-------------------------------------
-- 3D Maze generation script
-------------------------------------
-- A test by @Starbeamrainbowlabs
local M = {}

if arg[1] ~= nil then
	width = tonumber(arg[1])
else
	width = 35
end
if arg[2] ~= nil then
	height = tonumber(arg[2])
else
	height = 15
end
if arg[3] ~= nil then
	depth = tonumber(arg[3])
else
	depth = 7
end
if arg[4] ~= nil then
    seed = tonumber(arg[4])
else
    seed = os.time()
end

----------------------------------
-- function to print out the world
----------------------------------
function M.printspace(space, w, h, d)
	for z = 0, d - 1, 1 do
		for y = 0, h - 1, 1 do
			local line = ""
			for x = 0, w - 1, 1 do
				line = line .. space[z][y][x]
			end
			print(line)
		end
        print("")
	end
end

-- Initialise the world

function M.generate_maze(seed, width, height, depth)
	start_time = os.clock()
	
	print("Generating maze "..width.."x"..height.."x"..depth)
	math.randomseed(seed) -- seed the random number generator with the system clock

	width = width - 1
	height = height - 1

	local world = {}
	for z = 0, depth, 1 do
        world[z] = {}
		for y = 0, height, 1 do
			world[z][y] = {}
			for x = 0, width, 1 do
				world[z][y][x] = "#"
			end
		end
	end

	-- do a random walk to create pathways
	local nodes = {} -- the nodes left that we haven't investigated
	local curnode = 1 -- the node we are currently operating on
	local cx, cy, cz = 1, 1, 1 -- our current position
	table.insert(nodes, { x = cx, y = cy, z = cz })
	world[cz][cy][cx] = " "
	while #nodes > 0 do
		-- io.write("Nodes left: " .. curnode .. "\r")
		--print("Nodes left: " .. #nodes)

		local directions = "" -- the different directions we can move in
        if cz - 2 > 0 and world[cz - 2][cy][cx] == "#" then
            directions = directions .. "-"
        end
        if cz + 2 < depth and world[cz + 2][cy][cx] == "#" then
            directions = directions .. "+"
        end
		if cy - 2 > 0 and world[cz][cy - 2][cx] == "#" then
			directions = directions .. "u"
		end
		if cy + 2 < height and world[cz][cy + 2][cx] == "#" then
			directions = directions .. "d"
		end
		if cx - 2 > 0 and world[cz][cy][cx - 2] == "#" then
			directions = directions .. "l"
		end
		if cx + 2 < width and world[cz][cy][cx + 2] == "#" then
			directions = directions .. "r"
		end
        
		--print("radar output: '" .. directions .. "' (length: " .. #directions .. "), curnode: " .. curnode)
		if #directions > 0 then
			-- we still have somewhere that we can go
			local curdirnum = math.random(1, #directions)
			local curdir = string.sub(directions, curdirnum, curdirnum)
            
            if curdir == "+" then
                world[cz + 1][cy][cx] = " "
                world[cz + 2][cy][cx] = " "
                cz = cz + 2
            elseif curdir == "-" then
                world[cz - 1][cy][cx] = " "
                world[cz - 2][cy][cx] = " "
                cz = cz - 2
            elseif curdir == "u" then
				world[cz][cy - 1][cx] = " "
				world[cz][cy - 2][cx] = " "
				cy = cy - 2
			elseif curdir == "d" then
				world[cz][cy + 1][cx] = " "
				world[cz][cy + 2][cx] = " "
				cy = cy + 2
			elseif curdir == "l" then
				world[cz][cy][cx - 1] = " "
				world[cz][cy][cx - 2] = " "
				cx = cx - 2
			elseif curdir == "r" then
				world[cz][cy][cx + 1] = " "
				world[cz][cy][cx + 2] = " "
				cx = cx + 2
			end
            
			table.insert(nodes, { x = cx, y = cy, z = cz })
		else
			table.remove(nodes, curnode)
			if #nodes > 0 then
				curnode = math.random(1, #nodes)
				
				cx = nodes[curnode]["x"]
				cy = nodes[curnode]["y"]
                cz = nodes[curnode]["z"]
			end
		end
	end
	
	end_time = os.clock()
	
	return world, (end_time - start_time) * 1000
end

return M

-- local world = M.generate_maze3d(seed, width, height, depth)
-- 
-- M.printspace(world, width, height, depth)
-- end_time = os.clock()
-- print("Generation completed in " .. (end_time - start_time) .. "s.")