build_release_body.py

#!/usr/bin/env python3
"""
Build GitHub release notes: ChangeLog block for a semver (no "v" prefix) plus
GitHub auto-generated compare notes, written to a path for action-gh-release.
"""
from __future__ import annotations

import json
import os
import re
import sys
import urllib.error
import urllib.request


def extract_changelog_block(changelog: str, version: str) -> str:
    """Return lines from "Version {version}..." until the next long-dash separator."""
    if not version or not re.match(r"^[\d.]+$", version):
        return ""
    lines = changelog.splitlines()
    ver_re = re.compile(rf"^Version {re.escape(version)}[,\s(].*$")
    start_idx: int | None = None
    for i, line in enumerate(lines):
        if ver_re.match(line):
            start_idx = i
            break
    if start_idx is None:
        return ""
    sep = re.compile(r"^[-]{20,}\s*$")
    out: list[str] = []
    for j in range(start_idx, len(lines)):
        line = lines[j]
        if j > start_idx and sep.match(line):
            break
        out.append(line)
    return "\n".join(out) + "\n" if out else ""


def fetch_generated_notes(
    repository: str, tag_name: str, target_commitish: str, token: str
) -> str:
    """Call POST /repos/{owner}/{repo}/releases/generate-notes."""
    url = f"https://api.github.com/repos/{repository}/releases/generate-notes"
    payload = {
        "tag_name": tag_name,
        "target_commitish": target_commitish,
    }
    data = json.dumps(payload).encode("utf-8")
    req = urllib.request.Request(
        url,
        data=data,
        method="POST",
        headers={
            "Accept": "application/vnd.github+json",
            "X-GitHub-Api-Version": "2022-11-28",
            "Authorization": f"Bearer {token}",
            "User-Agent": "loganalyzer-release-workflow",
        },
    )
    try:
        with urllib.request.urlopen(req, timeout=120) as resp:
            body = json.loads(resp.read().decode("utf-8"))
    except (urllib.error.HTTPError, urllib.error.URLError) as e:
        return f"_Could not generate auto-release notes: {e}_\n"
    return (body or {}).get("body") or "_No body returned from GitHub._\n"


def main() -> int:
    if len(sys.argv) != 2:
        print("Usage: build_release_body.py <output.md>", file=sys.stderr)
        return 1
    out_path = sys.argv[1]

    tag_name = os.environ.get("GITHUB_REF_NAME", "")
    if not tag_name or not tag_name.startswith("v"):
        print("GITHUB_REF_NAME must be a v-prefixed tag (e.g. v4.1.13)", file=sys.stderr)
        return 1
    raw_ver = tag_name[1:]
    m = re.match(r"^([\d.]+)(?:[-+].*)?$", raw_ver)
    version = m.group(1) if m else raw_ver
    if not re.match(r"^[\d.]+$", version):
        print("Could not parse semver from tag; expected vX.Y.Z[qualifiers]", file=sys.stderr)
        return 1

    repo = os.environ.get("GITHUB_REPOSITORY", "")
    sha = os.environ.get("GITHUB_SHA", "")
    token = os.environ.get("GITHUB_TOKEN", "")
    if not repo or not sha or not token:
        print("Missing GITHUB_REPOSITORY, GITHUB_SHA, or GITHUB_TOKEN", file=sys.stderr)
        return 1

    cl_path = os.path.join(os.path.dirname(__file__), "..", "..", "ChangeLog")
    cl_path = os.path.normpath(cl_path)
    changelog_text = ""
    if os.path.isfile(cl_path):
        with open(cl_path, encoding="utf-8", errors="replace") as f:
            changelog_text = f.read()
    cl_block = extract_changelog_block(changelog_text, version)
    if not cl_block:
        cl_block = (
            f"_No matching **Version {version}** block in `ChangeLog`. "
            "Add one before publishing this tag, or read the full file in the source tree._\n\n"
        )

    auto = fetch_generated_notes(repo, tag_name, sha, token)

    body = f"""## Change log (from repository `ChangeLog`)

{cl_block}
---

## Commits and pull requests (auto-generated by GitHub)

{auto}"""
    with open(out_path, "w", encoding="utf-8", newline="\n") as f:
        f.write(body)
    return 0


if __name__ == "__main__":
    raise SystemExit(main())