#!/usr/bin/python3

"""
This helper script will set the modify date (mtime) of a selected file.
Copyright (C) 2024  Benjamin Burkhardt

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <https://www.gnu.org/licenses/>.
"""

"""

Useful links:
- https://docs.python.org/3/library/argparse.html#argparse-type
- https://docs.python.org/3/library/datetime.html
- https://www.tutorialspoint.com/How-to-get-file-creation-and-modification-date-times-in-Python
- https://docs.python.org/3/library/os.html#os.utime
- https://de.wikipedia.org/wiki/Modification,_Access,_Change
- https://en.wikipedia.org/wiki/Unit_prefix

"""

import argparse
import datetime
import os


class COLORS:
    HEADER = '\033[95m'
    OKBLUE = '\033[94m'
    OKCYAN = '\033[96m'
    OKGREEN = '\033[92m'
    WARNING = '\033[93m'
    FAIL = '\033[91m'
    ENDC = '\033[0m'
    BOLD = '\033[1m'
    UNDERLINE = '\033[4m'

class LOGGER:
    def __init__(self, verbose: bool = False):
        self.verbose = verbose

    def log(self,  to_log, verbose=False, end="\n"):
        to_log = to_log + COLORS.ENDC
        if (self.verbose and verbose) or not verbose:  # only print if it's not verbose or verbose is enabled
            print(to_log, end=end)

# set up the ArgumentParser for the CLI
parser = argparse.ArgumentParser(
    description='modify_mtime.py  Copyright (C) 2024  Benjamin Burkhardt\r\n'
                'This program comes with ABSOLUTELY NO WARRANTY and is licensed under the '
                'GNU General Public License 3.\r\n'
                'You should have received a copy of the GNU General Public License\r\n'
                'along with this program. If not, see <https://www.gnu.org/licenses/>.\r\n'
                '\r\n'
                'This helper script will set the modify date (mtime) of a selected file.\r\n'
                'The time arguments shall be given as positive or negative integers.\r\n'
                'BE AWARE THAT ALL CHANGES TO THE FILES CANNOT BE UNDONE! USE AT YOUR OWN RISK!',
    epilog='by Benjamin Burkhardt, 2024',
    add_help=False,
    formatter_class=argparse.RawTextHelpFormatter)

parser.add_argument('-f', '--file', type=str, default='')
parser.add_argument('-mus', '--microsecond', type=int, default=0)
parser.add_argument('-ms', '--millisecond', type=int, default=0)
parser.add_argument('-s', '--second', type=int, default=0)
parser.add_argument('-m', '--minute', type=int, default=0)
parser.add_argument('-h', '--hour', type=int, default=0)
parser.add_argument('-d', '--day', type=int, default=0, help='REQUIRED')
parser.add_argument('-mo', '--month', type=int, default=0, help='REQUIRED')
parser.add_argument('-y', '--year', type=int, default=0, help='REQUIRED')
parser.add_argument('-v', '--verbose', action='store_true', help='enable verbose output')  # on/off flag
parser.add_argument('--help', action='store_true', help='display this help message and exit')  # on/off flag

# parse given arguments
args = parser.parse_args()

# set up logger
logger = LOGGER(args.verbose)

# print help and exit if prompted to
if args.help:
    parser.print_help()
    exit(0)

# check for an empty filename argument
if args.file == '':
    logger.log(COLORS.FAIL + 'You need to specify a filename to set the modification time of it.')
    parser.print_usage()
    exit(1)
    
# check for missing year, month or day args
if args.year == 0 or args.month == 0 or args.day == 0:
    logger.log(COLORS.FAIL + 'You need to give at least the --year, --month and --day arguments!')
    parser.print_usage()
    exit(1)

# create the datetime object with the given date
new_absolute_time = datetime.datetime(year=args.year, month=args.month, day=args.day, hour=args.hour, minute=args.minute, second=args.second, microsecond=args.millisecond*1000+args.microsecond)

# log start of the manipulation process in verbose mode
if args.verbose:
    print(f'[DEBUG] Setting the new mtime')
    
# Now set it! 
atime_timestamp = os.stat(args.file).st_atime  # get atime timestamp (as os.utime requires this as an argument - we leave it unchanged)
mtime_timestamp = new_absolute_time.timestamp()  # get the mtime timestamp from the respective datetime object
os.utime(args.file, (atime_timestamp, mtime_timestamp))  # set the new mtime (atime stays unchanged)