ventshaft

glow = 0
function moveForward()
repeat
turtle.dig()
until turtle.forward()
end

function mineUp()
repeat
turtle.digUp()
until turtle.up()
end

function refuel()
if turtle.getFuelLevel() <= 5 then
turtle.select(16)
turtle.refuel(1)
end
end

function selectLadder()
turtle.select(15)
if turtle.getItemCount(15) == 1 then
turtle.select(1)
while not turtle.compareTo(15) do
for i = 1,12 do
turtle.select(i)
end
end
end
end

function selectDirt()
turtle.select(14)
if turtle.getItemCount(14) == 1 then
turtle.select(1)
while not turtle.compareTo(14) do
for i = 1,12 do
turtle.select(i)
end
end
end
end

function placeLadder()
selectLadder()
if not turtle.place() then
selectDirt()
moveForward()
turtle.place()
turtle.back()
selectLadder()
if not turtle.place() then
return false
end
end
end

function torch()
if glow == 6 then
turtle.digDown()
turtle.select(13)
turtle.placeDown()
glow = glow-glow
end
end
print "Place ladder instance in slot 15, Fuel in 16, and dirt/stone in 14. Torches go in 13."
print "When only one ladder or filler is in their slots, program will look elsewhere."
print "How deep do you want to mine? (z)"
z = io.read()
z = tonumber(z)
print "Press any key to run."
os.pullEvent("char")

for i = 1,z do
turtle.digDown()
turtle.down()
refuel()
end
moveForward()
refuel()
turtle.turnLeft()
turtle.turnLeft()
for i = 1,z do
if not placeLadder() then
--break
end
torch()
selectDirt()
turtle.placeDown()
mineUp()
refuel()
glow = glow+1
end