From fc8493e72e000f2bbd81267a890fb57da66b886c Mon Sep 17 00:00:00 2001
From: Mohammad Bagher Abiyat <zorofight94@gmail.com>
Date: Thu, 21 Mar 2024 07:23:25 +0330
Subject: [PATCH] gh app webhook

---
 packages/backend/nitro.config.ts              |  14 +++
 .../backend/server/routes/webhook.post.ts     | 113 +++++++++++++++++-
 packages/cli/index.ts                         |   1 -
 3 files changed, 125 insertions(+), 3 deletions(-)

diff --git a/packages/backend/nitro.config.ts b/packages/backend/nitro.config.ts
index 2468171b..58b05b5d 100644
--- a/packages/backend/nitro.config.ts
+++ b/packages/backend/nitro.config.ts
@@ -7,9 +7,23 @@ declare module "nitro-cloudflare-dev" {
     }
 }
 
+declare module "nitropack" {
+  interface NitroRuntimeConfig {
+    appId: string
+    webhookSecret: string
+    privateKey: string
+  }
+}
+
 // https://nitro.unjs.io/config
 export default defineNitroConfig({
   preset: 'cloudflare-pages',
   modules: [ncb],
   srcDir: "server",
+
+  runtimeConfig: {
+    appId: "",
+    webhookSecret: "",
+    privateKey: ""
+  }
 });
diff --git a/packages/backend/server/routes/webhook.post.ts b/packages/backend/server/routes/webhook.post.ts
index ff407e08..99223276 100644
--- a/packages/backend/server/routes/webhook.post.ts
+++ b/packages/backend/server/routes/webhook.post.ts
@@ -1,3 +1,112 @@
-export default eventHandler((event) => {
-  console.log(event)
+import { App } from "octokit";
+
+export default eventHandler(async (event) => {
+  const { appId, privateKey, webhookSecret } = useRuntimeConfig(event);
+  const app = new App({
+    appId,
+    privateKey,
+    webhooks: {
+      secret: webhookSecret,
+    },
+  });
+  app.webhooks.on("workflow_job", ({ octokit, payload }) => {
+    console.log(payload)
+  });
+  // event.context.cloudflare.request.
+
+  type EmitterWebhookEvent = Parameters<typeof app.webhooks.receive>[0]
+  const id: EmitterWebhookEvent['id'] = event.headers.get("x-github-delivery");
+  const name = event.headers.get("x-github-event") as EmitterWebhookEvent['name'];
+  const signature = event.headers.get("x-hub-signature-256") ?? "";
+  const payloadString = await event.context.cloudflare.request.text();
+  const payload: EmitterWebhookEvent['payload'] = JSON.parse(payloadString);
+
+  // Verify webhook signature
+  try {
+    await verifyWebhookSignature(payloadString, signature, webhookSecret);
+  } catch (error) {
+    app.log.warn(error.message);
+    return new Response(`{ "error": "${error.message}" }`, {
+      status: 400,
+      headers: { "content-type": "application/json" },
+    });
+  }
+
+  // Now handle the request
+  try {
+    await app.webhooks.receive({
+      id,
+      name,
+      payload,
+    } as EmitterWebhookEvent);
+
+    return new Response(`{ "ok": true }`, {
+      headers: { "content-type": "application/json" },
+    });
+  } catch (error) {
+    app.log.error(error);
+
+    return new Response(`{ "error": "${error.message}" }`, {
+      status: 500,
+      headers: { "content-type": "application/json" },
+    });
+  }
 });
+
+// https://github.com/gr2m/cloudflare-worker-github-app-example/blob/main/lib/verify.js
+export async function verifyWebhookSignature(
+  payload: string,
+  signature: string,
+  secret: string
+) {
+  if (!signature) {
+    throw new Error("Signature is missing");
+  } else if (!signature.startsWith("sha256=")) {
+    throw new Error("Invalid signature format");
+  }
+
+  const algorithm = { name: "HMAC", hash: "SHA-256" };
+  const enc = new TextEncoder();
+  const key = await crypto.subtle.importKey(
+    "raw",
+    enc.encode(secret),
+    algorithm,
+    false,
+    ["sign", "verify"]
+  );
+
+  const signed = await crypto.subtle.sign(
+    algorithm.name,
+    key,
+    enc.encode(payload)
+  );
+  const expectedSignature = "sha256=" + array2hex(signed);
+  if (!safeCompare(expectedSignature, signature)) {
+    throw new Error("Signature does not match event payload and secret");
+  }
+
+  // All good!
+}
+
+function array2hex(arr: ArrayBuffer) {
+  return [...new Uint8Array(arr)]
+    .map((x) => x.toString(16).padStart(2, "0"))
+    .join("");
+}
+
+/** Constant-time string comparison */
+function safeCompare(expected: string, actual: string) {
+  const lenExpected = expected.length;
+  let result = 0;
+
+  if (lenExpected !== actual.length) {
+    actual = expected;
+    result = 1;
+  }
+
+  for (let i = 0; i < lenExpected; i++) {
+    result |= expected.charCodeAt(i) ^ actual.charCodeAt(i);
+  }
+
+  return result === 0;
+}
diff --git a/packages/cli/index.ts b/packages/cli/index.ts
index c492c9eb..18b57e40 100644
--- a/packages/cli/index.ts
+++ b/packages/cli/index.ts
@@ -14,7 +14,6 @@ const eventPayload = await import(process.env.GITHUB_EVENT_PATH, {
   with: { type: "json" },
 });
 
-console.log(process.env)
 // console.log(octokit)
 // console.log(eventPayload)