last.fm incremental import

newest to oldest

psuedo code - last.fm import js:

get last import date from server
for page in all_scrobbles:
    store newest scrobble date in the list
    send page
    if earliest item in page < last import date:
        stop submitting
submit 'last import date' to server, which is the date of the most recent scrobble (or now)

oldest to newest

psuedo code - last.fm import js:

get last import date from server
get total number of pages in all scrobbles
do some sort of binary search to find the page which contains the last imported item

for page in all_scrobbles, reversed from the page which we found:
    submit page
    [sever] stores most recent date in this submission as last import date

-> client doesn't need to submit last import date, can be stopped and restarted at any time