document.addEventListener('DOMContentLoaded', async () => {
    // Initialize elements
    const videoElem = document.getElementById('video');
    const overlay = document.getElementById('overlay');
    const ctx = overlay.getContext('2d');
    const status = document.getElementById('status');
    const predictionSpan = document.getElementById('prediction');
    const confidenceBar = document.getElementById('confidenceBar');
    const datasetJSON = document.getElementById('datasetJSON');
    
    let labels = [];
    let recording = false;
    let recordingLabel = null;
    let predicting = false;
    let knnK = 5;
    let lastSpoken = null;

    // Set initial status
    setStatus('Initializing camera...');

    // === Utility Functions ===
    function setStatus(s) { 
        status.textContent = `Status: ${s}`; 
    }

    function speak(text) {
        if ('speechSynthesis' in window && text !== lastSpoken) {
            lastSpoken = text;
            const msg = new SpeechSynthesisUtterance(text);
            msg.rate = 1; 
            msg.pitch = 1;
            speechSynthesis.cancel();
            speechSynthesis.speak(msg);
        }
    }

    // === Landmark Processing ===
    function landmarksToVector(landmarks) {
        if (!landmarks || landmarks.length === 0) return null;
        
        const wrist = landmarks[0];
        const ref = landmarks[9] || landmarks[8];
        const dx = ref.x - wrist.x;
        const dy = ref.y - wrist.y;
        const scale = Math.hypot(dx, dy) || 1;
        
        const vec = [];
        for (let p of landmarks) {
            vec.push(
                (p.x - wrist.x) / scale,
                (p.y - wrist.y) / scale,
                (p.z - wrist.z) / scale
            );
        }
        return vec;
    }

    function euclid(a, b) {
        let s = 0;
        for (let i = 0; i < a.length; i++) { 
            const d = a[i] - b[i]; 
            s += d * d; 
        }
        return Math.sqrt(s);
    }

    function knnPredict(vec) {
        const all = [];
        for (const lab of labels) {
            for (const ex of lab.examples) {
                all.push({ label: lab.name, dist: euclid(vec, ex) });
            }
        }
        
        if (!all.length) return { label: null, confidence: 0 };
        
        all.sort((a, b) => a.dist - b.dist);
        const k = Math.min(knnK, all.length);
        const top = all.slice(0, k);
        
        const counts = {};
        for (const t of top) counts[t.label] = (counts[t.label] || 0) + 1;
        
        let best = null, bestCount = 0;
        for (const l in counts) {
            if (counts[l] > bestCount) {
                best = l;
                bestCount = counts[l];
            }
        }
        
        return { 
            label: best, 
            confidence: bestCount / k 
        };
    }

    // === UI: Labels Management ===
    document.getElementById('addLabel').addEventListener('click', () => {
        const name = document.getElementById('labelInput').value.trim();
        if (!name) return alert('Please enter a label name');
        if (labels.find(l => l.name === name)) return alert('Label already exists');
        
        labels.push({ name, examples: [] });
        renderLabels();
        document.getElementById('labelInput').value = '';
    });

    function renderLabels() {
        const labelsArea = document.getElementById('labelsArea');
        labelsArea.innerHTML = '';
        
        labels.forEach((lab, idx) => {
            const div = document.createElement('div');
            div.className = 'flex items-center justify-between bg-gray-700 p-2 rounded-lg';
            
            const labelBtn = document.createElement('button');
            labelBtn.className = `flex items-center gap-2 px-3 py-1 rounded-md transition ${
                recordingLabel === lab.name ? 'bg-teal-600 text-white' : 'bg-gray-600 hover:bg-gray-500'
            }`;
            labelBtn.innerHTML = `
                <i data-feather="${lab.name.length > 1 ? 'type' : 'hash'}" width="16"></i>
                ${lab.name} <span class="text-xs opacity-75">(${lab.examples.length})</span>
            `;
            labelBtn.addEventListener('click', () => {
                recordingLabel = lab.name;
                renderLabels();
            });
            
            const deleteBtn = document.createElement('button');
            deleteBtn.className = 'p-1 text-red-400 hover:text-red-300 rounded-full';
            deleteBtn.innerHTML = '<i data-feather="trash-2" width="16"></i>';
            deleteBtn.addEventListener('click', () => {
                if (confirm(`Delete label "${lab.name}"?`)) {
                    labels.splice(idx, 1);
                    if (recordingLabel === lab.name) recordingLabel = null;
                    renderLabels();
                }
            });
            
            div.appendChild(labelBtn);
            div.appendChild(deleteBtn);
            labelsArea.appendChild(div);
        });
        
        datasetJSON.value = JSON.stringify(labels, null, 2);
        feather.replace();
    }

    // === Data Management ===
    document.getElementById('saveBtn').addEventListener('click', () => {
        if (labels.length === 0) return alert('No data to save');
        
        const blob = new Blob([JSON.stringify(labels)], { type: 'application/json' });
        const url = URL.createObjectURL(blob);
        
        const a = document.createElement('a');
        a.href = url;
        a.download = 'handspeak_dataset.json';
        document.body.appendChild(a);
        a.click();
        document.body.removeChild(a);
        URL.revokeObjectURL(url);
        
        setStatus('Dataset saved');
    });

    document.getElementById('loadBtn').addEventListener('click', () => {
        document.getElementById('fileInput').click();
    });

    document.getElementById('fileInput').addEventListener('change', (e) => {
        const file = e.target.files[0];
        if (!file) return;
        
        const reader = new FileReader();
        reader.onload = () => {
            try {
                const data = JSON.parse(reader.result);
                if (!Array.isArray(data)) throw new Error('Invalid format');
                
                labels = data.map(l => ({ 
                    name: l.name, 
                    examples: l.examples || [] 
                }));
                
                renderLabels();
                setStatus('Dataset loaded successfully');
            } catch (err) {
                alert('Error loading file: ' + err.message);
            }
        };
        reader.readAsText(file);
    });

    // === Recording & Prediction ===
    document.getElementById('toggleRec').addEventListener('click', () => {
        recording = !recording;
        
        if (recording && !recordingLabel) {
            alert('Please select a label first');
            recording = false;
            return;
        }
        
        setStatus(recording ? `Recording examples for "${recordingLabel}"` : 'Ready');
        document.getElementById('toggleRec').textContent = recording ? 
            'Stop Recording' : 'Start Recording Examples';
            
        document.getElementById('toggleRec').className = recording ? 
            'w-full bg-red-600 hover:bg-red-500 text-white px-4 py-3 rounded-lg font-medium transition' :
            'w-full bg-blue-600 hover:bg-blue-500 text-white px-4 py-3 rounded-lg font-medium transition';
    });

    document.getElementById('predictToggle').addEventListener('click', () => {
        predicting = !predicting;
        
        if (predicting && labels.length === 0) {
            alert('Please add some labels and examples first');
            predicting = false;
            return;
        }
        
        setStatus(predicting ? 'Predicting...' : 'Ready');
        document.getElementById('predictToggle').textContent = predicting ? 
            'Stop Predicting' : 'Start Predicting';
            
        document.getElementById('predictToggle').className = predicting ? 
            'w-full bg-purple-700 hover:bg-purple-600 text-white px-4 py-3 rounded-lg font-medium transition' :
            'w-full bg-purple-600 hover:bg-purple-500 text-white px-4 py-3 rounded-lg font-medium transition';
    });

    // === MediaPipe Hands Setup ===
    const hands = new Hands({ 
        locateFile: (file) => `https://cdn.jsdelivr.net/npm/@mediapipe/hands/${file}` 
    });
    
    hands.setOptions({
        maxNumHands: 1,
        modelComplexity: 1,
        minDetectionConfidence: 0.7,
        minTrackingConfidence: 0.6
    });
    
    hands.onResults(onResults);
    
    const camera = new Camera(videoElem, {
        onFrame: async () => {
            await hands.send({ image: videoElem });
        },
        width: 640,
        height: 480
    });
    
    camera.start();
    
    // Results Handler
    function onResults(results) {
        ctx.save();
        ctx.clearRect(0, 0, overlay.width, overlay.height);
        ctx.drawImage(results.image, 0, 0, overlay.width, overlay.height);
        
        if (results.multiHandLandmarks) {
            for (const landmarks of results.multiHandLandmarks) {
                drawConnectors(ctx, landmarks, HAND_CONNECTIONS, {
                    color: '#10B981',
                    lineWidth: 4
                });
                
                drawLandmarks(ctx, landmarks, {
                    color: '#F59E0B',
                    lineWidth: 2,
                    radius: (data) => {
                        return lerp(data.from.z, -0.15, 0.1, 5, 1);
                    }
                });
            }
        }
        
        ctx.restore();
        
        // Process landmarks for recording/prediction