Doggy OS bootloader

local term = term
local fs = fs
local colors = colors

-- Function to check if a directory exists
local function directoryExists(path)
    return fs.isDir(path)
end

-- Function to check if a file exists
local function fileExists(path)
    return fs.exists(path) and not fs.isDir(path)
end

-- Function to list all bootable drives
local function listBootableDrives()
    local drives = {}
    for _, side in ipairs(rs.getSides()) do
        local path = side.."/disk/bootloader/VA11-ILLA.lua"
        if directoryExists(path) then
            table.insert(drives, side)
        end
    end
    return drives
end

-- Function to list installed operating systems on a drive
local function listInstalledOS(drive)
    local osList = {}
    if directoryExists(drive.."/disk/") then
        local files = fs.list(drive.."/disk/")
        for _, file in ipairs(files) do
            if file:match("%.Boot%d$") then
                table.insert(osList, file)
            end
        end
    end
    return osList
end

-- Function to display boot menu
local function displayBootMenu()
    term.clear()
    term.setCursorPos(1, 1)
    print("UEFI Boot Menu")
    print("Select an OS using arrow keys and press Enter to boot.")
    print("Use arrow keys to navigate, press 'q' to exit.")
    print()

    local drives = listBootableDrives()
    for i, drive in ipairs(drives) do
        term.setTextColor(colors.green)
        term.write(drive.."/disk")
        term.setTextColor(colors.white)
        local osList = listInstalledOS(drive)
        for _, os in ipairs(osList) do
            term.write(" "..os)
            if i == selectedDriveIndex and os == selectedOS then
                term.write(" <")
            end
            print()
        end
    end
end

-- Function to handle key input
local function handleInput()
    while true do
        local event, key = os.pullEvent("key")
        if key == keys.q then
            return false
        elseif key == keys.enter then
            if selectedDriveIndex and selectedOS then
                local selectedDrive = listBootableDrives()[selectedDriveIndex]
                fs.copy(selectedDrive.."/disk"..selectedOS, selectedDrive)
                return true
            end
        elseif key == keys.up or key == keys.down then
            local drives = listBootableDrives()
            if #drives > 0 then
                local numOS = #listInstalledOS(drives[selectedDriveIndex])
                if key == keys.up then
                    selectedOSIndex = (selectedOSIndex - 1) % numOS + 1
                elseif key == keys.down then
                    selectedOSIndex = (selectedOSIndex + 1) % numOS + 1
                end
            end
        end
    end
end

-- Main function
local function main()
    while true do
        displayBootMenu()
        if not handleInput() then
            break
        end
    end
    term.clear()
    term.setCursorPos(1, 1)
    print("Exiting UEFI Boot Menu")
end

-- Start the program
main()