Automatic "updated" dates

Feature requests
2

I asked for similiar things before (but with file’s metadata instead of git).

Currently I use the following pre-commit hook:

#!/usr/bin/env python3
import os
import subprocess
from datetime import datetime

updated_files = subprocess.run(['git', 'diff', '--name-only', '--cached'], stdout=subprocess.PIPE).stdout.decode('utf-8').strip()
updated_file_list = (f.strip() for f in updated_files.split("\n") if f.strip().endswith("index.md"))
for updated_file_name in updated_file_list:
    with open(updated_file_name, "r") as f:
        content = f.read()
    temp = content.split('+++', 2)
    frontmatter = temp[1]
    text_content = temp[2]
    # "parsing" toml manually to avoid introducing dependency
    items = frontmatter.split('\n')
    date_index = None
    update_index = None
    autoupdate = True
    template_index = 0
    for (index, item) in enumerate(items):
        if item.startswith("template"):
            # we'll insert the new created toml item after `template`
            template_index = index
        if item.startswith("date"):
            date_index = index
        if item.startswith("updated"):
            update_index = index
        if item.startswith("no_auto_update") and item.split("=")[1].strip(" ") != "false":
            autoupdate = False
    if autoupdate:
        version_count = int(subprocess.run(['git', 'rev-list', 'HEAD', '--count', '--', updated_file_name], stdout=subprocess.PIPE).stdout.decode('utf-8').strip())
        if version_count == 0:
            # new created file, insert created datetime if necessary
            if date_index is None:
                items.insert(template_index + 1, "date = {}".format(datetime.now().strftime("%Y-%m-%dT%H:%M:%S.000Z")))
        else:
            # updated file, update the updated datetime if necessary
            if update_index is None:
                items.insert(template_index + 1, "update = {}".format(datetime.now().strftime("%Y-%m-%dT%H:%M:%S.000Z")))
            else:
                items[update_index] = "update = {}".format(datetime.now().strftime("%Y-%m-%dT%H:%M:%S.000Z"))
        new_frontmatter = "\n".join(items)
        new_content = "+++\n" + new_frontmatter.strip("\n") + "\n+++" + text_content
        with open(updated_file_name, "w") as f:
            f.write(new_content)
        # re-add the updated file
        subprocess.run(['git', 'add', updated_file_name])