Jul 10, 2025 · Jun 16, 2025 · Jun 16, 2025 · Jul 10, 2025 · Jul 10, 2025 · Jun 16, 2025
diff --git a/backend/package-lock.json b/backend/package-lock.json
diff --git a/backend/package.json b/backend/package.json
    "@types/cors": "^2.8.17",
    "@types/express": "^4.17.21",
    "@types/node": "^20.12.13",
    "async-mutex": "^0.5.0",
    "cors": "^2.8.5",
    "dotenv": "^16.4.5",
    "express": "^4.19.2",
diff --git a/backend/src/controllers/eventsWebhook.ts b/backend/src/controllers/eventsWebhook.ts
 import crypto from'crypto';
 import crypto from"crypto";
 import { RequestHandler } from "express";
 import { eventInfo, fetchEvent, filterInPlace, replaceInPlace } from '../data/eventData';

 interface ChangesEntry {
  field: string;
  value: {
    event_id: string;
    item: string;
    verb: string;
  }
 }
 import { eventInfo, eventInfoMutex, fetchEvent } from "../data/eventData";
 import { filterInPlace, replaceInPlace } from "../util";

 interface FacebookWebhookNotificationEntry {
  id: string;
  changes: ChangesEntry[];
 }

 interface FacebookWebhookNotification {
  entry: FacebookWebhookNotificationEntry[];
 interface FacebookWebhookPayload {
  object: string;
  entry: Array<{
    id: string;
    changes: Array<{
      field: string;
      value: {
        event_id: string;
        item: string;
        verb: string;
      };
    }>;
  }>;
 }

 const verifySignature = (rawBody: Buffer, signatureHeader?: string): boolean => {
 const verifySignature = (
  rawBody: Buffer,
  signatureHeader?: string
 ): boolean => {
  if (!signatureHeader) return false;
  const [algo, signature] = signatureHeader.split('=');
  if (algo !=='sha256') return false;
  const [algo, signature] = signatureHeader.split("=");
  if (algo !=="sha256") return false;

  const expected = crypto
    .createHmac('sha256', process.env.FB_APP_SECRET as string)
    .createHmac("sha256", process.env.FB_APP_SECRET as string)
    .update(rawBody)
    .digest('hex');
    .digest("hex");

  return crypto.timingSafeEqual(Buffer.from(signature), Buffer.from(expected));
 }
 };

 export const EventsWebhookVerifier: RequestHandler = (req, res) => {
  const mode = req.query["hub.mode"];
 */

 export const EventsWebhookUpdate: RequestHandler = async (req, res) => {
  const signature = req.headers['x-hub-signature-256'];
  if (!req.rawBody || typeof signature !== "string" || !verifySignature(req.rawBody, signature)) {
  const signature = req.headers["x-hub-signature-256"];
  if (
    !req.rawBody ||
    typeof signature !== "string" ||
    !verifySignature(req.rawBody, signature)
  ) {
    return res.sendStatus(401);
  }

  const notif: FacebookWebhookNotification = req.body;
  if (!notif || !notif.entry || notif.object !== "page" || notif.entry.length === 0) {
  const notif: FacebookWebhookPayload = req.body;
  if (
    !notif ||
    !notif.entry ||
    notif.object !== "page" ||
    notif.entry.length === 0
  ) {
    return res.sendStatus(400);
  }

    for (const change of entry.changes) {
      if (change.field !== "feed" || change.value.item !== "event") continue;

      if (change.value.verb === "delete") {
        // we need filter *in place* because all imports are immutable (the REAL const)
        filterInPlace(eventInfo, (val, index, arr) => val.id !== change.value.event_id);
      } else {
        try {
      try {
        if (change.value.verb === "delete") {
          await eventInfoMutex.runExclusive(() =>
            filterInPlace(eventInfo, (val) => val.id !== change.value.event_id)
          );
          console.log(`Deleted event: ${change.value.event_id}`);
        } else if (change.value.verb === "edit") {
          const newEvent = await fetchEvent(change.value.event_id);

          eventInfoMutex.runExclusive(() =>
            replaceInPlace(
              eventInfo,
              (val) => val.id === change.value.event_id,
              newEvent
            )
          );
          console.log(`Edited event: ${change.value.event_id}`);
        } else if (change.value.verb === "add") {
          const newEvent = await fetchEvent(change.value.event_id);
          replaceInPlace(eventInfo, (val, index, arr) => val.id === change.value.event_id, newEvent);
        } catch(err) {
          console.log(`Wasn't able to update event for some reason: ${err}`);
          await eventInfoMutex.runExclusive(() => eventInfo.push(newEvent));
          console.log(`Added event: ${change.value.event_id}`);
        } else {
          console.warn(
            `Unknown verb "${change.value.verb}" for event ${change.value.event_id}`
          );
        }
      } catch (err) {
        console.error(
          `Error processing event: ${change.value.event_id}:\n${err}`
        );
        return res.sendStatus(500);
      }
    }
  }

  res.sendStatus(200);
 }
 };
diff --git a/backend/src/data/eventData.ts b/backend/src/data/eventData.ts
 import { Mutex } from "async-mutex";
 import { inspect } from "util";
 import { FacebookError, Result, ResultType } from "../util";

 class EventInfo {
  // god forbid a class have public members
  public id: string;
  }
 }

 // We are altering the array in place, pray we do not alter it from another thread
 // I don't even know if concurrent modification exception is a thing in JS
 // Maybe this is a single threaded moment :icant:
 export function filterInPlace<T>(
  arr: T[],
  predicate: (value: T, index: number, array: T[]) => boolean
 ): T[] {
  let write = 0;
  for (let read = 0; read < arr.length; read++) {
    const val = arr[read];
    if (predicate(val, read, arr)) {
      arr[write++] = val;
    }
  }
  arr.length = write;
  return arr;
 }

 // This one is definitely not thread safe lmao
 // TODO fix with a mutex probably
 export function replaceInPlace<T>(
  arr: T[],
  predicate: (value: T, index: number, array: T[]) => boolean,
  replacement: T
 ): number {
  const idx = arr.findIndex(predicate);
  if (idx !== -1) arr[idx] = replacement;
  return idx;
 }

 // we LOVE global variables
 export let eventInfo: EventInfo[] = [];

 interface FacebookEvent {
  id: string;
  name: string;

 // this isn't in .env for different module compatiblity
 const FB_API_VERSION = "v23.0";
 const DEFAULT_EVENT_LOCATION = "Everything everywhere all at once!!!";
 const DEFAULT_EVENT_IMAGE = "/images/events/default_event.jpg";

 // we LOVE global variables
 export const eventInfoMutex = new Mutex();
 export const eventInfo: EventInfo[] = [];

 export async function fetchEvents() {
  const response = await fetch(
    `https://graph.facebook.com/${FB_API_VERSION}/${process.env.FB_EVENT_PAGE_ID}/events?access_token=${process.env.FB_ACCESS_TOKEN}&fields=id,name,cover,place,start_time,end_time`
  );

  const res: FacebookEventsResponse = await response.json();

  if (!res || !res.data) {
    console.log("No events found...");
    return;
  const res: Result<FacebookEventsResponse, FacebookError> = await response.json();
  if (!res || res.type === ResultType.Err) {
    console.log(`No events found...\n${res}`);
    return [];
  }

  const processed = res.data.map(
  const processed = res.value.data.map(
    (e) =>
      new EventInfo(
        e.id,
        e.name,
        e.start_time,
        e.end_time,
        e.place?.name ??"Everything everywhere all at once!!!",
        e.cover?.source|| "/images/events/default_event.jpg"
        e.place?.name ??DEFAULT_EVENT_LOCATION,
        e.cover?.source?? DEFAULT_EVENT_IMAGE
      )
  );

 eventInfo = processed;
 return processed;
 }

 export async function fetchEvent(id: string) {
  const response = await fetch(
    `https://graph.facebook.com/${FB_API_VERSION}/${id}?access_token=${process.env.FB_ACCESS_TOKEN}&fields=id,name,cover,place,start_time,end_time`
  );

  const res: FacebookEvent = await response.json();
  const res:Result<FacebookEvent, FacebookError> = await response.json();

  if (!res) {
    throw new Error(`Couldn't get details for event ${id}`);
  if (!res || res.type === ResultType.Err) {
    throw new Error(
      `Couldn't fetch details for event ${id}\n${inspect(
        Object.getOwnPropertyDescriptor(res, "error")?.value
      )}`
    );
  }

  return new EventInfo(
    res.id,
    res.name,
    res.start_time,
    res.end_time,
    res.place?.name ??"Everything everywhere all at once!!!",
    res.cover?.source|| "/images/events/default_event.jpg"
    res.value.id,
    res.value.name,
    res.value.start_time,
    res.value.end_time,
    res.value.place?.name ??DEFAULT_EVENT_LOCATION,
    res.value.cover?.source?? DEFAULT_EVENT_IMAGE
  );
 }
diff --git a/backend/src/index.ts b/backend/src/index.ts
 import pingRoute from "./routes/ping";
 import eventsRoute from "./routes/events";
 import eventsWebhookRoute from "./routes/eventsWebhook";
 import { fetchEvents } from "./data/eventData";
 import {eventInfo, eventInfoMutex,fetchEvents } from "./data/eventData";

 dotenv.config();

 (async () => {
  try {
    await fetchEvents();
    const events = await fetchEvents();
    eventInfoMutex.runExclusive(() => eventInfo.concat(events));
    console.log("Events fetched successfully");
  } catch (error) {
    // do we ungracefully bail out here???
    console.error("Error fetching events:", error);
    // could just load from a backup file instead
    console.error("Error fetching events on startup:", error);
  }

  const app: Express = express();
  const port = process.env.PORT || 9000;


  // Middleware
  app.use(
    express.json({
    })
  );
  app.use(cors());


  app.use(pingRoute);
  app.use(eventsWebhookRoute);
  app.use(eventsRoute);


  app.listen(port, () => {
    console.log(`Server successfully started on port ${port}`);
  });
Original file line number	Diff line number	Diff line change
Expand Up		@@ -9,6 +9,7 @@
		"@types/cors": "^2.8.17",
		"@types/express": "^4.17.21",
		"@types/node": "^20.12.13",
		"async-mutex": "^0.5.0",
		"cors": "^2.8.5",
		"dotenv": "^16.4.5",
		"express": "^4.19.2",
Expand Down
Original file line number	Diff line number	Diff line change
		@@ -1,38 +1,38 @@
		import crypto from'crypto';
		import crypto from"crypto";
		import { RequestHandler } from "express";
		import { eventInfo, fetchEvent, filterInPlace, replaceInPlace } from '../data/eventData';

		interface ChangesEntry {
		field: string;
		value: {
		event_id: string;
		item: string;
		verb: string;
		}
		}
		import { eventInfo, eventInfoMutex, fetchEvent } from "../data/eventData";
		import { filterInPlace, replaceInPlace } from "../util";

		interface FacebookWebhookNotificationEntry {
		id: string;
		changes: ChangesEntry[];
		}

		interface FacebookWebhookNotification {
		entry: FacebookWebhookNotificationEntry[];
		interface FacebookWebhookPayload {
		object: string;
		entry: Array<{
		id: string;
		changes: Array<{
		field: string;
		value: {
		event_id: string;
		item: string;
		verb: string;
		};
		}>;
		}>;
		}

		const verifySignature = (rawBody: Buffer, signatureHeader?: string): boolean => {
		const verifySignature = (
		rawBody: Buffer,
		signatureHeader?: string
		): boolean => {
		if (!signatureHeader) return false;
		const [algo, signature] = signatureHeader.split('=');
		if (algo !=='sha256') return false;
		const [algo, signature] = signatureHeader.split("=");
		if (algo !=="sha256") return false;

		const expected = crypto
		.createHmac('sha256', process.env.FB_APP_SECRET as string)
		.createHmac("sha256", process.env.FB_APP_SECRET as string)
		.update(rawBody)
		.digest('hex');
		.digest("hex");

		return crypto.timingSafeEqual(Buffer.from(signature), Buffer.from(expected));
		}
		};

		export const EventsWebhookVerifier: RequestHandler = (req, res) => {
		const mode = req.query["hub.mode"];
Expand DownExpand Up		@@ -73,13 +73,22 @@ https://developers.facebook.com/docs/graph-api/webhooks/reference/page/#feed --
		*/

		export const EventsWebhookUpdate: RequestHandler = async (req, res) => {
		const signature = req.headers['x-hub-signature-256'];
		if (!req.rawBody \|\| typeof signature !== "string" \|\| !verifySignature(req.rawBody, signature)) {
		const signature = req.headers["x-hub-signature-256"];
		if (
		!req.rawBody \|\|
		typeof signature !== "string" \|\|
		!verifySignature(req.rawBody, signature)
		) {
		return res.sendStatus(401);
		}

		const notif: FacebookWebhookNotification = req.body;
		if (!notif \|\| !notif.entry \|\| notif.object !== "page" \|\| notif.entry.length === 0) {
		const notif: FacebookWebhookPayload = req.body;
		if (
		!notif \|\|
		!notif.entry \|\|
		notif.object !== "page" \|\|
		notif.entry.length === 0
		) {
		return res.sendStatus(400);
		}

Expand All		@@ -89,19 +98,40 @@ export const EventsWebhookUpdate: RequestHandler = async (req, res) => {
		for (const change of entry.changes) {
		if (change.field !== "feed" \|\| change.value.item !== "event") continue;

		if (change.value.verb === "delete") {
		// we need filter in place because all imports are immutable (the REAL const)
		filterInPlace(eventInfo, (val, index, arr) => val.id !== change.value.event_id);
		} else {
		try {
		try {
		if (change.value.verb === "delete") {
		await eventInfoMutex.runExclusive(() =>
		filterInPlace(eventInfo, (val) => val.id !== change.value.event_id)
		);
		console.log(`Deleted event: ${change.value.event_id}`);
		} else if (change.value.verb === "edit") {
		const newEvent = await fetchEvent(change.value.event_id);

		eventInfoMutex.runExclusive(() =>
		replaceInPlace(
		eventInfo,
		(val) => val.id === change.value.event_id,
		newEvent
		)
		);
		console.log(`Edited event: ${change.value.event_id}`);
		} else if (change.value.verb === "add") {
		const newEvent = await fetchEvent(change.value.event_id);
		replaceInPlace(eventInfo, (val, index, arr) => val.id === change.value.event_id, newEvent);
		} catch(err) {
		console.log(`Wasn't able to update event for some reason: ${err}`);
		await eventInfoMutex.runExclusive(() => eventInfo.push(newEvent));
		console.log(`Added event: ${change.value.event_id}`);
		} else {
		console.warn(
		`Unknown verb "${change.value.verb}" for event ${change.value.event_id}`
		);
		}
		} catch (err) {
		console.error(
		`Error processing event: ${change.value.event_id}:\n${err}`
		);
		return res.sendStatus(500);
		}
		}
		}

		res.sendStatus(200);
		}
		};
Original file line number	Diff line number	Diff line change
		@@ -1,3 +1,7 @@
		import { Mutex } from "async-mutex";
		import { inspect } from "util";
		import { FacebookError, Result, ResultType } from "../util";

		class EventInfo {
		// god forbid a class have public members
		public id: string;
Expand DownExpand Up		@@ -28,39 +32,6 @@ class EventInfo {
		}
		}

		// We are altering the array in place, pray we do not alter it from another thread
		// I don't even know if concurrent modification exception is a thing in JS
		// Maybe this is a single threaded moment :icant:
		export function filterInPlace<T>(
		arr: T[],
		predicate: (value: T, index: number, array: T[]) => boolean
		): T[] {
		let write = 0;
		for (let read = 0; read < arr.length; read++) {
		const val = arr[read];
		if (predicate(val, read, arr)) {
		arr[write++] = val;
		}
		}
		arr.length = write;
		return arr;
		}

		// This one is definitely not thread safe lmao
		// TODO fix with a mutex probably
		export function replaceInPlace<T>(
		arr: T[],
		predicate: (value: T, index: number, array: T[]) => boolean,
		replacement: T
		): number {
		const idx = arr.findIndex(predicate);
		if (idx !== -1) arr[idx] = replacement;
		return idx;
		}

		// we LOVE global variables
		export let eventInfo: EventInfo[] = [];

		interface FacebookEvent {
		id: string;
		name: string;
Expand All		@@ -76,51 +47,60 @@ interface FacebookEventsResponse {

		// this isn't in .env for different module compatiblity
		const FB_API_VERSION = "v23.0";
		const DEFAULT_EVENT_LOCATION = "Everything everywhere all at once!!!";
		const DEFAULT_EVENT_IMAGE = "/images/events/default_event.jpg";

		// we LOVE global variables
		export const eventInfoMutex = new Mutex();
		export const eventInfo: EventInfo[] = [];

		export async function fetchEvents() {
		const response = await fetch(
		`https://graph.facebook.com/${FB_API_VERSION}/${process.env.FB_EVENT_PAGE_ID}/events?access_token=${process.env.FB_ACCESS_TOKEN}&fields=id,name,cover,place,start_time,end_time`
		);

		const res: FacebookEventsResponse = await response.json();

		if (!res \|\| !res.data) {
		console.log("No events found...");
		return;
		const res: Result<FacebookEventsResponse, FacebookError> = await response.json();
		if (!res \|\| res.type === ResultType.Err) {
		console.log(`No events found...\n${res}`);
		return [];
		}

		const processed = res.data.map(
		const processed = res.value.data.map(
		(e) =>
		new EventInfo(
		e.id,
		e.name,
		e.start_time,
		e.end_time,
		e.place?.name ??"Everything everywhere all at once!!!",
		e.cover?.source\|\| "/images/events/default_event.jpg"
		e.place?.name ??DEFAULT_EVENT_LOCATION,
		e.cover?.source?? DEFAULT_EVENT_IMAGE
		)
		);

		eventInfo = processed;
		return processed;
		}

		export async function fetchEvent(id: string) {
		const response = await fetch(
		`https://graph.facebook.com/${FB_API_VERSION}/${id}?access_token=${process.env.FB_ACCESS_TOKEN}&fields=id,name,cover,place,start_time,end_time`
		);

		const res: FacebookEvent = await response.json();
		const res:Result<FacebookEvent, FacebookError> = await response.json();

		if (!res) {
		throw new Error(`Couldn't get details for event ${id}`);
		if (!res \|\| res.type === ResultType.Err) {
		throw new Error(
		`Couldn't fetch details for event ${id}\n${inspect(
		Object.getOwnPropertyDescriptor(res, "error")?.value
		)}`
		);
		}

		return new EventInfo(
		res.id,
		res.name,
		res.start_time,
		res.end_time,
		res.place?.name ??"Everything everywhere all at once!!!",
		res.cover?.source\|\| "/images/events/default_event.jpg"
		res.value.id,
		res.value.name,
		res.value.start_time,
		res.value.end_time,
		res.value.place?.name ??DEFAULT_EVENT_LOCATION,
		res.value.cover?.source?? DEFAULT_EVENT_IMAGE
		);
		}
Original file line number	Diff line number	Diff line change
Expand Up		@@ -4,22 +4,24 @@ import dotenv from "dotenv";
		import pingRoute from "./routes/ping";
		import eventsRoute from "./routes/events";
		import eventsWebhookRoute from "./routes/eventsWebhook";
		import { fetchEvents } from "./data/eventData";
		import {eventInfo, eventInfoMutex,fetchEvents } from "./data/eventData";

		dotenv.config();

		(async () => {
		try {
		await fetchEvents();
		const events = await fetchEvents();
		eventInfoMutex.runExclusive(() => eventInfo.concat(events));
		console.log("Events fetched successfully");
		} catch (error) {
		// do we ungracefully bail out here???
		console.error("Error fetching events:", error);
		// could just load from a backup file instead
		console.error("Error fetching events on startup:", error);
		}

		const app: Express = express();
		const port = process.env.PORT \|\| 9000;


		// Middleware
		app.use(
		express.json({
Expand All		@@ -29,11 +31,11 @@ dotenv.config();
		})
		);
		app.use(cors());


		app.use(pingRoute);
		app.use(eventsWebhookRoute);
		app.use(eventsRoute);


		app.listen(port, () => {
		console.log(`Server successfully started on port ${port}`);
		});
Expand Down