SEO

client/src/screens/browse/index.jsx

@@ -78,6 +78,18 @@ const BrowseScreen = () => {
     const { code, folderId } = useParams();
     const fb = useSelector((state) => state.fileBrowser);
 
+    useEffect(() => {
+        if (code) {
+            document.title = `${code.toUpperCase()} | CourseHub`;
+        } else {
+            document.title = "CourseHub";
+        }
+
+        return () => {
+            document.title = "CourseHub";
+        };
+    }, [code]);
+
     useEffect(() => {
         const cleaned = readAllCoursesCache();
         if (cleaned.length > 0) {

client/src/screens/error/index.jsx

@@ -1,6 +1,13 @@
-import React from "react";
+import React, { useEffect } from "react";
 
 const ErrorScreen = () => {
+    useEffect(() => {
+        document.title = "Page Not Found | CourseHub";
+        return () => {
+            document.title = "CourseHub";
+        };
+    }, []);
+
     return (
         <div
             style={{
@@ -14,4 +21,4 @@ const ErrorScreen = () => {
     );
 };
 
-export default ErrorScreen;
+export default ErrorScreen;

client/src/screens/landing/index.jsx

@@ -15,7 +15,9 @@ const LandingPage = () => {
     const dispatch = useDispatch();
     const navigate = useNavigate();
     const [loading, setLoading] = useState(true);
-
+    useEffect(() => {
+        document.title = "CourseHub";
+    }, []);
     useEffect(() => {
         clearLegacySessionLocalCoursesCache();
     }, []);

server/index.js

@@ -26,6 +26,8 @@ import fileRoutes from "./modules/file/file.routes.js";
 import folderRoutes from "./modules/folder/folder.routes.js";
 import yearRoutes from "./modules/year/year.routes.js";
 import studentRoutes from "./modules/student/student.routes.js";
+import seoRoutes from "./modules/seo/seo.routes.js";
+import seoMiddleware from "./middleware/seo.js";
 
 const app = express();
 const server = http.createServer(app);
@@ -61,6 +63,8 @@ app.use("/api/files", fileRoutes);
 app.use("/api/folder", folderRoutes);
 app.use("/api/year", yearRoutes);
 app.use("/api/student", studentRoutes);
+app.use(seoRoutes);
+
 app.use(
     "/homepage",
     catchAsync(async (req, res) => {
@@ -70,6 +74,10 @@ app.use(
     }),
 );
 
+app.use("/browse", seoMiddleware);
+
+app.get("*", (req, res) => res.sendFile(path.resolve(__dirname, "static", "index.html")));
+
 app.use((error, req, res, next) => {
     logger.error("Unhandled request error", {
         error,
@@ -83,7 +91,6 @@ app.use((error, req, res, next) => {
     const { status = 500, message = "Something went wrong!" } = error;
     return res.status(status).json({ error: true, message });
 });
-app.get("*", (req, res) => res.sendFile(path.resolve(__dirname, "static", "index.html")));
 
 async function closeServer() {
     if (!server.listening) return;
@@ -129,6 +136,8 @@ process.once("SIGTERM", () => void terminate({ signal: "SIGTERM", exitCode: 0 })
 process.once("uncaughtException", (error) => void terminate({ error, exitCode: 1 }));
 process.once("unhandledRejection", (error) => void terminate({ error, exitCode: 1 }));
 
+
+
 export async function start() {
     await connectDatabase();
     scheduler = initScheduler();

server/middleware/seo.js

@@ -0,0 +1,187 @@
+import fs from "node:fs";
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+import CourseModel from "../modules/course/course.model.js";
+import config from "../config/default.js";
+const courseCache = new Map(); 
+const CACHE_TTL_MS = 60 * 60 * 1000; 
+
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
+const BASE_URL =
+    config.clientURL || "https://coursehub.codingclub.in";
+
+const INDEX_HTML_PATH =
+    process.env.INDEX_HTML_PATH ||
+    path.resolve(__dirname, "../static/index.html");
+
+let cachedIndexHtml = null;
+let cachedIndexHtmlAt = 0;
+const INDEX_HTML_CACHE_TTL_MS = 10 * 60 * 1000;
+
+function getIndexHtml() {
+    const now = Date.now();
+    if (
+        !cachedIndexHtml ||
+        now - cachedIndexHtmlAt >= INDEX_HTML_CACHE_TTL_MS
+    ) {
+        try {
+            cachedIndexHtml = fs.readFileSync(INDEX_HTML_PATH, "utf-8");
+            cachedIndexHtmlAt = now;
+        } catch {
+            return null;
+        }
+    }
+    return cachedIndexHtml;
+}
+
+const BOT_UA_REGEX =
+    /googlebot|google-inspectiontool|chrome-lighthouse|storebot-google|bingbot|slurp|duckduckbot|baiduspider|yandexbot|facebot|facebookexternalhit|twitterbot|discordbot|whatsapp|telegrambot|linkedinbot|slackbot|applebot|ia_archiver|msnbot|ahrefsbot|semrushbot|dotbot|rogerbot|360spider|sogou|bytespider/i;
+
+function isBot(userAgent) {
+    if (!userAgent) return false;
+    return BOT_UA_REGEX.test(userAgent);
+}
+
+function escapeHtml(str) {
+    return String(str)
+        .replace(/&/g, "&")
+        .replace(/"/g, """)
+        .replace(/'/g, "'")
+        .replace(/</g, "&lt;")
+        .replace(/>/g, "&gt;");
+}
+
+function sanitizeJsonLd(json) {
+    return json.replace(/<\//g, "<\\/");
+}
+
+function injectCourseMetaTags(html, course) {
+    const courseSlug = encodeURIComponent(course.code.replace(/\s+/g, ""));
+    const courseUrl  = `${BASE_URL}/browse/${courseSlug}`;
+
+    const safeCode = escapeHtml(course.code);
+    const safeName = escapeHtml(course.name);
+
+    const title = `${safeCode} - ${safeName} Study Materials | CourseHub IIT Guwahati`;
+    const description =
+        `Find past papers, lecture slides, assignments, and notes for ` +
+        `${safeCode} — ${safeName} at IIT Guwahati. ` +
+        `Access all study materials on CourseHub.`;
+
+    const ogImage = `${BASE_URL}/og-image.png`;
+
+    const jsonLd = sanitizeJsonLd(
+        JSON.stringify({
+            "@context": "https://schema.org",
+            "@type": "Course",
+            name: `${course.code} — ${course.name}`,
+            description: `Find past papers, lecture slides, assignments, and notes for ${course.code} — ${course.name} at IIT Guwahati. Access all study materials on CourseHub.`,
+            provider: {
+                "@type": "Organization",
+                name: "CourseHub IIT Guwahati",
+                url: BASE_URL,
+            },
+            url: courseUrl,
+        }),
+    );
+
+    const injectedBlock = `
+    <meta name="description" content="${description}" />
+    <meta property="og:type" content="website" />
+    <meta property="og:site_name" content="CourseHub IIT Guwahati" />
+    <meta property="og:title" content="${title}" />
+    <meta property="og:description" content="${description}" />
+    <meta property="og:url" content="${courseUrl}" />
+    <meta property="og:image" content="${ogImage}" />
+    <meta name="twitter:card" content="summary_large_image" />
+    <meta name="twitter:title" content="${title}" />
+    <meta name="twitter:description" content="${description}" />
+    <meta name="twitter:image" content="${ogImage}" />
+    <link rel="canonical" href="${courseUrl}" />
+    <script type="application/ld+json">${jsonLd}</script>`;
+
+    let modified = html.replace(
+        /<title[^>]*>[\s\S]*?<\/title>/i,
+        () => `<title>${title}</title>`,
+    );
+
+    modified = modified.replace(
+        /<meta\s+name="description"[^>]*\/?>/i,
+        () => injectedBlock,
+    );
+
+    return modified;
+}
+
+export default async function seoMiddleware(req, res, next) {
+    const userAgent = req.headers["user-agent"] || "";
+
+    if (!isBot(userAgent)) {
+        return next();
+    }
+
+    const match = req.path.match(/^\/([^/]+)/);
+    if (!match) {
+        return next();
+    }
+
+    try {
+        const rawCode        = decodeURIComponent(match[1]);
+        const normalizedCode = rawCode.replace(/\s+/g, "");
+        const cacheKey       = normalizedCode.toLowerCase();
+        const cachedCourse   = courseCache.get(cacheKey);
+        let course;
+
+        if (cachedCourse && cachedCourse.expiresAt > Date.now()) {
+            course = cachedCourse.course;
+        } else {
+            const escapedCode = normalizedCode.replace(/[.*+?^${}()|[\]\\]/g, "\\$&");
+            const flexPattern = escapedCode.split("").join("\\s*");
+
+            course = await CourseModel.findOne({
+                code: { $regex: new RegExp(`^${flexPattern}$`, "i") },
+            })
+                .select("name code")
+                .lean();
+
+            courseCache.set(cacheKey, {
+                course,
+                expiresAt: Date.now() + CACHE_TTL_MS,
+            });
+        }
+
+        if (!course) {
+            const safeCode = escapeHtml(normalizedCode);
+            res.set("Vary", "User-Agent");
+            return res.status(404).send(
+                `<!DOCTYPE html>
+<html lang="en">
+<head>
+  <meta charset="UTF-8" />
+  <title>404 — Course Not Found | CourseHub IIT Guwahati</title>
+</head>
+<body>
+  <h1>404 — Course Not Found</h1>
+  <p>The course <strong>${safeCode}</strong> does not exist on CourseHub.</p>
+  <p><a href="${BASE_URL}/browse">Browse all courses</a></p>
+</body>
+</html>`,
+            );
+        }
+
+        const html = getIndexHtml();
+
+        if (!html) {
+            return next();
+        }
+
+        const modifiedHtml = injectCourseMetaTags(html, course);
+
+        res.set("Vary", "User-Agent");
+        res.set("Cache-Control", "public, max-age=3600, s-maxage=3600");
+        res.set("Content-Type", "text/html; charset=utf-8");
+        return res.send(modifiedHtml);
+    } catch (error) {
+        return next(error);
+    }
+}

server/modules/seo/seo.routes.js

@@ -0,0 +1,74 @@
+import express from "express";
+import CourseModel from "../course/course.model.js";
+import config from "../../config/default.js";
+
+const router = express.Router();
+const BASE_URL = config.clientURL || "https://coursehub.codingclub.in";
+
+// 1 sitemap.xml
+
+router.get("/sitemap.xml", async (req, res) => {
+    try {
+        const courses = await CourseModel.find().select("code updatedAt").lean();
+
+        let xml = `<?xml version="1.0" encoding="UTF-8"?>
+        <urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
+            <url>
+                <loc>${BASE_URL}/</loc>
+                <changefreq>weekly</changefreq>
+                <priority>1.0</priority>
+            </url>
+            <url>
+                <loc>${BASE_URL}/browse</loc>
+                <changefreq>daily</changefreq>
+                <priority>0.9</priority>
+            </url>`;
+
+        for (const course of courses) {
+            if (!course?.code) continue ;
+            const lastmod = course.updatedAt && !isNaN(new Date(course.updatedAt))
+                ? new Date(course.updatedAt).toISOString().split("T")[0]
+                : new Date().toISOString().split("T")[0];
+
+            xml += `
+                <url>
+                    <loc>${BASE_URL}/browse/${encodeURIComponent(course.code.replace(/\s+/g,""))}</loc>
+                    <lastmod>${lastmod}</lastmod>
+                    <changefreq>weekly</changefreq>
+                    <priority>0.8</priority>
+                </url>`;
+        }
+
+        xml += "\n</urlset>";
+
+        res.set("Cache-Control", "public, max-age=86400, s-maxage=86400")
+        res.set("Content-Type", "application/xml");
+        res.send(xml);
+    } catch (error) {
+        console.error("Error generating sitemap:", error);
+        res.status(500).send("Error generating sitemap");
+    }
+});
+
+// 2 robots.txt 
+
+router.get("/robots.txt", (req, res) => {
+    const robotsTxt = `User-agent: *
+Allow: /
+Allow: /browse
+Allow: /browse/
+
+Disallow: /dashboard
+Disallow: /profile
+Disallow: /loading
+Disallow: /api/
+Disallow: /admin/
+
+Sitemap: ${BASE_URL}/sitemap.xml`;
+
+    res.set("Cache-Control", "public, max-age=86400, s-maxage=86400");
+    res.set("Content-Type", "text/plain");
+    res.send(robotsTxt);
+});
+
+export default router;

server/static/index.html

@@ -1,11 +1,15 @@
 <!DOCTYPE html>
 <html lang="en">
-<head>
-    <meta charset="UTF-8">
-    <meta name="viewport" content="width=device-width, initial-scale=1.0">
-    <title>Document</title>
-</head>
-<body>
-    Server is running
-</body>
-</html>
+    <head>
+        <meta charset="UTF-8" />
+        <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+        <title>CourseHub</title>
+        <meta
+            name="description"
+            content="Your go-to platform for all your academic needs. Get access to past papers, lecture slides, assignments, tutorials, notes and more to help you ace your exams"
+        />
+    </head>
+    <body>
+        <div id="root"></div>
+    </body>
+</html>