-- (c) jas, wtfpl

local regen = {}
local cooldown = {}

local function regenerate(player)
        local hp = player:get_hp()
        if hp < 100 then
                local name = player:get_player_name()
                if cooldown[name] and cooldown[name] > 0 then
                        cooldown[name] = cooldown[name] - 1
                else
                        cooldown[name] = nil
                        if minetest.check_player_privs(name, "godmode") then
                                player:set_hp(100)
                        else
                                player:set_hp(hp + 2)
                        end
                end
        end
        minetest.after(0.34, regenerate, player)
end

minetest.register_privilege("godmode", {
        give_to_singleplayer = false,
        give_to_admin = false,
})

minetest.register_on_joinplayer(function(player)
        player:set_properties({hp_max = 100})
end)

minetest.register_on_player_hpchange(function(player, hp_change, reason)
        if hp_change > 0 then
                return
        end
        local name = player:get_player_name()
        if minetest.check_player_privs(name, "godmode") then
                return
        end
        cooldown[name] = 10
end)

minetest.register_on_joinplayer(function(player)
        regen[player:get_player_name()] = true
        regenerate(player)
end)

minetest.register_on_leaveplayer(function(player)
        regen[player:get_player_name()] = nil
end)
~