♻️ Refactor backend and add comments

server/index.js

@@ -1,4 +1,8 @@
 import express from "express";
+import cors from "cors";
+import cookieParser from "cookie-parser";
+
+// Import API endpoints
 import {
   getTimetable,
   getSubstitutions,
@@ -7,41 +11,51 @@ import {
 } from "./api/index.js";
 import { Auth } from "./api/auth.js";
 import { Parser } from "./parser/index.js";
-import cors from "cors";
-import cookieParser from "cookie-parser";
 
+// Check DSB Mobile credentials are supplied
+if (!process.env.DSB_USER || !process.env.DSB_PASSWORD) {
+  console.error("Error: DSB Auth environment variables missing!");
+  process.exit(1);
+}
+
+// Create the Webserver
 const app = express();
 const port = process.env.PORT || 3000;
 app.use(cors());
 app.use(cookieParser());
 app.use(express.urlencoded({ extended: true }));
 
-const auth = new Auth();
-
-if (!process.env.DSB_USER || !process.env.DSB_PASSWORD) {
-  console.error("Error: DSB Auth environment variables missing!");
-  process.exit(1);
-}
-const parser = new Parser(
+// Initialize the Parser and set it to update the
+// substitution plan at the specified update interval
+new Parser(
   process.env.DSB_USER,
   process.env.DSB_PASSWORD,
-  process.env.UPDATE_INTERVAL || 1 * 60 * 1000
+  process.env.UPDATE_INTERVAL || 1 * 60 * 1000 // Default to 1 minute
 );
 
+// Create new Auth class to store sessions
+const auth = new Auth();
 app.post("/login", auth.login);
-
+// Check login for every API request
 app.use("/api", auth.checkLogin);
+// Provide check endpoint so the frontend
+// can check if the user is logged in
 app.get("/api/check", (_req, res) => {
   res.sendStatus(200);
 });
+
+// Register API endpoints
 app.get("/api/timetable", getTimetable);
 app.get("/api/substitutions", getSubstitutions);
 app.get("/api/history", getHistory);
 app.get("/api/classes", getClasses);
+// Respond with 400 for non-existent endpoints
 app.get("/api/*", (_req, res) => {
   res.sendStatus(400);
 });
 
+// Supply frontend files if any other url
+// is requested to make vue router work
 app.use("/", express.static("../dist"));
 app.use("/*", express.static("../dist"));