import { drywet } from './helpers.mjs';

import { getAudioContext } from './audioContext.mjs';

let noiseCache = {};

// lazy generates noise buffers and keeps them forever

export function getNoiseBuffer(type, density) {

  const ac = getAudioContext();

  if (noiseCache[type]) {

    return noiseCache[type];

  }

  const bufferSize = 2 * ac.sampleRate;

  const noiseBuffer = ac.createBuffer(1, bufferSize, ac.sampleRate);

  const output = noiseBuffer.getChannelData(0);

  let lastOut = 0;

  let b0, b1, b2, b3, b4, b5, b6;

  b0 = b1 = b2 = b3 = b4 = b5 = b6 = 0.0;

  for (let i = 0; i < bufferSize; i++) {

    if (type === 'white') {

      output[i] = Math.random() * 2 - 1;

    } else if (type === 'brown') {

      let white = Math.random() * 2 - 1;

      output[i] = (lastOut + 0.02 * white) / 1.02;

      lastOut = output[i];

    } else if (type === 'pink') {

      let white = Math.random() * 2 - 1;

      b0 = 0.99886 * b0 + white * 0.0555179;

      b1 = 0.99332 * b1 + white * 0.0750759;

      b2 = 0.969 * b2 + white * 0.153852;

      b3 = 0.8665 * b3 + white * 0.3104856;

      b4 = 0.55 * b4 + white * 0.5329522;

      b5 = -0.7616 * b5 - white * 0.016898;

      output[i] = b0 + b1 + b2 + b3 + b4 + b5 + b6 + white * 0.5362;

      output[i] *= 0.11;

      b6 = white * 0.115926;

    } else if (type === 'crackle') {

      const probability = density * 0.01;

      if (Math.random() < probability) {

        output[i] = Math.random() * 2 - 1;

      } else {

        output[i] = 0;

      }

    }

  }

  // Prevent caching to randomize crackles

  if (type !== 'crackle') noiseCache[type] = noiseBuffer;

  return noiseBuffer;

}

// expects one of noises as type

export function getNoiseOscillator(type = 'white', t, density = 0.02) {

  const ac = getAudioContext();

  const o = ac.createBufferSource();

  o.buffer = getNoiseBuffer(type, density);

  o.loop = true;

  o.start(t);

  return {

    node: o,

    stop: (time) => o.stop(time),

  };

}

export function getNoiseMix(inputNode, wet, t) {

  const noiseOscillator = getNoiseOscillator('pink', t);

  const noiseMix = drywet(inputNode, noiseOscillator.node, wet);

  return {

    node: noiseMix,

    stop: (time) => noiseOscillator?.stop(time),

  };

}