HL7-1: add comments to code

packages/client/src/routes/+page.svelte

@@ -19,13 +19,13 @@
     import { dev } from '$app/environment';
 
     // connection state
-    let ws = $state<WebSocket | undefined>(undefined);
+    let ws = $state<WebSocket | undefined>(undefined); // websocket client
     let stationId = $state<string | undefined>(undefined); // stationId assigned by server
     let connectionState = $state<ConnectionState>(ConnectionState.disconnected);
 
     // client state
-    let composedMessage = $state('');
+    let composedMessage = $state(''); // content of text-box
-    let sentMessages = $state<ReceiveHl7v2Message[]>([]); // storing sent messages with client-timestamp for now
+    let sentMessages = $state<ReceiveHl7v2Message[]>([]); // sent messages stored as type ReceiveHl7v2Message because of the timestamp
     let receivedMessages = $state<ReceiveHl7v2Message[]>([]);
     let isSending = $state(false);
     let copySuccess = $state(false);
@@ -60,6 +60,7 @@
     };
     const segmentTypes = Object.keys(segmentTemplates) as Array<keyof typeof segmentTemplates>;
 
+    // handles the connection process and message handling
     function connectToServer() {
 
         console.log('Connecting to server...');
@@ -67,16 +68,20 @@
 
         const socket = new WebSocket(`${dev ? 'ws' : 'wss'}://${env.PUBLIC_SERVER}`);
 
+        // store websocket on successful connection
         socket.onopen = () => {
             console.log('WebSocket connection established.');
             ws = socket;
         };
 
+        // register message handlers
         socket.onmessage = (event) => {
 
+            // parse every message as type Message
             const message = JSON.parse(event.data) as Message;
             console.log('Message received from server:', message);
 
+            // react based on message type
             switch (message.type) {
 
                 // initial message from server assigning ID
@@ -99,12 +104,14 @@
             }
         };
 
+        // reset connection state and websocket client on disconnect
         socket.onclose = () => {
             console.log('WebSocket connection closed.');
             connectionState = ConnectionState.disconnected;
             ws = undefined;
         };
 
+        // reset connection state and websocket client on error
         socket.onerror = (error) => {
             console.error('WebSocket error:', error);
             connectionState = ConnectionState.disconnected;
@@ -112,7 +119,7 @@
         };
     }
 
-    // clean up on close
+    // reset connection state and websocket client on tab closed
     $effect(() => {
         return () => {
             if (ws && ws.readyState === WebSocket.OPEN) {
@@ -122,21 +129,26 @@
         };
     });
 
+    // adds the template of the provided segment type at the bottom of the textbox
     function addSegment(type: keyof typeof segmentTemplates) {
         const template = segmentTemplates[type].template();
         composedMessage += `\r\n${template}`;
     }
 
+    // handles sending a message to the websocket server
     function handleSendMessage(message: string) {
 
+        // check for active connection
         if (!ws || ws.readyState !== WebSocket.OPEN || isSending || !stationId) {
             console.log('Socket not ready');
             return;
         }
 
+        // set UI state
         isSending = true;
         deliveryError = '';
 
+        // construct Message object and send it
         const messageToSend = {
             type: 'send_hl7v2',
             payload: { message },
@@ -148,9 +160,12 @@
             payload: { message, timestamp: new Date().toISOString() },
         } as ReceiveHl7v2Message, ...sentMessages];
         composedMessage = segmentTemplates.MSH.template();
+
+        // reset UI state
         isSending = false;
     }
 
+    // copies the stationId to the clipboard and handles UI state
     function copyStationId() {
         if (stationId) {
             navigator.clipboard.writeText(stationId).then(() => {
@@ -163,6 +178,7 @@
 </script>
 
 
+<!-- 'component' for displaying a message in the message lists (sent and received) -->
 {#snippet message(msg: ReceiveHl7v2Message)}
     <div class="bg-foreground/10 p-3 rounded-md space-y-1">
         <p class="text-xs">{new Date(msg.payload.timestamp).toLocaleString()}</p>

packages/server/config.ts

@@ -1,23 +1,25 @@
+
+// define available configurations
 interface Config {
     port: number;
     prefixes: string[];
     poolSize: number;
 }
 
+// construct config object from environment variables
 export const config: Config = {
     port: parseInt(process.env.PORT || '8080', 10),
     prefixes: (process.env.PREFIXES || 'STA').split(","),
     poolSize: parseInt(process.env.POOL_SIZE || '100', 10),
 };
 
+// validate config
 if (isNaN(config.port) || config.port < 1024 || config.port > 49151) {
     throw new Error('Invalid PORT environment variable (1024 - 49151)');
 }
-
 if (config.prefixes.length === 0) {
     throw new Error('Invalid PREFIXES environment variable (length > 1)');
 }
-
 if (isNaN(config.poolSize) || config.poolSize < config.prefixes.length) {
-    throw new Error('Invalid PORT environment variable (poolSize >= prefix.length)');
+    throw new Error('Invalid pool size environment variable (poolSize >= prefix.length)');
 }

packages/server/index.ts

@@ -17,6 +17,7 @@ for (const prefix of config.prefixes) {
     }
 }
 
+// mixes the array randomly to avoid getting the same ID reassigned
 function shake(arr: any[]) {
     for (let i = arr.length - 1; i > 0; i--) {
         const j = Math.floor(Math.random() * (i + 1));
@@ -71,9 +72,11 @@ wss.on('connection', (ws) => {
 
     console.log(`Client connected. Assigning ID: ${stationId}`);
 
+    // listen for messages and defined message handling
     ws.on('message', (message) => {
         try {
 
+            // parse every message to type Message
             const parsedMessage: Message = JSON.parse(message.toString());
             console.log(`Received message from ${stationId}:`, parsedMessage);
 
@@ -81,6 +84,7 @@ wss.on('connection', (ws) => {
             if (parsedMessage.type === MessageType.send_hl7v2) {
 
                 const { message } = parsedMessage.payload;
+
                 // TODO: validate message
 
                 // get sender and recipient ID
@@ -98,6 +102,7 @@ wss.on('connection', (ws) => {
                 // Find the recipient's WebSocket connection in our map.
                 const recipientWs = clients.get(recipientId);
 
+                // check if recipient exists and is connected
                 if (recipientWs && recipientWs.readyState === WebSocket.OPEN) {
 
                     // The recipient is connected. Forward the message.
@@ -136,6 +141,7 @@ wss.on('connection', (ws) => {
         if (stationId) {
             availableIds.push(stationId);
         }
+        // shake IDs to avoid getting the same ID reassigned
         availableIds = shake(availableIds);
     });
 

packages/shared/types.ts

@@ -1,9 +1,12 @@
+
+// defines different connection states
 export enum ConnectionState {
     connecting = 'connecting',
     connected = 'connected',
     disconnected = 'disconnected',
 }
 
+// defines message types
 export enum MessageType {
     assign_id = 'assign_id',
     send_hl7v2 = 'send_hl7v2',
@@ -11,10 +14,12 @@ export enum MessageType {
     delivery_error = 'delivery_error',
 }
 
+// defines body of message types
 export type Message =
     | { type: MessageType.assign_id, payload: { stationId: string }}
     | { type: MessageType.send_hl7v2, payload: { message: string }}
     | { type: MessageType.receive_hl7v2, payload: { message: string, timestamp: string }}
     | { type: MessageType.delivery_error, payload: { error: string }}
 
+// required to define list of this message type
 export type ReceiveHl7v2Message = Extract<Message, { type: MessageType.receive_hl7v2 }>;