Limited Ammo? Help

Hello, I asked more than once this and I did not get any response, How would you do in this script c # so that when TotalAmmo is 0 you can not shoot ?, but if it is GREATER than 0 reload and keep firing. Please.
Thank you

maybe this helps you:

    public int ammo;
    public int reloadtime;
    private int currenttime;
    public int fullammo;
	
    void Start ()
    {
        currenttime = reloadtime;
    }

	void FixedUpdate ()
    {
        if(ammo == 0)
        {
            currenttime = -1;
        }
        if (currenttime == 0)
        {
            ammo = fullammo;
            currenttime = reloadtime;
        }
	}
}

your fullammo is your ammo you want to have when you reloaded. Ammo is your current ammo thats left. Just decrease ammo by 1 every time you shoot