older-than

#!/usr/bin/env python3
# Author: github.com/danielhoherd
# License: MIT
# Purpose: Return 0 if referenced file is older than the given time
#
# The idea for this was taken from <https://blog.afoolishmanifesto.com/posts/unreliable-cronjobs/>
import argparse
import datetime
import re
import sys
from pathlib import Path

time_units = {
    "s": 1,
    "m": 60,
    "h": 3600,
    "d": 86400,
}


def get_unix_mtime_of_file(file: str) -> int:
    """Return the mtime of the given file as a unix timestamp.

    Exit 0 on missing file.
    """
    file = Path(file)
    try:
        age = int(file.lstat().st_mtime)
    except FileNotFoundError:
        print(f"File not found: {file}")
        sys.exit(0)
    return age


def parse_timespec(spec: str) -> int:
    """Return the number of seconds the timespec represents."""
    pattern = re.compile("([0-9]+)([smhd])")
    try:
        num, unit = pattern.match(spec).groups()
    except AttributeError:
        sys.exit("There was an error matching the timespec. Check your formatting. Units must be one of: s, m, h, d")
    return int(num) * int(time_units[unit])


def main(file: str, timespec: str, verbose: bool) -> None:
    """Exit 0 if the referenced file is older than timespec."""

    file_time = get_unix_mtime_of_file(file)
    age_limit = parse_timespec(timespec)
    now = int(datetime.datetime.now().strftime("%s"))
    diff = now - file_time - age_limit

    if diff > 0:
        if verbose:
            print(f"{diff} seconds past")
        sys.exit(0)
    else:
        if verbose:
            print(f"{-diff} seconds left to go")
        sys.exit(1)


parser = argparse.ArgumentParser()
parser.add_argument("-f", "--file", help="Filename to reference", type=str, required=True)
parser.add_argument("-v", "--verbose", help="Be verbose", default=False, action="store_true")
parser.add_argument(
    "-t",
    "--timespec",
    help="Timespec to measure against in seconds, minutes, hours or days (eg: 5m, 1h, 3d)",
    type=str,
    required=True,
)
args = parser.parse_args()

if __name__ == "__main__":
    args = parser.parse_args()
    main(file=args.file, timespec=args.timespec, verbose=args.verbose)