ci: enforce canonical issue metadata policy

scripts/tracker_policy.py

@@ -0,0 +1,135 @@
+#!/usr/bin/env python3
+"""Enforce the repository's issue/PR metadata policy in Gitea Actions."""
+
+from __future__ import annotations
+
+import argparse
+import json
+import os
+import re
+import urllib.error
+import urllib.request
+from pathlib import Path
+from typing import Any
+
+
+ISSUE_REFERENCE = re.compile(
+    r"(?im)\b(?:close[sd]?|fix(?:e[sd])?|resolve[sd]?|part\s+of|"
+    r"related\s+to|refs?|references)\s+#(\d+)\b"
+)
+TRIAGE_LABEL = "Status/Needs Triage"
+
+
+def deliberate_issue_numbers(title: str, body: str) -> set[int]:
+    """Return same-repository issue numbers referenced intentionally."""
+    return {int(match) for match in ISSUE_REFERENCE.findall(f"{title}\n{body}")}
+
+
+class GiteaApi:
+    """Small API client using the Actions-provided repository token."""
+
+    def __init__(self, api_url: str, repository: str, token: str) -> None:
+        self.base = f"{api_url.rstrip('/')}/repos/{repository}"
+        self.token = token
+
+    def request(self, method: str, path: str, payload: object | None = None) -> Any:
+        data = None if payload is None else json.dumps(payload).encode()
+        request = urllib.request.Request(
+            f"{self.base}{path}",
+            data=data,
+            method=method,
+            headers={
+                "Authorization": f"token {self.token}",
+                "Content-Type": "application/json",
+            },
+        )
+        with urllib.request.urlopen(request, timeout=15) as response:
+            if response.status == 204:
+                return None
+            return json.load(response)
+
+
+def check_pull_request(event: dict[str, Any], api: GiteaApi) -> list[str]:
+    """Return policy violations for a pull_request event."""
+    pull = event["pull_request"]
+    errors: list[str] = []
+    labels = pull.get("labels") or []
+    if labels:
+        errors.append(
+            "PRs must be unlabeled; put tracker metadata on the linked issue "
+            f"(found: {', '.join(label['name'] for label in labels)})."
+        )
+
+    numbers = deliberate_issue_numbers(pull.get("title", ""), pull.get("body", ""))
+    if not numbers:
+        errors.append(
+            "PR must reference an issue with Closes/Fixes/Resolves #N, "
+            "Part of #N, Related to #N, Refs #N, or References #N."
+        )
+        return errors
+
+    real_issues = 0
+    for number in sorted(numbers):
+        try:
+            item = api.request("GET", f"/issues/{number}")
+        except urllib.error.HTTPError as error:
+            if error.code == 404:
+                errors.append(f"Referenced issue #{number} does not exist.")
+                continue
+            raise
+        if item.get("pull_request") is not None:
+            errors.append(f"#{number} is a pull request, not an issue.")
+        else:
+            real_issues += 1
+
+    if not real_issues and not errors:
+        errors.append("PR must reference at least one real issue.")
+    return errors
+
+
+def ensure_issue_label(event: dict[str, Any], api: GiteaApi) -> bool:
+    """Apply the triage label if an issue event leaves the issue unlabeled."""
+    issue = event["issue"]
+    if issue.get("pull_request") is not None or issue.get("labels"):
+        return False
+    labels = api.request("GET", "/labels?limit=100")
+    triage = next((label for label in labels if label["name"] == TRIAGE_LABEL), None)
+    if triage is None:
+        raise RuntimeError(f"repository label {TRIAGE_LABEL!r} does not exist")
+    api.request("POST", f"/issues/{issue['number']}/labels", {"labels": [triage["id"]]})
+    return True
+
+
+def _load_event(path: str) -> dict[str, Any]:
+    return json.loads(Path(path).read_text(encoding="utf-8"))
+
+
+def main() -> int:
+    parser = argparse.ArgumentParser()
+    parser.add_argument("command", choices=("check-pr", "label-issue"))
+    parser.add_argument("--event", default=os.environ.get("GITHUB_EVENT_PATH"))
+    args = parser.parse_args()
+    if not args.event:
+        parser.error("--event or GITHUB_EVENT_PATH is required")
+
+    api = GiteaApi(
+        os.environ["GITHUB_API_URL"],
+        os.environ["GITHUB_REPOSITORY"],
+        os.environ["GITHUB_TOKEN"],
+    )
+    event = _load_event(args.event)
+    if args.command == "check-pr":
+        errors = check_pull_request(event, api)
+        if errors:
+            print("\n".join(f"::error::{error}" for error in errors))
+            return 1
+        print("PR tracker policy passed.")
+        return 0
+
+    changed = ensure_issue_label(event, api)
+    print(f"Applied {TRIAGE_LABEL}." if changed else "Issue already has a label.")
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())