e

-- Function to generate a key for encryption and decryption
function generateKey()
    local chars = {}
    for i = 32, 126 do -- ASCII range for printable characters
        table.insert(chars, string.char(i))
    end

    local key = {}
    while #chars > 0 do
        local index = math.random(#chars)
        table.insert(key, table.remove(chars, index))
    end

    return table.concat(key)
end

-- Function to create a map from a key
function createMap(key)
    local map = {}
    for i = 32, 126 do
        map[string.char(i)] = key:sub(i - 31, i - 31)
    end
    return map
end

-- Function to invert a map
function invertMap(map)
    local invMap = {}
    for k, v in pairs(map) do
        invMap[v] = k
    end
    return invMap
end

-- Function to encrypt text using a key
function encrypt(text, key)
    local map = createMap(key)
    local encrypted = {}
    for i = 1, #text do
        local char = text:sub(i, i)
        table.insert(encrypted, map[char] or char)
    end
    return table.concat(encrypted)
end

-- Function to decrypt text using a key
function decrypt(text, key)
    local map = invertMap(createMap(key))
    local decrypted = {}
    for i = 1, #text do
        local char = text:sub(i, i)
        table.insert(decrypted, map[char] or char)
    end
    return table.concat(decrypted)
end

-- Function to save the key to a file
function saveKeyToFile(key, dir)
    local randomNumber = math.random(1, 1000)
    local fileName = dir .. "/key" .. randomNumber .. ".txt"
    local file = fs.open(fileName, "w")
    file.write(key)
    file.close()
    return fileName
end

-- Function to load the key from a file
function loadKeyFromFile(fileName)
    local file = fs.open(fileName, "r")
    local key = file.readAll()
    file.close()
    return key
end

-- Function to find the key file in a directory
function findKeyFile(dir)
    local files = fs.list(dir)
    for _, file in ipairs(files) do
        if file:match("^key%d+%.txt$") then
            return dir .. "/" .. file
        end
    end
    return nil
end

-- Function to load the encrypted text from the password file
function loadEncryptedText(userDir)
    local fileName = userDir .. "/password.txt"
    if not fs.exists(fileName) then
        print("Password file does not exist.")
        return nil
    end
    local file = fs.open(fileName, "r")
    local encryptedText = file.readAll()
    file.close()
    return encryptedText
end

-- Function to create a new user
function createUser()
    term.clear()
    term.setCursorPos(1, 1)
    print("Enter new username:")
    local username = read()

    -- Check if the username already exists
    if fs.exists("/disk/users/" .. username) then
        print("Username already exists. Try again.")
        sleep(2)
        return
    end

    -- Create a directory for the new user
    fs.makeDir("/disk/users/" .. username)

    -- Prompt for password
    local password
    repeat
        term.clear()
        term.setCursorPos(1, 1)
        print("Enter password:")
        password = read("*")

        print("Confirm password:")
        local confirmPassword = read("*")

        if password ~= confirmPassword then
            print("Passwords do not match. Try again.")
            sleep(2)
        end
    until password == confirmPassword

    -- Generate encryption key
    local key = generateKey()

    -- Encrypt the password
    local encryptedPassword = encrypt(password, key)

    -- Save the key to a file
    local keyFileName = saveKeyToFile(key, "/disk/users/" .. username)

    -- Store the encrypted password in a text file
    local passwordFile = fs.open("/disk/users/" .. username .. "/password.txt", "w")
    passwordFile.write(encryptedPassword)
    passwordFile.close()

    print("User created successfully.")
    sleep(2)
end

-- Function to delete a user
function deleteUser()
    term.clear()
    term.setCursorPos(1, 1)
    print("Enter username to delete:")
    local username = read()

    -- Check if the username exists
    if not fs.exists("/disk/users/" .. username) then
        print("User not found. Try again.")
        sleep(2)
        return
    end

    -- Check for the presence of block.txt
    if fs.exists("/disk/users/" .. username .. "/block.txt") then
        -- Display content of block.txt as an error message
        local file = fs.open("/disk/users/" .. username .. "/block.txt", "r")
        local errorMessage = file.readAll()
        file.close()
        print(errorMessage)
        sleep(2)
        return
    end

    -- Prompt for password to confirm deletion
    print("Enter password to confirm deletion:")
    local inputPassword = read("*")

    -- Load the key from the file
    local keyFileName = findKeyFile("/disk/users/" .. username)
    local key = loadKeyFromFile(keyFileName)

    -- Read and decrypt stored password from the file
    local encryptedPassword = loadEncryptedText("/disk/users/" .. username)
    local storedPassword = decrypt(encryptedPassword, key)

    -- Compare entered password with stored password
    if inputPassword == storedPassword then
        -- Delete the user directory
        fs.delete("/disk/users/" .. username)
        print("User deleted successfully.")
    else
        print("Incorrect password. Deletion failed.")
    end

    sleep(2)
end

-- Function for password recovery by admin
function passwordRecovery()
    term.clear()
    term.setCursorPos(1, 1)
    print("Enter admin username:")
    local adminUsername = read()

    -- Check if the entered user has admin privileges
    if not fs.exists("/disk/users/" .. adminUsername .. "/admin.txt") then
        print("Permission denied. Admin access required.")
        sleep(2)
        return
    end

    -- Prompt for admin password
    print("Enter admin password:")
    local adminPassword = read("*")

    -- Load the key from the file
    local keyFileName = findKeyFile("/disk/users/" .. adminUsername)
    local key = loadKeyFromFile(keyFileName)

    -- Read and decrypt stored admin password from the file
    local encryptedAdminPassword = loadEncryptedText("/disk/users/" .. adminUsername)
    local storedAdminPassword = decrypt(encryptedAdminPassword, key)

    -- Compare entered admin password with stored admin password
    if adminPassword == storedAdminPassword then
        print("Enter username for password reset:")
        local username = read()

        -- Check if the username exists
        if not fs.exists("/disk/users/" .. username) then
            print("User not found. Try again.")
            sleep(2)
            return
        end

        -- Confirm password reset
        print("Are you sure you want to reset the password for " .. username .. "? (y/n)")
        local confirm = read()
        if confirm:lower() ~= "y" then
            print("Password reset canceled.")
            sleep(2)
            return
        end

        -- Prompt for new password
        term.clear()
        term.setCursorPos(1, 1)
        print("Enter new password for " .. username .. ":")
        local newPassword = read("*")

        -- Generate encryption key
        local key = generateKey()

        -- Encrypt the new password
        local encryptedPassword = encrypt(newPassword, key)

        -- Save the key to a file
        local keyFileName = saveKeyToFile(key, "/disk/users/" .. username)

        -- Store the encrypted password in the text file
        local passwordFile = fs.open("/disk/users/" .. username .. "/password.txt", "w")
        passwordFile.write(encryptedPassword)
        passwordFile.close()

        print("Password reset successfully.")
    else
        print("Incorrect admin password. Password reset failed.")
    end

    sleep(2)
end

-- Function to exit and run /disk/os/gui
function exitProgram()
    term.clear()
    term.setCursorPos(1, 1)
    print("Exiting program...")
    sleep(1)
    shell.run("/disk/os/gui")
    error("Exiting program.")
end

-- Function for Security Card Login (insert or enter ID)
function securityCardLogin(username)
    while true do
        term.clear()
        term.setCursorPos(1, 1)
        print("Insert Security Card for " .. username .. " or enter User ID:")
        local input = read()

        -- Check if the username exists
        if not fs.exists("/disk/users/" .. username) then
            print("User not found. Try again.")
            sleep(2)
        else
            -- If input matches the user ID, login successful
            if input == username then
                print("Security Card login successful.")
                sleep(2)
                return
            else
                print("Security Card login failed. Try again.")
                sleep(2)
            end
        end
    end
end

-- Function to display the main menu
function mainMenu()
    while true do
        term.clear()
        term.setCursorPos(1, 1)
        print("Main Menu:")
        print("1. Create User")
        print("2. Delete User")
        print("3. Password Recovery")
        print("4. Exit")

        local choice = read()

        if choice == "1" then
            createUser()
        elseif choice == "2" then
            deleteUser()
        elseif choice == "3" then
            passwordRecovery()
        elseif choice == "4" then
            exitProgram()
        else
            print("Invalid choice. Try again.")
            sleep(2)
        end
    end
end

-- Main program entry point
mainMenu()