TRIGGER - Arrows

[leissaK]

On my map I am going to have an item for arrows. When you buy it you have x amount of arrows. Every time you attack you use an arrow and x's quantity is decreased by 1. When you have no arrows in your inventory you cannot attack. I know how to make the arrow part but I don't know how to make it so you cant attack when you dont got any. Maybe a spell is required? Well, I don't know. Someone who can help, please make it so I can change the item type (since I will use different arrows [wood, platinum, etc.]) I would also like it to have it so you can change the character condition.

I would greatly appreciate any help. Thanks.