TrackLayer

--
-- tracklayer
-- places tracks for long distances
-- places powered rails and redstone torches
-- also places powered rails for up/down hills
-- minimizes digging, preferring to follow the terrain where possible
--
-- Unfortunately, this includes following the terrain into water
-- handle that in advance with another program
--
-- slot setup:
-- slot 1 - scratch - anything we hafta dig - ejected after every dig
-- slot 2-5 - rails - plain ol' unpowered classic
-- slot 6-7 - powered rails
-- slot 8 - redstone torches
-- slot 9 - building material - use this for stairs when we go off a cliff
--

--[[

local function pause(a)
	local e, p1, p2, p3, p4, p5
	if a then
		print(a)
	end
	e = "derp"
	p1 = "derp"
	while p1 ~= 57 do
		e, p1, p2, p3, p4, p5 = os.pullEvent()
	end
end

]]--

local function count(s)
	turtle.select(s)
	return turtle.getItemCount(s)
end

local function check(s)
	turtle.select(s)
	return (turtle.getItemCount(s) ~= 0)
end

local function dig()
	if turtle.detect() then
--		pause("dig!")
		turtle.select(1)
		turtle.dig()
		if check(1) then turtle.drop() end
	end
end

local function digup()
	if turtle.detectUp() then
--		pause("digup!")
		turtle.select(1)
		turtle.digUp()
		if check(1) then turtle.drop() end
	end
end

local function digdown()
	if turtle.detectDown() then
--		pause("digdown!")
		turtle.select(1)
		turtle.digDown()
		if check(1) then turtle.drop() end
	end
end

local function up()
	digup()
	return turtle.up()
end

local function down()
	digdown()
	return turtle.down()
end

local function forward()
	dig()
	return turtle.forward()
end

local back = turtle.back
local right = turtle.turnRight
local left = turtle.turnLeft


--types:
--0 - rail
--1 - powrail
--2 - RS torch
--3 - building crap

-- look the fuck out, it's short-circuit 'or' reliance to leave the right thing select()ed

local function havetype(t)
	if type(t) ~= "number" then
		error("havetype needs a number")
		return false
	end
	if t == 0 then
		return check(2) or check(3) or check(4) or check(5)
	elseif t == 1 then
		return check(6) or check(7)
	elseif t == 2 then
		return check(8)
	elseif t == 3 then
		return check(9)
	else
		error("havetype doesn't grok: ", t)
		return false
	end
end

local function counttype(t)
	if type(t) ~= "number" then
		error("counttype needs a number")
		return false
	end
	if t == 0 then
		if count(2) > 0 then
			return count(2)
		elseif count(3) > 0 then
			return count(3)
		elseif count(4) > 0 then
			return count(4)
		else
			return count(5)
		end
	elseif t == 1 then
		if count(6) > 0 then
			return count(6)
		else
			return count(7)
		end
	elseif t == 2 then
		return count(8)
	elseif t == 3 then
		return count(9)
	else
		error("counttype doesn't grok: ", t)
		return false
	end
end


local function put(t)
	if type(t) == "nil" then
		t = 0
	end
	if not havetype(t) then
		print("waiting for more mats, type ", t)
		while not havetype(t) do
			sleep(1)
		end
	end
	
	-- ugly hack to work around turtle API grabbing from other slots when current slot items won't place (ie. placing track over air w/ stone in another slot)
	local c = counttype(t)
--	pause(c)
	local rv = turtle.placeDown()
--	pause(counttype(t))
	if rv and c == counttype(t) then
		digdown()
		return false
	else
		return rv
	end
end

local function track(t)
	if not put(t) then
		-- must be a hill
		if turtle.detectDown() then
			up()
			put(1)
			return 1
		else
			down()
			if not put(1) then
				down()
				put(3)
				up()
				put(1)
			end
			return -1
		end
	end
	return 0
end



-------- void main(int argc, char ** argv)  or whatever

local argv = {...}

local i, j

i = 64
j = 8

if #argv > 0 then
	i = tonumber(argv[1])
	if i == nil or i < 1 then
		i = 64
	end
	j = tonumber(argv[2])
	if j == nil or j < 1 then
		j = 8
	end
end

print("Placing ", i, " rails.")
print("Powered at intervals of ", j, ".")

-- open by moving up a block, assuming we're placed on the ground at our starting location
up()

local rv

-- while I haven't built out to the parameter limit
while i > 0 do
--	pause(i)
	if i % j == 0 then
		print("i = ", i, " : powered rail")
		rv = track(1)
		right()
		forward()
		down()
		put(3)
		up()
		put(2)
		back()
		left()
	else
		rv = track(0)
	end
	-- move ahead
	forward()
	-- decrement counter
	i = i - 1
end

turtle.down()