[Docs Site] Comment matched CODEOWNERS entries on PRs

Author: KianNH

.github/workflows/ci.yml

@@ -27,6 +27,8 @@ jobs:
             node_modules/.astro/assets
           key: static
 
+      - run: npx tsx bin/post-codeowners-comment/index.ts
+
       - run: npm ci
       - run: npm run check
 

bin/post-codeowners-comment/constants.ts

@@ -0,0 +1,3 @@
+export const GITHUB_ACTIONS_BOT_ID = 41898282;
+export const COMMENT_PREFIX =
+	"This pull request requires reviews from **CODEOWNERS** as it changes files that match the following patterns:";

bin/post-codeowners-comment/index.ts

@@ -0,0 +1,95 @@
+import * as core from "@actions/core";
+import * as github from "@actions/github";
+import type { PullRequestEvent } from "@octokit/webhooks-types";
+
+import { loadOwners, matchFile } from "codeowners-utils";
+import { GITHUB_ACTIONS_BOT_ID, COMMENT_PREFIX } from "./constants.ts";
+
+async function run(): Promise<void> {
+	try {
+		if (!process.env.GITHUB_TOKEN) {
+			core.setFailed(`Could not find GITHUB_TOKEN in env`);
+			process.exit();
+		}
+
+		const octokit = github.getOctokit(process.env.GITHUB_TOKEN);
+		const payload = github.context.payload as PullRequestEvent;
+
+		const { owner, repo } = github.context.repo;
+		const pullRequestNumber = payload.number;
+
+		const files = await octokit.paginate(octokit.rest.pulls.listFiles, {
+			owner,
+			repo,
+			pull_number: pullRequestNumber,
+		});
+
+		const codeowners = await loadOwners(process.cwd());
+
+		if (!codeowners) {
+			throw new Error("Unable to load CODEOWNERS file.");
+		}
+
+		const matchedPatterns = [
+			...new Set(
+				files.flatMap((file) => matchFile(file.filename, codeowners) ?? []),
+			),
+		];
+
+		const { data: comments } = await octokit.rest.issues.listComments({
+			owner,
+			repo,
+			issue_number: pullRequestNumber,
+			per_page: 100,
+		});
+
+		const existingComment = comments.find(
+			(comment) =>
+				comment.user?.id === GITHUB_ACTIONS_BOT_ID &&
+				comment.body?.includes(COMMENT_PREFIX),
+		);
+
+		if (existingComment) {
+			core.info(`Found existing comment with ID ${existingComment.id}`);
+		} else {
+			core.info(`No existing comment found`);
+		}
+
+		const comment = [
+			COMMENT_PREFIX,
+			"| Pattern | Owners |",
+			"| ------- | ------ |",
+			...matchedPatterns.map(
+				(pattern) =>
+					`| ${pattern.pattern} | ${pattern.owners.map((owner) => "`" + owner + "`").join(", ")} |`,
+			),
+		].join("\n");
+
+		if (existingComment) {
+			core.info(
+				`Updating ${existingComment.id} with ${JSON.stringify(comment)}`,
+			);
+			await octokit.rest.issues.updateComment({
+				owner,
+				repo,
+				comment_id: existingComment.id,
+				body: comment,
+			});
+		} else {
+			core.info(`Creating new comment with ${JSON.stringify(comment)}`);
+			await octokit.rest.issues.createComment({
+				owner,
+				repo,
+				issue_number: pullRequestNumber,
+				body: comment,
+			});
+		}
+	} catch (error) {
+		if (error instanceof Error) {
+			core.setFailed(error.message);
+		}
+		process.exit();
+	}
+}
+
+run();