make a nested file from a flat file data

Question

I am newbie for coding and I looking for simple solution for conversaton of the flat file (4 columns) like

A-data//A-ID//B-data//B-ID sample1//123//sample2//456

where A-ID have a direct connection to the B-ID (like a directed graph A => B).

I need to make the new flat file according to the algorithm:

• if the B-ID (row1) matches A-ID of the row2 ((A+1)-ID)) make new row where A-data//A-ID//B-data//B-ID//(A+1)-data//(A+1)-ID

• then compare B-ID (row1) with A-ID of the row3 and etc until end of the table or until zero matches

• nesting (A-B-C-D...) should be limited to the 6 members

Seems simple for oldies but difficult for me, so any help is appreciated...