if not turtle then
    printError("not a turtle")
    return
end

_G._TOS_VER = "N/A"
local tos_ver_fp = io.open("/.tos-ver", "r")
if tos_ver_fp then
    _G._TOS_VER = tos_ver_fp:read("l")
    tos_ver_fp:close()
end

if fs.exists("/disk/update.json") then
    local info_fp = io.open("/disk/update.json", "r")
    local info = textutils.unserializeJSON(info_fp:read("a"))
    info_fp:close()
    print("OTP version: " .. info.ver)
    print("H/W version: " .. _TOS_VER)
    if info.ver == _TOS_VER then
        print("Running on latest firmware")
    else
        print("Performing an update...")
        for i = 1, #info.files do
            local file = info.files[i]
            term.write(file.dst, "...")
            if fs.exists(file.dst) then
                term.write(" [DEL] ...")
                fs.delete(file.dst)
            end
            fs.copy("/disk" .. file.src, file.dst)
            print(" OK, copied from", file.src)
        end
        print("Writing new version info")
        io.open("/.tos-ver", "w"):write(info.ver):close()
        print("Rebooting")
        return os.reboot()
    end
end

shell.run("fg", "main.lua")