-------------------------------------
-- Maze generation script
-------------------------------------
-- A test by @Starbeamrainbowlabs

local M = {}

-- Intelligent table printing function: http://coronalabs.com/blog/2014/09/02/tutorial-printing-table-contents/

-- 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

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

-- Initialise the world

function M.generate_maze(seed, width, height, path_length, path_width)
	start_time = os.clock()
	
    if not path_length then path_length = 2 end
    if not path_width then path_width = 1 end
    
	-- minetest.log("action", "width: "..width..", height: "..height)
	math.randomseed(seed) -- seed the random number generator with the system clock

	width = width - 1
	height = height - 1

	local world = {}
	for y = 0, height, 1 do
		world[y] = {}
		for x = 0, width, 1 do
			world[y][x] = "#"
		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 = 1, 1 -- our current position
	table.insert(nodes, { x = cx, y = cy })
	world[cy][cx] = " "
	while #nodes > 0 do
		-- io.write("Nodes left: " .. curnode .. "\r")
		--print("Nodes left: " .. #nodes)
		-- print("Currently at (" .. cx .. ", " .. cy .. "), up: "..(cy-path_length)..", down: "..cy+path_length..", left: "..cx-path_length..", right: "..cx+path_length..", width: "..width..", height: "..height)
		
		local directions = "" -- the different directions we can move
		if cy - path_length > 0 and world[cy - path_length][cx] == "#" then
			directions = directions .. "u"
			-- print("up | cy: "..cy..", target: "..cy-path_length..", value: '"..world[cy - path_length][cx].."', path_length: "..path_length)
		end
		if cy + path_length < height and world[cy + path_length][cx] == "#" then
			directions = directions .. "d"
			-- print("down | cy: "..cy..", target: "..cy+path_length..", value: '"..world[cy + path_length][cx].."', path_length: "..path_length)
		end
		if cx - path_length > 0 and world[cy][cx - path_length] == "#" then
			directions = directions .. "l"
			-- print("left | cx: "..cx..", target: "..cx-path_length..", value: '"..world[cy][cx - path_length].."', path_length: "..path_length)
		end
		if cx + path_length < width and world[cy][cx + path_length] == "#" then
			directions = directions .. "r"
			-- print("right | cx: "..cx..", target: "..cx+path_length..", value: '"..world[cy][cx + path_length].."', path_length: "..path_length)
		end
		-- print("radar output: '" .. directions .. "' (length: " .. #directions .. "), curnode: " .. curnode)
		
		local shift_attention = math.random(0, 9)
		
		if #directions > 0 then
			-- we still have somewhere that we can go
			--print("This node is not a dead end yet.")
			local curdirnum = math.random(1, #directions)
			local curdir = string.sub(directions, curdirnum, curdirnum)
			if curdir == "u" then
                for ix = cx,cx+(path_width-1) do
                    for iy = cy-path_length,cy do
                        world[iy][ix] = " "
                    end
                end
				-- world[cy - 1][cx] = " "
				-- world[cy - 2][cx] = " "
				cy = cy - path_length
			elseif curdir == "d" then
                for ix = cx,cx+path_width-1 do
                    for iy = cy,cy+path_length+(path_width-1) do
                        world[iy][ix] = " "
                    end
                end
				-- world[cy + 1][cx] = " "
				-- world[cy + 2][cx] = " "
				cy = cy + path_length
			elseif curdir == "l" then
                for iy = cy,cy+path_width-1 do
                    for ix = cx-path_length,cx do
                        world[iy][ix] = " "
                    end
                end
				-- world[cy][cx - 1] = " "
				-- world[cy][cx - 2] = " "
				cx = cx - path_length
			elseif curdir == "r" then
                for iy = cy,cy+(path_width-1) do
                    for ix = cx,cx+path_length+(path_width-1) do
                        world[iy][ix] = " "
                    end
                end
				-- world[cy][cx + 1] = " "
				-- world[cy][cx + 2] = " "
				cx = cx + path_length
			end
			
			-- print("Now at ("..cx..", "..cy..")")
			
			-- If the number of directions we could travel in was 1, then we've just travelled in the last remaining direction possible
			if #directions > 1 then
				table.insert(nodes, { x = cx, y = cy })
			end
		else
			--print("The node at " .. curnode .. " is a dead end.")
			table.remove(nodes, curnode)
		end
		
		if #directions == 0 or shift_attention <= 1 then
			if #nodes > 0 then
				--print("performing teleport.");
				curnode = math.random(1, #nodes)
				cx = nodes[curnode]["x"]
				cy = nodes[curnode]["y"]
			end
		end
		
		-- M.printspace(world, width, height)
        -- io.read("*l")
	end
    
	end_time = os.clock()
    
	return world, (end_time - start_time) * 1000
end

-- local world, time   = generate_maze(os.time(), width, height)
-- printspace(world, width, height)
-- print("Generation completed in " .. time .. "s.")

return M