local on_leaves = {} -- functions(name)
local timeout = 5 -- seconds
xmaps.dynamic_add_media_all = function(path, on_all_received)
	if not minetest.features.dynamic_add_media_table then
		-- minetest.dynamic_add_media() blocks in
		-- Minetest 5.3 and 5.4 until media loads
		minetest.dynamic_add_media(path, function() end)
		on_all_received()
		return
	end
	-- minetest.dynamic_add_media() never blocks
	-- in Minetest 5.5, callback runs *for each client*
	-- who has received & loaded the media
	-- all players currently online must still receive it
	local to_receive = {}
	for _, player in pairs(minetest.get_connected_players()) do
		local name = player:get_player_name()
		-- Only clients with protocol version >= 39 can receive dynamic media.
		if minetest.get_player_information(name).protocol_version >= 39 then
			to_receive[name] = true
		end
	end
	local function remove_to_receive(name)
		to_receive[name] = nil
		if next(to_receive) == nil then
			on_leaves[remove_to_receive] = nil
			on_all_received()
		end
	end
	on_leaves[remove_to_receive] = true
	minetest.dynamic_add_media(
		{filepath = path},
		function(name)
			assert(name)
			if not to_receive[name] then
				minetest.log("warning", ("xmaps: %s received media despite not being connected"):format(name))
				return
			end
			remove_to_receive(name)
		end
	)
	minetest.after(timeout, function()
		if next(to_receive) ~= nil then
			local names = {}
			for name in pairs(to_receive) do
				table.insert(names, name)
			end
			table.sort(names)
			minetest.log("warning", ("xmaps: sending media to %s timed out"):format(table.concat(names, ", ")))
		end
		on_leaves[remove_to_receive] = nil
		on_all_received()
	end)
end

minetest.register_on_leaveplayer(
	function(player)
		local player_name = player:get_player_name()
		for on_leave in pairs(on_leaves) do
			on_leave(player_name)
		end
	end
)