chatroom service

-- Table to hold active private chatrooms
local privateChatrooms = {}

-- Function to check if a file exists
local function fileExists(path)
    local file = fs.open(path, "r")
    if file then
        file.close()
        return true
    end
    return false
end

-- Function to download or create the XOR key for encryption
local function downloadOrCreateKey(protocol)
    local keyFilePath = protocol .. "_XOR.key"

    -- Check if the key file exists
    if fileExists(keyFilePath) then
        print("Encryption key for protocol " .. protocol .. " found.")
    else
        -- Simulate downloading or generating the key
        print("Downloading encryption key for protocol " .. protocol .. "...")
        local key = "defaultEncryptionKey123"  -- Can customize this key

        -- Save the key to a file
        local file = fs.open(keyFilePath, "w")
        file.write(key)
        file.close()
        print("Encryption key saved as " .. keyFilePath)
    end

    -- Read the key from the file
    local file = fs.open(keyFilePath, "r")
    local key = file.readAll()
    file.close()

    return key
end

-- XOR encryption function for message security
local function xorEncryptDecrypt(message, key)
    local encrypted = {}
    for i = 1, #message do
        local char = string.byte(message, i)
        local keyChar = string.byte(key, (i - 1) % #key + 1)
        table.insert(encrypted, string.char(bit.bxor(char, keyChar)))
    end
    return table.concat(encrypted)
end

-- Function to display a message within a chatroom
local function displayMessage(protocol, senderId, message)
    term.setTextColor(colors.yellow)
    print("[" .. protocol .. "] [" .. senderId .. "]: " .. message)
    term.setTextColor(colors.white) -- Reset text color
end

-- Function to handle messages for a private chatroom
local function handlePrivateMessages(protocol, encryptionKey)
    while true do
        local senderId, encryptedMessage, receivedProtocol = rednet.receive(protocol)
        if receivedProtocol == protocol then
            local decryptedMessage = xorEncryptDecrypt(encryptedMessage, encryptionKey)

            -- Split username and message
            local username, chatMessage = decryptedMessage:match("^(.-): (.+)$")
            if username and chatMessage then
                displayMessage(protocol, username, chatMessage)
            else
                displayMessage(protocol, senderId, decryptedMessage)
            end
        end
    end
end

-- Function to send messages within a private chatroom
local function sendPrivateMessage(protocol, username, encryptionKey)
    while true do
        print("[" .. protocol .. "] Type your message (or 'exit' to leave): ")
        local message = read()
        if message == "exit" then
            print("Exiting chatroom " .. protocol)
            break
        end

        local formattedMessage = username .. ": " .. message
        local encryptedMessage = xorEncryptDecrypt(formattedMessage, encryptionKey)
        rednet.broadcast(encryptedMessage, protocol)
        displayMessage(protocol, username, message)
    end
end

-- Function to create or join a private chatroom with password protection
local function createOrJoinPrivateChatroom(protocol, username)
    -- Check if the chatroom already exists
    if privateChatrooms[protocol] then
        -- If the chatroom exists, ask for the password to join
        print("Chatroom for protocol " .. protocol .. " exists.")
        print("Enter the password to join:")
        local passwordAttempt = read("*")  -- Read password securely (hidden input)

        -- Verify password
        if privateChatrooms[protocol].password == passwordAttempt then
            print("Password accepted! Joining chatroom...")
        else
            print("Incorrect password. Access denied.")
            return
        end
    else
        -- If the chatroom doesn't exist, create it with a password
        print("Creating new chatroom for protocol: " .. protocol)
        print("Enter a password for this chatroom:")
        local password = read("*")  -- Read password securely (hidden input)

        -- Save the password for this chatroom
        local encryptionKey = downloadOrCreateKey(protocol)
        privateChatrooms[protocol] = { encryptionKey = encryptionKey, password = password }

        print("Chatroom created with password protection.")
    end

    -- Start handling messages and sending messages for this protocol
    parallel.waitForAny(
        function() handlePrivateMessages(protocol, privateChatrooms[protocol].encryptionKey) end,
        function() sendPrivateMessage(protocol, username, privateChatrooms[protocol].encryptionKey) end
    )
end

-- Function to list available modems
local function listModems()
    local modems = {}
    for _, side in ipairs(peripheral.getNames()) do
        if peripheral.getType(side) == "modem" then
            table.insert(modems, side)
        end
    end
    return modems
end

-- Function to set up the modem for communication
local function setupModem()
    local modems = listModems()
    if #modems == 0 then
        print("No modems found! Please attach a modem and restart.")
        return nil
    end

    print("Available modems:")
    for i, side in ipairs(modems) do
        print(i .. ": " .. side)
    end

    rednet.open(modems[1]) -- Open the first modem found
    print("Modem on " .. modems[1] .. " initialized.")
    return modems[1]
end

-- Main server function to manage connections and private chatrooms
term.clear()
term.setCursorPos(1, 1)

print("Welcome to the Protocol Private Chatroom Server with Password Protection")

-- Setup modem for server communication
local modemSide = setupModem()
if modemSide == nil then return end -- Exit if no modem found

while true do
    print("Enter a protocol for a private chatroom (or 'exit' to quit): ")
    local protocol = read()

    if protocol == "exit" then
        print("Server shutting down...")
        break
    end

    if protocol ~= "" then
        print("Enter your username: ")
        local username = read()

        createOrJoinPrivateChatroom(protocol, username)
    end
end