bluesky-commit-bot / main.ts

import { AtpAgent, RichText } from "@atproto/api";
import express from "express";
import { timingSafeEqual } from "node:crypto";
import { Buffer } from "node:buffer";

const usermap: Record<string, string> = JSON.parse(
	await Deno.readTextFile(new URL("./usermap.json", import.meta.url)),
);

const WEBHOOK_SECRET = Deno.env.get("WEBHOOK_SECRET")!;

const agent = new AtpAgent({
	service: Deno.env.get("PDS")!,
});
const app = express();

await agent.login({
	identifier: Deno.env.get("IDENTIFIER")!,
	password: Deno.env.get("PASSWORD")!,
});

async function verifySignature(
	payload: string,
	signature: string,
): Promise<boolean> {
	const key = await crypto.subtle.importKey(
		"raw",
		new TextEncoder().encode(WEBHOOK_SECRET),
		{ name: "HMAC", hash: "SHA-256" },
		false,
		["sign"],
	);
	const sig = await crypto.subtle.sign(
		"HMAC",
		key,
		new TextEncoder().encode(payload),
	);
	const expected = `sha256=${Array.from(new Uint8Array(sig))
		.map((b) => b.toString(16).padStart(2, "0"))
		.join("")}`;
	try {
		return timingSafeEqual(Buffer.from(expected), Buffer.from(signature));
	} catch {
		return false;
	}
}

app.post(
	"/webhook",
	express.text({ type: "application/json" }),
	async (req: any, res: any) => {
		const signature = req.headers["x-hub-signature-256"];
		if (!signature || !(await verifySignature(req.body, signature))) {
			return res.status(401).send("Unauthorized");
		}

		const payload = JSON.parse(req.body);
		res.status(202).send("Accepted");

		const githubEvent = req.headers["x-github-event"];

		if (githubEvent === "push") {
			const commits = payload.commits;

			for (const commit of commits) {
				if (
					commit.author.name === "github-actions[bot]" ||
					commit.author.name === "github-actions"
				) {
					continue;
				}
				const bskyHandle = usermap[commit.author.username.toLowerCase()];
				const author = bskyHandle ? `@${bskyHandle}` : commit.author.name;
				const title = commit.message.split("\n")[0];
				const message = `New change made!\n\n${author} - ${title}\n${commit.url}`;
				const rt = new RichText({ text: message });
				await rt.detectFacets(agent);
				await agent.post({
					text: rt.text,
					facets: rt.facets,
				});
			}
		}
	},
);

const PORT = Deno.env.get("PORT") || 3000;
app.listen(PORT, () => {
	console.log(`Server is running on port ${PORT}`);
});