replace "created" date in dokuwiki meta files with the date, derived from the file (page) name

dokuwiki_date_from_filename.py

#!/usr/bin/python3

'''In dokuwiki metadata is stored in separate files, such as data/meta[/namespace]/[...]/page_name.meta
   It is critical for blog plugin to have correct "created" timestamp for individual entries (files)
   as this determines the order the entries appear on summary page. This scirpt helps to 'restore' the
   "created" timestamp in metafiles in case a metafile created anew by dokuwiki. This migh happen if
   for some reason meta file were lost or didn't exist at all (e.g. the blog files were imported from
   other app, such as vimwiki)."created" - is a tagname in dokuwiki meta files.
   The script searches through meta files in dokuwiki data folder and replaces timestamp with
   new one, generated from the date of the file, which is encoded in file name prefix of YYYY-DD-MM format.
   ASSUMPTIONS:
    - dokuwiki 'blog' plugin is installed;
    - dokuwiki plugin.blog.dateprefix = %Y:%Y-%m-%d (i.e. filenames have YYYY-DD-MM prefix. Remember, git do 
      not stores ctime!)
    NOTES:
    - page (or blog entry) files are not always accompanied by designated meta file. This is the case if files
      are created outside of dokuwiki php eninge (restorded from backup or imported)
    - this script will not create new meta files; it will only attempt to amend existing ones.
'''


import os, re
from datetime import datetime
import argparse



parser = argparse.ArgumentParser(description = 'search through files in dokuwiki data folder and replace timestamp with new one')
parser.add_argument('-m','--meta-dir', type=str, dest='meta_dir', required=True,
        help='root directory for metadata files')
parser.add_argument('-n','--dry-run', action='store_const', const=True, dest='dry_run',
        help='do not modify files')

args = parser.parse_args()

re_metafile = re.compile(r'.*\.meta$')
re_timestamp = re.compile(r'(?<=i:)\d{8,}(?=;)', flags=re.MULTILINE)
re_timestamp_created = re.compile(r'(?<="created";i:)\d{8,}(?=;)', flags=re.MULTILINE)


def date_from_filename(fl_name):
    return datetime.strptime(fl_name[:10], '%Y-%m-%d')

def inplace_sub_time(fl_meta_path, new_time):
    with open(fl_meta_path, 'r') as fl_meta:
        fl_content = fl_meta.read()
    #
    fl_content, n_matches = re.subn(rf'("created";i:)\d+',rf'\1{new_time}',fl_content,flags=re.MULTILINE)
    if not n_matches:
        return False
    #
    with open(fl_meta_path, 'w') as fl_meta:
        fl_meta.write(fl_content)
        return True

for root,dirs,files in os.walk(args.meta_dir):
    for fl_name in files:
        if not re_metafile.match(fl_name):
            continue
        try:
            fl_date = date_from_filename(fl_name)
            fl_timestamp = str(int(fl_date.timestamp()))
        except ValueError:
            continue

        fl_path = os.path.join(root, fl_name)
        with open(fl_path, 'r') as fl:
            fl_data = fl.read()

        #first attempt to find and replace timestamp for "created" key.
        # Do not replace the values immediately to avoid unnecessary
        # re-writing of meta files
        t_stamps = set(re.findall(re_timestamp_created, fl_data))
        if len(t_stamps) > 0:
            if fl_timestamp in t_stamps:
                continue
            fl_data = re.sub(re_timestamp_created, fl_timestamp, fl_data, re.MULTILINE)
        #in some cases "created" key is absent in metadata file. Try to find
        # and amend "modified" value then
        else:
            t_stamps = set(re.findall(re_timestamp, fl_data))
            if len(t_stamps) == 0 or (fl_timestamp in t_stamps):
                continue
            fl_data = re.sub(rf'{min(t_stamps)}',fl_timestamp, fl_data, re.MULTILINE)

        if not args.dry_run:
            with open(fl_path, 'w') as fl:
                fl.write(fl_data)
        print(fl_path + '\n  replace timestamp ' + min(t_stamps) + ' with '+fl_timestamp)