const btn = document.getElementById('btn');
const canvas = document.getElementById('visualizer');
const ctx = canvas.getContext('2d');

let audioContext;
let analyser;
let dataArray;
let micStream;
let animationId;
let isListening = false;

async function startMic() {
    audioContext = new (window.AudioContext || window.webkitAudioContext)();
    micStream = await navigator.mediaDevices.getUserMedia({ audio: true });
    const source = audioContext.createMediaStreamSource(micStream);

    analyser = audioContext.createAnalyser();
    analyser.fftSize = 512;

    const bufferLength = analyser.fftSize;
    dataArray = new Uint8Array(bufferLength);

    source.connect(analyser);
    draw();
}

function stopMic() {
    micStream.getTracks().forEach(track => track.stop());
    audioContext.close();
    cancelAnimationFrame(animationId);
}

function draw() {
    animationId = requestAnimationFrame(draw);

    analyser.getByteTimeDomainData(dataArray);

    ctx.fillStyle = '#fff';
    ctx.fillRect(0, 0, canvas.width, canvas.height);

    ctx.lineWidth = 2;
    ctx.strokeStyle = '#000';
    ctx.beginPath();

    const sliceWidth = canvas.width / dataArray.length;
    let x = 0;

    for (let i = 0; i < dataArray.length; i++) {
        const v = dataArray[i] / 128.0;
        const y = v * canvas.height / 2;

        i === 0 ? ctx.moveTo(x, y) : ctx.lineTo(x, y);
        x += sliceWidth;
    }

    ctx.lineTo(canvas.width, canvas.height / 2);
    ctx.stroke();
}

btn.addEventListener('click', async () => {
    if (!isListening) {
        await startMic();
    } else {
        stopMic();
    }
    isListening = !isListening;
});