script.js

// Audio Context and State
let audioContext = null;
let isPlaying = false;
let currentMode = 'spatial'; // 'spatial' or 'monaural'
let rampMode = 'none'; // 'none', 'up', 'down'
let rampDuration = 60;
let activeNoiseType = null;

// Nodes
let binauralNodes = {
    leftOsc: null,
    rightOsc: null,
    leftGain: null,
    rightGain: null,
    merger: null,
    masterGain: null,
    modulator: null // For monaural
};

let noiseNodes = {
    leftBuffer: null,
    rightBuffer: null,
    leftSource: null,
    rightSource: null,
    leftGain: null,
    rightGain: null,
    leftPanner: null,
    rightPanner: null,
    masterGain: null,
    filter: null
};

let visualizer = {
    analyser: null,
    canvas: null,
    ctx: null,
    animationId: null
};

// Initialize Audio Context
function initAudioContext() {
    if (!audioContext) {
        audioContext = new (window.AudioContext || window.webkitAudioContext)();
        setupVisualizer();
    }
    if (audioContext.state === 'suspended') {
        audioContext.resume();
    }
}

// Setup Visualizer
function setupVisualizer() {
    const canvas = document.getElementById('audioVisualizer');
    const ctx = canvas.getContext('2d');
    
    // Handle high DPI displays
    const dpr = window.devicePixelRatio || 1;
    const rect = canvas.getBoundingClientRect();
    canvas.width = rect.width * dpr;
    canvas.height = rect.height * dpr;
    ctx.scale(dpr, dpr);
    
    visualizer.canvas = canvas;
    visualizer.ctx = ctx;
    
    visualizer.analyser = audioContext.createAnalyser();
    visualizer.analyser.fftSize = 2048;
    visualizer.analyser.smoothingTimeConstant = 0.8;
    
    drawVisualizer();
}

function drawVisualizer() {
    if (!visualizer.ctx) return;
    
    const { ctx, canvas, analyser } = visualizer;
    const width = canvas.width / (window.devicePixelRatio || 1);
    const height = canvas.height / (window.devicePixelRatio || 1);
    
    ctx.fillStyle = 'rgba(0, 0, 0, 0.2)';
    ctx.fillRect(0, 0, width, height);
    
    if (isPlaying && analyser) {
        const bufferLength = analyser.frequencyBinCount;
        const dataArray = new Uint8Array(bufferLength);
        analyser.getByteFrequencyData(dataArray);
        
        const barWidth = (width / bufferLength) * 2.5;
        let barHeight;
        let x = 0;
        
        for (let i = 0; i < bufferLength; i++) {
            barHeight = (dataArray[i] / 255) * height * 0.8;
            
            // Create gradient for bars
            const gradient = ctx.createLinearGradient(0, height, 0, height - barHeight);
            gradient.addColorStop(0, 'rgba(6, 182, 212, 0.8)'); // Cyan
            gradient.addColorStop(0.5, 'rgba(168, 85, 247, 0.8)'); // Purple
            gradient.addColorStop(1, 'rgba(236, 72, 153, 0.8)'); // Pink
            
            ctx.fillStyle = gradient;
            ctx.fillRect(x, height - barHeight, barWidth, barHeight);
            
            // Add glow effect
            ctx.shadowBlur = 10;
            ctx.shadowColor = 'rgba(236, 72, 153, 0.5)';
            
            x += barWidth + 1;
        }
        ctx.shadowBlur = 0;
    } else {
        // Idle animation
        const time = Date.now() * 0.001;
        ctx.strokeStyle = 'rgba(6, 182, 212, 0.3)';
        ctx.lineWidth = 2;
        ctx.beginPath();
        
        for (let x = 0; x < width; x++) {
            const y = height / 2 + Math.sin(x * 0.01 + time) * 20 * Math.sin(time * 0.5);
            if (x === 0) ctx.moveTo(x, y);
            else ctx.lineTo(x, y);
        }
        ctx.stroke();
    }
    
    visualizer.animationId = requestAnimationFrame(drawVisualizer);
}

// Binaural Beat Generation
function createBinauralBeats() {
    const carrier = parseFloat(document.getElementById('carrierSlider').value);
    const beat = parseFloat(document.getElementById('beatSlider').value);
    
    // Cleanup existing
    stopBinaural();
    
    // Create nodes
    binauralNodes.masterGain = audioContext.createGain();
    binauralNodes.masterGain.connect(audioContext.destination);
    binauralNodes.masterGain.connect(visualizer.analyser);
    
    if (currentMode === 'spatial') {
        // Spatial/Binaural mode: Different frequencies per ear
        binauralNodes.leftOsc = audioContext.createOscillator();
        binauralNodes.rightOsc = audioContext.createOscillator();
        binauralNodes.leftGain = audioContext.createGain();
        binauralNodes.rightGain = audioContext.createGain();
        binauralNodes.merger = audioContext.createChannelMerger(2);
        
        // Left ear: carrier
        binauralNodes.leftOsc.frequency.value = carrier;
        binauralNodes.leftOsc.connect(binauralNodes.leftGain);
        binauralNodes.leftGain.connect(binauralNodes.merger, 0, 0);
        
        // Right ear: carrier + beat
        binauralNodes.rightOsc.frequency.value = carrier + beat;
        binauralNodes.rightOsc.connect(binauralNodes.rightGain);
        binauralNodes.rightGain.connect(binauralNodes.merger, 0, 1);
        
        binauralNodes.merger.connect(binauralNodes.masterGain);
        
        binauralNodes.leftOsc.start();
        binauralNodes.rightOsc.start();
    } else {
        // Monaural mode: Amplitude modulation at beat frequency
        binauralNodes.leftOsc = audioContext.createOscillator();
        binauralNodes.modulator = audioContext.createOscillator();
        binauralNodes.modulatorGain = audioContext.createGain();
        
        // Carrier tone
        binauralNodes.leftOsc.frequency.value = carrier;
        
        // Modulator for amplitude
        binauralNodes.modulator.frequency.value = beat;
        binauralNodes.modulatorGain.gain.value = 0.5; // Modulation depth
        
        // Connect modulator to gain
        binauralNodes.modulator.connect(binauralNodes.modulatorGain.gain);
        
        // Create constant offset for gain
        const constantOffset = audioContext.createGain();
        constantOffset.gain.value = 0.5;
        binauralNodes.leftOsc.connect(constantOffset);
        constantOffset.connect(binauralNodes.modulatorGain);
        
        // Connect to both channels equally (monaural)
        binauralNodes.merger = audioContext.createChannelMerger(2);
        binauralNodes.modulatorGain.connect(binauralNodes.merger, 0, 0);
        binauralNodes.modulatorGain.connect(binauralNodes.merger, 0, 1);
        binauralNodes.merger.connect(binauralNodes.masterGain);
        
        binauralNodes.leftOsc.start();
        binauralNodes.modulator.start();
    }
    
    // Apply ramping
    applyRamp(binauralNodes.masterGain.gain, 0.3);
}

function stopBinaural() {
    if (binauralNodes.leftOsc) {
        try { binauralNodes.leftOsc.stop(); } catch(e) {}
        binauralNodes.leftOsc = null;
    }
    if (binauralNodes.rightOsc) {
        try { binauralNodes.rightOsc.stop(); } catch(e) {}
        binauralNodes.rightOsc = null;
    }
    if (binauralNodes.modulator) {
        try { binauralNodes.modulator.stop(); } catch(e) {}
        binauralNodes.modulator = null;
    }
    if (binauralNodes.masterGain) {
        binauralNodes.masterGain.disconnect();
    }
}

// Noise Generation (Always Spatial)
function createNoise(type) {
    stopNoise();
    activeNoiseType = type;
    
    const bufferSize = 2 * audioContext.sampleRate; // 2 seconds buffer
    const numChannels = 2; // Stereo
    const buffer = audioContext.createBuffer(numChannels, bufferSize, audioContext.sampleRate);
    
    // Generate noise data
    for (let channel = 0; channel < numChannels; channel++) {
        const data = buffer.getChannelData(channel);
        
        if (type === 'white') {
            // White noise: random -1 to 1
            for (let i = 0; i < bufferSize; i++) {
                data[i] = Math.random() * 2 - 1;
            }
        } else if (type === 'pink') {
            // Pink noise: 1/f using Paul Kellet's method
            let b0 = 0, b1 = 0, b2 = 0, b3 = 0, b4 = 0, b5 = 0, b6 = 0;
            for (let i = 0; i < bufferSize; i++) {
                const white = Math.random() * 2 - 1;
                b0 = 0.99886 * b0 + white * 0.0555179;
                b1 = 0.99332 * b1 + white * 0.0750759;
                b2 = 0.96900 * b2 + white * 0.1538520;
                b3 = 0.86650 * b3 + white * 0.3104856;
                b4 = 0.55000 * b4 + white * 0.5329522;
                b5 = -0.7616 * b5 - white * 0.0168980;
                data[i] = b0 + b1 + b2 + b3 + b4 + b5 + b6 + white * 0.5362;
                data[i] *= 0.11; // Normalize
                b6 = white * 0.115926;
            }
        } else if (type === 'brown') {
            // Brown noise: 1/f² (integration of white noise)
            let lastOut = 0;
            for (let i = 0; i < bufferSize; i++) {
                const white = Math.random() * 2 - 1;
                data[i] = (lastOut + (0.02 * white)) / 1.02;
                lastOut = data[i];
                data[i] *= 3.5; // Normalize
            }
        }
    }
    
    // Create spatial setup
    noiseNodes.masterGain = audioContext.createGain();
    noiseNodes.leftSource = audioContext.createBufferSource();
    noiseNodes.rightSource = audioContext.createBufferSource();
    noiseNodes.leftGain = audioContext.createGain();
    noiseNodes.rightGain = audioContext.createGain();
    noiseNodes.leftPanner = audioContext.createStereoPanner();
    noiseNodes.rightPanner = audioContext.createStereoPanner();
    
    // Set up looping
    noiseNodes.leftSource.buffer = buffer;
    noiseNodes.rightSource.buffer = buffer;
    noiseNodes.leftSource.loop = true;
    noiseNodes.rightSource.loop = true;
    
    // Get spatial width
    const spatialWidth = parseInt(document.getElementById('spatialWidthSlider').value) / 100;
    const panValue = spatialWidth; // 0 = center, 1 = full side
    
    // Left channel fully left
    noiseNodes.leftPanner.pan.value = -panValue;
    noiseNodes.leftSource.connect(noiseNodes.leftGain);
    noiseNodes.leftGain.connect(noiseNodes.leftPanner);
    noiseNodes.leftPanner.connect(noiseNodes.masterGain);
    
    // Right channel fully right (with slight offset for true spatial feel)
    noiseNodes.rightPanner.pan.value = panValue;
    noiseNodes.rightSource.connect(noiseNodes.rightGain);
    noiseNodes.rightGain.connect(noiseNodes.rightPanner);
    noiseNodes.rightPanner.connect(noiseNodes.masterGain);
    
    // Add slight delay to right channel for enhanced spatialization
    if (spatialWidth > 0.5) {
        const delay = audioContext.createDelay();
        delay.delayTime.value = 0.01; // 10ms delay
        noiseNodes.rightPanner.disconnect();
        noiseNodes.rightPanner.connect(delay);
        delay.connect(noiseNodes.masterGain);
    }
    
    noiseNodes.masterGain.connect(audioContext.destination);
    noiseNodes.masterGain.connect(visualizer.analyser);
    
    // Set volume
    const volume = parseInt(document.getElementById('noiseVolumeSlider').value) / 100;
    noiseNodes.masterGain.gain.value = volume;
    
    noiseNodes.leftSource.start();
    noiseNodes.rightSource.start();
    
    // Add slight variation between channels for true spatial effect
    // By starting at slightly different offsets
    noiseNodes.rightSource.playbackRate.value = 0.999; // Slight pitch difference creates beating
    
    updateNoiseButtonStates();
}

function stopNoise() {
    if (noiseNodes.leftSource) {
        try { noiseNodes.leftSource.stop(); } catch(e) {}
        noiseNodes.leftSource = null;
    }
    if (noiseNodes.rightSource) {
        try { noiseNodes.rightSource.stop(); } catch(e) {}
        noiseNodes.rightSource = null;
    }
    if (noiseNodes.masterGain) {
        noiseNodes.masterGain.disconnect();
    }
    activeNoiseType = null;
    updateNoiseButtonStates();
}

function updateNoiseButtonStates() {
    const buttons = ['pinkNoiseBtn', 'brownNoiseBtn', 'whiteNoiseBtn'];
    const types = ['pink', 'brown', 'white'];
    
    buttons.forEach((id, index) => {
        const btn = document.getElementById(id);
        if (activeNoiseType === types[index]) {
            btn.classList.add('playing');
            btn.querySelector('i[data-lucide="play-circle"]').setAttribute('data-lucide', 'stop-circle');
        } else {
            btn.classList.remove('playing');
            btn.querySelector('i[data-lucide="stop-circle"]')?.setAttribute('data-lucide', 'play-circle');
        }
    });
    
    lucide.createIcons();
}

// Ramping Functionality
function applyRamp(gainNode, targetValue) {
    const now = audioContext.currentTime;
    
    if (rampMode === 'none') {
        gainNode.setValueAtTime(targetValue, now);
    } else if (rampMode === 'up') {
        gainNode.setValueAtTime(0.001, now);
        gainNode.exponentialRampToValueAtTime(targetValue, now + rampDuration);
    } else if (rampMode === 'down') {
        gainNode.setValueAtTime(targetValue, now);
        gainNode.exponentialRampToValueAtTime(0.001, now + rampDuration);
        // Stop after ramp down
        setTimeout(() => {
            stopAll();
        }, rampDuration * 1000);
    }
}

function stopAll() {
    stopBinaural();
    stopNoise();
    isPlaying = false;
    updatePlayButton();
}

function updatePlayButton() {
    const btn = document.getElementById('playBinauralBtn');
    const stopBtn = document.getElementById('stopAllBtn');
    
    if (isPlaying) {
        btn.innerHTML = '<i data-lucide="pause" class="w-6 h-6"></i><span>Stop Binaural</span>';
        btn.classList.remove('from-cyan-400', 'via-purple-500', 'to-pink-500');
        btn.classList.add('from-red-400', 'via-red-500', 'to-rose-600');
        
        stopBtn.disabled = false;
        stopBtn.classList.remove('opacity-50', 'cursor-not-allowed');
    } else {
        btn.innerHTML = '<i data-lucide="play" class="w-6 h-6"></i><span>Generate Binaural Beat</span>';
        btn.classList.add('from-cyan-400', 'via-purple-500', 'to-pink-500');
        btn.classList.remove('from-red-400', 'via-red-500', 'to-rose-600');
        
        stopBtn.disabled = true;
        stopBtn.classList.add('opacity-50', 'cursor-not-allowed');
    }
    lucide.createIcons();
}

// Event Listeners
document.addEventListener('DOMContentLoaded', () => {
    // Mode selection
    document.getElementById('spatialBtn').addEventListener('click', () => {
        currentMode = 'spatial';
        document.getElementById('spatialBtn').classList.add('active', 'from-cyan-500', 'to-blue-500', 'text-white');
        document.getElementById('spatialBtn').classList.remove('bg-white/10', 'text-purple-200');
        document.getElementById('monauralBtn').classList.remove('active', 'from-purple-500', 'to-pink-500', 'text-white');
        document.getElementById('monauralBtn').classList.add('bg-white/10', 'text-purple-200');
        document.getElementById('modeDescription').textContent = 'Different frequencies in each ear create the beat perception';
    });
    
    document.getElementById('monauralBtn').addEventListener('click', () => {
        currentMode = 'monaural';
        document.getElementById('monauralBtn').classList.add('active', 'from-purple-500', 'to-pink-500', 'text-white');
        document.getElementById('monauralBtn').classList.remove('bg-white/10', 'text-purple-200');
        document.getElementById('spatialBtn').classList.remove('active', 'from-cyan-500', 'to-blue-500', 'text-white');
        document.getElementById('spatialBtn').classList.add('bg-white/10', 'text-purple-200');
        document.getElementById('modeDescription').textContent = 'Same frequency in both ears with amplitude modulation';
    });
    
    // Ramp selection
    const rampButtons = {
        'rampNone': 'none',
        'rampUp': 'up',
        'rampDown': 'down'
    };
    
    Object.keys(rampButtons).forEach(id => {
        document.getElementById(id).addEventListener('click', () => {
            rampMode = rampButtons[id];
            Object.keys(rampButtons).forEach(btnId => {
                const btn = document.getElementById(btnId);
                if (btnId === id) {
                    btn.classList.add('active', 'from-purple-500', 'to-pink-500', 'text-white');
                    btn.classList.remove('bg-white/10', 'text-purple-200');
                } else {
                    btn.classList.remove('active', 'from-purple-500', 'to-pink-500', 'text-white');
                    btn.classList.add('bg-white/10', 'text-purple-200');
                }
            });
        });
    });
    
    // Sliders
    document.getElementById('carrierSlider').addEventListener('input', (e) => {
        document.getElementById('carrierValue').textContent = e.target.value + ' Hz';
        if (isPlaying && currentMode === 'spatial') {
            const beat = parseFloat(document.getElementById('beatSlider').value);
            binauralNodes.leftOsc.frequency.setValueAtTime(parseFloat(e.target.value), audioContext.currentTime);
            binauralNodes.rightOsc.frequency.setValueAtTime(parseFloat(e.target.value) + beat, audioContext.currentTime);
        } else if (isPlaying) {
            binauralNodes.leftOsc.frequency.setValueAtTime(parseFloat(e.target.value), audioContext.currentTime);
        }
    });
    
    document.getElementById('beatSlider').addEventListener('input', (e) => {
        document.getElementById('beatValue').textContent = e.target.value + ' Hz';
        if (isPlaying) {
            const carrier = parseFloat(document.getElementById('carrierSlider').value);
            const beat = parseFloat(e.target.value);
            if (currentMode === 'spatial') {
                binauralNodes.rightOsc.frequency.setValueAtTime(carrier + beat, audioContext.currentTime);
            } else {
                binauralNodes.modulator.frequency.setValueAtTime(beat, audioContext.currentTime);
            }
        }
    });
    
    document.getElementById('rampDuration').addEventListener('input', (e) => {
        rampDuration = parseInt(e.target.value);
        document.getElementById('rampDurationValue').textContent = rampDuration + 's';
    });
    
    document.getElementById('noiseVolumeSlider').addEventListener('input', (e) => {
        const value = e.target.value;
        document.getElementById('noiseVolumeValue').textContent = value + '%';
        if (noiseNodes.masterGain) {
            noiseNodes.masterGain.gain.setValueAtTime(value / 100, audioContext.currentTime);
        }
    });
    
    document.getElementById('spatialWidthSlider').addEventListener('input', (e) => {
        const value = parseInt(e.target.value);
        const label = value < 30 ? 'Narrow' : value < 70 ? 'Medium' : 'Wide';
        document.getElementById('spatialWidthValue').textContent = label;
        
        if (activeNoiseType) {
            // Recreate noise with new spatial settings
            createNoise(activeNoiseType);
        }
    });
    
    // Brainwave presets
    document.querySelectorAll('.brainwave-btn').forEach(btn => {
        btn.addEventListener('click', () => {
            const carrier = btn.dataset.carrier;
            const beat = btn.dataset.beat;
            document.getElementById('carrierSlider').value = carrier;
            document.getElementById('beatSlider').value = beat;
            document.getElementById('carrierValue').textContent = carrier + ' Hz';
            document.getElementById('beatValue').textContent = beat + ' Hz';
            
            // Visual feedback
            btn.style.transform = 'scale(0.95)';
            setTimeout(() => btn.style.transform = '', 100);
        });
    });
    
    // Play buttons
    document.getElementById('playBinauralBtn').addEventListener('click', () => {
        initAudioContext();
        if (isPlaying) {
            stopBinaural();
            isPlaying = false;
        } else {
            createBinauralBeats();
            isPlaying = true;
        }
        updatePlayButton();
    });
    
    // Noise buttons (toggle behavior)
    document.getElementById('pinkNoiseBtn').addEventListener('click', () => {
        initAudioContext();
        if (activeNoiseType === 'pink') {
            stopNoise();
        } else {
            createNoise('pink');
        }
    });
    
    document.getElementById('brownNoiseBtn').addEventListener('click', () => {
        initAudioContext();
        if (activeNoiseType === 'brown') {
            stopNoise();
        } else {
            createNoise('brown');
        }
    });
    
    document.getElementById('whiteNoiseBtn').addEventListener('click', () => {
        initAudioContext();
        if (activeNoiseType === 'white') {
            stopNoise();
        } else {
            createNoise('white');
        }
    });
    
    document.getElementById('stopAllBtn').addEventListener('click', stopAll);
    
    // Particle background animation
    initParticles();
});

// Particle System
function initParticles() {
    const canvas = document.getElementById('particleCanvas');
    const ctx = canvas.getContext('2d');
    
    function resize() {
        canvas.width = window.innerWidth;
        canvas.height = window.innerHeight;
    }
    resize();
    window.addEventListener('resize', resize);
    
    const particles = [];
    const particleCount = 50;
    
    for (let i = 0; i < particleCount; i++) {
        particles.push({
            x: Math.random() * canvas.width,
            y: Math.random() * canvas.height,
            radius: Math.random() * 3 + 1,
            vx: (Math.random() - 0.5) * 0.5,
            vy: (Math.random() - 0.5) * 0.5,
            color: `hsla(${Math.random() * 60 + 240}, 70%, 60%, ${Math.random() * 0.3})`
        });
    }
    
    function animate() {
        ctx.clearRect(0, 0, canvas.width, canvas.height);
        
        particles.forEach(p => {
            p.x += p.vx;
            p.y += p.vy;
            
            if (p.x < 0 || p.x > canvas.width) p.vx *= -1;
            if (p.y < 0 || p.y > canvas.height) p.vy *= -1;
            
            ctx.beginPath();
            ctx.arc(p.x, p.y, p.radius, 0, Math.PI * 2);
            ctx.fillStyle = p.color;
            ctx.fill();
        });
        
        // Connect nearby particles
        particles.forEach((p1, i) => {
            particles.slice(i + 1).forEach(p2 => {
                const dx = p1.x - p2.x;
                const dy = p1.y - p2.y;
                const distance = Math.sqrt(dx * dx + dy * dy);
                
                if (distance < 100) {
                    ctx.beginPath();
                    ctx.moveTo(p1.x, p1.y);
                    ctx.lineTo(p2.x, p2.y);
                    ctx.strokeStyle = `rgba(147, 51, 234, ${0.1 * (1 - distance / 100)})`;
                    ctx.stroke();
                }
            });
        });
        
        requestAnimationFrame(animate);
    }
    animate();
}

// Cleanup on page unload
window.addEventListener('beforeunload', () => {
    stopAll();
    if (audioContext) {
        audioContext.close();
    }
});