Find in range and closest.

[laggyluk]

i think in any case you need to check against all the enemies.
something like this:

indexOfClosest:=-1;
closest:=Infinity;
for i:=0 to length(enemies)-1 do begin
   d:=distance(player,enemies[i]);
   if (d<closest) and (d<=inRange) then begin
      indexOfClosest:=i;
      closest:=d;
   end;
end;