Webhooks

import { Agent, getAgentByName, routeAgentRequest } from "agents";

export class WebhookAgent extends Agent {
	async onRequest(request) {
		if (request.method !== "POST") {
			return new Response("Method not allowed", { status: 405 });
		}

		const rawBody = await request.text();
		const signature = request.headers.get("X-Hub-Signature-256");
		if (
			!(await verifyGitHubWebhook(rawBody, signature, this.env.WEBHOOK_SECRET))
		) {
			return new Response("Invalid signature", { status: 401 });
		}

		let payload;
		try {
			payload = JSON.parse(rawBody);
		} catch {
			return new Response("Invalid payload", { status: 400 });
		}

		await this.processEvent(payload);
		return new Response("OK");
	}

	async processEvent(payload) {
		// Store event, update state, trigger actions...
	}
}

async function verifyGitHubWebhook(rawBody, signature, secret) {
	if (!signature || !/^sha256=[0-9a-f]{64}$/i.test(signature)) return false;

	const encoder = new TextEncoder();
	const key = await crypto.subtle.importKey(
		"raw",
		encoder.encode(secret),
		{ name: "HMAC", hash: "SHA-256" },
		false,
		["verify"],
	);
	const signatureBytes = Uint8Array.from(
		signature.slice("sha256=".length).match(/.{2}/g) ?? [],
		(byte) => Number.parseInt(byte, 16),
	);

	return crypto.subtle.verify(
		"HMAC",
		key,
		signatureBytes,
		encoder.encode(rawBody),
	);
}

export default {
	async fetch(request, env) {
		const url = new URL(request.url);

		if (url.pathname === "/webhooks/github" && request.method === "POST") {
			const rawBody = await request.clone().text();
			const signature = request.headers.get("X-Hub-Signature-256");
			if (
				!(await verifyGitHubWebhook(rawBody, signature, env.WEBHOOK_SECRET))
			) {
				return new Response("Invalid signature", { status: 401 });
			}

			let payload;
			try {
				payload = JSON.parse(rawBody);
			} catch {
				return new Response("Invalid payload", { status: 400 });
			}

			const repository = payload.repository?.full_name;
			if (!repository) {
				return new Response("Missing repository", { status: 400 });
			}

			const agentName = repository.toLowerCase().replace(/\//g, "-");
			const agent = await getAgentByName(env.WebhookAgent, agentName);
			return agent.fetch(request);
		}

		return (
			(await routeAgentRequest(request, env)) ||
			new Response("Not found", { status: 404 })
		);
	},
};

import { Agent, getAgentByName, routeAgentRequest } from "agents";

export class WebhookAgent extends Agent<Env> {
	async onRequest(request: Request): Promise<Response> {
		if (request.method !== "POST") {
			return new Response("Method not allowed", { status: 405 });
		}

		const rawBody = await request.text();
		const signature = request.headers.get("X-Hub-Signature-256");
		if (
			!(await verifyGitHubWebhook(
				rawBody,
				signature,
				this.env.WEBHOOK_SECRET,
			))
		) {
			return new Response("Invalid signature", { status: 401 });
		}

		let payload: unknown;
		try {
			payload = JSON.parse(rawBody);
		} catch {
			return new Response("Invalid payload", { status: 400 });
		}

		await this.processEvent(payload);
		return new Response("OK");
	}

	private async processEvent(payload: unknown) {
		// Store event, update state, trigger actions...
	}
}

async function verifyGitHubWebhook(
	rawBody: string,
	signature: string | null,
	secret: string,
): Promise<boolean> {
	if (!signature || !/^sha256=[0-9a-f]{64}$/i.test(signature)) return false;

	const encoder = new TextEncoder();
	const key = await crypto.subtle.importKey(
		"raw",
		encoder.encode(secret),
		{ name: "HMAC", hash: "SHA-256" },
		false,
		["verify"],
	);
	const signatureBytes = Uint8Array.from(
		signature.slice("sha256=".length).match(/.{2}/g) ?? [],
		(byte) => Number.parseInt(byte, 16),
	);

	return crypto.subtle.verify(
		"HMAC",
		key,
		signatureBytes,
		encoder.encode(rawBody),
	);
}

export default {
	async fetch(request: Request, env: Env): Promise<Response> {
		const url = new URL(request.url);

		if (url.pathname === "/webhooks/github" && request.method === "POST") {
			const rawBody = await request.clone().text();
			const signature = request.headers.get("X-Hub-Signature-256");
			if (
				!(await verifyGitHubWebhook(
					rawBody,
					signature,
					env.WEBHOOK_SECRET,
				))
			) {
				return new Response("Invalid signature", { status: 401 });
			}

			let payload: { repository?: { full_name?: string } };
			try {
				payload = JSON.parse(rawBody);
			} catch {
				return new Response("Invalid payload", { status: 400 });
			}

			const repository = payload.repository?.full_name;
			if (!repository) {
				return new Response("Missing repository", { status: 400 });
			}

			const agentName = repository.toLowerCase().replace(/\//g, "-");
			const agent = await getAgentByName(env.WebhookAgent, agentName);
			return agent.fetch(request);
		}

		return (
			(await routeAgentRequest(request, env)) ||
			new Response("Not found", { status: 404 })
		);
	},
} satisfies ExportedHandler<Env>;