cc turtle excavator v2

args = { ... }
if #args ~= 3 then
    print("Usage: quarry <length> <width> <depth>")
    return
end
x = tonumber(args[1])
y = tonumber(args[2])
z = tonumber(args[3])

function dig(n)
    for i=1,n do
        invCheck()
        turtle.dig()
        turtle.forward()
        turtle.digUp()
    end
end

function digPlane(x,y)
    for i=1,y do
        dig(x-1)
        if i==y then
            if y%2==0 then
                turtle.turnLeft()
            else
                turtle.turnLeft()
                turtle.turnLeft()
                dig(x)
            end
        elseif i%2==0 then
            turtle.turnRight()
            dig(1)
            turtle.turnRight()
        else
            turtle.turnLeft()
            dig(1)
            turtle.turnLeft()
        end
    end
end

function digVolume(x,y,z)
    for i=1,math.ceil(z/2) do
        if fuelCheck(x+y+z) then
            for i=1,2 do
                if turtle.detectDown() then
                    if not turtle.digDown() then
                        break
                    end
                end
                turtle.down()
            end
            digPlane(x,y)
        end
    end
end

function invCheck()
    if turtle.getItemDetail(14) ~= nil then
        turtle.select(16)
        turtle.placeUp()
        for i=2,15 do
            turtle.select(i)
            turtle.dropUp()
        end
        turtle.select(1)
    end
end

function fuelCheck(threshold)
    fuel = turtle.getFuelLevel()
    print("Current fuel: ", fuel)
    if fuel <= threshold then
        return turtle.refuel()
    end
    return true
end

digVolume(x,y,z)