-- Custom protocol (default)
local chatProtocol = "doggyChat"

-- 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 list all profiles
local function listProfiles()
    local profilesDir = "./dogchat/profiles/"
    if not fs.isDir(profilesDir) then
        return {}
    end

    local profiles = fs.list(profilesDir)
    return profiles
end

-- Function to download or create the XOR.key file
local function downloadOrCreateKey()
    local keyFilePath = "XOR.key"

    if fileExists(keyFilePath) then
        term.setTextColor(colors.green)
        print("Encryption key found.")
        term.setTextColor(colors.white)
    else
        term.setTextColor(colors.yellow)
        print("Downloading encryption key...")
        local key = "x3A7rB8zD2L5qW4nH1"
        local file = fs.open(keyFilePath, "w")
        file.write(key)
        file.close()
        print("Encryption key downloaded and saved as XOR.key.")
        term.setTextColor(colors.white)
    end

    local file = fs.open(keyFilePath, "r")
    local key = file.readAll()
    file.close()

    return key
end

-- XOR encryption function
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 create a new profile
local function createProfile()
    term.clear()
    term.setCursorPos(1, 1)
    term.setTextColor(colors.cyan)
    print("Enter a username for the new profile:")
    term.setTextColor(colors.white)
    local username = read()

    local profilePath = "./dogchat/profiles/" .. username
    if fileExists(profilePath) then
        term.setTextColor(colors.red)
        print("Profile already exists.")
        term.setTextColor(colors.white)
        return
    end

    term.setTextColor(colors.cyan)
    print("Enter a password for the profile:")
    term.setTextColor(colors.white)
    local password = read("*")

    local encryptionKey = downloadOrCreateKey()
    local hashedPassword = xorEncryptDecrypt(password, encryptionKey)

    fs.makeDir(profilePath)
    local passwordFile = fs.open(profilePath .. "/password.txt", "w")
    passwordFile.write(hashedPassword)
    passwordFile.close()

    term.setTextColor(colors.green)
    print("Profile created successfully.")
    term.setTextColor(colors.white)
end

-- Function to delete a profile
local function deleteProfile()
    term.clear()
    term.setCursorPos(1, 1)
    local profiles = listProfiles()
    if #profiles == 0 then
        term.setTextColor(colors.red)
        print("No profiles found.")
        term.setTextColor(colors.white)
        return
    end

    term.setTextColor(colors.cyan)
    print("Select a profile to delete:")
    term.setTextColor(colors.white)
    for i, profile in ipairs(profiles) do
        print(i .. ". " .. profile)
    end

    local choice = tonumber(read())
    if not choice or choice < 1 or choice > #profiles then
        term.setTextColor(colors.red)
        print("Invalid choice.")
        term.setTextColor(colors.white)
        return
    end

    local username = profiles[choice]
    local profilePath = "./dogchat/profiles/" .. username

    term.setTextColor(colors.cyan)
    print("Enter the password for " .. username .. " to confirm deletion:")
    term.setTextColor(colors.white)
    local password = read("*")

    local encryptionKey = downloadOrCreateKey()
    local passwordFile = fs.open(profilePath .. "/password.txt", "r")
    local storedPassword = passwordFile.readAll()
    passwordFile.close()

    if xorEncryptDecrypt(password, encryptionKey) == storedPassword then
        fs.delete(profilePath)
        term.setTextColor(colors.green)
        print("Profile deleted successfully.")
        term.setTextColor(colors.white)
    else
        term.setTextColor(colors.red)
        print("Incorrect password. Deletion canceled.")
        term.setTextColor(colors.white)
    end
end

-- Function to load an existing profile
local function loadProfile()
    term.clear()
    term.setCursorPos(1, 1)
    local profiles = listProfiles()
    if #profiles == 0 then
        term.setTextColor(colors.red)
        print("No profiles found.")
        term.setTextColor(colors.white)
        return nil
    end

    term.setTextColor(colors.cyan)
    print("Select a profile to log in:")
    term.setTextColor(colors.white)
    for i, profile in ipairs(profiles) do
        print(i .. ". " .. profile)
    end

    local choice = tonumber(read())
    if not choice or choice < 1 or choice > #profiles then
        term.setTextColor(colors.red)
        print("Invalid choice.")
        term.setTextColor(colors.white)
        return nil
    end

    local username = profiles[choice]
    local profilePath = "./dogchat/profiles/" .. username

    term.setTextColor(colors.cyan)
    print("Enter the password for " .. username .. ":")
    term.setTextColor(colors.white)
    local password = read("*")

    local encryptionKey = downloadOrCreateKey()
    local passwordFile = fs.open(profilePath .. "/password.txt", "r")
    local storedPassword = passwordFile.readAll()
    passwordFile.close()

    if xorEncryptDecrypt(password, encryptionKey) == storedPassword then
        term.setTextColor(colors.green)
        print("Login successful.")
        term.setTextColor(colors.white)
        return username
    else
        term.setTextColor(colors.red)
        print("Incorrect password.")
        term.setTextColor(colors.white)
        return nil
    end
end

-- Function to manage settings
local function settingsMenu()
    term.clear()
    term.setCursorPos(1, 1)
    while true do
        term.setTextColor(colors.cyan)
        print("Settings Menu:")
        term.setTextColor(colors.white)
        print("1. Create a new profile")
        print("2. Delete a profile")
        print("3. Back to main menu")
        local choice = read()

        if choice == "1" then
            createProfile()
        elseif choice == "2" then
            deleteProfile()
        elseif choice == "3" then
            break
        else
            term.setTextColor(colors.red)
            print("Invalid choice. Please try again.")
            term.setTextColor(colors.white)
        end
    end
end

-- Function to list all connected 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 setup the modem
local function setupModem()
    local modems = listModems()
    if #modems == 0 then
        term.setTextColor(colors.red)
        print("No modems found! Please connect a modem and restart.")
        term.setTextColor(colors.white)
        return nil
    end

    term.setTextColor(colors.cyan)
    print("Connected modems:")
    term.setTextColor(colors.white)
    for i, side in ipairs(modems) do
        print(i .. ": " .. side)
    end

    rednet.open(modems[1])
    term.setTextColor(colors.green)
    print("Using modem on " .. modems[1])
    term.setTextColor(colors.white)
    return modems[1]
end

-- Function to display a message in the chat with history support
local messageHistory = {}

local function displayMessage(senderId, message, isOlderClient)
    term.setTextColor(colors.yellow)
    if isOlderClient then
        print("[Unknown User (" .. senderId .. ")]: " .. message)
    else
        print("[" .. senderId .. "]: " .. message)
    end
    table.insert(messageHistory, {senderId = senderId, message = message})
    term.setTextColor(colors.white)

    -- Display last 5 messages
    print("\n--- Message History ---")
    for i = math.max(#messageHistory - 5, 1), #messageHistory do
        print("[" .. messageHistory[i].senderId .. "]: " .. messageHistory[i].message)
    end
end

-- Function to handle incoming messages
local function handleIncomingMessages(encryptionKey)
    while true do
        local senderId, encryptedMessage, protocol = rednet.receive(chatProtocol)
        local decryptedMessage = xorEncryptDecrypt(encryptedMessage, encryptionKey)

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

-- Function to send a message
local function sendMessage(username, encryptionKey)
    while true do
        term.setTextColor(colors.cyan)
        print("Type your message (or 'exit' to quit): ")
        term.setTextColor(colors.white)
        local userInput = read()
        if userInput == "exit" then
            term.setTextColor(colors.green)
            print("Exiting chat...")
            term.setTextColor(colors.white)
            shell.run("/disk/os/gui")
            break
        end

        local formattedMessage = username .. ": " .. userInput
        local encryptedMessage = xorEncryptDecrypt(formattedMessage, encryptionKey)

        rednet.broadcast(encryptedMessage, chatProtocol)
        displayMessage(username, userInput, false)
    end
end

-- Main function
local function main()
    term.clear()
    term.setCursorPos(1, 1)
    print("Doggy Chat - Secure Chat")
    local username = loadProfile()

    if username then
        local encryptionKey = downloadOrCreateKey()
        setupModem()

        parallel.waitForAny(
            function() handleIncomingMessages(encryptionKey) end,
            function() sendMessage(username, encryptionKey) end
        )
    end
end

-- Run the program
main()