// /* ================================================================ 
//    1. WELCOME VOICE & INITIALIZATION
// ================================================================ */
// window.onload = () => {
//     if (sessionStorage.getItem('isShuttingDown') === 'true') {
//         sessionStorage.removeItem('isShuttingDown');
//         return;
//     }
    
//     // Welcome sound & speech logic
//     setTimeout(() => {
//         const nameElement = document.getElementById('user-name-data');
//         let actualName = (nameElement && nameElement.innerText.trim() !== "") ? nameElement.innerText.trim() : "User";
        
//         const message = `Welcome ${actualName} to the Voice Vision world.`;
//         const speech = new SpeechSynthesisUtterance(message);
//         speech.rate = 0.9;
//         window.speechSynthesis.speak(speech);
//     }, 1500);
// };

// /* ================================================================ 
//    2. DASHBOARD DYNAMIC CONTROLS (POWER ON / OFF)
// ================================================================ */
// let cameraOn = false;
// let isDetecting = false;

// async function handlePowerOn() {
//     const video = document.getElementById('video');
//     const cameraBox = document.getElementById('cameraBox');
//     const powerBtn = document.getElementById('powerBtn');
    
//     try {
//         // Muted hona zaroori hai browser policy ke liye
//         const stream = await navigator.mediaDevices.getUserMedia({ 
//             video: { width: 640, height: 480 } 
//         });
//         video.srcObject = stream;
//         cameraOn = true;
        
//         cameraBox.style.display = 'block';
//         powerBtn.style.display = 'none';
//         document.getElementById('startDetectBtn').style.display = 'inline-block';
//         document.getElementById('powerOffBtn').style.display = 'inline-block';
        
//         window.speechSynthesis.speak(new SpeechSynthesisUtterance("System online."));
//     } catch (err) {
//         alert("Camera permission denied!");
//         console.error(err);
//     }
// }

// function handlePowerOff() {
//     sessionStorage.setItem('isShuttingDown', 'true');
//     window.location.reload(); 
// }

// /* ================================================================ 
//    3. DETECTION LOGIC (Cloud Optimized)
// ================================================================ */
// function handleStartDetection() {
//     isDetecting = true;
//     document.getElementById('modeButtonsGroup').style.display = 'flex';
//     document.getElementById('startDetectBtn').style.display = 'none';
    
//     window.speechSynthesis.speak(new SpeechSynthesisUtterance("Detection started."));
    
//     // Detection loop shuru karein
//     captureAndSend();
// }

// async function captureAndSend() {
//     if (!cameraOn || !isDetecting) return;

//     const video = document.getElementById('video');
//     const canvas = document.createElement('canvas'); // Arzi canvas frame lene ke liye
//     canvas.width = 640;
//     canvas.height = 480;
//     const ctx = canvas.getContext('2d');
    
//     ctx.drawImage(video, 0, 0, 640, 480);
//     const dataUrl = canvas.toDataURL('image/jpeg', 0.6); // Quality kam taake fast transfer ho

//     try {
//         const response = await fetch('/process_frame', {
//             method: 'POST',
//             headers: { 'Content-Type': 'application/json' },
//             body: JSON.stringify({ image: dataUrl })
//         });

//         const result = await response.json();
        
//         if (result.detections) {
//             // Screen par boxes draw karne wala function
//             drawDetections(result.detections);
            
//             // Agar koi object milay to bolein
//             if (result.detections.length > 0) {
//                 const labels = result.detections.map(d => d.label).join(", ");
//                 // Sirf tab bolein jab naya object aaye (optional)
//                 // window.speechSynthesis.speak(new SpeechSynthesisUtterance("I see " + labels));
//             }
//         }
//     } catch (error) {
//         console.log("Error sending frame:", error);
//     }

//     // Har 1 second baad agla frame bhejein (Cloud ke liye 1s safe hai)
//     if (isDetecting) setTimeout(captureAndSend, 1000);
// }

// // Canvas par Boxes draw karne ka function
// function drawDetections(detections) {
//     const canvas = document.getElementById('detectionCanvas');
//     if (!canvas) return;
//     const ctx = canvas.getContext('2d');
//     ctx.clearRect(0, 0, canvas.width, canvas.height); // Purane boxes saaf karein

//     detections.forEach(det => {
//         const [x1, y1, x2, y2] = det.box;
        
//         // Box style
//         ctx.strokeStyle = "#00FF00";
//         ctx.lineWidth = 3;
//         ctx.strokeRect(x1, y1, x2 - x1, y2 - y1);

//         // Label style
//         ctx.fillStyle = "#00FF00";
//         ctx.font = "18px Arial";
//         ctx.fillText(`${det.label} (${Math.round(det.confidence * 100)}%)`, x1, y1 > 20 ? y1 - 5 : y1 + 20);
//     });
// }

// function logout() {
//     window.location.href = "/logout";
// }


/* ================================================================ 
   1. GLOBAL VARIABLES & VOICE SETTINGS
================================================================ */
let cameraOn = false;
let isDetecting = false;
let isProcessing = false;
let lastSpokenTime = 0; // Smoothness ke liye
let lastMessage = "";

function speak(text, force = false) {
    const now = Date.now();
    // Smoothness: Har 2 second se pehle dobara mat bolein (agar STOP na ho)
    if (!force && (now - lastSpokenTime < 2000)) return; 
    if (text === lastMessage && !force) return;

    window.speechSynthesis.cancel();
    let msg = new SpeechSynthesisUtterance(text);
    msg.rate = 0.9; // Fast se slow kar diya (insani awaz)
    msg.pitch = 1.0;
    
    lastSpokenTime = now;
    lastMessage = text;
    window.speechSynthesis.speak(msg);
}

/* ================================================================ 
   2. POWER OFF & LOGOUT (THE RESET FIX)
================================================================ */
async function stopSystemProperly() {
    isDetecting = false;
    cameraOn = false;
    
    // Camera Hardware Release
    const video = document.getElementById('video');
    if (video && video.srcObject) {
        video.srcObject.getTracks().forEach(track => track.stop());
        video.srcObject = null;
    }
    window.speechSynthesis.cancel();
}

async function handlePowerOff() {
    speak("System shutting down. Please wait.", true);
    await stopSystemProperly();
    setTimeout(() => {
        window.location.replace(window.location.href); // Hard reload
    }, 1000);
}

async function logout() {
    speak("Logging out. Goodbye.", true);
    await stopSystemProperly();
    setTimeout(() => {
        window.location.replace("/logout"); // Server-side logout
    }, 1000);
}

/* ================================================================ 
   3. DETECTION LOGIC (WITH SMOOTHING)
================================================================ */
async function handlePowerOn() {
    const video = document.getElementById('video');
    try {
        const stream = await navigator.mediaDevices.getUserMedia({ video: { width: 640, height: 480 } });
        video.srcObject = stream;
        cameraOn = true;
        document.getElementById('powerBtn').style.display = 'none';
        document.getElementById('startDetectBtn').style.display = 'inline-block';
        document.getElementById('powerOffBtn').style.display = 'inline-block';
        speak("System Online.", true);
    } catch (err) {
        alert("Camera error. Please refresh.");
    }
}

function handleStartDetection() {
    isDetecting = true;
    document.getElementById('modeButtonsGroup').style.display = 'flex';
    document.getElementById('startDetectBtn').style.display = 'none';
    speak("Detection Active.", true);
    captureLoop();
}

async function captureLoop() {
    if (!cameraOn || !isDetecting) return;
    if (isProcessing) {
        setTimeout(captureLoop, 200);
        return;
    }

    const video = document.getElementById('video');
    const canvas = document.createElement('canvas');
    canvas.width = 640; canvas.height = 480;
    canvas.getContext('2d').drawImage(video, 0, 0, 640, 480);
    
    isProcessing = true;
    try {
        const response = await fetch('/process_frame', {
            method: 'POST',
            headers: { 'Content-Type': 'application/json' },
            body: JSON.stringify({ image: canvas.toDataURL('image/jpeg', 0.4) })
        });
        const result = await response.json();
        if (result.detections && isDetecting) {
            updateUI(result.detections);
        }
    } catch (e) { console.log("Loop skip..."); }
    
    isProcessing = false;
    // Delay barha diya taake system par bojh na paray
    setTimeout(captureLoop, 800); 
}

function updateUI(detections) {
    const canvas = document.getElementById('detectionCanvas');
    const ctx = canvas.getContext('2d');
    ctx.clearRect(0, 0, canvas.width, canvas.height);

    if (detections.length > 0) {
        let obj = detections[0];
        // Visuals
        ctx.strokeStyle = "#00FF00"; ctx.lineWidth = 4;
        ctx.strokeRect(obj.x, obj.y, obj.w, obj.h);
        ctx.fillStyle = "#00FF00"; ctx.font = "bold 20px Arial";
        ctx.fillText(obj.label.toUpperCase(), obj.x, obj.y - 10);

        // VI Logic
        let direction = obj.x + (obj.w/2) < 213 ? "on your left" : (obj.x + (obj.w/2) > 426 ? "on your right" : "in front");
        let area = (obj.w * obj.h) / (640*480);
        let msg = area > 0.4 ? `STOP! ${obj.label} very close` : `${obj.label} ${direction}`;
        speak(msg, area > 0.4); // Force speak if very close
    }
}