Integrated context-aware chatbot

backend/.env.example

@@ -1,7 +1,8 @@
 JWT_SECRET=
 REFRESH_SECRET=
 SALTING=
-API_URL='http://localhost:4000/api/v1'
+API_URL=
+GEMINI_API_KEY=
 GOOGLE_CLIENT_ID=
 GOOGLE_CLIENT_SECRET=
 GOOGLE_CALLBACK_URL=

backend/package.json

@@ -39,6 +39,7 @@
     "typescript": "^5.8.3"
   },
   "dependencies": {
+    "@google/generative-ai": "^0.24.1",
     "@types/axios": "^0.14.4",
     "@types/bcrypt": "^6.0.0",
     "@types/cookie-parser": "^1.4.10",
@@ -59,6 +60,7 @@
     "helmet": "^8.1.0",
     "jsonwebtoken": "^9.0.2",
     "multer": "^2.0.2",
+    "node-fetch": "^3.3.2",
     "passport": "^0.7.0",
     "resend": "^6.5.2",
     "zod": "^4.0.9"

backend/src/ai/chatBrain.ts

@@ -0,0 +1,142 @@
+const formatHistory = (history: { from: string; text: string }[] = []) =>
+  history
+    .map((m) => `${m.from === "user" ? "User" : "Assistant"}: ${m.text}`)
+    .join("\n");
+
+export function buildPrompt({
+  path,
+  ragData,
+  userAnswer,
+  questionContext,
+  history = [],
+}: {
+  path: string;
+  ragData: any;
+  userAnswer: string;
+  questionContext?: any;
+  history?: { from: string; text: string }[];
+}) {
+  const baseRole = `
+You are Cortex, an intelligent AI analyst for "Call of Code".
+STRICT LIMITATION: Your knowledge is limited EXCLUSIVELY to DSA and Interview Experiences.
+
+🎯 YOUR GOALS:
+1. If user says hi or hello, greet them back briefly and ask how you can assist in DSA/Interview prep.
+2. Provide accurate, concise, and relevant answers ONLY related to DSA problems or interview experiences.
+3. Politely refuse to answer anything outside DSA/Interviews with the Refusal Message below.
+
+💡 SPECIAL INSTRUCTIONS BASED ON CONTEXT:
+1. DSA HELP (3-Step Method): 
+   - Start with a **simple hint** only.
+   - If user asks for solution (e.g., "give code", "solve it"), provide: (a) Brute-force logic + code, (b) Optimal solution + code.
+   - Suggest 2-3 similar practice problems from LeetCode/GFG/CodeChef.
+2. CAREER QUESTIONS: Define the role, list skills, give a step-by-step roadmap, and suggest learning platforms.
+3. INTERVIEW ANALYSIS: Provide direct answers based on stories. DO NOT give hints for interview data queries.
+
+RULES:
+- If the query is NOT about DSA/Interviews, use the Refusal Message: "I am Cortex, specialized only in DSA and Interview analysis. Let's stay focused on your preparation!"
+- Do NOT start a mock interview. Do NOT act as Alex.
+- Use Markdown (bold, headers, code blocks) and emojis 🚀.
+`;
+
+  console.log("🧠 QUESTION CONTEXT IN chatBrain 👉", questionContext);
+
+ // --- CASE 1: DSA TOPIC ONLY ---
+if (questionContext?.type === "DSA" && questionContext.isTopicOnly) {
+  const questionsList = ragData?.relatedQuestions 
+    ? ragData.relatedQuestions.map((q: any) => `- ${q.title}`).join("\n")
+    : "No questions listed for this topic yet.";
+
+  return `
+${baseRole}
+User is browsing: ${questionContext.topicTitle}
+Available Questions in this topic:
+${questionsList}
+
+Instructions:
+- Briefly explain the importance of ${questionContext.topicTitle} in interviews.
+- If user asks what to solve, suggest questions from the list above.
+
+User Query: ${userAnswer}
+`;
+}
+
+  // --- CASE 2: SPECIFIC DSA QUESTION ---
+  if (questionContext?.type === "DSA" && questionContext.questionId) {
+    const context = ragData ? `QUESTION: ${ragData.question}\nCONCEPT: ${ragData.concept}` : "No specific details available.";
+
+    return `
+${baseRole}
+Conversation so far:
+${formatHistory(history)}
+
+CURRENT QUESTION: ${questionContext.questionName} (${questionContext.topicTitle})
+${context}
+
+USER ANSWER / CODE:
+${userAnswer}
+
+Instructions:
+- Give ONLY a hint first.
+- Point out logical mistakes.
+`;
+  }
+
+  // --- CASE 3: INTERVIEW ANALYST (COLLECTION) ---
+  if (questionContext?.type === "INTERVIEW_COLLECTION") {
+    // Check if ragData exists and has items
+    const allExperiences = (Array.isArray(ragData) && ragData.length > 0)
+      ? ragData.slice(0, 10).map((exp: any) => // Top 10 for performance
+          `Student: ${exp.member?.name || "User"} | Company: ${exp.company} | Verdict: ${exp.verdict} | Summary: ${exp.role}`
+        ).join("\n")
+      : "No specific interview stories found in the database.";
+
+    return `
+${baseRole}
+CONTEXT: The user is looking at the Interview Experiences page.
+DATABASE SUMMARY (Last few stories):
+${allExperiences}
+
+User Question: ${userAnswer}
+
+Instructions:
+- Analyze the common patterns in the stories provided.
+- Identify common mistakes leading to "Rejected" verdicts.
+- Determine which companies focused more on DSA.
+- If they ask for details of a specific person, tell them to click on that card for a deep-dive analysis.
+`;
+  }
+
+  // --- CASE 4: SINGLE INTERVIEW EXPERIENCE ---
+if (questionContext?.type === "INTERVIEW_EXPERIENCE") {
+  const current = ragData?.currentInterview || questionContext;
+  const content = ragData?.currentInterview?.content || "Story content loading...";
+  const studentName = current.member?.name || current.studentName || "the candidate";
+
+  return `
+${baseRole}
+CONTEXT: Interview for ${current.company}.
+CANDIDATE: ${studentName} | VERDICT: ${current.verdict}
+DATA: """${content}"""
+
+INSTRUCTIONS:
+1. If the user says "hi" or "hello", greet them professionally and ask what they want to know specifically.
+2. Provide the FULL ANALYSIS ONLY if the user asks a specific question (e.g., "what rounds?", "questions?", "give analysis").
+3. Use this format for analysis:
+   🔍 **Analysis: ${current.company} Journey**
+   - **The Process**: ...
+   - **Technical Deep-Dive**: ...
+   - **The Verdict Factor**: ...
+
+User Query: ${userAnswer}
+`;
+}
+
+  // --- CASE 5: DEFAULT FALLBACK ---
+  return `
+${baseRole}
+Conversation so far:
+${formatHistory(history)}
+User message: ${userAnswer}
+`;
+}

backend/src/app.ts

@@ -8,6 +8,9 @@ import { errorHandler } from './utils/apiError';
 import rateLimit from 'express-rate-limit';
 import helmet from 'helmet';
 import cookieParser from 'cookie-parser'
+import chatRoutes from "./routes/chat.route";
+
+
 
 
 const app = express();
@@ -32,6 +35,8 @@ app.use(limiter)
 app.use(cookieParser());
 app.use(json());
 app.use(urlencoded({ extended: true }));
+app.use(express.json()); 
+app.use("/chat", chatRoutes); 
 
 const upload = multer({ storage: multer.memoryStorage(),
   limits: { fileSize: 2 * 1024 * 1024 }

backend/src/controllers/chatController.ts

@@ -0,0 +1,59 @@
+import { Request, Response } from "express";
+import { fetchRAGContext } from "../services/retrival";
+import { buildPrompt } from "../ai/chatBrain";
+import { geminiModel } from "../services/ai";
+
+export async function chatController(req: Request, res: Response) {
+  try {
+    const {
+      path,
+      userAnswer,
+      questionContext,
+      history = [], // Added default value
+    } = req.body;
+
+    // Fetch RAG data 
+    const ragData = await fetchRAGContext(questionContext);
+
+
+    if (ragData) {
+      console.log(` Context Loaded: ${ragData.company || ragData.topicTitle || 'General'}`);
+    }
+
+    const prompt = buildPrompt({
+      path,
+      ragData,
+      userAnswer,
+      questionContext,
+      history,
+    });
+
+    // Call Gemini
+    const chat = geminiModel.startChat({
+      history: [], 
+    });
+
+    try {
+      const result = await chat.sendMessage(prompt);
+      const reply = result.response.text();
+      return res.json({ reply }); // Explicit return
+    } catch (aiError: any) {
+      // ⚠️ Handle Gemini Specific Overload (503)
+      if (aiError.status === 503 || aiError.message?.includes("503")) {
+        return res.status(503).json({
+          reply: "Google's AI servers are a bit busy 🧠⚡. Please wait 5-10 seconds and try again!",
+        });
+      }
+      throw aiError; // Pass to main catch
+    }
+
+  } catch (error) {
+    console.error("🚨 Chat Controller Error:", error);
+    const err = error as Error;
+
+    res.status(500).json({
+      reply: "Cortex encountered an issue. Let's try that again in a moment.",
+      error: process.env.NODE_ENV === 'development' ? err.message : undefined // Hide technical error in production
+    });
+  }
+}

backend/src/routes/chat.route.ts

@@ -0,0 +1,8 @@
+import { Router } from "express";
+import { chatController } from "../controllers/chatController";
+
+const chatRouter = Router();
+
+chatRouter.post("/", chatController);
+
+export default chatRouter;

backend/src/services/ai.ts

@@ -0,0 +1,7 @@
+import { GoogleGenerativeAI } from "@google/generative-ai";
+
+const genAI = new GoogleGenerativeAI(process.env.GEMINI_API_KEY!);
+
+export const geminiModel = genAI.getGenerativeModel({
+  model: "gemini-2.5-flash",
+});