feat: user following

src/lib/index.ts

@@ -1,10 +1,12 @@
 // place files you want to import through the `$lib` alias in this folder.
 
-type WLEDAPI = {
-    seg: Array<{ id: string, col: Array<[number, number, number]> }>
-}
+import { createTwitchClient } from "./twitch";
 
-const getAddr = (addr: string) => `http://${addr}/json/state`
+type WLEDAPI = {
+    seg: Array<{ id: string; col: Array<[number, number, number]> }>;
+};
+
+const getAddr = (addr: string) => `http://${addr}/json/state`;
 
 const buildReq = (hex: string): WLEDAPI => {
     // hex is not validated.
@@ -16,17 +18,25 @@ const buildReq = (hex: string): WLEDAPI => {
     const b = hexValues & 255;
 
     return {
-        seg: [{
-            id: "0",
-            col: [[r, g, b]],
-        }]
-    }
-}
+        seg: [
+            {
+                id: "0",
+                col: [[r, g, b]],
+            },
+        ],
+    };
+};
 
 export const createLedClient = (addr: string) => {
     return {
         async setColor(hex: string) {
-            await fetch(getAddr(addr), { method: "POST", body: JSON.stringify(buildReq(hex)) });
-        }
-    }
-}
+            await fetch(getAddr(addr), {
+                method: "POST",
+                body: JSON.stringify(buildReq(hex)),
+            });
+        },
+    };
+};
+
+// export const twitchClient = createTwitchClient();
+// twitchClient.subscribeToFollow();

src/lib/twitch.ts

@@ -0,0 +1,90 @@
+import { HASH_SECRET, TWITCH_APP_CLIENT_ID, TWITCH_APP_SECRET } from "$env/static/private";
+import { z } from "zod";
+
+const authBodyValidator = z.object({
+    access_token: z.string(),
+    expires_in: z.number(),
+    token_type: z.enum(["bearer"]),
+});
+
+type TwitchSubscribeBody = {
+    type: "channel.follow";
+    version: 2;
+    transport: {
+        method: "webhook";
+        callback: string;
+        secret: string;
+    };
+};
+
+// Not the complete event, but the information we need.
+export const twitchFollowEvent = z.object({
+    subscription: z.object({
+        type: z.enum(['channel.follow']),
+    }),
+    event: z.object({
+        user_name: z.string(),
+    }),
+});
+
+/*
+ *curl -X POST 'https://api.twitch.tv/helix/eventsub/subscriptions' \
+-H 'Authorization: Bearer 2gbdx6oar67tqtcmt49t3wpcgycthx' \
+-H 'Client-Id: wbmytr93xzw8zbg0p1izqyzzc5mbiz' \
+-H 'Content-Type: application/json' \
+-d '{"type":"channel.follow","version":"2","condition":{"broadcaster_user_id":"1234", "moderator_user_id": "1234"},"transport":{"method":"webhook","callback":"https://example.com/callback","secret":"s3cre77890ab"}}' 
+    */
+
+// Webhook -> Redeem of channel reward
+export const createTwitchClient = () => {
+    const getAccessToken = async () => {
+        const twitchAuthResponse = await fetch(
+            `https://id.twitch.tv/oauth2/token?client_id=${TWITCH_APP_CLIENT_ID}&client_secret=${TWITCH_APP_SECRET}&grant_type=client_credentials`,
+            {
+                method: "POST",
+                headers: {
+                    "Content-Type": "application/x-www-form-urlencoded",
+                },
+            },
+        );
+
+        const { access_token } = authBodyValidator.parse(
+            await twitchAuthResponse.json(),
+        );
+
+        return access_token;
+    };
+
+    const _access_token = getAccessToken();
+
+    const subscribeToFollow = async () => {
+        const twitchSubResponse = await fetch(
+            "https://api.twitch.tv/helix/eventsub/subscriptions",
+            {
+                method: "POST",
+                headers: {
+                    Authorization: `Bearer ${await _access_token}`,
+                    "Client-Id": TWITCH_APP_CLIENT_ID,
+                    "Content-Type": "application/json",
+                },
+                body: JSON.stringify({
+                    type: "channel.follow",
+                    version: 2,
+                    transport: {
+                        callback: "http://localhost:5173/api/webhook",
+                        method: "webhook",
+                        secret: HASH_SECRET,
+                    },
+                } satisfies TwitchSubscribeBody),
+            },
+        );
+
+        const res = await twitchSubResponse.json();
+
+        console.log(res);
+    };
+
+    return {
+        subscribeToFollow,
+    };
+};

src/routes/+page.server.ts

@@ -1,7 +1,7 @@
 import { createLedClient } from "$lib";
 import { fail, type Actions } from "@sveltejs/kit";
 
-const client = createLedClient("192.168.1.215");
+export const client = createLedClient("192.168.1.215");
 
 export const actions: Actions = {
     async default({ request }) {
@@ -15,5 +15,5 @@ export const actions: Actions = {
         // TODO: validate actual HEX
 
         await client.setColor(color.toString());
-    }
-}
+    },
+};

src/routes/api/webhook/+server.ts

@@ -0,0 +1,61 @@
+import { createHmac, timingSafeEqual } from "node:crypto";
+import type { RequestHandler } from "@sveltejs/kit";
+import { HASH_SECRET } from "$env/static/private";
+import { twitchFollowEvent } from "$lib/twitch";
+import { create } from "node:domain";
+import { createLedClient } from "$lib";
+import { client } from "../../+page.server";
+
+const getHmacMessage = (request: Request, body: string): string => {
+    return (
+        request.headers.get(TWITCH_MESSAGE_ID) +
+        request.headers.get(TWITCH_MESSAGE_TIMESTAMP) + body
+    );
+};
+
+const getHmac = (secret: string, message: string): string => {
+    return createHmac("sha256", secret).update(message).digest("hex");
+};
+
+const verifyMessage = (hmac: string, verifySignature: string): boolean => {
+    return timingSafeEqual(Buffer.from(hmac), Buffer.from(verifySignature));
+};
+
+const HMAC_PREFIX = "sha256=";
+
+const TWITCH_MESSAGE_ID = "Twitch-Eventsub-Message-Id".toLowerCase();
+const TWITCH_MESSAGE_TIMESTAMP =
+    "Twitch-Eventsub-Message-Timestamp".toLowerCase();
+const TWITCH_MESSAGE_SIGNATURE =
+    "Twitch-Eventsub-Message-Signature".toLowerCase();
+
+export const fallback: RequestHandler = async ({ request }) => {
+    const body = await request.text();
+
+    const message = getHmacMessage(request, body);
+    const hmac = HMAC_PREFIX + getHmac(HASH_SECRET, message);
+
+    if (!verifyMessage(hmac, request.headers.get(TWITCH_MESSAGE_SIGNATURE)!)) {
+        console.log("Invalid request");
+        throw new Error("go away");
+    } else {
+        // Get JSON object from body, so you can process the message.
+        const jsonBody = JSON.parse(body);
+
+        console.log(jsonBody);
+        const event = twitchFollowEvent.safeParse(jsonBody);
+        if (!event.success) {
+            console.log("Not a follow event");
+            console.log(event.error);
+            return new Response();
+        }
+
+        const { user_name } = event.data.event;
+
+        client.setColor("#FFFFFF");
+
+        // Handle notification...
+        console.log(`${user_name} has just subscribed`);
+        return new Response();
+    }
+};