feat: Add Interview Streak Tracking Feature (#625)

backend/.env.example

@@ -43,6 +43,11 @@ GITHUB_TOKEN=github_pat_your_token_here
 EMAIL_SERVICE=gmail
 
 # Gmail: use an App Password (Google Account → Security → 2-Step Verification → App Passwords)
+
+# Google Calendar OAuth (optional; enables interview prep calendar sync)
+# GOOGLE_CLIENT_ID=your-google-client-id
+# GOOGLE_CLIENT_SECRET=your-google-client-secret
+# GOOGLE_REDIRECT_URI=http://localhost:8000/api/google-calendar/callback
 # Ethereal: use credentials from https://ethereal.email
 EMAIL_USER=your_email@gmail.com
 EMAIL_PASS=xxxx xxxx xxxx xxxx

backend/config/validateEnv.js

@@ -10,6 +10,10 @@ const optionalEnvGroups = Object.freeze([
     feature: "Jobs for You",
     keys: ["ADZUNA_APP_ID", "ADZUNA_API_KEY"],
   },
+  {
+    feature: "Google Calendar integration",
+    keys: ["GOOGLE_CLIENT_ID", "GOOGLE_CLIENT_SECRET", "GOOGLE_REDIRECT_URI"],
+  },
 ]);
 
 const validateEnv = () => {

backend/controllers/googleCalendarController.js

@@ -0,0 +1,99 @@
+const User = require("../models/User");
+const {
+  getGoogleCalendarAuthUrl,
+  exchangeGoogleCalendarCode,
+  createOrUpdateGoogleCalendarEvent,
+  getGoogleCalendarConnectionStatus,
+  encryptSecret,
+} = require("../services/googleCalendarService.js");
+
+const connectGoogleCalendar = async (req, res) => {
+  try {
+    const { authUrl } = getGoogleCalendarAuthUrl(req.user?._id?.toString() || "anonymous");
+    return res.status(200).json({ success: true, authUrl });
+  } catch (error) {
+    console.error("Google Calendar connect error:", error.message);
+    return res.status(500).json({ success: false, message: error.message || "Unable to connect Google Calendar" });
+  }
+};
+
+const handleGoogleCalendarCallback = async (req, res) => {
+  try {
+    const { code, state, error } = req.query;
+
+    if (error) {
+      return res.status(400).json({ success: false, message: "Google authorization failed" });
+    }
+
+    if (!code || !state) {
+      return res.status(400).json({ success: false, message: "Invalid Google callback payload" });
+    }
+
+    const [userId] = state.split(":");
+    const tokens = await exchangeGoogleCalendarCode(code);
+
+    const user = await User.findById(userId);
+    if (!user) {
+      return res.status(404).json({ success: false, message: "User not found" });
+    }
+
+    user.googleCalendarConnected = true;
+    user.googleCalendarEmail = user.email;
+    user.googleCalendarConnectedAt = new Date();
+    user.googleCalendarAccessToken = encryptSecret(tokens.accessToken);
+    user.googleCalendarRefreshToken = encryptSecret(tokens.refreshToken);
+    user.googleCalendarTokenExpiry = tokens.expiryDate ? new Date(tokens.expiryDate) : null;
+    await user.save();
+
+    return res.status(200).json({ success: true, message: "Google Calendar connected successfully" });
+  } catch (error) {
+    console.error("Google Calendar callback error:", error.message);
+    return res.status(500).json({ success: false, message: error.message || "Unable to complete Google Calendar connection" });
+  }
+};
+
+const getGoogleCalendarStatus = async (req, res) => {
+  try {
+    const status = await getGoogleCalendarConnectionStatus(req.user);
+    return res.status(200).json({ success: true, ...status });
+  } catch (error) {
+    console.error("Google Calendar status error:", error.message);
+    return res.status(500).json({ success: false, message: error.message || "Unable to fetch Google Calendar status" });
+  }
+};
+
+const syncGoogleCalendarEvent = async (req, res) => {
+  try {
+    const { title, description, startTime, endTime, reminderMinutes, eventId } = req.body || {};
+
+    if (!title || !startTime || !endTime) {
+      return res.status(400).json({ success: false, message: "title, startTime, and endTime are required" });
+    }
+
+    const result = await createOrUpdateGoogleCalendarEvent(req.user, {
+      title,
+      description,
+      startTime,
+      endTime,
+      reminderMinutes,
+      eventId,
+    });
+
+    await User.findByIdAndUpdate(req.user._id, {
+      googleCalendarLastSyncedAt: new Date(),
+    });
+
+    return res.status(200).json({ success: true, event: result });
+  } catch (error) {
+    console.error("Google Calendar sync error:", error.message);
+    const statusCode = error.message === "expired" ? 401 : 500;
+    return res.status(statusCode).json({ success: false, message: error.message === "expired" ? "Google OAuth token has expired. Please reconnect Google Calendar." : error.message || "Unable to sync Google Calendar event" });
+  }
+};
+
+module.exports = {
+  connectGoogleCalendar,
+  handleGoogleCalendarCallback,
+  getGoogleCalendarStatus,
+  syncGoogleCalendarEvent,
+};

backend/controllers/sessionController.js

@@ -1,7 +1,8 @@
 const Session = require("../models/Session");
 const Question = require("../models/Question");
+const User = require("../models/User");
 const mongoose = require("mongoose");
-
+const { getInterviewStreakUpdate } = require("../utils/interviewStreak");
 
 const MAX_SESSIONS = Number(process.env.MAX_SESSIONS) || 50;
 const MAX_EXPERIENCE = 50;
@@ -92,9 +93,38 @@ await createdSession[0].save({
   session: mongoSession,
 });
 
+            const user = await User.findById(userId).session(mongoSession);
+            if (!user) {
+                throw new Error("USER_NOT_FOUND");
+            }
+
+            const practiceDate = new Date().toISOString().split("T")[0];
+            const streakUpdate = getInterviewStreakUpdate(
+                {
+                    interviewStreak: Number(user.interviewStreak || 0),
+                    longestInterviewStreak: Number(user.longestInterviewStreak || 0),
+                    interviewStreakBadges: Array.isArray(user.interviewStreakBadges) ? user.interviewStreakBadges : [],
+                    interviewStreakLastPracticeDate: user.interviewStreakLastPracticeDate,
+                },
+                practiceDate
+            );
+
+            if (streakUpdate.changed) {
+                user.interviewStreak = Math.max(0, streakUpdate.streak);
+                user.longestInterviewStreak = Math.max(0, streakUpdate.longestStreak);
+                user.interviewStreakBadges = streakUpdate.badges;
+                user.interviewStreakLastPracticeDate = practiceDate;
+                await user.save({ session: mongoSession });
+            }
+
             res.status(201).json({
                 success: true,
                 session: createdSession[0],
+                streakSummary: {
+                    current: user.interviewStreak,
+                    longest: user.longestInterviewStreak,
+                    badges: user.interviewStreakBadges,
+                },
             });
         });
     } catch (err) {
@@ -105,6 +135,13 @@ await createdSession[0].save({
             });
         }
 
+        if (err.message === "USER_NOT_FOUND") {
+            return res.status(404).json({
+                success: false,
+                message: "User not found.",
+            });
+        }
+
         console.error("Create session error:", err);
         return res.status(500).json({
             success: false,

backend/models/User.js

@@ -53,6 +53,18 @@ const UserSchema = new mongoose.Schema(
         },
 
         unlockedAchievements: { type: [String], default: [] },
+        interviewStreak: { type: Number, default: 0, min: 0 },
+        longestInterviewStreak: { type: Number, default: 0, min: 0 },
+        interviewStreakBadges: { type: [String], default: [] },
+        interviewStreakLastPracticeDate: { type: String, default: null },
+
+        googleCalendarConnected: { type: Boolean, default: false },
+        googleCalendarEmail: { type: String, default: null },
+        googleCalendarConnectedAt: { type: Date, default: null },
+        googleCalendarAccessToken: { type: String, default: null },
+        googleCalendarRefreshToken: { type: String, default: null },
+        googleCalendarTokenExpiry: { type: Date, default: null },
+        googleCalendarLastSyncedAt: { type: Date, default: null },
 
         //Email Verification
         isEmailVerified: { type: Boolean, default: false },
@@ -90,6 +102,8 @@ UserSchema.set("toJSON", {
     delete ret.emailVerificationToken;
     delete ret.emailVerificationExpires;
     delete ret.tokenVersion;
+    delete ret.googleCalendarAccessToken;
+    delete ret.googleCalendarRefreshToken;
     return ret;
   },
 });