mine

local args = {...}
local w = args[1] or 3
local h = args[2] or 3

function fuel()
    turtle.refuel()
    if not turtle.getFuelLevel() == 0 then
        print("Out of fuel")
        return false
    end
    return true
end

function square()
    turtle.dig()
    turtle.forward()
    turtle.turnRight()

    for i = 1, h-1 do
        for _ = 1, w-1 do
            turtle.dig()
            turtle.forward()
        end

        if i < h-1 then
            turtle.digDown()
            turtle.down()

            for _ = 1, 2 do
                turtle.turnLeft()
            end
        end
    end
end

function move()
    while true do
        square()

        if h % 2 == 1 then
            for _ = 1, 2 do
                turtle.turnLeft()
            end

            for _ = 1, w-1 do
                turtle.forward()
            end
        end

        turtle.turnRight()

        for _ = 1, h-2 do
            turtle.up()
        end
    end
end

if fuel() then
    move()
end