dropped item scanner need help

hello, I want to make a plugin were a player can define a certain chest as a scanner (with a chat command). That chest is suppose to scan any dropped items next to it, and if that item is the same as the first slot in the chest, then it adds it to the next slot, and then, the chest powers any red stone next to it.

The only part I am not sure how to do, is how do i scan for item ids next to the scanner, and how would i collect them.

Any help would be appreciated (like a function for getting the ids of the items next to scanner).
Thank you.