For "HOURS:MINUTES:SECONDS" start-end timestamp pair, return the difference in seconds.

timestamp_delta.py

#!/usr/bin/env python3

# License: MIT. https://github.com/Rainyan

from datetime import datetime
import sys

# Usage:
#   $ python timestamp_delta.py 00:12:34 02:01:13
#   $ 6519


def timestamp_delta(start: str, end: str) -> int:
    """For "HOURS:MINUTES:SECONDS" start-end timestamp pair,
    return the difference in seconds.

    If hours are omitted, assumes 0 hours.
    If hours and minutes are omitted, assumes 0 hours and minutes.
    If end time is earlier than start time, returns a negative difference.
    Max supported timestamp value is 23:59:59.
        TODO: support >23:59:59 times
    """
    start_parts = start.split(":")
    assert len(start_parts) > 0
    assert len(start_parts) <= 4
    start_parts = ["0"] * (abs(len(start_parts) - 3)) + start_parts
    assert int(start_parts[0]) < 24, "Max supported timestamp value is 23:59:59."
    start = ":".join(start_parts)

    end_parts = end.split(":")
    assert len(end_parts) > 0
    assert len(end_parts) <= 4
    end_parts = ["0"] * (abs(len(end_parts) - 3)) + end_parts
    assert int(end_parts[0]) < 24, "Max supported timestamp value is 23:59:59."
    end = ":".join(end_parts)

    format = "%H:%M:%S"
    time_start = datetime.strptime(start, format)
    time_end = datetime.strptime(end, format)

    if time_end > time_start:
        return (time_end - time_start).seconds
    return -(time_start - time_end).seconds


if __name__ == "__main__":
    print(timestamp_delta(sys.argv[1], sys.argv[2]))