library Grind {
    include "cj_types_priv.j";

    define private ABILITY = 'A000';

    private struct list { int a, b = 0; };

    private list All, Last;

    callback onInit() {
        All = list.create();
        Last = All;
    }

    public list Create() {
        list l = Last;
        l.a = list.create();
        l.b = list.create();
        Last = l.b;
        return l.a;
    }

    public void Add(list l, int id) {
        whilenot l.b == 0 { l = l.b; }
        l.a = id;
        l.b = list.create();
    }

    callback onUnitSpellEffect(ABILITY) {
        item it = GetSpellTargetItem();
        int id = GetItemTypeId(it);
        for (list l = All; l.b != 0; l = l.b) {
            list l2 = l.a;
            loop {
                if id == l2.a {
                    if list(l2.b).b != 0 {
                        RemoveItem(it);
                        UnitAddItemById(GetTriggerUnit(), list(l2.b).a);
                    }
                    return;
                }
                exitwhen l2.b == 0;
                l2 = l2.b;
            }
        }
        id = GetItemCharges(it)
        if id > 0 { SetItemCharges(it, id + 1); }
    }
}