import structio


async def main(n):
    print(f"[main] Starting sliding timer with timeout {n}")
    i = structio.clock()
    with structio.skip_after(2) as scope:
        while n:
            # This looks weird, but it allows us to
            # handle floating point values (basically
            # if n equals say, 7.5, then this loop will
            # sleep 7.5 seconds instead of 8), which would
            # otherwise cause this loop to run forever and
            # the deadline to shift indefinitely into the
            # future (because n would never reach zero, getting
            # immediately negative instead)
            shift = min(n, 1)
            print(f"[main] Waiting {shift:.2f} second{'' if shift == 1 else 's'}")
            await structio.sleep(shift)
            print(f"[main] Shifting deadline")
            # Updating the scope's timeout causes
            # its deadline to shift accordingly!
            scope.timeout += shift
            n -= shift
        print("[main] Deadline shifting complete")
    # Should take about n seconds to run, because we shift
    # the deadline of the cancellation n times and wait at most
    # 1 second after every shift
    print(f"[main] Exited in {structio.clock() - i:.2f} seconds")


structio.run(main, 7.5)