mineshaft

wood = {}
nextColDir = "up"
nextRowDir = "right"

function digTunnel(length)
	for i = 1, length, 1 do
		for k = 1, 4, 1 do
			if not digSide(nextColDir) then
				return false
			end
			invFull("back", 2)
			nextColDir = swapColDir(nextColDir)
			turn(nextRowDir)
			nextRowDir = swapRowDir(nextRowDir)
			for j = 1, 3, 1 do
				if not digCenter(nextColDir) then
					return false
				end
				invFull("back", 2)
				nextColDir = swapColDir(nextColDir)
			end
			if not digSide(nextColDir) then
				return false
			end
			invFull("back", 2)
			nextColDir = swapColDir(nextColDir)
			turn(nextRowDir)
		end
		if not addSupports() then
			return false
		end
		invFull(nextRowDir, 2)
	end
	return true
end

function addSupports()
	turn(nextRowDir)
	forward()
	turn(nextRowDir)
	forward()
	turn(nextRowDir)
	if not placeBeams(nextColDir) then
		return false
	end
	nextColDir = swapColDir(nextColDir)
	turn(nextRowDir)
	turn(nextRowDir)
	nextRowDir = swapRowDir(nextRowDir)
	forward()
	if nextColDir == "up" then
		digDown()
		if not placeWood("down") then
			return false
		end
		up()
		up()
		if not placeWood("up") then
			return false
		end
	elseif nextColDir == "down" then
		if not placeWood("up") then
			return false
		end
		down()
		down()
		digDown()
		if not placeWood("down") then
			return false
		end
	end
	nextColDir = swapColDir(nextColDir)
	forward()
	if not placeBeams(nextColDir) then
		return false
	end
	nextColDir = swapColDir(nextColDir)
	turn(nextRowDir)
	nextRowDir = swapRowDir(nextRowDir)
	forward()
	turn(nextRowDir)
	forward()
	nextRowDir = swapRowDir(nextRowDir)
	turn(nextRowDir)
	return true
end

function  placeBeams(direction)
	success = true
	if direction == "up" then
		digDown()
		sucess = placeWood("down")
		sucess = placeWood("front")
		up()
		sucess = placeWood("front")
		up()
		sucess = placeWood("front")
		sucess = placeWood("up")
	elseif direction == "down" then
		sucess = placeWood("up")
		sucess = placeWood("front")
		down()
		sucess = placeWood("front")
		down()
		digDown()
		sucess = placeWood("front")
		sucess = placeWood("down")
	end
	return success
end

function digSide(direction)
	local success = true
	dig()
	forward()
	if direction == "up" then
		digDown()
		success = placeWood("down")
		for i = 1, 2, 1 do
			digUp()
			up()
		end
		digUp()
		success = placeWood("up")
	else
		digUp()
		success = placeWood("up")
		for i = 1, 2, 1 do
			digDown()
			down()
		end
		digDown()
		success = placeWood("down")
	end
	return success
end

function digCenter(direction)
	local success = true
	dig()
	forward()
	if direction == "up" then
		digUp()
		up()
		digUp()
		up()
		digUp()
	else
		digUp()
		for i = 1, 2, 1 do
			digDown()
			down()
		end
	end
	return success
end

function placeWood(dir)
	hasWood = true
	if (wood == nil) or (sum(wood) == 0) then
		hasWood = findWood()
	end
	if not hasWood then
		return false
	end

	woodSlot = 1
	for i = 1, 14, 1 do
		if wood[i] > 0 then
			woodSlot = i
		end
	end
	turtle.select(woodSlot)
	success = true
	if dir == "front" then
		success = turtle.place()
	elseif dir == "up" then
		success = turtle.placeUp()
	elseif dir == "down" then
		success = turtle.placeDown()
	end
	wood[woodSlot] = turtle.getItemCount(woodSlot)
	return success
end

function findWood()
	for i = 1, 14, 1 do
		turtle.select(i)
		wood[i] = turtle.getItemCount(i)
	end
	if not (sum(wood) == 0) then
		return true
	else
		return false
	end
end