HW-10-Socket-Programming/src/main/java/com/university/chat/Server/ClientSession.java

package com.university.chat.Server;

import com.university.chat.Common.ChatMessage;
import com.university.chat.Common.FileMessage;
import com.university.chat.Common.MessageType;

import java.io.*;
import java.net.Socket;
import java.nio.file.Files;

public class ClientSession implements Runnable {

    private String username;
    UserManager userManager = null;
    Socket socket = null;
    ObjectOutputStream outputStream = null;
    ObjectInputStream inputStream = null;

    public ClientSession(Socket socket, UserManager userManager) throws IOException {
        // TODO : Create an ObjectOutputStream from socket.getOutputStream()
        //         and an ObjectInputStream from socket.getInputStream().
        this.userManager = userManager;
        this.socket = socket;
        outputStream = new ObjectOutputStream(socket.getOutputStream());
        outputStream.flush();
        inputStream = new ObjectInputStream(socket.getInputStream());
    }

    @Override
    public void run() {
        try {

            // TODO: Welcome the user (login step)
            //  1. Read the first object sent by the client.
            //  2. Check it's a ChatMessage with type LOGIN.
            //  3. Extract the username.
            //  4. Try to register the user via userManager.addUser(...).
            //  5. If the username is taken, send back LOGIN_FAILED and close the socket.
            //  6. Otherwise, create the user's folders with FileManager.createUserFolders(...)
            //      and send back LOGIN_SUCCESS.

            System.out.println("Welcome");
            Object object = inputStream.readObject();

            if(object instanceof ChatMessage) {
                ChatMessage chatMessage = (ChatMessage) object;

                if(chatMessage.getType().equals(MessageType.LOGIN)) {
                    username = chatMessage.getSender();

                    if (userManager.addUser(username, this)) {
                        FileManager.createUserFolders(username);
                        outputStream.writeObject(MessageType.LOGIN_SUCCESS);
                        outputStream.flush();
                    }
                    else {
                        outputStream.writeObject(MessageType.LOGIN_FAILED);
                        outputStream.flush();
                        socket.close();
                    }
                }
            }

            // TODO: Main message loop
            //   In a loop, call in.readObject(), you can separate messages by their type:
            //     - if it's a ChatMessage      -> call handleChatMessage(msg)
            //     - if it's a FileMessage      -> call handleFileMessage(fileMsg)
            //   Keep looping until the connection is closed (an exception will be thrown).

            while (!socket.isClosed()) {
                object = inputStream.readObject();

                if(object instanceof ChatMessage)
                    handleChatMessage((ChatMessage) object);
                else if(object instanceof FileMessage)
                    handleFileMessage((FileMessage) object);
            }

        } catch (Exception e) {
            System.out.println("Disconnected: " + username);
        } finally {
            // TODO: Remove the user from UserManager so they no longer
            //        receive broadcasts or appear in users list
            userManager.removeUser(username);
        }
    }


    private void handleChatMessage(ChatMessage msg) throws IOException {
        switch (msg.getType()) {
            case PUBLIC_MESSAGE -> {
                // TODO: Broadcast this message to every connected client.
                for (ClientSession clientSession : userManager.getAllSessions()) {
                    clientSession.outputStream.writeObject(msg);
                    clientSession.outputStream.flush();
                }
            }
            case PRIVATE_MESSAGE -> {
                // TODO: Forward this message to the receiver user.
                userManager.getUser(msg.getReceiver()).outputStream.writeObject(msg);
                userManager.getUser(msg.getReceiver()).outputStream.flush();
            }
            case USER_LIST -> {
                // TODO: Reply to the requester with the list of online users.
                ChatMessage chatMessage = new ChatMessage(MessageType.USER_LIST, "UserManager", username, userManager.listUsers());
                outputStream.writeObject(chatMessage);
                outputStream.flush();
            }
        }
    }

    private void handleFileMessage(FileMessage fileMsg) throws IOException {
        // Storing the file
        var sentPath = FileManager.getSentPath(fileMsg.getSender(), fileMsg.getFilename());
        var recvPath = FileManager.getReceivedPath(fileMsg.getReceiver(), fileMsg.getFilename());

        Files.write(sentPath, fileMsg.getData());
        Files.write(recvPath, fileMsg.getData());

        // TODO: Forward the received file-message to the destination user.
        ClientSession recieverSession = userManager.getUser(fileMsg.getReceiver());
        recieverSession.outputStream.writeObject(fileMsg);
        recieverSession.outputStream.flush();
    }
}