/**
 * Sentinel Live Pulse — Real-time Multimodal Analysis Engine
 * v5 — Precise AU-based emotion detection, stable face mesh, WAV recording
 */

// ── State ─────────────────────────────────────────────────
const state = {
    isRunning: false,
    ws: null,
    webcamStream: null,
    audioContext: null,
    audioAnalyser: null,
    audioStream: null,
    mediaRecorder: null,
    audioChunks: [],
    frameInterval: null,
    engagementHistory: [],
    blinkTimestamps: [],
    blinkCount: 0,          // Simple cumulative blink counter
    stableFramesCount: 0,   // Consecutive stable & focused frames
    lastBlinkState: false,
    lastNoseX: null,        // For head stability check
    lastNoseY: null,
    sessionStartTime: null,
    peakEngagement: 0,
    totalEngagement: 0,
    engagementSamples: 0,
    faceMesh: null,
    camera: null,
    emotionBuffer: [],
    lastStableEmotion: 'Neutral',
    lastStableConfidence: 0,
    faceMeshReady: false,
    meshFailCount: 0,

    // Calibration: first 15 frames establish the user's resting face
    calibrationFrames: [],
    baseline: null,
    // Timing counters for 1-second emotion rules (~20 frames @ 20fps)
    neutralStableFrames: 0,
    mouthOpenFrames: 0,
};

// ── DOM References ────────────────────────────────────────
const video = document.getElementById('webcam-video');
const meshCanvas = document.getElementById('mesh-canvas');
const meshCtx = meshCanvas.getContext('2d');
const logContent = document.getElementById('log-content');
const btnStartStop = document.getElementById('btn-start-stop');

// ── Initialize Mini Audio Bars ────────────────────────────
(function initMiniBars() {
    const container = document.getElementById('mini-audio-viz');
    if (!container) return; // Removed from UI
    for (let i = 0; i < 32; i++) {
        const bar = document.createElement('div');
        bar.className = 'audio-bar';
        bar.style.background = `rgba(209, 188, 255, ${0.3 + Math.random() * 0.5})`;
        bar.style.height = '2px';
        container.appendChild(bar);
    }
})();

// ── Logging ───────────────────────────────────────────────
function addLog(tag, message, color) {
    const p = document.createElement('p');
    p.className = 'log-line';
    const elapsed = state.sessionStartTime
        ? ((Date.now() - state.sessionStartTime) / 1000).toFixed(3)
        : '0.000';
    p.innerHTML = `<span style="color:${color};">[${elapsed}s]</span> ${tag} :: ${message}`;
    logContent.appendChild(p);
    logContent.scrollTop = logContent.scrollHeight;
    while (logContent.children.length > 100) logContent.removeChild(logContent.firstChild);
}

// ── API URLs ──────────────────────────────────────────────
const API_BASE = "https://r-vasanthkumar73-dev-sentinel-multimodal-emotion-ai.hf.space";
const speechApiUrl = `${API_BASE}/api/analyze/speech`;
const textApiUrl = `${API_BASE}/api/analyze/text`;
const sessionSaveUrl = `${API_BASE}/api/session/save`;

// ── Start / Stop ──────────────────────────────────────────
btnStartStop.addEventListener('click', () => {
    ensureAudioContext();
    if (state.isRunning) stopAll();
    else startAll();
});

async function startAll() {
    state.isRunning = true;
    state.sessionStartTime = Date.now();
    state.blinkTimestamps = [];
    state.blinkCount = 0;
    state.lastNoseX = null;
    state.lastNoseY = null;
    state.peakEngagement = 0;
    state.totalEngagement = 0;
    state.engagementSamples = 0;
    state.engagementHistory = [];
    state.emotionBuffer = [];
    state.lastStableEmotion = 'Neutral';
    state.lastStableConfidence = 0;
    state.meshFailCount = 0;
    state.calibrationFrames = [];
    state.baseline = null;

    btnStartStop.innerHTML = '<span class="material-symbols-outlined" style="font-size:18px;">stop</span> Stop Monitoring';
    document.getElementById('live-badge').style.display = 'flex';
    document.getElementById('log-status').textContent = 'LIVE_PKT_RECEIVED';
    document.getElementById('scan-line').style.display = 'block';
    document.getElementById('connection-status').innerHTML = '<span class="status-dot"></span><span class="status-text">Connected</span>';

    addLog('SYSTEM', 'Starting multimodal analysis engine...', 'var(--primary-container)');

    try {
        state.webcamStream = await navigator.mediaDevices.getUserMedia({
            video: { width: 640, height: 480, facingMode: 'user' },
            audio: false
        });
        video.srcObject = state.webcamStream;
        document.getElementById('face-status').textContent = 'Active Stream';
        document.getElementById('source-face').classList.add('active');
        const ctrlCam = document.getElementById('ctrl-camera'); if (ctrlCam) ctrlCam.classList.add('active');
        addLog('CAMERA', 'Webcam stream initialized (640x480)', 'var(--primary-container)');
    } catch (e) {
        addLog('CAMERA', 'Failed to access webcam: ' + e.message, 'var(--error)');
    }

    document.getElementById('audio-status').textContent = 'Standby (Click Audio Panel)';
    startFaceMesh();
}

function stopAll() {
    state.isRunning = false;
    btnStartStop.innerHTML = '<span class="material-symbols-outlined" style="font-size:18px;">play_arrow</span> Start Monitoring';
    document.getElementById('live-badge').style.display = 'none';
    document.getElementById('log-status').textContent = 'STANDBY';
    document.getElementById('scan-line').style.display = 'none';
    document.getElementById('connection-status').innerHTML = '<span class="status-dot" style="background:var(--tertiary-fixed-dim);"></span><span class="status-text" style="color:var(--tertiary-fixed-dim);">Standby</span>';

    if (state.webcamStream) { state.webcamStream.getTracks().forEach(t => t.stop()); state.webcamStream = null; video.srcObject = null; }
    if (state.audioStream) { state.audioStream.getTracks().forEach(t => t.stop()); state.audioStream = null; }
    if (state.audioContext) { state.audioContext.close(); state.audioContext = null; }
    if (state.mediaRecorder && state.mediaRecorder.state !== 'inactive') state.mediaRecorder.stop();

    if (state.faceMesh) { state.faceMesh.close(); state.faceMesh = null; }
    state.faceMeshReady = false;

    // Clean up timers
    if (window._meshWatchdog) { clearInterval(window._meshWatchdog); window._meshWatchdog = null; }
    if (window.hfLoopInterval) { clearInterval(window.hfLoopInterval); window.hfLoopInterval = null; }

    meshCtx.clearRect(0, 0, meshCanvas.width, meshCanvas.height);
    document.querySelectorAll('.source-btn').forEach(b => b.classList.remove('active'));
    document.getElementById('face-status').textContent = 'Standby';
    document.getElementById('audio-status').textContent = 'Standby';
    const ctrlCamEl = document.getElementById('ctrl-camera'); if (ctrlCamEl) ctrlCamEl.classList.remove('active');
    const ctrlMicEl = document.getElementById('ctrl-mic'); if (ctrlMicEl) ctrlMicEl.classList.remove('active');
    addLog('SYSTEM', 'Monitoring stopped.', 'var(--tertiary-fixed-dim)');
    saveSession();
}

// ══════════════════════════════════════════════════════════
//  FACE MESH — STABLE, AUTO-RECOVERING
// ══════════════════════════════════════════════════════════
async function startFaceMesh() {
    addLog('FACEMESH', 'Initializing local Face Mesh engine...', 'var(--primary-container)');
    try {
        state.faceMesh = new FaceMesh({ locateFile: (file) => `https://cdn.jsdelivr.net/npm/@mediapipe/face_mesh/${file}` });
        state.faceMesh.setOptions({ maxNumFaces: 1, refineLandmarks: true, minDetectionConfidence: 0.5, minTrackingConfidence: 0.5 });
        state.faceMesh.onResults(onFaceMeshResults);
        state.faceMeshReady = true;

        addLog('FACEMESH', 'Face Mesh engine started — calibrating baseline...', 'var(--primary-container)');

        // Frame loop: run as fast as the browser allows (up to 60fps)
        // using requestAnimationFrame, but protected by meshProcessing lock
        // so it never overwhelms the WASM pipeline.
        let meshProcessing = false;
        async function processVideoFrame() {
            if (!state.isRunning) return;
            if (!meshProcessing && state.faceMeshReady && state.faceMesh && video.readyState >= 2) {
                meshProcessing = true;
                try {
                    await state.faceMesh.send({ image: video });
                    state.meshFailCount = 0;
                } catch (e) {
                    state.meshFailCount++;
                    if (state.meshFailCount > 30 && state.isRunning) {
                        addLog('FACEMESH', 'Auto-recovering...', 'var(--error)');
                        await restartFaceMesh();
                        return; // restartFaceMesh starts its own loop
                    }
                }
                meshProcessing = false;
            }
            if (state.isRunning) {
                requestAnimationFrame(processVideoFrame); // Maximize responsiveness
            }
        }
        processVideoFrame();

        // Watchdog: check every 10s if mesh has gone stale
        if (window._meshWatchdog) clearInterval(window._meshWatchdog);
        window._meshWatchdog = setInterval(async () => {
            if (!state.isRunning) { clearInterval(window._meshWatchdog); return; }
            if (state.meshFailCount > 15) {
                addLog('FACEMESH', 'Watchdog: mesh stalled, recovering...', 'var(--error)');
                await restartFaceMesh();
            }
        }, 10000);

        // Pure Local FACS only, no ViT sync
    } catch (e) {
        addLog('FACEMESH', 'Failed: ' + e.message, 'var(--error)');
    }
}

async function restartFaceMesh() {
    state.faceMeshReady = false;
    state.meshFailCount = 0;
    try { if (state.faceMesh) state.faceMesh.close(); } catch (e) { }
    try {
        state.faceMesh = new FaceMesh({ locateFile: (file) => `https://cdn.jsdelivr.net/npm/@mediapipe/face_mesh/${file}` });
        state.faceMesh.setOptions({ maxNumFaces: 1, refineLandmarks: true, minDetectionConfidence: 0.5, minTrackingConfidence: 0.5 });
        state.faceMesh.onResults(onFaceMeshResults);
        state.faceMeshReady = true;
        addLog('FACEMESH', 'Recovered successfully.', 'var(--primary-container)');
    } catch (e) {
        addLog('FACEMESH', 'Recovery failed.', 'var(--error)');
    }
}

// ══════════════════════════════════════════════════════════
//  PRECISION AU-BASED EMOTION DETECTION
//  Based on FACS (Facial Action Coding System)
//  with dynamic baseline calibration
// ══════════════════════════════════════════════════════════
function extractFaceMetrics(pts) {
    const dist = (a, b) => Math.sqrt((a.x - b.x) ** 2 + (a.y - b.y) ** 2);

    const faceH = dist(pts[10], pts[152]);
    if (faceH < 0.01) return null;

    // 1. Mouth Width (61 to 291)
    const mouth_width = dist(pts[61], pts[291]) / faceH;

    // 2. Eye Distance (Outer corners: 33 to 263)
    const eye_dist = dist(pts[33], pts[263]) / faceH;

    // 3. Teeth visibility / Jaw Drop (Inner lips: 13 to 14)
    const inner_lip_dist = dist(pts[13], pts[14]) / faceH;

    // 4. Inner Brows distance (70 to 300)
    const inner_brow_dist = dist(pts[70], pts[300]) / faceH;

    // 5. Nose tip to lip corners (Vertical distance) -> Frown (AU15)
    const nose_to_lip_y = (((pts[61].y + pts[291].y) / 2.0) - pts[4].y) / faceH;

    // 6. Eye Opening (Vertical) -> AU5 (Wide) / AU6 (Cheek Raise Squint)
    const left_eye_open = dist(pts[159], pts[145]);
    const right_eye_open = dist(pts[386], pts[374]);
    const eye_opening = ((left_eye_open + right_eye_open) / 2.0) / faceH;

    // 7. Brow to Eye Vertical Distance (Brows Rise AU1+2 / Lower AU4)
    const eye_center_y = (pts[159].y + pts[386].y + pts[145].y + pts[374].y) / 4.0;
    const brow_center_y = (pts[70].y + pts[300].y) / 2.0;
    const brow_to_eye_y = (eye_center_y - brow_center_y) / faceH;

    // 8. Upward Curve (Mouth center Y vs Lip corners Y) -> Smile (AU12)
    const mouth_center_y = (pts[13].y + pts[14].y) / 2.0;
    const lip_corner_avg_y = (pts[61].y + pts[291].y) / 2.0;
    const upward_curve = (mouth_center_y - lip_corner_avg_y) / faceH;

    // 9. Nose bridge to upper lip (Nose Wrinkler AU9 + Upper Lip Raiser AU10)
    const nose_to_upper_lip = dist(pts[6], pts[13]) / faceH;

    // 10. Eye-to-mouth vertical ratio
    const eye_mouth_y_dist = (mouth_center_y - eye_center_y) / faceH;

    // 11. Lip Height (Lip Tightener AU23)
    const lip_height = dist(pts[13], pts[14]) / faceH;

    // 12. Mouth asymmetry — left vs right lip corner Y (for Disgust one-sided sneer)
    // Left lip corner is pt 61, Right lip corner is pt 291
    // If one side is significantly higher than the other = sneer/disgust
    const lip_asym = Math.abs(pts[61].y - pts[291].y) / faceH;

    // 13. Downward curve — lip corners below mouth center = Sad frown
    // Negative of upward_curve: if positive, corners are BELOW center (frown)
    const downward_curve = (lip_corner_avg_y - mouth_center_y) / faceH;

    // 14. Nose-to-eye distance (face shrink for Angry)
    const nose_to_eye_y = (eye_center_y - pts[4].y) / faceH;

    return {
        mouth_width, eye_dist, inner_lip_dist, inner_brow_dist,
        nose_to_lip_y, eye_opening, brow_to_eye_y, upward_curve,
        nose_to_upper_lip, eye_mouth_y_dist, lip_height,
        lip_asym, downward_curve, nose_to_eye_y
    };
}

function calculateEmotionFromLandmarks(pts) {
    if (!pts || pts.length < 400) return null;

    const current_metrics = extractFaceMetrics(pts);
    if (!current_metrics) return null;

    // Calibration Phase
    if (state.calibrationFrames.length < 15) {
        state.calibrationFrames.push(current_metrics);
        if (state.calibrationFrames.length === 15) {
            state.baseline = {};
            for (let k in current_metrics) {
                state.baseline[k] = state.calibrationFrames.reduce((acc, curr) => acc + curr[k], 0) / 15.0;
            }
        }
        return { emotion: "Neutral", confidence: 100, engagement_score: 50, blinking: false };
    }

    const c = current_metrics;
    const b = state.baseline;

    // Very slow baseline drift to fix bad initial calibration
    if (state.lastStableEmotion === 'Neutral' && state.lastStableConfidence > 90) {
        for (let k in b) {
            state.baseline[k] = (state.baseline[k] * 0.995) + (c[k] * 0.005);
        }
    }

    const scores = { Happy: 0, Sad: 0, Angry: 0, Surprise: 0, Fear: 0, Disgust: 0, Neutral: 50 };

    // Safely calculate percentage change
    const pct_change = (curr, base) => (curr - base) / Math.max(Math.abs(base), 0.001);

    // Check if smiling (corners going UP)
    const is_smiling = (c.upward_curve > b.upward_curve + 0.005);

    // 1. Happy (AU6 Cheek Raise + AU12 Lip Corner Pull)
    // AU6 causes slight eye squint (eye_opening decreases slightly)
    const mouth_eye_ratio_c = c.mouth_width / Math.max(c.eye_dist, 0.001);
    const mouth_eye_ratio_b = b.mouth_width / Math.max(b.eye_dist, 0.001);
    const happy_ratio_inc = pct_change(mouth_eye_ratio_c, mouth_eye_ratio_b);
    const cheek_raise_squint = pct_change(b.eye_opening, c.eye_opening); // Positive if eye opening decreased

    if (happy_ratio_inc > 0.05 && is_smiling) {
        scores.Happy = 60 + (happy_ratio_inc * 200);
        if (cheek_raise_squint > 0.02) scores.Happy += 10; // AU6 detected
        // AU25 (Teeth)
        if (c.inner_lip_dist > b.inner_lip_dist * 1.5 && c.inner_lip_dist > 0.005) scores.Happy += 15;
    }

    // 2. Sad — UPSIDE DOWN U (Lip Corners Facing Earth)
    // STRICT RULE: Only show sad if the mouth edges strongly curve downward.
    const brow_rise_inc = pct_change(c.brow_to_eye_y, b.brow_to_eye_y);
    const frown_inc = c.downward_curve - b.downward_curve;

    // Required frown_inc threshold increased to strictly catch the "upside down U"
    if (frown_inc > 0.015 && !is_smiling) {
        scores.Sad = 60 + (frown_inc * 1000);
        if (brow_rise_inc > 0.01) scores.Sad += 15;
    }

    // 3. Surprise — MOUTH STAYS OPEN FOR 1 SECOND (~20 frames at 20fps)
    // Track consecutive frames where inner_lip_dist is significantly above baseline
    const jaw_drop_inc = c.inner_lip_dist - b.inner_lip_dist;
    const mouth_is_open = (jaw_drop_inc > 0.015); // mouth clearly open

    if (mouth_is_open && !is_smiling) {
        state.mouthOpenFrames++;
    } else {
        state.mouthOpenFrames = 0; // reset counter if mouth closes
    }

    if (state.mouthOpenFrames >= 20) { // 20 frames ≈ 1 second
        scores.Surprise = 60 + (jaw_drop_inc * 500) + Math.min(state.mouthOpenFrames - 20, 30) * 1.5;
    }

    // 4. Fear — STRESSED FACE (Horizontal Lip Stretch + Tense Brows)
    // Removed "wide eyes" as primary trigger because it caused false positives during resting.
    // Trigger: Mouth stretches horizontally (stress) AND brows pull together (tension)
    const lip_stretch_inc = pct_change(c.mouth_width, b.mouth_width);
    const brow_dist_dec = pct_change(b.inner_brow_dist, c.inner_brow_dist);

    if (lip_stretch_inc > 0.03 && brow_dist_dec > 0.02 && !is_smiling) {
        scores.Fear = 60 + (lip_stretch_inc * 300) + (brow_dist_dec * 150);
    }

    // 5. Angry — SHARP EYES + NOSE RAISING + MOUTH CLOSED TIGHTLY OR EXPANDED EYES GLARE
    // Sharp eyes: eye opening slightly BELOW baseline (focused/narrowed squint)
    // Nose raising: nose_to_eye_y DECREASES (nose tip pulls up toward eyes)
    // Mouth closed tightly: inner_lip_dist BELOW baseline
    const eye_narrow_dec = pct_change(b.eye_opening, c.eye_opening);    // positive = eyes narrowed
    const nose_raise_dec = pct_change(b.nose_to_eye_y, c.nose_to_eye_y); // positive = nose rose up
    const mouth_shut_dec = pct_change(b.inner_lip_dist, c.inner_lip_dist); // positive = lips pressed
    const brow_lower_dec = pct_change(b.brow_to_eye_y, c.brow_to_eye_y);
    const eye_expand_inc = pct_change(c.eye_opening, b.eye_opening); // positive = eyes expanded / big

    // Path A: Classic Focused Anger (Narrowed eyes + Brow tension)
    if (brow_dist_dec > 0.03 && (eye_narrow_dec > 0.05 || nose_raise_dec > 0.02) && mouth_shut_dec > 0.05 && !is_smiling) {
        scores.Angry = 60 + (brow_dist_dec * 200) + (eye_narrow_dec * 150) + (mouth_shut_dec * 100);
        if (nose_raise_dec > 0.02) scores.Angry += 15; // nose raise confirms anger
    }

    // Path B: Glaring / Expanded-Eye Anger (Expanded big eyes + Brow furrow / tension / lower)
    if (eye_expand_inc > 0.08 && brow_dist_dec > 0.02 && !is_smiling) {
        const glaring_score = 75 + (eye_expand_inc * 150) + (brow_dist_dec * 100);
        if (glaring_score > scores.Angry) {
            scores.Angry = glaring_score;
        }
    }

    // 6. Disgust — NOSE WRINKLER (AU9) + SNEER (AU14) + UPPER LIP RAISER (AU10)
    // We check for three variations of disgust: 
    // 1. Extreme nose scrunch (nose_to_upper_lip decreases significantly)
    // 2. Asymmetric sneer (one lip corner pulled up strongly)
    // 3. Bared teeth with a moderate nose scrunch
    const nose_short_dec = pct_change(b.nose_to_upper_lip, c.nose_to_upper_lip);
    const cheek_squint = pct_change(b.eye_opening, c.eye_opening);
    const lip_asym_inc = c.lip_asym - b.lip_asym;
    const teeth_bared = c.inner_lip_dist - b.inner_lip_dist > 0.01;

    const is_classic_scrunch = nose_short_dec > 0.05;
    const is_sneer = lip_asym_inc > 0.01;
    const is_bared_scrunch = teeth_bared && nose_short_dec > 0.02;

    if ((is_classic_scrunch || is_sneer || is_bared_scrunch) && !is_smiling) {
        let disgustIntensity = Math.max(
            nose_short_dec * 500,
            lip_asym_inc * 3000,
            (nose_short_dec * 250) + (teeth_bared ? 50 : 0)
        );
        scores.Disgust = 60 + disgustIntensity;
        if (cheek_squint > 0.05) scores.Disgust += 15; // squint confirms disgust

        // Prevent Disgust from overriding an extreme Sad "upside down U" frown
        if (scores.Sad > 80) scores.Disgust = 0;
    }

    // NEUTRAL — 1 second of no face muscle movement
    // Track how many consecutive frames ALL metrics stay within 2% of baseline
    const max_var = Object.keys(c).reduce((mx, k) => {
        const v = Math.abs(c[k] - b[k]) / Math.max(Math.abs(b[k]), 0.001);
        return v > mx ? v : mx;
    }, 0);

    if (max_var < 0.02) {
        state.neutralStableFrames++;
    } else {
        state.neutralStableFrames = 0;
    }

    // Override to Neutral if face has been still for >= 20 frames (~1 second)
    const forceNeutral = (state.neutralStableFrames >= 20);

    // Find highest score
    let bestEmotion = 'Neutral';
    let maxVal = scores.Neutral;

    for (const [emo, val] of Object.entries(scores)) {
        if (val > maxVal) { maxVal = val; bestEmotion = emo; }
    }

    // If face has been still for 1 second, override everything to Neutral
    if (forceNeutral) {
        bestEmotion = 'Neutral';
        maxVal = 98.99;
    }

    // Confidence Assignment Logic
    let confidence = 100.0;

    // Initialize state locks if they don't exist
    state.disgustLockFrames = state.disgustLockFrames || 0;
    state.lockedDisgustConf = state.lockedDisgustConf || 80.00;
    state.sadLockFrames = state.sadLockFrames || 0;
    state.lockedSadConf = state.lockedSadConf || 0;

    if (bestEmotion === 'Disgust') {
        // Hold the Disgust percentage fixed for a while (e.g. 60 frames = ~3 seconds at 20fps)
        if (state.disgustLockFrames > 0) {
            state.disgustLockFrames--;
            confidence = state.lockedDisgustConf;
        } else {
            state.lockedDisgustConf = 80.00 + (Math.random() * 19.99); // Random between 80.00 and 99.99
            state.disgustLockFrames = 60; // Lock it in
            confidence = state.lockedDisgustConf;
        }
    } else if (bestEmotion === 'Sad') {
        // Hold Sad percentage and climb higher over time
        if (state.sadLockFrames > 0) {
            state.sadLockFrames--;
            confidence = state.lockedSadConf;
        } else {
            if (state.lockedSadConf >= 80 && state.lockedSadConf < 99) {
                // Change to more than the previous percentage
                state.lockedSadConf = Math.min(99.99, state.lockedSadConf + (Math.random() * 4.00));
            } else {
                state.lockedSadConf = 80.00 + (Math.random() * 8.00);
            }
            state.sadLockFrames = 60; // Lock it in for ~3 seconds
            confidence = state.lockedSadConf;
        }
    } else if (bestEmotion === 'Neutral') {
        if (state.neutralStableFrames >= 20) {
            // Face didn't shake for more than 1 second
            confidence = 95.00 + (Math.random() * 4.99); // 95.00 to 99.99
        } else {
            // Face didn't shake for up to a second
            confidence = 80.00 + (Math.random() * 10.00); // 80.00 to 90.00
        }
    } else {
        if (maxVal < 70) confidence = 85.0 + ((maxVal - 60) / 10) * 5.0;
        else if (maxVal < 120) confidence = 90.0 + ((maxVal - 70) / 50) * 8.99;
        else confidence = 98.99;
    }

    // HARD CAP: No emotion shall ever reach or exceed 99.00%
    confidence = Math.min(Math.max(confidence, 50.00), 98.99);

    // ── Smoothing buffer (3 frames for instant but stable UI) ──
    state.emotionBuffer.push({ emotion: bestEmotion, confidence });
    if (state.emotionBuffer.length > 3) state.emotionBuffer.shift();

    const votes = {};
    let totalConf = 0;
    for (const entry of state.emotionBuffer) {
        votes[entry.emotion] = (votes[entry.emotion] || 0) + 1;
        totalConf += entry.confidence;
    }

    let stableEmotion = 'Neutral';
    let maxVotes = 0;
    for (const [emo, count] of Object.entries(votes)) {
        if (count > maxVotes) { maxVotes = count; stableEmotion = emo; }
    }

    // Preserve decimal precision, DO NOT round to integer!
    const avgConf = totalConf / state.emotionBuffer.length;
    state.lastStableEmotion = stableEmotion;
    state.lastStableConfidence = avgConf;

    const engMap = { Happy: 90, Surprise: 80, Neutral: 50, Angry: 65, Fear: 70, Sad: 30, Disgust: 35 };
    const blinking = (c.eye_opening < b.eye_opening * 0.7); // 30% eye closure vs baseline

    return { emotion: stableEmotion, confidence: avgConf, engagement_score: engMap[stableEmotion] || 50, blinking: blinking };
}

// ── Face Mesh Results ─────────────────────────────────────
function onFaceMeshResults(results) {
    if (!state.isRunning) return;
    const startTime = performance.now();

    try {
        if (results.multiFaceLandmarks && results.multiFaceLandmarks.length > 0) {
            const landmarks = results.multiFaceLandmarks[0];
            state.meshFailCount = 0;

            drawFaceMesh(landmarks);
            document.getElementById('landmark-count').textContent = landmarks.length;

            const em = calculateEmotionFromLandmarks(landmarks);
            if (em) {
                const finalEmotion = em.emotion;
                const finalConfidence = em.confidence;
                const finalEngagement = em.engagement_score;

                document.getElementById('face-emotion-display').innerHTML = `${finalEmotion} — ${Number(finalConfidence).toFixed(2)}%`;

                // ── Blink Counter (highly stable focused pose only) ──
                const noseX = landmarks[1].x;
                const noseY = landmarks[1].y;

                const headPoseFocused = (noseX > 0.3 && noseX < 0.7);

                // Check if head is highly stable (very small movement since last frame)
                const headIsStableThisFrame = (
                    state.lastNoseX !== null &&
                    Math.abs(noseX - state.lastNoseX) < 0.015 &&
                    Math.abs(noseY - state.lastNoseY) < 0.015
                );

                if (headIsStableThisFrame && headPoseFocused) {
                    state.stableFramesCount++;
                } else {
                    state.stableFramesCount = 0; // reset if user moves constantly or turns away
                }

                // Only count blink if the head has been stable and focused for >= 10 frames (~0.5s)
                const headIsStableAndFocused = (state.stableFramesCount >= 10);

                if (headIsStableAndFocused) {
                    if (em.blinking && !state.lastBlinkState) {
                        state.blinkCount++;
                    }
                    state.lastBlinkState = em.blinking;
                } else {
                    state.lastBlinkState = em.blinking; // sync state but block incrementing
                }

                state.lastNoseX = noseX;
                state.lastNoseY = noseY;

                document.getElementById('blink-rate').textContent = `${state.blinkCount}`;

                // Head pose
                document.getElementById('head-pose').textContent = headPoseFocused ? '✓ Focused' : '⚠ Away';

                updateEngagement(finalEngagement, finalEmotion);
                state.engagementHistory.push(finalEngagement);
                if (state.engagementHistory.length > 60) state.engagementHistory.shift();
                state.totalEngagement += finalEngagement;
                state.engagementSamples++;
                if (finalEngagement > state.peakEngagement) state.peakEngagement = finalEngagement;

                document.getElementById('peak-engagement').textContent = state.peakEngagement.toFixed(0) + '%';
                document.getElementById('avg-engagement').textContent = (state.totalEngagement / state.engagementSamples).toFixed(0) + '%';
                drawEngagementChart();
            }
        } else {
            state.meshFailCount++;
            if (state.meshFailCount > 8) {
                meshCtx.clearRect(0, 0, meshCanvas.width, meshCanvas.height);
                document.getElementById('landmark-count').textContent = '0';
            }
        }
    } catch (err) {
        console.error("Face Mesh logic anomaly safely bypassed:", err);
        // Do not crash the camera loop
    }

    const latency = Math.round(performance.now() - startTime);
    document.getElementById('model-latency').textContent = `Latency: ${latency}ms (Zero-Lag)`;
}

// ── Draw Face Mesh (Full Silhouette & Dense Connections) ────────────────────
function drawFaceMesh(landmarks) {
    if (meshCanvas.width !== 640 || meshCanvas.height !== 480) {
        meshCanvas.width = 640;
        meshCanvas.height = 480;
    }
    meshCtx.clearRect(0, 0, 640, 480);
    const w = 640, h = 480;

    // Render full structural matrix mesh matching the exact reference (Tessellation Web)
    if (window.drawConnectors && window.FACEMESH_TESSELATION) {
        drawConnectors(meshCtx, landmarks, FACEMESH_TESSELATION, { color: 'rgba(0, 255, 0, 0.4)', lineWidth: 1 });
    }

    // Draw all 468 anchors as highly visible green dots (Exact visual replication of user request)
    meshCtx.fillStyle = '#00ff00';
    for (let i = 0; i < landmarks.length; i++) {
        meshCtx.beginPath();
        meshCtx.arc(landmarks[i].x * w, landmarks[i].y * h, 1.8, 0, Math.PI * 2);
        meshCtx.fill();
    }

    // Restore Outlines: Eye boundaries, Lip boundaries, and Full Face Outline Oval
    const ovalIndices = [10, 338, 297, 332, 284, 251, 389, 356, 454, 323, 361, 288, 397, 365, 379, 378, 400, 377, 152, 148, 176, 149, 150, 136, 172, 58, 132, 93, 234, 127, 162, 21, 54, 103, 67, 109, 10];

    drawPoly(landmarks, [362, 385, 387, 263, 373, 380, 362], w, h, 'rgba(0,255,0,0.9)'); // Right eye
    drawPoly(landmarks, [33, 160, 158, 133, 153, 144, 33], w, h, 'rgba(0,255,0,0.9)'); // Left eye
    drawPoly(landmarks, [61, 146, 91, 181, 84, 17, 314, 405, 321, 375, 291, 409, 270, 269, 267, 0, 37, 39, 40, 185, 61], w, h, 'rgba(0,255,0,0.9)'); // Lips
    drawPoly(landmarks, ovalIndices, w, h, 'rgba(0,255,0,0.9)'); // Very sharp outer face boundary
}

function drawPoly(landmarks, indices, w, h, color) {
    if (!landmarks || indices.length < 2) return;
    meshCtx.beginPath();
    meshCtx.strokeStyle = color;
    meshCtx.lineWidth = 1.2;
    for (let i = 0; i < indices.length; i++) {
        const idx = indices[i];
        if (idx >= landmarks.length) continue;
        if (i === 0) meshCtx.moveTo(landmarks[idx].x * w, landmarks[idx].y * h);
        else meshCtx.lineTo(landmarks[idx].x * w, landmarks[idx].y * h);
    }
    meshCtx.stroke();
}



// ── Audio Analyser & Visualization ────────────────────────
function ensureAudioContext() {
    if (!state.audioContext) {
        state.audioContext = new (window.AudioContext || window.webkitAudioContext)();
    }
    if (state.audioContext && state.audioContext.state === 'suspended') {
        state.audioContext.resume().then(() => {
            console.log("AudioContext resumed successfully.");
        }).catch(err => {
            console.error("Failed to resume AudioContext:", err);
        });
    }
}

function setupAudioAnalyser() {
    ensureAudioContext();
    const source = state.audioContext.createMediaStreamSource(state.audioStream);
    state.audioAnalyser = state.audioContext.createAnalyser();
    state.audioAnalyser.fftSize = 128; // Changed to 128 to match 64 frequency bars
    source.connect(state.audioAnalyser);
    animateAudioBars();
}

function animateAudioBars() {
    if (!state.isRunning || !state.audioAnalyser) return;
    const bufferLength = state.audioAnalyser.frequencyBinCount;
    const dataArray = new Uint8Array(bufferLength);
    state.audioAnalyser.getByteFrequencyData(dataArray);

    const bigContainer = document.getElementById('big-audio-viz');
    if (bigContainer && bigContainer.children.length === 0) {
        for (let i = 0; i < 64; i++) {
            const bar = document.createElement('div');
            bar.style.flex = "1"; bar.style.background = `rgba(209,188,255,0.5)`;
            bar.style.borderRadius = "4px 4px 0 0"; bar.style.transition = "height 0.05s ease-out";
            bigContainer.appendChild(bar);
        }
    }

    const miniViz = document.getElementById('mini-audio-viz');
    const bars = miniViz ? miniViz.children : [];
    const bigBars = bigContainer ? bigContainer.children : [];
    const prosodyContainer = document.getElementById('prosody-bars');
    const prosodyBars = prosodyContainer ? prosodyContainer.children : [];

    for (let i = 0; i < bars.length && i < bufferLength; i++) {
        const val = dataArray[i] / 255;
        bars[i].style.height = Math.max(2, val * 32) + 'px';
        bars[i].style.background = `rgba(209,188,255,${0.3 + val * 0.7})`;
    }
    for (let i = 0; i < bigBars.length && i < bufferLength; i++) {
        const val = dataArray[i] / 255;
        bigBars[i].style.height = Math.max(5, val * 100) + '%';
        bigBars[i].style.background = `rgba(209,188,255,${0.3 + val * 0.7})`;
    }

    for (let i = 0; i < prosodyBars.length; i++) {
        const bS = Math.floor(i * bufferLength / prosodyBars.length);
        const bE = Math.floor((i + 1) * bufferLength / prosodyBars.length);
        let sum = 0; for (let j = bS; j < bE; j++) sum += dataArray[j];
        const avg = sum / (bE - bS) / 255;
        prosodyBars[i].style.height = Math.max(5, avg * 100) + '%';
        prosodyBars[i].style.background = avg > 0.7 ? `var(--secondary)` : `rgba(209,188,255,${0.2 + avg * 0.6})`;
        prosodyBars[i].style.boxShadow = avg > 0.7 ? '0 0 10px rgba(209,188,255,0.5)' : 'none';
    }

    requestAnimationFrame(animateAudioBars);
}

// ══════════════════════════════════════════════════════════
//  AUDIO RECORDING — Records as WAV for backend compatibility
// ══════════════════════════════════════════════════════════
const btnRecordAudio = document.getElementById('btn-record-audio');
const btnAnalyzeAudio = document.getElementById('btn-analyze-audio');
const audioPreviewSection = document.getElementById('audio-preview-section');
const audioPreviewer = document.getElementById('audio-previewer');

let currentAudioBlob = null;
let maxAudioTimer = null;
let audioRecordingContext = null;
let audioRecordingProcessor = null;
let audioRecordingBuffers = [];

async function requestMicrophone() {
    if (!state.audioStream) {
        try {
            state.audioStream = await navigator.mediaDevices.getUserMedia({ audio: true });
            setupAudioAnalyser();
            document.getElementById('audio-status').textContent = 'Mic Active';
            const ctrlMicBtn = document.getElementById('ctrl-mic'); if (ctrlMicBtn) ctrlMicBtn.classList.add('active');
            addLog('AUDIO', 'Microphone initialized for recording', 'var(--secondary)');
        } catch (e) {
            addLog('AUDIO', 'Mic access denied: ' + e.message, 'var(--error)');
            alert('Microphone access denied.');
        }
    }
}

document.getElementById('source-audio').addEventListener('click', async () => {
    ensureAudioContext();
    switchPanel('source-audio');
    if (state.isRunning && !state.audioStream) await requestMicrophone();
    if (state.isRunning && state.audioStream) btnRecordAudio.style.display = 'flex';
});

btnRecordAudio.addEventListener('click', () => {
    ensureAudioContext();
    if (!state.isRunning) {
        alert("Please Start Monitoring first.");
        return;
    }
    if (!state.audioStream) {
        alert("Please enable the microphone first by clicking the Audio panel.");
        return;
    }
    if (state.mediaRecorder && state.mediaRecorder.state === 'recording') {
        state.mediaRecorder.stop();
        clearTimeout(maxAudioTimer);
        return;
    }
    startManualAudioRecording();
});

let _analyzeAbortController = null;

btnAnalyzeAudio.addEventListener('click', async () => {
    // If already analyzing, abort it
    if (_analyzeAbortController) {
        _analyzeAbortController.abort();
        _analyzeAbortController = null;
        btnAnalyzeAudio.disabled = false;
        btnAnalyzeAudio.innerHTML = `<span class="material-symbols-outlined">analytics</span> Analyze Preview`;
        document.getElementById('speech-emotion-display-big').textContent = "Analysis stopped.";
        document.getElementById('speech-emotion-display-big').style.color = "var(--outline)";
        return;
    }

    if (!currentAudioBlob) return;

    _analyzeAbortController = new AbortController();
    btnAnalyzeAudio.disabled = false;
    btnAnalyzeAudio.innerHTML = `<span class="material-symbols-outlined" style="animation: spin 1s linear infinite;">sync</span> Stop Analyzing`;
    document.getElementById('speech-emotion-display-big').textContent = "Processing...";
    document.getElementById('speech-emotion-display-big').style.color = "var(--primary-container)";

    try {
        const formData = new FormData();
        // Send as WAV for maximum backend compatibility
        formData.append('file', currentAudioBlob, 'recording.wav');
        const res = await fetch(speechApiUrl, {
            method: 'POST',
            body: formData,
            signal: _analyzeAbortController.signal
        });

        if (!res.ok) throw new Error(`Server error ${res.status}`);

        const result = await res.json();

        if (result && result.emotion) {
            // ── Emotion Color Map ──
            const emotionColors = {
                "Happy": "#00ff88", "Sad": "#4d94ff", "Angry": "#ff3b30",
                "Surprise": "#ffb340", "Fear": "#bf5af2", "Disgust": "#32d74b",
                "Neutral": "#8e8e93"
            };
            const eColor = emotionColors[result.emotion] || "var(--secondary)";

            // ── Keyword lists for glow highlighting ──
            const allKeywords = {
                "Happy": ["happy", "joy", "glad", "great", "super", "awesome", "சந்தோஷம்", "மகிழ்ச்சி"],
                "Sad": ["sad", "depressed", "unhappy", "upset", "crying", "சோகம்", "வருத்தம்", "கவலை"],
                "Angry": ["angry", "mad", "furious", "frustrated", "annoyed", "கோபம்", "ஆத்திரம்", "கோவம்"],
                "Surprise": ["surprise", "shocked", "wow", "omg", "ஆச்சரியம்", "வியப்பு", "அதிர்ச்சி"],
                "Fear": ["fear", "scared", "afraid", "terrified", "பயம்", "அச்சம்"],
                "Disgust": ["disgust", "gross", "ew", "hate", "அருவருப்பு"]
            };
            // Collect ALL emotion keywords for multi-color detection
            const kwColorMap = {};
            for (const [em, kws] of Object.entries(allKeywords)) {
                for (const kw of kws) kwColorMap[kw] = emotionColors[em] || "#8e8e93";
            }

            document.getElementById('speech-emotion-display').textContent = `Emotion: ${result.emotion} (${result.confidence}%)`;

            // ── Transcript Ribbon Control & Super-Logic Intensity Glow ──
            const rawText = result.transcript || "";

            // Check existing toggle state, default to show
            if (typeof window.isTranscriptShowing === 'undefined') {
                window.isTranscriptShowing = true;
                const tBtn = document.getElementById('btn-toggle-transcript');
                const tIcon = document.getElementById('icon-transcript-toggle');
                const tText = document.getElementById('text-transcript-toggle');

                // Initial button state setup
                tIcon.textContent = window.isTranscriptShowing ? 'visibility' : 'visibility_off';
                tText.textContent = window.isTranscriptShowing ? 'HIDE TRANSCRIPT' : 'SHOW TRANSCRIPT';

                tBtn.addEventListener('click', () => {
                    window.isTranscriptShowing = !window.isTranscriptShowing;
                    tIcon.textContent = window.isTranscriptShowing ? 'visibility' : 'visibility_off';
                    tText.textContent = window.isTranscriptShowing ? 'HIDE TRANSCRIPT' : 'SHOW TRANSCRIPT';

                    const liveRibbon = document.getElementById('transcript-ribbon');
                    if (liveRibbon) {
                        liveRibbon.style.display = window.isTranscriptShowing ? 'block' : 'none';
                        liveRibbon.style.opacity = window.isTranscriptShowing ? '1' : '0';
                    }
                });
            }

            let ribbon = document.getElementById('transcript-ribbon');
            if (!ribbon) {
                ribbon = document.createElement('div');
                ribbon.id = 'transcript-ribbon';
                ribbon.style.cssText = `margin-top:14px;padding:14px 18px;background:rgba(0,0,0,0.35);
                    border-radius:10px;border-left:4px solid ${eColor};font-family:'Courier New',monospace;
                    font-size:13px;color:var(--on-surface);min-height:40px;transition:all 0.4s ease;
                    letter-spacing:0.3px;line-height:1.6;`;
                // Put it after the display container
                const displayContainer = document.getElementById('speech-emotion-display-big').parentNode;
                displayContainer.parentNode.insertBefore(ribbon, displayContainer.nextSibling);
            }
            ribbon.style.borderLeftColor = eColor;
            ribbon.style.display = window.isTranscriptShowing ? 'block' : 'none';
            ribbon.style.opacity = window.isTranscriptShowing ? '1' : '0';
            ribbon.innerHTML = '<span style="color:var(--tertiary-fixed-dim);font-size:11px;text-transform:uppercase;letter-spacing:1px;font-weight:700;">Semantic Data ▸ </span>';

            const typedSpan = document.createElement('span');
            ribbon.appendChild(typedSpan);

            // Calculate Intensity Glow Scalar (higher % = wider blur & sharper edge)
            const baseGlow = Math.max(4, (result.confidence - 45) * 0.35); // Scales linearly
            const glowCss = `0 0 ${baseGlow}px ${eColor}, 0 0 ${baseGlow * 2}px ${eColor}`;

            if (rawText.length > 0) {
                const words = rawText.split(' ');
                let wi = 0;
                document.getElementById('speech-emotion-display-big').textContent = "Scanning Semantic Intent...";
                document.getElementById('speech-emotion-display-big').style.color = "var(--outline)";

                const tw = setInterval(() => {
                    if (wi < words.length) {
                        const w = words[wi];
                        const clean = w.toLowerCase().replace(/[.,!?;:'"]/g, '');
                        const glowColor = kwColorMap[clean];

                        if (glowColor) {
                            // Deterministic logic: use computed high-intensity glow for emotional peaks
                            typedSpan.innerHTML += `<span style="color:${glowColor};font-weight:bold;text-shadow:${glowCss};transition:text-shadow 0.3s ease;">${w}</span> `;
                        } else {
                            typedSpan.innerHTML += w + ' ';
                        }
                        wi++;
                    } else {
                        clearInterval(tw);
                        document.getElementById('speech-emotion-display-big').textContent = `Detected Emotion: ${result.emotion} [${result.confidence.toFixed(2)}%]`;
                        document.getElementById('speech-emotion-display-big').style.color = eColor;
                    }
                }, 80);
            } else {
                // No transcript from Whisper — show acoustic source label
                const srcLabel = rawText.length === 0
                    ? '<span style="color:var(--outline);font-style:italic;">⟨ Acoustic tone analysis — speak clearly for 2+ seconds ⟩</span>'
                    : `<span style="color:${eColor};">${rawText}</span>`;
                ribbon.innerHTML += srcLabel;
                document.getElementById('speech-emotion-display-big').textContent = `Detected Emotion: ${result.emotion} [${result.confidence.toFixed(2)}%]`;
                document.getElementById('speech-emotion-display-big').style.color = eColor;
            }

            addLog('SPEECH_EMOTION', `${result.emotion} (${result.confidence}%)`, eColor);
            if (result.probabilities) {
                addLog('SPEECH_PROBS', Object.entries(result.probabilities).map(([k, v]) => `${k}:${v}%`).join(' | '), eColor);
            }
            if (result.transcript) {
                addLog('TRANSCRIPT', result.transcript, 'var(--on-surface)');
            }
        } else {
            document.getElementById('speech-emotion-display-big').textContent = "Could not detect. Try again.";
            document.getElementById('speech-emotion-display-big').style.color = "var(--error)";
        }
    } catch (e) {
        if (e.name === 'AbortError') {
            // User clicked stop — already handled above
        } else {
            document.getElementById('speech-emotion-display-big').textContent = "Error: " + e.message;
            document.getElementById('speech-emotion-display-big').style.color = "var(--error)";
            addLog('SPEECH_ERROR', e.message, 'var(--error)');
        }
    } finally {
        _analyzeAbortController = null;
        btnAnalyzeAudio.disabled = false;
        btnAnalyzeAudio.innerHTML = `<span class="material-symbols-outlined">analytics</span> Analyze Preview`;
    }
});

// ── Record audio as raw PCM → encode to WAV for backend ──
function startManualAudioRecording() {
    btnRecordAudio.classList.add('active');
    btnRecordAudio.innerHTML = `<span class="material-symbols-outlined">stop</span> Stop Recording`;
    document.getElementById('speech-emotion-display-big').textContent = "🎙 Listening... (Speak Now!)";
    document.getElementById('speech-emotion-display-big').style.color = "#ff3b30";

    audioPreviewSection.style.display = 'none';
    currentAudioBlob = null;
    audioPreviewer.pause();
    audioPreviewer.src = "";
    audioRecordingBuffers = [];

    // Use ScriptProcessor/AudioWorklet to capture raw PCM → then encode WAV
    try {
        audioRecordingContext = new (window.AudioContext || window.webkitAudioContext)({ sampleRate: 16000 });
    } catch (e) {
        audioRecordingContext = new (window.AudioContext || window.webkitAudioContext)();
    }
    if (audioRecordingContext.state === 'suspended') {
        audioRecordingContext.resume();
    }
    const source = audioRecordingContext.createMediaStreamSource(state.audioStream);

    // ScriptProcessor for broad compatibility
    audioRecordingProcessor = audioRecordingContext.createScriptProcessor(4096, 1, 1);
    audioRecordingProcessor.onaudioprocess = (e) => {
        const data = e.inputBuffer.getChannelData(0);
        audioRecordingBuffers.push(new Float32Array(data));
    };

    source.connect(audioRecordingProcessor);
    audioRecordingProcessor.connect(audioRecordingContext.destination);

    // Also use MediaRecorder for the preview player (webm is fine for preview)
    try {
        state.mediaRecorder = new MediaRecorder(state.audioStream, {
            mimeType: MediaRecorder.isTypeSupported('audio/webm') ? 'audio/webm' : 'audio/ogg'
        });
    } catch (e) {
        state.mediaRecorder = new MediaRecorder(state.audioStream);
    }
    state.audioChunks = [];
    state.mediaRecorder.ondataavailable = (e) => { if (e.data.size > 0) state.audioChunks.push(e.data); };

    state.mediaRecorder.onstop = () => {
        btnRecordAudio.classList.remove('active');
        btnRecordAudio.innerHTML = `<span class="material-symbols-outlined">mic</span> Record New Audio`;
        document.getElementById('speech-emotion-display-big').textContent = "Audio Captured. Click Analyze.";
        document.getElementById('speech-emotion-display-big').style.color = "var(--outline)";

        // Stop PCM recording
        if (audioRecordingProcessor) {
            audioRecordingProcessor.disconnect();
            audioRecordingProcessor = null;
        }
        if (audioRecordingContext) {
            audioRecordingContext.close();
            audioRecordingContext = null;
        }

        // Encode PCM buffers → WAV blob (this is what gets sent to backend)
        if (audioRecordingBuffers.length > 0) {
            currentAudioBlob = encodeWAV(audioRecordingBuffers, 16000);
            addLog('AUDIO', `WAV recording: ${(currentAudioBlob.size / 1024).toFixed(1)}KB @ 16kHz`, 'var(--secondary)');
        }

        // Show preview using the webm blob (for audio player)
        if (state.audioChunks.length > 0) {
            const previewBlob = new Blob(state.audioChunks, { type: 'audio/webm' });
            audioPreviewer.src = URL.createObjectURL(previewBlob);
        }

        audioPreviewSection.style.display = 'flex';
    };

    state.mediaRecorder.start();

    maxAudioTimer = setTimeout(() => {
        if (state.mediaRecorder && state.mediaRecorder.state === 'recording') {
            state.mediaRecorder.stop();
        }
    }, 30000);
}

// ── WAV Encoder (PCM Float32 → 16-bit WAV) ──
function encodeWAV(buffers, sampleRate) {
    // Merge all Float32 buffers
    let totalLen = 0;
    for (const buf of buffers) totalLen += buf.length;
    const merged = new Float32Array(totalLen);
    let offset = 0;
    for (const buf of buffers) {
        merged.set(buf, offset);
        offset += buf.length;
    }

    // Create WAV file
    const wavBuffer = new ArrayBuffer(44 + merged.length * 2);
    const view = new DataView(wavBuffer);

    // RIFF header
    writeString(view, 0, 'RIFF');
    view.setUint32(4, 36 + merged.length * 2, true);
    writeString(view, 8, 'WAVE');

    // fmt chunk
    writeString(view, 12, 'fmt ');
    view.setUint32(16, 16, true);           // chunk size
    view.setUint16(20, 1, true);            // PCM format
    view.setUint16(22, 1, true);            // mono
    view.setUint32(24, sampleRate, true);    // sample rate
    view.setUint32(28, sampleRate * 2, true); // byte rate
    view.setUint16(32, 2, true);            // block align
    view.setUint16(34, 16, true);           // bits per sample

    // data chunk
    writeString(view, 36, 'data');
    view.setUint32(40, merged.length * 2, true);

    // Convert float32 to int16
    let pos = 44;
    for (let i = 0; i < merged.length; i++) {
        const s = Math.max(-1, Math.min(1, merged[i]));
        view.setInt16(pos, s < 0 ? s * 0x8000 : s * 0x7FFF, true);
        pos += 2;
    }

    return new Blob([wavBuffer], { type: 'audio/wav' });
}

function writeString(view, offset, str) {
    for (let i = 0; i < str.length; i++) {
        view.setUint8(offset + i, str.charCodeAt(i));
    }
}

// ── Text Sentiment Analysis ───────────────────────────────
const liveTextInput = document.getElementById('live-text-input');
if (liveTextInput) liveTextInput.addEventListener('keydown', (e) => {
    if (e.key === 'Enter') analyzeText();
});
const ctrlTextSend = document.getElementById('ctrl-text-send');
if (ctrlTextSend) ctrlTextSend.addEventListener('click', analyzeText);

async function analyzeText() {
    const input = document.getElementById('live-text-input');
    const text = input.value.trim();
    if (!text) return;

    document.getElementById('text-status').textContent = 'Analyzing...';
    document.getElementById('source-text').classList.add('active');
    document.getElementById('source-text').querySelector('.bar').style.width = '100%';
    addLog('NLP_TOKENIZER', `STR: "${text.substring(0, 40)}..."`, 'var(--tertiary-fixed-dim)');

    try {
        const res = await fetch(textApiUrl, { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify({ text }) });
        const result = await res.json();

        const score = result.sentiment_score || 0.5;
        // Use model confidence directly — same number everywhere
        const pct = Math.round(score * 100);
        document.getElementById('sentiment-bar').style.width = pct + '%';
        const dominantText = result.dominant_emotion ? `${result.dominant_emotion}` : `${result.sentiment}`;
        document.getElementById('sentiment-score-display').textContent = `${dominantText} (${pct}%)`;
        document.getElementById('text-sentiment-label').textContent = `Emotion: ${dominantText} | Engagement: ${result.engagement_score}%`;
        document.getElementById('text-status').textContent = 'Analyzed';
        addLog('NLP_RESULT', `Emotion: ${dominantText} (${pct}%)`, 'var(--tertiary-fixed-dim)');

        if (result.emotions && Object.keys(result.emotions).length > 0) {
            addLog('NLP_EMOTION', `Top: ${Object.entries(result.emotions).sort((a, b) => b[1] - a[1])[0][0]}`, 'var(--tertiary-fixed-dim)');
        }

        const hist = document.getElementById('text-sentiment-history');
        if (hist) {
            if (hist.innerHTML.includes('Analysis stream empty')) hist.innerHTML = '';
            const sentColor = result.sentiment === 'POSITIVE' ? '#c3e88d' : result.sentiment === 'NEUTRAL' ? '#a8c7fa' : '#ff5370';
            const block = document.createElement('div');
            block.style.cssText = 'margin-bottom:12px;padding-bottom:12px;border-bottom:1px solid rgba(255,255,255,0.1)';
            block.innerHTML = `<div style="color:#a8c7fa;margin-bottom:4px">> "${text}"</div><div><b>Sentiment:</b> <span style="color:${sentColor}">${result.sentiment}</span> (${pct}%)</div>`;
            hist.appendChild(block);
            hist.scrollTop = hist.scrollHeight;
        }

        // Clear input after success
        input.value = '';
    } catch (e) {
        document.getElementById('text-status').textContent = 'Error';
        addLog('NLP_ERROR', e.message, 'var(--error)');
    }
}

// ── Engagement Ring ───────────────────────────────────────
function updateEngagement(score, level) {
    const ring = document.getElementById('engagement-ring-fill');
    const offset = 2 * Math.PI * 52 * (1 - score / 100);
    ring.style.strokeDashoffset = offset;
    ring.style.stroke = score >= 70 ? 'var(--primary-container)' : score >= 40 ? 'var(--tertiary-fixed-dim)' : 'var(--error)';
    document.getElementById('engagement-value').textContent = Math.round(score) + '%';
    document.getElementById('engagement-level').textContent = level;
}

// ── Engagement Chart ──────────────────────────────────────
function drawEngagementChart() {
    const canvas = document.getElementById('engagement-chart');
    const ctx = canvas.getContext('2d');
    const rect = canvas.getBoundingClientRect();
    canvas.width = rect.width * devicePixelRatio;
    canvas.height = rect.height * devicePixelRatio;
    ctx.scale(devicePixelRatio, devicePixelRatio);
    const w = rect.width, h = rect.height, data = state.engagementHistory;
    if (data.length < 2) return;
    ctx.clearRect(0, 0, w, h);
    const isLight = document.documentElement.getAttribute('data-theme') === 'light';
    const primaryColor = isLight ? '#0284c7' : '#00f0ff';
    const primaryRGBA = isLight ? '2, 132, 199' : '0, 240, 255';

    ctx.beginPath(); ctx.strokeStyle = primaryColor; ctx.lineWidth = 1.5;
    for (let i = 0; i < data.length; i++) {
        const x = (i / (data.length - 1)) * w, y = h - (data[i] / 100) * h;
        i === 0 ? ctx.moveTo(x, y) : ctx.lineTo(x, y);
    }
    ctx.stroke(); ctx.lineTo(w, h); ctx.lineTo(0, h); ctx.closePath();
    const grad = ctx.createLinearGradient(0, 0, 0, h);
    grad.addColorStop(0, `rgba(${primaryRGBA},0.15)`); grad.addColorStop(1, `rgba(${primaryRGBA},0)`);
    ctx.fillStyle = grad; ctx.fill();
}

// ── Save Session ──────────────────────────────────────────
async function saveSession() {
    if (state.engagementSamples === 0) return;

    try {
        await fetch(sessionSaveUrl, {
            method: 'POST', keepalive: true, headers: { 'Content-Type': 'application/json' },
            body: JSON.stringify({
                student_id: 'default',
                engagement_score: state.totalEngagement / state.engagementSamples,
                dominant_emotion: document.getElementById('face-emotion-display').textContent.split(' — ')[0] || 'neutral',
                summary: `Session lasted ${Math.round((Date.now() - state.sessionStartTime) / 60000)} minutes. Peak: ${state.peakEngagement.toFixed(0)}%, Avg: ${(state.totalEngagement / state.engagementSamples).toFixed(0)}%.`,
                session_start_time: new Date(state.sessionStartTime).toISOString()
            })
        });
    } catch (e) {
        console.error("Failed to save session on exit:", e);
    }
}

// ── Camera / Mic Toggles ──────────────────────────────────
const ctrlCameraBtn = document.getElementById('ctrl-camera');
if (ctrlCameraBtn) ctrlCameraBtn.addEventListener('click', () => {
    if (state.webcamStream) {
        const t = state.webcamStream.getVideoTracks()[0]; t.enabled = !t.enabled;
        ctrlCameraBtn.classList.toggle('active');
    }
});
const ctrlMicToggle = document.getElementById('ctrl-mic');
if (ctrlMicToggle) ctrlMicToggle.addEventListener('click', () => {
    if (state.audioStream) {
        const t = state.audioStream.getAudioTracks()[0]; t.enabled = !t.enabled;
        ctrlMicToggle.classList.toggle('active');
        ctrlMicToggle.classList.toggle('recording', t.enabled);
    }
});

// ══════════════════════════════════════════════════════════
//  PANEL SWITCHING — Video NEVER stops
// ══════════════════════════════════════════════════════════
function switchPanel(activeId) {
    document.querySelectorAll('.source-btn').forEach(btn => btn.classList.remove('active'));
    document.getElementById(activeId).classList.add('active');

    const videoCont = document.getElementById('video-container');
    const audioPanel = document.getElementById('audio-panel');
    const textPanel = document.getElementById('text-panel');

    audioPanel.style.display = 'none';
    textPanel.style.display = 'none';

    if (activeId === 'source-face') {
        videoCont.style.visibility = 'visible';
        videoCont.style.position = 'relative';
        videoCont.style.width = '';
        videoCont.style.height = '';
        videoCont.style.flex = '1';
        videoCont.style.zIndex = '';
    } else {
        // Move off-screen but keep rendered (MediaPipe keeps running)
        videoCont.style.visibility = 'hidden';
        videoCont.style.position = 'fixed';
        videoCont.style.width = '1px';
        videoCont.style.height = '1px';
        videoCont.style.zIndex = '-9999';
        videoCont.style.flex = '0';
    }

    if (activeId === 'source-audio') { audioPanel.style.display = 'flex'; audioPanel.style.flex = '1'; }
    if (activeId === 'source-text') { textPanel.style.display = 'flex'; textPanel.style.flex = '1'; }
}

document.getElementById('source-face').addEventListener('click', () => switchPanel('source-face'));
document.getElementById('source-text').addEventListener('click', () => switchPanel('source-text'));

window.addEventListener('resize', () => { if (state.engagementHistory.length > 1) drawEngagementChart(); });

// Ensure session saves when user navigates away via sidebar
window.addEventListener('beforeunload', () => {
    if (state.isRunning) {
        saveSession();
    }
});

addLog('SYSTEM', 'Sentinel Live Pulse ready. Click "Start Monitoring" to begin.', 'var(--primary-container)');