drowning.lua

local function check_player(player, timer)
	local _, armor_inv = armor.get_valid_player(armor, player, "[spacesuit]")
	if not armor_inv then
		-- inventory not found (somehow?), skip check
		return
	end

	local has_helmet = armor_inv:contains_item("armor", "spacesuit:helmet")
	local has_chestplate = armor_inv:contains_item("armor", "spacesuit:chestplate")
	local has_pants = armor_inv:contains_item("armor", "spacesuit:pants")
	local has_boots = armor_inv:contains_item("armor", "spacesuit:boots")

	local has_full_suit = has_helmet and has_chestplate and has_pants and has_boots

	local armor_list = armor_inv:get_list("armor")

	-- does the player wear a suit?
	spacesuit.set_player_wearing(player, has_full_suit, has_helmet, armor_list)

	if has_full_suit and player:get_breath() < 10 then

		for i, stack in pairs(armor_inv:get_list("armor")) do
			if not stack:is_empty() then
				local name = stack:get_name()
				if name:sub(1, 10) == "spacesuit:" then
					local use = minetest.get_item_group(name, "armor_use") * timer or 0
					armor:damage(player, i, stack, use)
				end
			end
		end

		player:set_breath(10)

	elseif not has_full_suit then
		-- check if player is in vacuum without spacesuit
		local is_admin = minetest.check_player_privs(player:get_player_name(), "privs")
		if not is_admin then
			local ppos = player:get_pos()
			local node = minetest.get_node(ppos)
			if node.name == "vacuum:vacuum" then
				-- player does not wear a suit, let him/her suffer!
				local breath = player:get_breath()
				if breath > 0 then
					player:set_breath(math.max(0, player:get_breath() - 4))
				end
				if  breath < 4 then
					player:set_hp( player:get_hp() - 2, "drown" )
				end
			end
		end
	end
end

local timer = 0
minetest.register_globalstep(function(dtime)
	timer = timer + dtime;
	if timer >= 2 then
		for _,player in ipairs(minetest.get_connected_players()) do
			check_player(player, timer)
		end
		timer = 0
	end
end)