add exif-adjust-timestamp helper

#!/usr/bin/env python3

# vim:tabstop=4 softtabstop=4 shiftwidth=4 textwidth=160 smarttab expandtab colorcolumn=160

#

# Copyright (C) 2025 Birte Kristina Friesel

#

# SPDX-License-Identifier: BSD-2-Clause

from datetime import datetime, timedelta

import argparse

import json

import subprocess

import sys

if __name__ == "__main__":

    parser = argparse.ArgumentParser(

        formatter_class=argparse.RawDescriptionHelpFormatter, description=__doc__

    )

    parser.add_argument("delta", type=int, help="Time delta [minutes]")

    parser.add_argument("images", type=str, nargs="+")

    args = parser.parse_args()

    delta = timedelta(minutes=args.delta)

    for filename in args.images:

        data = dict()

        try:

            exiftool = subprocess.run(

                [

                    "exiftool",

                    "-json",

                    "-d",

                    "%s",

                    "-escapeHTML",

                    "-groupNames",

                    filename,

                ],

                stdout=subprocess.PIPE,

                text=True,

            )

            if exiftool.returncode == 0:

                data = json.loads(exiftool.stdout)[0]

        except FileNotFoundError:

            pass

        old_timestamp = datetime.fromtimestamp(int(data["EXIF:DateTimeOriginal"]))

        new_timestamp = old_timestamp + delta

        print(f"{filename} : {old_timestamp} → {new_timestamp}")

        exiftool_cmd = [

            "exiftool",

            "-P",

            "-EXIF:DateTimeOriginal=" + str(new_timestamp),

            filename,

        ]

        try:

            subprocess.run(

                exiftool_cmd,

                stdout=subprocess.PIPE,

                stderr=subprocess.PIPE,

                text=True,

            )

        except subprocess.CalledProcessError as e:

            print(

                f"Cannot to write exif tags for {filename}: {exiftool_cmd} returned {e.returncode}"

            )

            print(f"exiftool stdout:\n{e.stdout}\n")

            print(f"exiftool stderr:\n{e.stdout}\n")