how to cleanup archive based on datetime

Hello,

I know there is a tool `pg_archivecleanup`, but it only accepts wal
filename. What if I want to clean up all archived wal before a
specified datetime?

Though I could check the ctime fo each wal and figure out which to
remove, but it looks like not a elegent way to do this.

Also I tried to parse each wal and compare with the specified datetime
in a binary-search way, but it is based on the fact that every COMMIT
time in wal is sequential, but it looks like not the case..

Hence I wonder what is the best practice for this task?

Thank you in advance!
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Magodo