DStore.java

import java.io.*;
import java.net.*;
import java.util.HashSet;

public class DStore {

    private final static HashSet<String> fileList = new HashSet<>();
    private static PrintWriter controller;

    public static void main(String[] args) {
        //Take arguments from command line
        int port = Integer.parseInt(args[0]);
        int cPort = Integer.parseInt(args[1]);
        Float timeout = Float.parseFloat(args[2]);
        String fileFolder = args[3];

        //Make connection with controller & listen to send acknowledgments
        try{
            Socket socket = new Socket(InetAddress.getLocalHost(),cPort);
            controller = new PrintWriter(socket.getOutputStream());

            //Send "JOIN port" to  controller
            controller.write("JOIN "+port);

            //New thread to listen for "LIST" & "REMOVE FILENAME"
            new Thread(() -> {
                try {
                    BufferedReader contIn = new BufferedReader(new InputStreamReader(socket.getInputStream()));
                    while(true){
                        String received = contIn.readLine();
                        String command = received.split(" ")[0];

                        switch (command) {
                            case "LIST" -> listToController();
                            case "REMOVE" -> removeFile(fileFolder,(received.split(" ")[1]));
                        }
                    }
                }catch (Exception e){
                    System.out.println("error "+e);
                }
            }).start();

        }catch (Exception e){
            System.out.println("error "+e);
        }

        //Create socket to listen for store, load & remove requests
        try{
            //Create server socket to listen for connections
            ServerSocket ss = new ServerSocket(port);

            //Listen for connections
            while(true){
                try{
                    //Accept connection to new thread
                    Socket client = ss.accept();

                    //Make output stream returning to client
                    OutputStream out = client.getOutputStream();

                    //Get instruction from connection
                    InputStream in = client.getInputStream();
                    byte[] buf = new byte[1000];
                    int bufLen = in.read(buf);
                    String firstBuffer = new String(buf, 0, bufLen);

                    //Get command
                    int firstSpace = firstBuffer.indexOf(" ");
                    String command = firstBuffer.substring(0, firstSpace);

                    //Get filename
                    int secondSpace = firstBuffer.indexOf(" ", firstSpace + 1);
                    String fileName = firstBuffer.substring(firstSpace, secondSpace);

                    //Proceed depending on command
                    switch (command) {
                        case "STORE" -> {
                            //Get file size (text after third space)
                            int thirdSpace = firstBuffer.indexOf(" ", secondSpace + 1);
                            int fileSize = Integer.parseInt(firstBuffer.substring(secondSpace, thirdSpace));

                            //Store file in new thread and update list
                            new Thread(new StoreThread(controller,fileFolder,fileName,in,out,client,fileSize)).start();
                            fileList.add(fileName);
                        }
                        case "LOAD_DATA" -> //Load file in new thread
                                new Thread(new LoadThread((fileFolder+File.separator+fileName),in,out,client)).start();
                    }
                }catch (Exception e){
                    System.out.println("error "+e);
                }
            }
        }catch (Exception e){
            System.out.println("error "+e);
        }
    }

    private static void listToController() {
        //Compile list as string
        StringBuilder stringList = new StringBuilder();

        for (String s : fileList) {
            stringList.append(s).append(" ");
        }

        //Return value
        controller.write(stringList.toString());
    }

    private static void removeFile(String filePath, String fileName){
        //Remove file from folder
        File file = new File(filePath+File.separator+fileName);
        file.delete();

        //Remove file from list
        fileList.remove(fileName);
    }
}