feat: implement AI-driven behavioral video sentiment analyzer (#1744)

frontend/package.json

@@ -15,6 +15,7 @@
     "@monaco-editor/react": "^4.7.0",
     "@tailwindcss/vite": "^4.1.12",
     "axios": "^1.11.0",
+    "face-api.js": "^0.22.2",
     "framer-motion": "^12.42.2",
     "html2pdf.js": "^0.14.0",
     "lucide-react": "^0.542.0",

frontend/src/components/VideoSentimentAnalyzer.jsx

@@ -0,0 +1,107 @@
+import React, { useEffect, useRef, useState } from 'react';
+import * as faceapi from 'face-api.js';
+
+const VideoSentimentAnalyzer = ({ onAnalysisComplete }) => {
+  const videoRef = useRef();
+  const [isModelLoaded, setIsModelLoaded] = useState(false);
+  const [expressions, setExpressions] = useState({});
+  const [isAnalyzing, setIsAnalyzing] = useState(false);
+
+  useEffect(() => {
+    const loadModels = async () => {
+      try {
+        await faceapi.nets.tinyFaceDetector.loadFromUri('/models');
+        await faceapi.nets.faceExpressionNet.loadFromUri('/models');
+        setIsModelLoaded(true);
+      } catch (err) {
+        console.error("Error loading face-api models", err);
+      }
+    };
+    loadModels();
+  }, []);
+
+  const startVideo = () => {
+    navigator.mediaDevices.getUserMedia({ video: true })
+      .then((stream) => {
+        videoRef.current.srcObject = stream;
+        setIsAnalyzing(true);
+      })
+      .catch((err) => console.error(err));
+  };
+
+  const stopVideo = () => {
+    const stream = videoRef.current?.srcObject;
+    if (stream) {
+      stream.getTracks().forEach(track => track.stop());
+    }
+    setIsAnalyzing(false);
+    if (onAnalysisComplete) {
+        onAnalysisComplete(expressions);
+    }
+  };
+
+  const handleVideoPlay = () => {
+    setInterval(async () => {
+      if (videoRef.current && isAnalyzing) {
+        const detections = await faceapi.detectAllFaces(
+          videoRef.current,
+          new faceapi.TinyFaceDetectorOptions()
+        ).withFaceExpressions();
+
+        if (detections.length > 0) {
+            setExpressions(detections[0].expressions);
+        }
+      }
+    }, 1000);
+  };
+
+  return (
+    <div className="p-4 bg-gray-900 rounded-xl shadow-lg border border-gray-700">
+      <h2 className="text-xl font-bold text-white mb-4">AI Behavioral Sentiment Analyzer</h2>
+
+      {!isModelLoaded ? (
+        <p className="text-gray-400">Loading AI Models...</p>
+      ) : (
+        <div className="flex flex-col items-center">
+          <div className="relative w-full max-w-md aspect-video bg-black rounded-lg overflow-hidden mb-4">
+            <video
+              ref={videoRef}
+              autoPlay
+              muted
+              onPlay={handleVideoPlay}
+              className="w-full h-full object-cover"
+            />
+          </div>
+
+          <div className="flex gap-4 mb-4">
+             {!isAnalyzing ? (
+                 <button onClick={startVideo} className="px-4 py-2 bg-blue-600 text-white rounded-lg hover:bg-blue-500 transition-colors">
+                     Start Mock Interview
+                 </button>
+             ) : (
+                 <button onClick={stopVideo} className="px-4 py-2 bg-red-600 text-white rounded-lg hover:bg-red-500 transition-colors">
+                     End Session
+                 </button>
+             )}
+          </div>
+
+          {Object.keys(expressions).length > 0 && (
+             <div className="w-full bg-gray-800 p-4 rounded-lg">
+                <h3 className="text-white font-semibold mb-2">Real-time Analysis</h3>
+                <div className="grid grid-cols-2 gap-2 text-sm">
+                    {Object.entries(expressions).map(([exp, val]) => (
+                        <div key={exp} className="flex justify-between text-gray-300">
+                            <span className="capitalize">{exp}</span>
+                            <span>{(val * 100).toFixed(1)}%</span>
+                        </div>
+                    ))}
+                </div>
+             </div>
+          )}
+        </div>
+      )}
+    </div>
+  );
+};
+
+export default VideoSentimentAnalyzer;