println("Sending: 500 NEZNAMY PRIKAZ");
                        rs.get(i).dataReady=false;
                        return;
                        }

                     break;
                     }

                  }

        } catch(IOException e){
            e.printStackTrace();
        }

        if(rs.get(i).fromClient.endsWith("\r\n"))
        rs.get(i).fromClient = rs.get(i).fromClient.substring(0,
                                        rs.get(i).fromClient.indexOf("\r\n"));
        else System.out.println("chyba, neobsahuje ukoncovaci znaky \r\n");

        System.out.println("Data accepted (" + rs.get(i).fromClient + ") from client: " + i);

    }

    // returns type of command> -1:unknown; 1:krok; 2: vlevo; 3: zvedni; 4: opravit
    int getTypeOfCommand(int i){

        //client didn't use my name
        if(!rs.get(i).fromClient.startsWith(rs.get(i).robotsName)) return -1;

        else {

            //delete my name from the message
            rs.get(i).fromClient = rs.get(i).fromClient.substring(rs.get(i).robotsName.length()+1);

            String[] substrings = rs.get(i).fromClient.split(" ");

            if(substrings[0].equals("KROK")) {return 1;}
            if(substrings[0].equals("VLEVO")) {return 2;}
            if(substrings[0].equals("ZVEDNI")) {return 3;}
            if(substrings[0].equals("OPRAVIT")) {return 4;}


        }

    return -1;
    }

}

//represents robots state
class RobotState {

public final String robotsName= "Ty pekelny stroji" ,

        SECRET="DONT TELL ENYONE, IT'S A SECRET ... BLA BLA BLA.";


String fromClient="";
int stepsWithoutDefect=0;
boolean dataReady=false;


/**
 * position of the robot
 */
int positionX;
int positionY;
int rotation;
int broken=0;

Random rnd = new Random();


    /** buffer size in bytes */
    int sz = 1024 * 512;
    /** initiolized size of StringBuilder */
    StringBuilder sb = new StringBuilder(2*sz);

// random generation of the position and rotation of the robot
public RobotState(){

positionX = rnd.nextInt(17); if(rnd.nextBoolean()) positionX=positionX-2*positionX;
positionY = rnd.nextInt(17);  if(rnd.nextBoolean()) positionY=positionY-2*positionY;
rotation = rnd.nextInt(4); // 0-up;1-right;2-down;3-left

}

}