let mic, fft;
let pitchHistory = [];
const minPitch = 50;
const maxPitch = parseFloat(getUrlParameter('cutoff')) || 300;

function setup() {
    createCanvas(800, 400);
    mic = new p5.AudioIn();
    mic.start();
    fft = new p5.FFT(0, 2048);
    fft.setInput(mic);
    textSize(16);
}

function draw() {
    background(240);

    drawPitchRanges();

    let timeDomain = fft.waveform(2048, 'float32');
    let frequency = autoCorrelate(timeDomain);

    if (frequency > minPitch && frequency < maxPitch) {
        pitchHistory.push(frequency);

        if (pitchHistory.length > width) {
            pitchHistory.splice(0, 1);
        }
    }

    drawPitchPlot();
}

function drawPitchRanges() {
    noStroke();
    fill(135, 206, 250, 100);
    rect(0, frequencyToY(180), width, frequencyToY(85) - frequencyToY(180));  // "Male" range
    fill(255, 182, 193, 100);
    rect(0, frequencyToY(255), width, frequencyToY(165) - frequencyToY(255)); // "Female" range

    stroke(0);
    fill(0);
    textAlign(LEFT);
    text('Typical "Male" Range (85-180 Hz)', 10, frequencyToY(85) - 5);
    text('Typical "Female" Range (165-255 Hz)', 10, frequencyToY(165) - 5);
}

function frequencyToY(freq) {
    return map(freq, minPitch, maxPitch, height, 0);
}

function drawPitchPlot() {
    noFill();
    stroke(50);
    beginShape();
    for (let i = 0; i < pitchHistory.length; i++) {
        vertex(i, frequencyToY(pitchHistory[i]));
    }
    endShape();
}

function autoCorrelate(buf) {
    let size = buf.length;
    let rms = 0;

    for (let i = 0; i < size; i++) {
        let val = buf[i];
        rms += val * val;
    }
    rms = Math.sqrt(rms / size);

    if (rms < 0.01) // Likely silence/noise
        return -1;

    let r1 = 0, r2 = size - 1;
    for (let i = 0; i < size / 2; i++) {
        if (Math.abs(buf[i]) < 0.2) {
            r1 = i;
            break;
        }
    }
    for (let i = 1; i < size / 2; i++) {
        if (Math.abs(buf[size - i]) < 0.2) {
            r2 = size - i;
            break;
        }
    }

    buf = buf.slice(r1, r2);
    size = buf.length;

    let c = new Array(size).fill(0);
    for (let i = 0; i < size; i++) {
        for (let j = 0; j < size - i; j++) {
            c[i] = c[i] + buf[j] * buf[j + i];
        }
    }

    let d = 0;
    while (c[d] > c[d + 1]) d++;
    let maxval = -1, maxpos = -1;
    for (let i = d; i < size; i++) {
        if (c[i] > maxval) {
            maxval = c[i];
            maxpos = i;
        }
    }

    let T0 = maxpos;
    let x1 = c[T0 - 1], x2 = c[T0], x3 = c[T0 + 1];
    let a = (x1 + x3 - 2 * x2) / 2;
    let b = (x3 - x1) / 2;

    if (a) T0 = T0 - b / (2 * a);

    let sampleRate = getAudioContext().sampleRate;
    return sampleRate / T0;
}

function getUrlParameter(name) {
    name = name.replace(/[\[\]]/g, '\\$&');
    let regex = new RegExp('[?&]' + name + '(=([^&#]*)|&|#|$)');
    let results = regex.exec(window.location.href);
    if (!results) return null;
    if (!results[2]) return '';
    return decodeURIComponent(results[2].replace(/\+/g, ' '));
}