Converting timetstamp between diffract timezones.

timeconvert.py

import time
from datetime import datetime, timedelta

# pip install pytz is required.
from pytz import timezone
import pytz
import os
import sys
import argparse

__version_info__ = (0, 2, 0)
__version__ = ".".join(map(str, __version_info__))

ALIASES = {
    "KST": "Asia/Seoul"
}


def timezone_type(tz_string: str):
    try:
        tz = timezone(ALIASES.get(tz_string, tz_string))
    except pytz.exceptions.UnknownTimeZoneError:
        raise argparse.ArgumentTypeError(f"Unknown Timezone: {tz_string}")
    return tz

class PrintAndReturnAction(argparse.Action):
    def __init__(self,
                 option_strings,
                 dest,
                 help=None,
                 metavar=None):
        super().__init__(
            option_strings=option_strings,
            dest=dest,
            nargs=0,
            const=True,
            default=None,
            required=False,
            help=help)
    def __call__(self, parser, namespace, values, option_string=None):
        for tz in pytz.all_timezones:
            print(f"{tz}")
        parser.exit()


def get_options(argv: list) -> argparse.Namespace:
    default_timeformat = "%Y-%m-%d %H:%M:%S"
    parser = argparse.ArgumentParser(prog="timeconvert")
    parser.add_argument(
        "-v", "--version", action="version", version=f"%(prog)s {__version__}"
    )
    parser.add_argument("--list-tz", action=PrintAndReturnAction, help="Print all timezones")
    parser.add_argument("--print-epoch", action='store_true', help="Print epochtime")
    parser.add_argument(
        "--format",
        type=str,
        default=default_timeformat,
        help="TimeFormat for timestamp argument, default: %(default)s",
    )
    parser.add_argument(
        "timestamp",
        type=str,
        help="Timstamp string transfer to other timezone"
    )
    parser.add_argument("origin_tz", type=timezone_type, help="Origin timezone for timestamp, 'now/NOW' is supported")
    parser.add_argument("target_tz", type=timezone_type, nargs='+', help="Target timezone for timestamp")

    options, argv = parser.parse_known_args(argv)

    try:
        if options.timestamp.upper() == 'NOW':
            options.timestamp = datetime.now(options.origin_tz)
        else:
            dt = datetime.strptime(options.timestamp, options.format)
            options.timestamp = options.origin_tz.localize(dt)
    except Exception as e:
        print(e)
        raise SystemExit()

    return options


def main():
    UTC = timezone("UTC")
    options = get_options(sys.argv[1:])

    print(f"{str(options.origin_tz):<20}: {options.timestamp.strftime(options.format)}")
    for target in options.target_tz:
        target_dt = options.timestamp.astimezone(target)
        print(f"{str(target):<20}: {target_dt.strftime(options.format)}")

    if options.print_epoch:
        print(f"{'epoch':<20}: {options.timestamp.astimezone(UTC).timestamp()}")


if __name__ == "__main__":
    main()