From 6354b4639fa9ea3bca89a740993fc1ff2e854ffb Mon Sep 17 00:00:00 2001
From: Kostas Drakontidis <gedra100sh@gmail.com>
Date: Sat, 26 Jul 2025 12:33:08 +0300
Subject: [PATCH] Added comments

---
 signaling_server/server.ts | 26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/signaling_server/server.ts b/signaling_server/server.ts
index b645cc2..073d62e 100644
--- a/signaling_server/server.ts
+++ b/signaling_server/server.ts
@@ -29,6 +29,11 @@ type ParseFailure = {
     error: "Invalid JSON." | "Invalid Schema.";
 };
 
+/*
+ * Gets a JSON string, parses it and returns a JSON object.
+ * On success, the success key is true and the data key contains the parsed
+ * data. On failure, success is false and error key contains the error.
+ */
 function safeParse(raw: string): ParseSuccess | ParseFailure {
     let parsed;
 
@@ -47,19 +52,24 @@ function safeParse(raw: string): ParseSuccess | ParseFailure {
     }
 }
 
+// Handler function that kicks inactive clients.
 function timeoutHandler(id: string, p2p: P2P, ws_client: WebSocket) {
     ws_client.close(WS_CODE.TIMEOUT, "Timeout.");
     logger.info("Kicked client due to inactivity.");
     p2p.removeClient(id);
 }
 
+// Handles register event
 function register(p2p: P2P, ws_client: WebSocket, data: Register) {
     const { username, password } = data;
 
+    // Check if client credentials where provided
     if ((username == config.authentication.client.username) && (password == config.authentication.client.password)) {
+        // Check if the server is online
         if (p2p.getServer() != null) {
+            // Add client to the map and start the timer
             const id = p2p.addClient(ws_client);
-            
+
             p2p.setClientTimeout(id, p2p, ws_client, timeoutHandler);
             logger.info(`Client registered, timeout set and assigned ID: [${id}].`);
             logger.info(`Registered clients: ${p2p.getMapSize()}.`);
@@ -68,6 +78,7 @@ function register(p2p: P2P, ws_client: WebSocket, data: Register) {
             logger.error("Client connected but server offline.");
             ws_client.close(WS_CODE.BACKEND_OFFLINE, "Backend offline.");
         }
+    // Check if server credentials where provided and set the server
     } else if ((username == config.authentication.server.username) && (password == config.authentication.server.password)) {
         logger.info("Server set.");
         p2p.setServer(ws_client);
@@ -77,10 +88,12 @@ function register(p2p: P2P, ws_client: WebSocket, data: Register) {
     }
 }
 
+// Handles offer event
 function offer(p2p: P2P, ws_client: WebSocket, data: Offer): void {
     const { id, offer } = data;
     const peer = p2p.getPeer(id, ws_client);
 
+    // Get the peer and forward the offer to it
     if (peer != null) {
         p2p.clearClientTimeout(id);
         logger.info(`Forwarded offer, reset timeout ID: [${id}].`);
@@ -90,10 +103,12 @@ function offer(p2p: P2P, ws_client: WebSocket, data: Offer): void {
     }
 }
 
+// Handles answer event
 function answer(p2p: P2P, ws_client: WebSocket, data: Answer): void {
     const { id, answer } = data;
     const peer = p2p.getPeer(id, ws_client);
 
+    // Get the peer and forward the answer to it
     if (peer != null) {
         logger.info(`Forwarded answer ID: [${id}].`);
         peer.send(JSON.stringify({ type: "answer", id: id, answer: answer }));
@@ -102,10 +117,12 @@ function answer(p2p: P2P, ws_client: WebSocket, data: Answer): void {
     }
 }
 
+// Handles candidate event
 function candidate(p2p: P2P, ws_client: WebSocket, data: Candidate): void {
     const { id, candidate } = data;
     const peer = p2p.getPeer(id, ws_client);
 
+    // Get the peer and forward the candidate to it
     if (peer != null) {
         logger.info(`Forwarded candidate ID: [${id}].`);
         peer.send(JSON.stringify({ type: "candidate", id: id, candidate: candidate }));
@@ -115,13 +132,17 @@ function candidate(p2p: P2P, ws_client: WebSocket, data: Candidate): void {
 }
 
 (() => {
-    const wss = new WebSocket.WebSocketServer({ port: 3000 });
+    // Start the websocket server
+    const wss = new WebSocket.WebSocketServer({ port: config.wss_port });
+    logger.info(`Started WebSocket server. Listening on port: ${config.wss_port}`)
 
+    // Create the P2P instance
     const p2p = new P2P();
     logger.info("Created P2P instance.");
 
     wss.on("connection", async (ws_client) => {
         ws_client.on("message", async (ws_msg) => {
+            // Parse received message and call the corresponding handler
             const parsed = safeParse(ws_msg.toString());
 
             if (parsed.success) {
@@ -141,6 +162,7 @@ function candidate(p2p: P2P, ws_client: WebSocket, data: Candidate): void {
             }
         });
 
+        // Remove the client on disconnect and inform the peer
         ws_client.on("close", (code, reason) => {
             if ((code != WS_CODE.INVALID_CREDENTIALS) &&
                 (code != WS_CODE.BACKEND_OFFLINE) &&