// credits to webdirt: https://github.com/dktr0/WebDirt/blob/41342e81d6ad694a2310d491fef7b7e8b0929efe/js-src/Graph.js#L597

export var vowelFormant = {

  a: { freqs: [660, 1120, 2750, 3000, 3350], gains: [1, 0.5012, 0.0708, 0.0631, 0.0126], qs: [80, 90, 120, 130, 140] },

  e: { freqs: [440, 1800, 2700, 3000, 3300], gains: [1, 0.1995, 0.1259, 0.1, 0.1], qs: [70, 80, 100, 120, 120] },

  i: { freqs: [270, 1850, 2900, 3350, 3590], gains: [1, 0.0631, 0.0631, 0.0158, 0.0158], qs: [40, 90, 100, 120, 120] },

  o: { freqs: [430, 820, 2700, 3000, 3300], gains: [1, 0.3162, 0.0501, 0.0794, 0.01995], qs: [40, 80, 100, 120, 120] },

  u: { freqs: [370, 630, 2750, 3000, 3400], gains: [1, 0.1, 0.0708, 0.0316, 0.01995], qs: [40, 60, 100, 120, 120] },

  ae: { freqs: [650, 1515, 2400, 3000, 3350], gains: [1, 0.5, 0.1008, 0.0631, 0.0126], qs: [80, 90, 120, 130, 140] },

  aa: { freqs: [560, 900, 2570, 3000, 3300], gains: [1, 0.5, 0.0708, 0.0631, 0.0126], qs: [80, 90, 120, 130, 140] },

  oe: { freqs: [500, 1430, 2300, 3000, 3300], gains: [1, 0.2, 0.0708, 0.0316, 0.01995], qs: [40, 60, 100, 120, 120] },

  ue: { freqs: [250, 1750, 2150, 3200, 3300], gains: [1, 0.1, 0.0708, 0.0316, 0.01995], qs: [40, 60, 100, 120, 120] },

  y: { freqs: [400, 1460, 2400, 3000, 3300], gains: [1, 0.2, 0.0708, 0.0316, 0.02995], qs: [40, 60, 100, 120, 120] },

  uh: { freqs: [600, 1250, 2100, 3100, 3500], gains: [1, 0.3, 0.0608, 0.0316, 0.01995], qs: [40, 70, 100, 120, 130] },

  un: { freqs: [500, 1240, 2280, 3000, 3500], gains: [1, 0.1, 0.1708, 0.0216, 0.02995], qs: [40, 60, 100, 120, 120] },

  en: { freqs: [600, 1480, 2450, 3200, 3300], gains: [1, 0.15, 0.0708, 0.0316, 0.02995], qs: [40, 60, 100, 120, 120] },

  an: { freqs: [700, 1050, 2500, 3000, 3300], gains: [1, 0.1, 0.0708, 0.0316, 0.02995], qs: [40, 60, 100, 120, 120] },

  on: { freqs: [500, 1080, 2350, 3000, 3300], gains: [1, 0.1, 0.0708, 0.0316, 0.02995], qs: [40, 60, 100, 120, 120] },

  get æ() {

    return this.ae;

  },

  get ø() {

    return this.oe;

  },

  get ɑ() {

    return this.aa;

  },

  get å() {

    return this.aa;

  },

  get ö() {

    return this.oe;

  },

  get ü() {

    return this.ue;

  },

  get ı() {

    return this.y;

  },

};

if (typeof GainNode !== 'undefined') {

  class VowelNode extends GainNode {

    constructor(ac, letter) {

      super(ac);

      if (!vowelFormant[letter]) {

        throw new Error('vowel: unknown vowel ' + letter);

      }

      const { gains, qs, freqs } = vowelFormant[letter];

      const makeupGain = ac.createGain();

      for (let i = 0; i < 5; i++) {

        const gain = ac.createGain();

        gain.gain.value = gains[i];

        const filter = ac.createBiquadFilter();

        filter.type = 'bandpass';

        filter.Q.value = qs[i];

        filter.frequency.value = freqs[i];

        this.connect(filter);

        filter.connect(gain);

        gain.connect(makeupGain);

      }

      makeupGain.gain.value = 8; // how much makeup gain to add?

      this.connect = (target) => makeupGain.connect(target);

      return this;

    }

  }

  AudioContext.prototype.createVowelFilter = function (letter) {

    return new VowelNode(this, letter);

  };

}