-------------------------------------
-- 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, path_length, path_width, path_depth, branching_factor)
	local start_time = os.clock()
    if not path_length then path_length = 2 end
    if not path_width then path_width = 1 end
	if not path_depth then path_depth = 1 end
	if not branching_factor then branching_factor = 3 end
	
	-- print("Generating maze "..width.."x"..height.."x"..depth.." | path: length "..path_length.." width "..path_width.." depth "..path_depth)
	math.randomseed(seed) -- seed the random number generator with the system clock

	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 - path_length > 0 and world[cz - path_length][cy][cx] == "#" then
            directions = directions .. "-"
        end
        if cz + path_length < depth-path_depth and world[cz + path_length][cy][cx] == "#" then
            directions = directions .. "+"
        end
		if cy - path_length > 0 and world[cz][cy - path_length][cx] == "#" then
			directions = directions .. "u"
		end
		if cy + path_length < height-path_width and world[cz][cy + path_length][cx] == "#" then
			directions = directions .. "d"
		end
		if cx - path_length > 0 and world[cz][cy][cx - path_length] == "#" then
			directions = directions .. "l"
		end
		if cx + path_length < width-path_width and world[cz][cy][cx + path_length] == "#" then
			directions = directions .. "r"
		end
		
		-- If this is 1 or less, then we will switch our attention to another candidate node after moving
		local shift_attention = math.random(0, branching_factor)
        
		--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
				for iz = cz,cz+path_length+(path_depth-1) do
					for ix = cx,cx+(path_width-1) do
						for iy = cy,cy+(path_width-1) do
							world[iz][iy][ix] = " "
						end
					end
				end
                -- world[cz + 1][cy][cx] = " "
                -- world[cz + 2][cy][cx] = " "
                cz = cz + path_length
            elseif curdir == "-" then
				for iz = cz-path_length,cz do
					for ix = cx,cx+(path_width-1) do
						for iy = cy,cy+(path_width-1) do
							world[iz][iy][ix] = " "
						end
					end
				end
                -- world[cz - 1][cy][cx] = " "
                -- world[cz - 2][cy][cx] = " "
                cz = cz - path_length
            elseif curdir == "u" then
				for iz = cz,cz+(path_depth-1) do
	                for ix = cx,cx+(path_width-1) do
	                    for iy = cy-path_length,cy do
	                        world[iz][iy][ix] = " "
	                    end
	                end
				end
				-- world[cz][cy - 1][cx] = " "
				-- world[cz][cy - 2][cx] = " "
				cy = cy - path_length
			elseif curdir == "d" then
				for iz = cz,cz+(path_depth-1) do
	                for ix = cx,cx+(path_width-1) do
	                    for iy = cy,cy+path_length+(path_width-1) do
	                        world[iz][iy][ix] = " "
							-- print("[tunnel/d] ("..ix..", "..iy..", "..iz..")")
	                    end
	                end
				end
				-- world[cz][cy + 1][cx] = " "
				-- world[cz][cy + 2][cx] = " "
				cy = cy + path_length
			elseif curdir == "l" then
				for iz = cz,cz+(path_depth-1) do
	                for iy = cy,cy+(path_width-1) do
	                    for ix = cx-path_length,cx do
	                        world[iz][iy][ix] = " "
	                    end
	                end
				end
				-- world[cz][cy][cx - 1] = " "
				-- world[cz][cy][cx - 2] = " "
				cx = cx - path_length
			elseif curdir == "r" then
				for iz = cz,cz+(path_depth-1) do
	                for iy = cy,cy+(path_width-1) do
	                    for ix = cx,cx+path_length+(path_width-1) do
	                        world[iz][iy][ix] = " "
	                    end
	                end
				end
				-- world[cz][cy][cx + 1] = " "
				-- world[cz][cy][cx + 2] = " "
				cx = cx + path_length
			end
            
			table.insert(nodes, { x = cx, y = cy, z = cz })
		else
			table.remove(nodes, curnode)
		end
		
		if #directions == 0 or shift_attention <= 1 then
			if #nodes > 0 then
				curnode = math.random(1, #nodes)
				
				cx = nodes[curnode]["x"]
				cy = nodes[curnode]["y"]
                cz = nodes[curnode]["z"]
			end
		end
	end
	
	-- WARNING: os.clock() isn't accurate, because it gives the total **CPU time**, not **real time**!
	local 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.")