MoreMesecons/moremesecons_teleporter/init.lua

local teleporters = {}
local teleporters_rids = {}


local register = function(pos)
	if not vector.get_data_from_pos(teleporters_rids, pos.z,pos.y,pos.x) then
		table.insert(teleporters, pos)
		vector.set_data_to_pos(teleporters_rids, pos.z,pos.y,pos.x, #teleporters)
	end
end

local teleport_nearest = function(pos)
	local MAX_TELEPORTATION_DISTANCE = 50
	local MAX_PLAYER_DISTANCE = 25

	-- Search the nearest player
	local nearest = nil
	local min_distance = MAX_PLAYER_DISTANCE
	local players = minetest.get_connected_players()
	for index, player in pairs(players) do
		local distance = vector.distance(pos, player:getpos())
		if distance < min_distance then
			min_distance = distance
			nearest = player
		end
	end

	if not nearest then
		-- If there is no nearest player (maybe too far...)
		return
	end

	-- Search other teleporter and teleport
	if not minetest.registered_nodes["moremesecons_teleporter:teleporter"] then return end

	local newpos = {}
	for i = 1, #teleporters do
		if minetest.get_node(teleporters[i]).name == "moremesecons_teleporter:teleporter" then
			if teleporters[i].y == pos.y and teleporters[i].x == pos.x and teleporters[i].z ~= pos.z then
				newpos = {x=teleporters[i].x, y=teleporters[i].y+1, z=teleporters[i].z}
			elseif teleporters[i].z == pos.z and teleporters[i].x == pos.x and teleporters[i].y ~= pos.y then
				newpos = {x=teleporters[i].x, y=teleporters[i].y+1, z=teleporters[i].z}
			elseif teleporters[i].z == pos.z and teleporters[i].y == pos.y and teleporters[i].x ~= pos.x then
				newpos = {x=teleporters[i].x, y=teleporters[i].y+1, z=teleporters[i].z}
			end
		end
	end
	if newpos.x then
		-- If there is another teleporter BUT too far, delete newpos.
		if vector.distance(newpos, pos) > MAX_TELEPORTATION_DISTANCE then
			newpos = {}
		end
	end
	if not newpos.x then
		newpos = {x=pos.x, y=pos.y+1, z=pos.z} -- If newpos doesn't exist, teleport on the actual teleporter.
	end
	nearest:moveto(newpos)
	minetest.log("action", "Player "..nearest:get_player_name().." was teleport with a MoreMesecons Teleporter.")
end

minetest.register_craft({
	output = "moremesecons_teleporter:teleporter 2",
	recipe = {{"default:diamond","default:stick","default:mese"}}
})
minetest.register_node("moremesecons_teleporter:teleporter", {
	tiles = {"moremesecons_teleporter.png"},
	paramtype = "light",
	walkable = true,
	groups = {cracky=3},
	description="Teleporter",
	mesecons = {effector = {
		state = mesecon.state.off,
		action_on = teleport_nearest
	}},
	sounds = default.node_sound_stone_defaults(),
	on_construct = register,
	on_destruct = function(pos)
		local RID = vector.get_data_from_pos(teleporters_rids, pos.z,pos.y,pos.x)
		if RID then
			table.remove(teleporters, RID)
			vector.remove_data_from_pos(teleporters_rids, pos.z,pos.y,pos.x)
		end
	end,
})


minetest.register_lbm({
	name = "moremesecons_teleporter:add_teleporter",
	nodenames = {"moremesecons_teleporter:teleporter"},
	action = register
})