-- Clear the screen and set up colors
term.clear()
term.setBackgroundColor(colors.black)
term.setTextColor(colors.white)
term.clear()

-- Define the width and height of the screen
local width, height = term.getSize()

-- Function to center text on the screen
local function centerText(y, text, textColor)
    local x = math.floor((width - #text) / 2)
    term.setCursorPos(x, y)
    term.setTextColor(textColor)
    term.write(text)
end

-- Function to display a box with title
local function drawBox(y, height, title, message)
    local boxWidth = width - 4
    local x = 2
    -- Draw top border
    term.setTextColor(colors.cyan)
    term.setBackgroundColor(colors.gray)
    term.setCursorPos(x, y)
    term.write(string.rep("─", boxWidth))
    -- Title row
    term.setCursorPos(x + 2, y + 1)
    term.setTextColor(colors.white)
    term.setBackgroundColor(colors.cyan)
    term.write(title)
    -- Message rows
    term.setBackgroundColor(colors.black)
    for i = 1, height - 2 do
        term.setCursorPos(x + 2, y + i + 1)
        term.write(message[i] or "")
    end
    -- Draw bottom border
    term.setCursorPos(x, y + height)
    term.write(string.rep("─", boxWidth))
end

-- ASCII art for fatal error screen
local fatalArt = {
    "     |\\_/|                  ",
    "     | X X    FATAL ERROR    ",
    "     |   <>              _   ",
    "     |  _/\\------____ ((| |))",
    "     |               `--' |  ",
    " _____|_       ___|   |___.  ",
    "/_/_____/____/_______|       "
}

-- ASCII art for warning screen
local warningArt = {
    "     |\\_/|                  ",
    "     | ? ?    SECURITY ERROR ",
    "     |   <>              _   ",
    "     |  _/\\------____ ((| |))",
    "     |               `--' |  ",
    " _____|_       ___|   |___.  ",
    "/_/_____/____/_______|       "
}

-- Function to prompt for admin credentials with improved UI
local function authenticateAdmin()
    term.clear()
    local authHeight = 8
    local message = {
        "Enter your username and password.",
        "You are required to authenticate as admin.",
        "",
        "(Please be aware of the case sensitivity of your credentials)."
    }
    drawBox(2, authHeight, "Admin Authentication Required", message)

    -- Username input
    centerText(height // 2, "Enter Username:", colors.white)
    term.setCursorPos((width - 20) // 2, height // 2 + 1)
    local username = read()

    -- Password input
    local passwordPath = "/disk/users/" .. username .. "/password.txt"
    local adminPath = "/disk/users/" .. username .. "/admin.txt"

    if fs.exists(adminPath) and fs.exists(passwordPath) then
        -- Password field with hidden characters
        centerText(height // 2 + 2, "Enter Password:", colors.white)
        term.setCursorPos((width - 20) // 2, height // 2 + 3)
        local enteredPassword = read("*")

        -- Check if the password is correct
        local file = fs.open(passwordPath, "r")
        local storedPassword = file.readAll()
        file.close()

        if enteredPassword == storedPassword then
            -- Success message
            centerText(height // 2 + 4, "Authentication Successful!", colors.green)
            sleep(1)
            return true  -- Authentication successful
        else
            -- Failure message
            centerText(height // 2 + 4, "Authentication Failed", colors.red)
            sleep(2)
        end
    else
        -- If the user doesn't exist or there's no password
        centerText(height // 2 + 4, "Authentication Failed: User Not Found", colors.red)
        sleep(2)
    end
    return false  -- Authentication failed
end

-- Function to show an error message with ASCII art
local function showError(message, isFatal)
    term.clear()

    -- Determine ASCII art and color based on error type
    local artColor = isFatal and colors.red or colors.yellow
    local art = isFatal and fatalArt or warningArt

    -- Display the ASCII art
    local startLine = math.floor((height - #art) / 2) - 2
    term.setTextColor(artColor)
    for i, line in ipairs(art) do
        centerText(startLine + i, line, artColor)
    end

    -- Display error message below the ASCII art
    term.setTextColor(colors.white)
    centerText(startLine + #art + 2, "Error:", colors.white)
    centerText(startLine + #art + 3, message, colors.white)

    -- Move "Please contact support." to the bottom in white
    centerText(height - 2, "Press DEL for Admin Override", colors.white)

    -- Wait for DEL key or keep the screen static
    while true do
        local event, key = os.pullEvent("key")
        if key == keys.delete then
            if authenticateAdmin() then
                return  -- Exit the error screen if authentication succeeds
            end
        end
        sleep(0.1)
    end
end

-- Function to check for boot.lock file
local function checkBootLock()
    if fs.exists("/boot.lock") then
        showError("System Disabled", false)  -- Warning
    end
end

-- Function to check if .settings file exists and contains shell.allow_disk_startup
local function isSecureBootConfigured()
    local settingsPath = "/.settings"
    if fs.exists(settingsPath) then
        local file = fs.open(settingsPath, "r")
        if file then
            local contents = file.readAll()
            file.close()
            -- Check if .settings contains shell.allow_disk_startup
            if not string.find(contents, 'shell%.allow_disk_startup') then
                return false  -- shell.allow_disk_startup not found
            end
        end
    else
        -- .settings file doesn't exist
        return false  -- Secure boot configuration file is missing
    end
    return true  -- Secure boot is properly configured
end

-- Function to check for malicious paths in a file
local function containsMaliciousPaths(filePath)
    if not fs.exists(filePath) then
        return false
    end

    local file = fs.open(filePath, "r")
    if not file then
        return false
    end

    local contents = file.readAll()
    file.close()

    local maliciousPaths = {
        "/disk/os/", "/disk/boot/", "/disk/bootloader/", "/disk/security/", "/disk/users/", "/disk/",
        "disk/os", "disk/boot", "disk/bootloader", "disk/security", "disk/users", "disk"
    }

    for _, path in ipairs(maliciousPaths) do
        if string.find(contents, path, 1, true) then
            return true
        end
    end

    return false
end

-- Function to check if /disk2/startup or /disk2/startup.lua includes malicious paths
local function checkMaliciousBoot()
    if containsMaliciousPaths("/disk2/startup") then
        showError("Malicious Boot Device: /disk2/startup", false)  -- Warning
    elseif containsMaliciousPaths("/disk2/startup.lua") then
        showError("Malicious Boot Device: /disk2/startup.lua", false)  -- Warning
    end
end

-- Function to check if /disk/users directory is empty
local function checkEmptyUsers()
    local usersDir = "/disk/users"
    if fs.exists(usersDir) and fs.isDir(usersDir) then
        local files = fs.list(usersDir)
        if #files == 0 then
            showError("No user data found", false)  -- Warning
        end
    else
        showError("No user data found", false)  -- Warning
    end
end

-- Function to check if /disk/boot/BIOS exists
local function checkCriticalBootFiles()
    if not fs.exists("/disk/boot/boot-animation") then
        showError("/disk/boot/BIOS Cannot be loaded", true)  -- Fatal
    end
end

-- Function to check if any user has admin.txt
local function checkAdmin()
    local usersDir = "/disk/users"
    if fs.exists(usersDir) and fs.isDir(usersDir) then
        local users = fs.list(usersDir)
        for _, user in ipairs(users) do
            local adminPath = fs.combine(usersDir, user, "admin.txt")
            if fs.exists(adminPath) then
                return true
            end
        end
    end
    return false
end

-- Function to check if no-os file exists
local function checkFirmware()
    if not fs.exists("/no-os") then
        showError("System Firmware Corrupted", true)  -- Fatal
    end
end

-- Main function to initiate checks and continue boot process
local function main()
    checkBootLock()
    if not isSecureBootConfigured() then
        showError("Secure Boot Service Unavailable", true)  -- Fatal
    end
    checkMaliciousBoot()
    checkEmptyUsers()
    checkCriticalBootFiles()
    if not checkAdmin() then
        showError("No system administrators found", false)  -- Warning
    end
    checkFirmware()

    -- If no issues found, continue with normal boot process
    shell.run("/disk/boot/BIOS")
    print("No issues detected. Continuing boot process...")
    shell.run("/disk/error/crash")
    -- Your normal boot code here
end

-- Start the main function
main()