update_readme_changelog.py

#!/usr/bin/env python3

from __future__ import annotations

import re
import sys
from pathlib import Path

PROJECT_ROOT = Path(__file__).parent / ".."
CHANGELOG_FILE = PROJECT_ROOT / "docs" / "changelog.md"
README_FILE = PROJECT_ROOT / "README.md"

# https://regexr.com/622ds
FIRST_5_CHANGELOG_ENTRIES_REGEX = re.compile(r"""(^###.*?(?=###)){5}""", re.DOTALL | re.MULTILINE)

# https://regexr.com/622e5
README_CHANGELOG_SECTION = re.compile(
    r"""(?<=<!-- START bin\/update_readme_changelog.py -->\n).*(?=<!-- END bin\/update_readme_changelog.py -->)""",
    re.DOTALL,
)


def main():
    changelog_text = CHANGELOG_FILE.read_text()
    readme_text = README_FILE.read_text()

    mini_changelog_match = FIRST_5_CHANGELOG_ENTRIES_REGEX.search(changelog_text)
    assert mini_changelog_match, "Failed to find the first few changelog entries"

    mini_changelog = "\n".join(
        [
            "",
            "<!-- this section was generated by bin/update_readme_changelog.py -- do not edit manually -->",
            "",
            mini_changelog_match.group(0).strip(),
            "",
            "",
        ]
    )

    if not re.search(README_CHANGELOG_SECTION, readme_text):
        sys.exit("Changelog section not found in README")

    readme_text = re.sub(README_CHANGELOG_SECTION, mini_changelog, readme_text)
    README_FILE.write_text(readme_text)


if __name__ == "__main__":
    main()