calculate hours between then and now

hourlapse.py

#! /usr/bin/env python3
import argparse
import datetime
import math
import sys


DEFAULT_FORMAT = r"%Y-%m-%d %H:%M"


def main():
    parser = argparse.ArgumentParser(
        prog="hourlapse", description="Calculate hours between then and now."
    )
    parser.add_argument(
        "then", type=str, help="date and time as " + DEFAULT_FORMAT.replace(r"%", "%%")
    )
    parser.add_argument(
        "-f",
        "--format",
        type=str,
        required=False,
        default=DEFAULT_FORMAT,
        dest="format",
        help="format of then using strptime format codes",
    )
    args = parser.parse_args()
    then = datetime.datetime.strptime(args.then, args.format)
    now = datetime.datetime.now()
    now = now.replace(second=0, microsecond=0)
    delta = now - then
    hourlapse = round(delta.total_seconds() / 3600, 1)
    print(f"{hourlapse:.1f} {'hour' if math.isclose(abs(hourlapse), 1.0) else 'hours'}")
    return 0


if __name__ == "__main__":
    sys.exit(main())