[Computer Craft] Turtle GPS builder

if not turtle then
    print("Error Not turtle")
    return
end

local mov = {}

mov.forward = function ()
    while not turtle.forward() do
        sleep(1)
    end
    return true
end
mov.back = function ()
    while not turtle.back() do
        sleep(1)
    end
    return true
end
mov.up = function ()
    while not turtle.up() do
        sleep(1)
    end
    return true
end
mov.down = function ()
    while not turtle.down() do
        sleep(1)
    end
    return true
end
mov.place = function ()
    while not turtle.place() do
        sleep(1)
    end
end

local base = nil

if turtle.getFuelLevel() < 600 then
    print("600 fuel is required")
    return
else
    if fs.exists("custom") then
        print("custom program detected")
        print("please Enter base Station number")
        local failFlag = false
        repeat
            if failFlag then
                print("Error Not number")
                print("try again")
            end
            write(" > ")
            base = tonumber(read())
            failFlag = true
        until type(base) == "number"
    end
    print("Please Place 4 computers in slot one")
    print("4 modems in slot two")
    print("if mineing turtle then")
    print("1 disk drive in slot three")
    print("if not mineing then")
    print("4 disk drive in slot three")
    print("blank floopy disk in slot four")
    print("press Enter key to continue")
    while true do
        local event , key = os.pullEvent("key")
        if key == 28 then break end
    end
    print("Launching")
end
local set = {}
set[1] = {x = 0,y = 3,z = 254}
set[2] = {x = 3,y = 0,z = 251}
set[3] = {x = 0,y = -3,z = 254}
set[4] = {x = -3,y = 0,z = 251}

while turtle.up() do -- sends it up till it hits max hight
end

for a = 1,4 do
    for i = 1,2 do
        mov.forward()
    end
    turtle.select(1)
    mov.place()
    mov.back()
    turtle.select(2)
    mov.place()
    mov.down()
    mov.forward()
    turtle.select(3)
    mov.place()
    turtle.select(4)
    turtle.drop()
    -- make disk custom
    fs.delete("disk/startup")
    file = fs.open("disk/startup","w")
    file.write([[
fs.copy("disk/install","startup")
fs.delete("disk/startup")
if fs.exists("disk/custom") then
    fs.copy("disk/custom","custom")
    fs.delete("disk/custom")
end
print("sleep in 10")
sleep(10)
os.reboot()
]])
    file.close()
    if fs.exists("custom") then
        fs.copy("custom","disk/custom")
    end
        file = fs.open("disk/install","w")
        file.write([[
if fs.exists("custom") then
    shell.run("custom","host",]]..set[a]["x"]..","..set[a]["y"]..","..set[a]["z"]..","..(base or "nil")..[[)
else
    shell.run("gps","host",]]..set[a]["x"]..","..set[a]["y"]..","..set[a]["z"]..[[)
end
]])
        file.close()
    -- end make disk custom
    turtle.turnLeft()
    mov.forward()
    mov.up()
    turtle.turnRight()
    mov.forward()
    turtle.turnRight()
    peripheral.call("front","turnOn")
    mov.down()
    turtle.suck()
    turtle.select(3)
    turtle.dig()
    mov.up()
    -- reboot would be here
    turtle.turnRight()
    for i = 1,3 do
        mov.forward()
    end
    turtle.turnLeft()
    mov.forward()
    if a == 1 or a == 3 then
        for i = 1,3 do
        mov.down()
        end
    elseif a == 2 or a == 4 then
        for i = 1,3 do
        mov.up()
        end
    end
end

while turtle.down() do -- brings turtle down
end
turtle = tMove
print("Finished")