labeler: pass Github Action event data to script

This way, the script can take action based on specific events when that
data is available.

hacking/pr_labeler/label.py

@@ -4,11 +4,13 @@
 from __future__ import annotations
 
 import dataclasses
+import json
 import os
 from collections.abc import Collection
+from contextlib import suppress
 from functools import cached_property
 from pathlib import Path
-from typing import Union
+from typing import Any, Union
 
 import github
 import github.Auth
@@ -45,16 +47,30 @@ def get_repo(authed: bool = True) -> tuple[github.Github, github.Repository.Repo
     return gclient, repo
 
 
+def get_event_info() -> dict[str, Any]:
+    event_json = os.environ.get("event_json")
+    if not event_json:
+        return {}
+    with suppress(json.JSONDecodeError):
+        return json.loads(event_json)
+    return {}
+
+
 @dataclasses.dataclass()
 class LabelerCtx:
     client: github.Github
     repo: github.Repository.Repository
     dry_run: bool
+    event_info: dict[str, Any]
 
     @property
     def member(self) -> IssueOrPr:
         raise NotImplementedError
 
+    @property
+    def event_member(self) -> dict[str, Any]:
+        raise NotImplementedError
+
     @cached_property
     def previously_labeled(self) -> frozenset[str]:
         labels: set[str] = set()
@@ -78,6 +94,10 @@ class IssueLabelerCtx(LabelerCtx):
     def member(self) -> IssueOrPr:
         return self.issue
 
+    @property
+    def event_member(self) -> dict[str, Any]:
+        return self.event_info.get("issue", {})
+
 
 @dataclasses.dataclass()
 class PRLabelerCtx(LabelerCtx):
@@ -87,6 +107,10 @@ class PRLabelerCtx(LabelerCtx):
     def member(self) -> IssueOrPr:
         return self.pr
 
+    @property
+    def event_member(self) -> dict[str, Any]:
+        return self.event_info.get("pull_request", {})
+
 
 def create_comment(ctx: IssueOrPrCtx, body: str) -> None:
     if ctx.dry_run:
@@ -167,7 +191,13 @@ def process_pr(
         authed = True
     gclient, repo = get_repo(authed=authed)
     pr = repo.get_pull(pr_number)
-    ctx = PRLabelerCtx(client=gclient, repo=repo, pr=pr, dry_run=dry_run)
+    ctx = PRLabelerCtx(
+        client=gclient,
+        repo=repo,
+        pr=pr,
+        dry_run=dry_run,
+        event_info=get_event_info(),
+    )
     if pr.state != "open":
         log(ctx, "Refusing to process closed ticket")
         return
@@ -187,7 +217,13 @@ def process_issue(
         authed = True
     gclient, repo = get_repo(authed=authed)
     issue = repo.get_issue(issue_number)
-    ctx = IssueLabelerCtx(client=gclient, repo=repo, issue=issue, dry_run=dry_run)
+    ctx = IssueLabelerCtx(
+        client=gclient,
+        repo=repo,
+        issue=issue,
+        dry_run=dry_run,
+        event_info=get_event_info(),
+    )
     if issue.state != "open":
         log(ctx, "Refusing to process closed ticket")
         return