From cbecd513a481c6f26b0f83f6637544640c413bf1 Mon Sep 17 00:00:00 2001
From: Nour Alharithi <nour.alharithi@gmail.com>
Date: Tue, 7 Nov 2023 11:26:14 -0800
Subject: [PATCH] better error handling

---
 src/wsConnectionManager.ts | 50 ++++++++++++++++++++++++++++++++------
 1 file changed, 42 insertions(+), 8 deletions(-)

diff --git a/src/wsConnectionManager.ts b/src/wsConnectionManager.ts
index abf798f..270002e 100644
--- a/src/wsConnectionManager.ts
+++ b/src/wsConnectionManager.ts
@@ -24,7 +24,11 @@ const REDIS_PASSWORD = process.env.REDIS_PASSWORD;
 
 async function main() {
 	const redisClient = new RedisClient(REDIS_HOST, REDIS_PORT, REDIS_PASSWORD);
-	const lastMessageRetriever = new RedisClient(REDIS_HOST, REDIS_PORT, REDIS_PASSWORD);
+	const lastMessageRetriever = new RedisClient(
+		REDIS_HOST,
+		REDIS_PORT,
+		REDIS_PASSWORD
+	);
 
 	await redisClient.connect();
 	await lastMessageRetriever.connect();
@@ -39,20 +43,34 @@ async function main() {
 		});
 
 		// Save and persist last message
-		lastMessageRetriever.client.set(`last_update_${subscribedChannel}`, message);
+		lastMessageRetriever.client.set(
+			`last_update_${subscribedChannel}`,
+			message
+		);
+	});
+
+	redisClient.client.on('error', (error) => {
+		console.error('Redis client error:', error);
 	});
 
 	wss.on('connection', (ws: WebSocket) => {
 		console.log('Client connected');
 
 		ws.on('message', async (msg) => {
-			const parsedMessage = JSON.parse(msg.toString());
+			let parsedMessage: any;
+			let messageType: string;
+			try {
+				parsedMessage = JSON.parse(msg.toString());
+				messageType = parsedMessage.type.toLowerCase();
+			} catch (e) {
+				return;
+			}
 
-			switch (parsedMessage.type.toLowerCase()) {
+			switch (messageType) {
 				case 'subscribe': {
 					const channel = parsedMessage.channel;
 					if (!subscribedChannels.has(channel)) {
-						console.log('Subscribing to channel', channel);
+						console.log('Trying to subscribe to channel', channel);
 						redisClient.client
 							.subscribe(channel)
 							.then(() => {
@@ -62,7 +80,7 @@ async function main() {
 								ws.send(
 									JSON.stringify({
 										channel,
-										error: `Invalid channel: ${channel}`,
+										error: `Error subscribing to channel: ${channel}`,
 									})
 								);
 								return;
@@ -76,9 +94,10 @@ async function main() {
 					channelSubscribers.get(channel).add(ws);
 
 					// Fetch and send last message
-					const lastMessage = await lastMessageRetriever.client.get(`last_update_${channel}`);
+					const lastMessage = await lastMessageRetriever.client.get(
+						`last_update_${channel}`
+					);
 					if (lastMessage !== null) {
-						console.log('sending last message on new subscribe');
 						ws.send(JSON.stringify({ channel, data: lastMessage }));
 					}
 					break;
@@ -91,6 +110,7 @@ async function main() {
 					}
 					break;
 				}
+				case undefined:
 				default:
 					break;
 			}
@@ -122,6 +142,12 @@ async function main() {
 			// Clear any existing intervals and timeouts
 			clearInterval(pingIntervalId);
 			clearTimeout(pongTimeoutId);
+			channelSubscribers.forEach((subscribers, channel) => {
+				if (subscribers.delete(ws) && subscribers.size === 0) {
+					redisClient.client.unsubscribe(channel);
+					channelSubscribers.delete(channel);
+				}
+			});
 		});
 
 		ws.on('disconnect', () => {
@@ -136,8 +162,16 @@ async function main() {
 	server.listen(WS_PORT, () => {
 		console.log(`connection manager running on ${WS_PORT}`);
 	});
+
+	server.on('error', (error) => {
+		console.error('Server error:', error);
+	});
 }
 
+process.on('unhandledRejection', (reason, promise) => {
+	console.error('Unhandled Rejection at:', promise, 'reason:', reason);
+});
+
 async function recursiveTryCatch(f: () => void) {
 	try {
 		await f();