package serverftp;
import java.io.*;
import java.net.*;

public class ServerFTP {

    static String[] id = {"cp 1","cp 2","cp 3"};
    static String[] pass = {"123","456","789"};

    static BufferedReader[] msgFromClient = new BufferedReader[3];
    static PrintWriter[] msgToClient = new PrintWriter[3];
    static InputStream[] fileFromClient = new InputStream[3];
    static OutputStream[] fileToClient = new OutputStream[3];

    public static void main(String[] args) throws Exception {
        ServerSocket welcome = new ServerSocket(6789);

        // connecting the three clients
        for(int i=0; i<3; i++) {
            System.out.println("Waiting for Client "+i);
            Socket clientSocket;
            clientSocket = welcome.accept();

            while(true) {
                System.out.println("Connecting Client "+i);

                BufferedReader fromClient = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
                PrintWriter toClient = new PrintWriter(clientSocket.getOutputStream(),true);

                // get id pass from client
                String clientId = fromClient.readLine();
                System.out.println(clientId);
                String clientPass = fromClient.readLine();
                System.out.println(clientPass);

                // check id pass and feedback
                if(clientId.equals(id[i]) && clientPass.equals(pass[i])) {
                    toClient.println("ok");

                    msgFromClient[i] = fromClient;
                    msgToClient[i] = toClient;
                    fileFromClient[i] = clientSocket.getInputStream();
                    fileToClient[i] = clientSocket.getOutputStream();

                    break;
                } else {
                    toClient.println("error");
                }
            }

            ClientThread ct = new ClientThread(i);
            ct.start();
            System.out.println("Client "+i+" connected!");
        }

        welcome.close();
    }

}

class ClientThread extends Thread {
    int cid;
    String msg;

    public ClientThread(int client_id) {
        cid = client_id;

        try {
            // telling client it's serial
            ServerFTP.msgToClient[cid].println(Integer.toString(cid));
        } catch(Exception ex) {
            ex.printStackTrace();
        }
    }

    @Override
    public void run() {
        while(true) {
            try {
                // get request from receiver
                msg = ServerFTP.msgFromClient[cid].readLine();
                if(msg.equals("get list")) {
                    System.out.println(cid+" "+msg);

                    msg = ServerFTP.msgFromClient[cid].readLine();
                    System.out.println(cid+" "+msg);

                    for(int i=0; i<3; i++) {
                        if(i==cid) continue;

                        // send sender request for file list
                        ServerFTP.msgToClient[i].println("give list");
                        System.out.println("request sent to client "+i);

                        // get file count from sender
                        msg = ServerFTP.msgFromClient[i].readLine();
                        System.out.println("file count caught!!!"); // THIS LINE NEVER EXECUTES
                        System.out.println("File count "+msg);
                    }
                }
            } catch(Exception ex) {
                ex.printStackTrace();
            }
        }
    }
}

package clientftp_1;
import java.io.*;
import java.net.*;

public class ClientFTP_1 {

    static String[] allPaths = {   "...path...\client_1_folder",
                            "...path...\client_2_folder",
                            "...path...\client_3_folder"};

    public static void main(String[] args) throws Exception {
        InetAddress inetAddress = InetAddress.getLocalHost();
        Socket server = new Socket(inetAddress,6789);
        int myId;

        // login phase
        BufferedReader fromUser = new BufferedReader(new InputStreamReader(System.in));
        BufferedReader fromServer = new BufferedReader(new InputStreamReader(server.getInputStream()));
        PrintWriter toServer = new PrintWriter(server.getOutputStream(),true);
        InputStream getFile = server.getInputStream();
        OutputStream sendFile = server.getOutputStream();
        while(true) {
            System.out.println("id: ");
            String msg = fromUser.readLine();
            toServer.println(msg);

            System.out.println("password: ");
            msg = fromUser.readLine();
            toServer.println(msg);

            msg = fromServer.readLine();
            if(msg.equals("ok")) {
                System.out.println("Connection Successful!");
                myId = Integer.parseInt(fromServer.readLine());
                System.out.println("Client serial is: "+myId);
                System.out.println("Folder path is: "+allPaths[myId]);
                break;
            } else {
                System.out.println("Error! Try again please.");
            }
        }

        ServerThread st = new ServerThread(allPaths[myId],fromUser,fromServer,toServer,getFile,sendFile);
        st.start();
        UserThread ut = new UserThread(allPaths[myId],fromUser,fromServer,toServer,getFile,sendFile);
        ut.start();
    }
}

class ServerThread extends Thread {
    String folderPath;
    String msg;
    BufferedReader msgFromServer,msgFromUser;
    PrintWriter msgToServer;
    InputStream fileFromServer;
    OutputStream fileToServer;
    public ServerThread(String path,BufferedReader fromUser,BufferedReader fromServer,PrintWriter toServer,InputStream getFile,OutputStream sendFile) throws Exception {
        folderPath = path;
        msgFromUser = fromUser;
        msgFromServer = fromServer;
        msgToServer = toServer;
        fileFromServer = getFile;
        fileToServer = sendFile;
    }

    @Override
    public void run() {
        System.out.println("Server Thread Started");
        while(true) {
            try {
                // receive request
                msg = msgFromServer.readLine();
                System.out.println("request received from server");
                if(msg.equals("give list")) {
                    // get filenames
                    File folder = new File(folderPath);
                    File[] fileList = folder.listFiles();
                    int cnt = fileList.length;
                    System.out.println("count calculated");

                    // sned file count to server
                    msgToServer.println(Integer.toString(cnt));
                    System.out.println("count sent to server"); // THIS LINE PRINTS
                }
            } catch(Exception ex) {
                ex.printStackTrace();
            }
        }
    }
}

class UserThread extends Thread {
    String folderPath;
    String msg;
    BufferedReader msgFromServer,msgFromUser;
    PrintWriter msgToServer;
    InputStream fileFromServer;
    OutputStream fileToServer;
    public UserThread(String path,BufferedReader fromUser,BufferedReader fromServer,PrintWriter toServer,InputStream getFile,OutputStream sendFile) throws Exception {
        folderPath = path;
        msgFromUser = fromUser;
        msgFromServer = fromServer;
        msgToServer = toServer;
        fileFromServer = getFile;
        fileToServer = sendFile;
    }

    @Override
    public void run() {
        System.out.println("USer Thread Started");
        while(true) {
            try {
                // input from user
                msg = msgFromUser.readLine();
                if(msg.equals("get list")) {
                    // send request to server
                    msgToServer.println("get list");
                    msgToServer.println("fahim list");
                }
            } catch(Exception ex) {
                ex.printStackTrace();
            }
        }
    }
}