bore

length = 0
materialSlot = 1
allOut = false

function forward()
	for i=1,20 do
		if turtle.detect() then
			turtle.dig()
		else
			break
		end
	end

	for i=1,20 do
		if not turtle.forward() then
			turtle.dig()
			sleep(2)
		else
			break
		end
	end
end

function up()
	digUp()
	turtle.up()
end

function down()
	digDown()
	turtle.down()
end

function digUp()
	for i=1,20 do
		if turtle.detectUp() then
			turtle.digUp()
		else
			break
		end
	end
end

function digDown()
	if turtle.detectDown() then
		turtle.digDown()
	end
end

function ensureMaterial()
	if allOut then
		return false
	end

	if turtle.getItemCount(materialSlot) < 3 then
		organizeMaterial()
	end
	if turtle.getItemCount(materialSlot) < 3 then
		print("No more material")
		allOut = true
		return false
	end
	return true
end

function organizeMaterial()
	local i
	materialCount = turtle.getItemCount(materialSlot)

	if materialCount < 3 then
--		print("Attempting to refill slot ", materialSlot)
		for i=2,16 do
			turtle.select(i)
			if turtle.compareTo(materialSlot) then
				turtle.transferTo(materialSlot)
			end
		end
	end
	turtle.select(materialSlot)
end

function bore(len)
	for i=1,len do
		forward()
		digUp()
		digDown()
	end
end

function boreUpper(len)
	for i=1,len do
		forward()
		digUp()
		digDown()
		placeBlockUp()
	end
end

function boreLower(len)
	for i=1,len do
		digDown()
		placeBlockDown()
		forward()
	end
end

function placeBlock()
	if ensureMaterial() then
		turtle.select(materialSlot)
		turtle.place()
	end
end

function placeBlockUp()
	if ensureMaterial() then
		turtle.select(materialSlot)
		turtle.placeUp()
	end
end

function placeBlockDown()
	if ensureMaterial() then
		turtle.select(materialSlot)
		turtle.placeDown()
	end
end


function sideWall()
	for i=1,length do
		placeBlockUp()
		placeBlockDown()
		turtle.back()
		placeBlock()
	end
end

args = {...}
nArgs = #args

if nArgs ~= 1 then
	print("Usage: bore <length>")
		return
end

length = tonumber(args[1])
if length == nil then
  print("\"", args[1], "\" is not a valid length") return
end

digUp()
turtle.up()
bore(length)		-- Right-hand wall
sideWall()

turtle.turnLeft()
forward()
turtle.turnRight()
up()
boreUpper(length)

turtle.turnLeft()
turtle.turnLeft()
down()
down()
boreLower(length)

turtle.turnRight()
forward()
turtle.turnRight()
forward()
boreLower(length)

turtle.turnLeft()
turtle.turnLeft()
up()
up()
boreUpper(length)

forward()
turtle.turnRight()
forward()
turtle.turnRight()
boreUpper(length)

turtle.turnLeft()
turtle.turnLeft()
down()
down()
boreLower(length)

turtle.turnRight()
forward()
turtle.turnRight()
up()
bore(length)
sideWall()

--[[
forward()
turtle.turnLeft()
bore(length)
sideWall()
--]]