feat: implement notification system for course events and updates

client/src/components/Navbar.jsx

@@ -92,58 +92,14 @@ function Navbar({ showBack }) {
       .then((d) => Array.isArray(d) && setNotifs(d));
 
     const socket = getSocket(user.id);
-    socket.on("new-course", (notif) => {
-      setNotifs((prev) => [
-        {
-          id: notif.id || Date.now(),
-          message: notif.message,
-          createdAt: notif.createdAt,
-          read: false,
-        },
-        ...prev,
-      ]);
-    });
-    socket.on("live-class-scheduled", (data) => {
-      setNotifs((prev) => [
-        {
-          id: `lc_${Date.now()}`,
-          message: `📹 Live class scheduled: "${data.title}"`,
-          createdAt: new Date().toISOString(),
-          read: false,
-        },
-        ...prev,
-      ]);
-    });
-    socket.on("live-class-status", (data) => {
-      if (data.status === "live") {
-        setNotifs((prev) => [
-          {
-            id: `lcs_${Date.now()}`,
-            message: `🔴 A live class just started!`,
-            createdAt: new Date().toISOString(),
-            read: false,
-          },
-          ...prev,
-        ]);
-      }
-    });
-    socket.on("student-enrolled", (data) => {
-      setNotifs((prev) => [
-        {
-          id: `enroll_${Date.now()}`,
-          message: data.message || "A student enrolled in your course",
-          createdAt: new Date().toISOString(),
-          read: false,
-        },
-        ...prev,
-      ]);
+
+    // Single unified listener — backend persists to DB before emitting
+    socket.on("notification:new", (notif) => {
+      setNotifs((prev) => [{ ...notif, read: false }, ...prev]);
     });
 
     return () => {
-      socket.off("new-course");
-      socket.off("live-class-scheduled");
-      socket.off("live-class-status");
-      socket.off("student-enrolled");
+      socket.off("notification:new");
     };
   }, [user?.id, isAuthenticated]);
 

server/app/controllers/assignmentController.js

@@ -2,6 +2,7 @@ import Assignment from "../models/Assignment.js";
 import Submission from "../models/Submission.js";
 import Course from "../models/Course.js";
 import { emitToCourse, emitToUser } from "../services/socketService.js";
+import { pushNotification } from "../services/notificationService.js";
 
 // ─── POST /api/courses/:courseId/assignments ──────────────────────────────────
 export async function createAssignment(req, res) {
@@ -29,6 +30,12 @@ export async function createAssignment(req, res) {
 
     const formatted = formatAssignment(assignment);
     emitToCourse(courseId, "assignment:new", formatted);
+
+    // Notify every enrolled student
+    course.enrolledStudents.forEach((studentId) => {
+      pushNotification(studentId.toString(), `📝 New assignment: "${title}"`, "course");
+    });
+
     res.status(201).json(formatted);
   } catch (err) {
     console.error("createAssignment error:", err);
@@ -144,14 +151,19 @@ export async function submitAssignment(req, res) {
       { upsert: true, new: true }
     );
 
-    // Notify teacher in real-time
+    // Notify teacher in real-time (socket) + persist notification
     emitToUser(course.teacher.toString(), "assignment:submitted", {
       assignmentId: id,
       assignmentTitle: assignment.title,
       studentId,
       courseId: assignment.course.toString(),
       submittedAt: now,
     });
+    pushNotification(
+      course.teacher.toString(),
+      `📤 A student submitted assignment: "${assignment.title}"`,
+      "course"
+    );
 
     res.status(201).json(formatSubmission(submission));
   } catch (err) {
@@ -218,7 +230,7 @@ export async function gradeSubmission(req, res) {
     submission.status = "graded";
     await submission.save();
 
-    // Notify the student of their grade
+    // Notify the student of their grade (socket) + persist notification
     emitToUser(submission.student.toString(), "assignment:graded", {
       assignmentId: submission.assignment._id.toString(),
       assignmentTitle: submission.assignment.title,
@@ -227,6 +239,11 @@ export async function gradeSubmission(req, res) {
       feedback: submission.feedback,
       maxScore: submission.assignment.maxScore,
     });
+    pushNotification(
+      submission.student.toString(),
+      `✅ Your assignment "${submission.assignment.title}" was graded: ${submission.score}/${submission.assignment.maxScore}`,
+      "course"
+    );
 
     res.json(formatSubmission(submission));
   } catch (err) {

server/app/controllers/enrollmentController.js

@@ -2,8 +2,8 @@ import Enrollment from "../models/Enrollment.js";
 import Course from "../models/Course.js";
 import Material from "../models/Material.js";
 import CompletedMaterial from "../models/CompletedMaterial.js";
-import Notification from "../models/Notification.js";
 import { getIO } from "../services/socketService.js";
+import { pushNotification } from "../services/notificationService.js";
 
 // ─── POST /api/enrollments ────────────────────────────────────────────────────
 export async function enroll(req, res) {
@@ -30,13 +30,17 @@ export async function enroll(req, res) {
       { upsert: true, new: true }
     );
 
-    // Notify the teacher
+    // Notify the teacher (persists to DB + emits notification:new)
+    pushNotification(
+      course.teacher.toString(),
+      `🎓 A new student enrolled in "${course.title}"`,
+      "course"
+    );
+    // Keep student-enrolled for StudentDashboard / other listeners
     try {
-      const notifMessage = `A new student enrolled in "${course.title}"`;
-      await Notification.create({ user: course.teacher, message: notifMessage, type: "course" });
       const io = getIO();
       io.to(`user:${course.teacher}`).emit("student-enrolled", {
-        message: notifMessage,
+        message: `A new student enrolled in "${course.title}"`,
         courseId,
         studentId,
       });

server/app/controllers/liveClassController.js

@@ -3,6 +3,7 @@ import ClassComment from "../models/ClassComment.js";
 import ClassQuestion from "../models/ClassQuestion.js";
 import Course from "../models/Course.js";
 import { getIO } from "../services/socketService.js";
+import { pushNotification } from "../services/notificationService.js";
 
 // ─── POST /api/courses/:courseId/live-classes ─────────────────────────────────
 export async function createLiveClass(req, res) {
@@ -32,17 +33,24 @@ export async function createLiveClass(req, res) {
       meetingLink: classType === "meetLink" ? meetingLink || "" : "",
     });
 
-    // Notify enrolled students via socket
+    // Notify enrolled students via socket + persist notification
     try {
       const io = getIO();
       course.enrolledStudents.forEach((studentId) => {
+        // Keep live-class-scheduled for StudentDashboard reload
         io.to(`user:${studentId}`).emit("live-class-scheduled", {
           liveClassId: liveClass._id,
           title: liveClass.title,
           courseId,
           scheduledAt: liveClass.scheduledAt,
           type: liveClass.type,
         });
+        // Persist + push notification:new
+        pushNotification(
+          studentId.toString(),
+          `📹 Live class scheduled: "${liveClass.title}"`,
+          "course"
+        );
       });
     } catch {
       /* non-critical */
@@ -170,6 +178,14 @@ export async function updateLiveClassStatus(req, res) {
           status,
           type: liveClass.type,
         });
+        // Persist notification when class goes live
+        if (status === "live") {
+          pushNotification(
+            studentId.toString(),
+            `🔴 Live class started: "${liveClass.title}"`,
+            "course"
+          );
+        }
       });
 
       // Also broadcast inside the live class room (for participants currently in it)

server/app/controllers/materialController.js

@@ -4,6 +4,7 @@ import CompletedMaterial from "../models/CompletedMaterial.js";
 import Enrollment from "../models/Enrollment.js";
 import { uploadToCloudinary, getResourceType } from "../utils/cloudinary.js";
 import { emitToCourse, emitToUser } from "../services/socketService.js";
+import { pushNotification } from "../services/notificationService.js";
 
 // ─── POST /api/courses/:courseId/materials/upload ────────────────────────────
 export async function uploadMaterialFile(req, res) {
@@ -42,6 +43,12 @@ export async function uploadMaterialFile(req, res) {
 
     const formatted = formatMaterial(material);
     emitToCourse(courseId, "material:new", formatted);
+
+    // Notify every enrolled student
+    course.enrolledStudents.forEach((studentId) => {
+      pushNotification(studentId.toString(), `📎 New material added: "${title}"`, "course");
+    });
+
     res.status(201).json(formatted);
   } catch (err) {
     console.error("uploadMaterialFile error:", err);
@@ -75,6 +82,12 @@ export async function addMaterial(req, res) {
 
     const formatted = formatMaterial(material);
     emitToCourse(courseId, "material:new", formatted);
+
+    // Notify every enrolled student
+    course.enrolledStudents.forEach((studentId) => {
+      pushNotification(studentId.toString(), `📎 New material added: "${title}"`, "course");
+    });
+
     res.status(201).json(formatted);
   } catch (err) {
     console.error("addMaterial error:", err);
@@ -124,6 +137,12 @@ export async function updateMaterial(req, res) {
 
     const formatted = formatMaterial(material);
     emitToCourse(courseId, "material:updated", formatted);
+
+    // Notify every enrolled student that content was updated
+    course.enrolledStudents.forEach((studentId) => {
+      pushNotification(studentId.toString(), `✏️ Material updated: "${material.title}"`, "course");
+    });
+
     res.json(formatted);
   } catch (err) {
     console.error("updateMaterial error:", err);

server/app/controllers/quizController.js

@@ -2,6 +2,7 @@ import Quiz from "../models/Quiz.js";
 import QuizResult from "../models/QuizResult.js";
 import Course from "../models/Course.js";
 import { emitToCourse, emitToUser } from "../services/socketService.js";
+import { pushNotification } from "../services/notificationService.js";
 
 // ─── POST /api/courses/:courseId/quizzes ──────────────────────────────────────
 export async function createQuiz(req, res) {
@@ -30,6 +31,12 @@ export async function createQuiz(req, res) {
 
     const formatted = formatQuiz(quiz);
     emitToCourse(courseId, "quiz:new", formatted);
+
+    // Notify every enrolled student
+    course.enrolledStudents.forEach((studentId) => {
+      pushNotification(studentId.toString(), `📊 New quiz: "${title}"`, "course");
+    });
+
     res.status(201).json(formatted);
   } catch (err) {
     console.error("createQuiz error:", err);
@@ -151,7 +158,7 @@ export async function submitQuiz(req, res) {
 
     const formatted = formatResult(result);
 
-    // Notify teacher of new submission
+    // Notify teacher of new submission (socket) + persist notification
     emitToUser(course.teacher.toString(), "quiz:submitted", {
       quizId: id,
       quizTitle: quiz.title,
@@ -160,6 +167,11 @@ export async function submitQuiz(req, res) {
       score,
       totalPoints,
     });
+    pushNotification(
+      course.teacher.toString(),
+      `📊 A student submitted quiz "${quiz.title}" — score: ${score}/${totalPoints}`,
+      "course"
+    );
 
     res.status(201).json(formatted);
   } catch (err) {

server/app/services/notificationService.js

@@ -0,0 +1,23 @@
+import Notification from "../models/Notification.js";
+import { emitToUser } from "./socketService.js";
+
+/**
+ * Persist a notification to MongoDB and push it in real-time to the user's
+ * personal socket room via the `notification:new` event.
+ *
+ * Always fire-and-forget (never throws) — callers don't need try/catch.
+ */
+export async function pushNotification(userId, message, type = "course") {
+  try {
+    const notif = await Notification.create({ user: userId, message, type });
+    emitToUser(userId.toString(), "notification:new", {
+      id: notif._id,
+      message: notif.message,
+      type: notif.type,
+      read: notif.read,
+      createdAt: notif.createdAt,
+    });
+  } catch {
+    // non-critical — never crash the main request
+  }
+}