-- Password Authentication System with Event API for CC:Tweaked

-- Function to encrypt/decrypt password using a simple Caesar cipher
local function caesarCipher(text, shift)
    local result = {}
    for i = 1, #text do
        local char = text:sub(i, i)
        local ascii = string.byte(char)
        -- Encrypt/Decrypt uppercase letters
        if ascii >= 65 and ascii <= 90 then
            char = string.char(((ascii - 65 + shift) % 26) + 65)
        -- Encrypt/Decrypt lowercase letters
        elseif ascii >= 97 and ascii <= 122 then
            char = string.char(((ascii - 97 + shift) % 26) + 97)
        end
        table.insert(result, char)
    end
    return table.concat(result)
end

-- Function to read the encrypted password from the file
local function readEncryptedPassword()
    local file, err = fs.open("key.pass", "r")
    if not file then
        print("Error reading password file: " .. err)
        return nil  -- Return nil if the file doesn't exist
    end
    local encryptedPassword = file.readAll()
    file.close()
    return encryptedPassword
end

-- Function to create a new password and save it to the file
local function createNewPassword()
    term.clear()
    local screenWidth, screenHeight = term.getSize()

    -- Centered message for new password creation
    local noPasswordMsg = "No password found."
    local newPasswordMsg = "Create a new password."
    term.setCursorPos((screenWidth - #noPasswordMsg) / 2, screenHeight / 2 - 2)
    print(noPasswordMsg)
    term.setCursorPos((screenWidth - #newPasswordMsg) / 2, screenHeight / 2 - 1)
    print(newPasswordMsg)

    -- Prompt to enter new password
    local prompt = "Enter new password (min 6 chars): "
    term.setCursorPos((screenWidth - #prompt) / 2, screenHeight / 2)
    write(prompt)

    local newPassword = ""
    -- Use event API to gather input character by character
    while true do
        local event, key = os.pullEvent("key")
        if key == keys.enter then
            if #newPassword >= 6 then
                break
            else
                term.setCursorPos((screenWidth - #prompt) / 2, screenHeight / 2 + 1)
                print("Password too short. Try again.")
                term.setCursorPos((screenWidth - #prompt) / 2, screenHeight / 2)
                write(prompt)
                newPassword = ""
            end
        elseif key == keys.backspace then
            newPassword = newPassword:sub(1, -2)
            term.setCursorPos((screenWidth - #prompt) / 2 + #prompt, screenHeight / 2)
            write(string.rep(" ", 20)) -- Clear previous input
            term.setCursorPos((screenWidth - #prompt) / 2 + #prompt, screenHeight / 2)
            write(newPassword) -- Display updated password
        else
            newPassword = newPassword .. string.char(key)
            term.setCursorPos((screenWidth - #prompt) / 2 + #prompt, screenHeight / 2)
            write(newPassword)
        end
    end

    local encryptedPassword = caesarCipher(newPassword, 3)  -- Encrypt with a shift of 3

    -- Write the encrypted password to the file
    local file, err = fs.open("key.pass", "w")
    if not file then
        print("Error writing password file: " .. err)
        return nil
    end
    file.write(encryptedPassword)
    file.close()

    local successMsg = "Password created successfully!"
    term.setCursorPos((screenWidth - #successMsg) / 2, screenHeight / 2 + 1)
    print(successMsg)
    sleep(2)  -- Pause before proceeding
    return newPassword
end

-- Decrypt the password read from the file
local function getDecryptedPassword()
    local encryptedPassword = readEncryptedPassword()
    if encryptedPassword then
        return caesarCipher(encryptedPassword, -3)  -- Decrypting with a shift of -3
    end
    return nil
end

-- ASCII Art to be displayed
local asciiArt = {
    "     |\\_/|                  ",
    "     | @ @                   ",
    "     |   <>              _  ",
    "     |  _/\\------____ ((| |))",
    "     |               --' |  ",
    " ____|_       ___|   |___.'  ",
    "/_/_____/____/_______|       "
}

-- Function to display ASCII art and centered password prompt
local function displayAsciiArt()
    term.clear()
    local screenWidth, screenHeight = term.getSize()
    local artHeight = #asciiArt

    -- Display each line of the ASCII art centered
    for i, line in ipairs(asciiArt) do
        local lineWidth = #line
        local startX = math.floor((screenWidth - lineWidth) / 2)
        local startY = math.floor((screenHeight - artHeight) / 2) + i - 1
        term.setCursorPos(startX, startY)
        term.write(line)
    end

    -- Center the "Enter Password:" prompt below the ASCII art
    local prompt = "Enter Password: "
    local promptX = math.floor((screenWidth - #prompt) / 2)
    local promptY = math.floor((screenHeight - artHeight) / 2) + artHeight + 1
    term.setCursorPos(promptX, promptY)
    write(prompt)
end

-- Function to prompt for password
local function promptForPassword(correctPassword)
    displayAsciiArt()

    local input = ""
    -- Use event API to gather input character by character
    while true do
        local event, key = os.pullEvent("key")
        if key == keys.enter then
            if input == correctPassword then
                return true
            else
                term.setTextColor(colors.red)
                local deniedMsg = "Access Denied! Incorrect Password."
                term.setCursorPos((term.getSize() - #deniedMsg) / 2, term.getSize() / 2 + #asciiArt + 2)
                print(deniedMsg)
                term.setTextColor(colors.white) -- Reset color to white after
                sleep(2)  -- Pause before restarting
                return false
            end
        elseif key == keys.backspace then
            input = input:sub(1, -2)
            term.setCursorPos((term.getSize() - #prompt) / 2 + #prompt, term.getSize() / 2 + #asciiArt)
            write(string.rep(" ", 20)) -- Clear previous input
            term.setCursorPos((term.getSize() - #prompt) / 2 + #prompt, term.getSize() / 2 + #asciiArt)
            write(input) -- Display updated input
        else
            input = input .. string.char(key)
            term.setCursorPos((term.getSize() - #prompt) / 2 + #prompt, term.getSize() / 2 + #asciiArt)
            write(input)
        end
    end
end

-- Main loop to handle authentication
local decryptedPassword = getDecryptedPassword()

if not decryptedPassword then
    decryptedPassword = createNewPassword()  -- Prompt to create a new password
end

local authenticated = false

while not authenticated do
    authenticated = promptForPassword(decryptedPassword)
end

-- Code for your main boot process can go here
term.clear()
local welcomeMsg = "Welcome to your system!"
term.setCursorPos((term.getSize() - #welcomeMsg) / 2, term.getSize() / 2)
print(welcomeMsg)
-- Additional initialization code can be added here

shell.run("bootloader")