controller-v2/client/src/lib/peqAudio.ts

// ============================================================
// PEQ Audio Processing - Migrated from old/audio.js
// ============================================================

import * as echarts from 'echarts';

export const TYPE_PEAK = 4;
export const TYPE_LOWSHELF = 5;
export const TYPE_HIGHSHELF = 6;
export const TYPE_LOWPASS = 0;
export const TYPE_HIGHPASS = 1;
export const TYPE_BANDPASS = 2;
export const TYPE_NOTCH = 3;
export const TYPE_ALLPASS = 7;

// Filter type mapping (device uses numeric type; pass-through when already a number)
export function getFilterType(typeName: string | number): number {
  if (typeof typeName === "number" && Number.isFinite(typeName)) {
    return typeName;
  }
  switch (typeName) {
    case 'LPF':
    case 'LOW_PASS':
      return TYPE_LOWPASS;
    case 'HPF':
    case 'HIGH_PASS':
      return TYPE_HIGHPASS;
    case 'BPF':
    case 'BAND_PASS':
      return TYPE_BANDPASS;
    case 'NOTCH':
      return TYPE_NOTCH;
    case 'PEAK':
    case 'PEAKING':
      return TYPE_PEAK;
    case 'LSHELF':
    case 'LOW_SHELF':
      return TYPE_LOWSHELF;
    case 'HSHELF':
    case 'HIGH_SHELF':
      return TYPE_HIGHSHELF;
    case 'APF':
    case 'ALL_PASS':
      return TYPE_ALLPASS;
    default:
      return TYPE_PEAK;
  }
}

export function getFilterShortName(type: string): string {
  switch (type) {
    case 'LOW_PASS':
      return 'LPF';
    case 'HIGH_PASS':
      return 'HPF';
    case 'BAND_PASS':
      return 'BPF';
    case 'LOW_SHELF':
      return 'LSHELF';
    case 'HIGH_SHELF':
      return 'HSHELF';
    case 'ALL_PASS':
      return 'APF';
    case 'PEAKING':
      return 'PEAK';
    default:
      return type;
  }
}

// Coefficients class
class Coeff {
  b0 = 0;
  b1 = 0;
  b2 = 0;
  a0 = 0;
  a1 = 0;
  a2 = 0;

  setB0(v: number) { this.b0 = v; }
  setB1(v: number) { this.b1 = v; }
  setB2(v: number) { this.b2 = v; }
  setA0(v: number) { this.a0 = v; }
  setA1(v: number) { this.a1 = v; }
  setA2(v: number) { this.a2 = v; }
  getB0() { return this.b0; }
  getB1() { return this.b1; }
  getB2() { return this.b2; }
  getA0() { return this.a0; }
  getA1() { return this.a1; }
  getA2() { return this.a2; }
}

// Complex number class
class Complex {
  constructor(public real: number, public image: number) {}

  add(a: Complex): Complex {
    return new Complex(this.real + a.real, this.image + a.image);
  }

  sub(a: Complex): Complex {
    return new Complex(this.real - a.real, this.image - a.image);
  }

  div(a: Complex): Complex {
    const denominator = a.real * a.real + a.image * a.image;
    const newReal = (this.real * a.real + this.image * a.image) / denominator;
    const newImage = (this.image * a.real - this.real * a.image) / denominator;
    return new Complex(newReal, newImage);
  }

  mul(a: Complex): Complex {
    const newReal = this.real * a.real - this.image * a.image;
    const newImage = this.image * a.real + this.real * a.image;
    return new Complex(newReal, newImage);
  }

  mulScalar(a: number): Complex {
    return new Complex(this.real * a, this.image * a);
  }

  addScalar(a: number): Complex {
    return new Complex(this.real + a, this.image);
  }
}

function getAmplitude(complex: Complex): number {
  return Math.sqrt(Math.pow(complex.real, 2) + Math.pow(complex.image, 2));
}

function getFreqw(coeff: Coeff, w: number): Complex {
  const complex = new Complex(Math.cos(w), -Math.sin(w));
  const b2 = (complex.mul(complex)).mulScalar(coeff.getB2());
  const b1 = complex.mulScalar(coeff.getB1());
  const hup = b2.add(b1).addScalar(coeff.getB0());
  const a2 = (complex.mul(complex)).mulScalar(coeff.getA2());
  const a1 = complex.mulScalar(coeff.getA1());
  const hdown = a2.add(a1).addScalar(coeff.getA0());
  return hup.div(hdown);
}

function getFreqwList(coeffList: Coeff[], w: number): Complex {
  let h = getFreqw(coeffList[0], w);
  coeffList.slice(1).forEach((item) => {
    h = h.mul(getFreqw(item, w));
  });
  return h;
}

function getFreqzn(coeff: Coeff, fs: number, f: number[]): number[] {
  const n = f.length;
  const h = new Array(n);
  for (let i = 0; i < n; i++) {
    const w = (2 * Math.PI * f[i]) / fs;
    const complex = getFreqw(coeff, w);
    h[i] = 20 * Math.log10(getAmplitude(complex));
  }
  return h;
}

function getFreqznList(coeffList: Coeff[], fs: number, f: number[]): number[] {
  const n = f.length;
  const h = new Array(n);
  for (let i = 0; i < n; i++) {
    const w = (2 * Math.PI * f[i]) / fs;
    const complex = getFreqwList(coeffList, w);
    h[i] = 20 * Math.log10(getAmplitude(complex));
  }
  return h;
}

/**
 * Calculate filter coefficients matrix
 */
export function getSectionsMatrix(
  gain: number,
  fc: number,
  q: number,
  type: number,
  bypass: boolean,
  fs: number
): Coeff {
  const w = (2 * fc) / fs;
  const bypassStatus = bypass ? 1 : 0;
  const bqtype = type + bypassStatus * 10;
  const sA = Math.pow(10, gain / 40);
  const sqrt_sA = Math.sqrt(sA);
  const sin_w = Math.sin(Math.PI * w);
  const cos_w = Math.cos(Math.PI * w);
  const alpha = sin_w / (2 * q);

  let b0 = 0, b1 = 0, b2 = 0, a0 = 0, a1 = 0, a2 = 0;

  switch (bqtype) {
    case TYPE_PEAK:
      b0 = 1 + alpha * sA;
      b1 = -2 * cos_w;
      b2 = 1 - alpha * sA;
      a0 = 1 + alpha / sA;
      a1 = b1;
      a2 = 1 - alpha / sA;
      break;
    case TYPE_LOWSHELF:
      b0 = sA * ((sA + 1) - (sA - 1) * cos_w + 2 * sqrt_sA * alpha);
      b1 = 2 * sA * ((sA - 1) - (sA + 1) * cos_w);
      b2 = sA * ((sA + 1) - (sA - 1) * cos_w - 2 * sqrt_sA * alpha);
      a0 = (sA + 1) + (sA - 1) * cos_w + 2 * sqrt_sA * alpha;
      a1 = -2 * ((sA - 1) + (sA + 1) * cos_w);
      a2 = (sA + 1) + (sA - 1) * cos_w - 2 * sqrt_sA * alpha;
      break;
    case TYPE_HIGHSHELF:
      b0 = sA * ((sA + 1) + (sA - 1) * cos_w + 2 * sqrt_sA * alpha);
      b1 = -2 * sA * ((sA - 1) + (sA + 1) * cos_w);
      b2 = sA * ((sA + 1) + (sA - 1) * cos_w - 2 * sqrt_sA * alpha);
      a0 = (sA + 1) - (sA - 1) * cos_w + 2 * sqrt_sA * alpha;
      a1 = 2 * ((sA - 1) - (sA + 1) * cos_w);
      a2 = (sA + 1) - (sA - 1) * cos_w - 2 * sqrt_sA * alpha;
      break;
    case TYPE_LOWPASS:
      b0 = (1 - cos_w) / 2;
      b1 = 1 - cos_w;
      b2 = b0;
      a0 = 1 + alpha;
      a1 = -2 * cos_w;
      a2 = 1 - alpha;
      break;
    case TYPE_HIGHPASS:
      b0 = (1 + cos_w) / 2;
      b1 = -(1 + cos_w);
      b2 = b0;
      a0 = 1 + alpha;
      a1 = -2 * cos_w;
      a2 = 1 - alpha;
      break;
    case TYPE_BANDPASS:
      b0 = alpha;
      b1 = 0;
      b2 = -alpha;
      a0 = 1 + alpha;
      a1 = -2 * cos_w;
      a2 = 1 - alpha;
      break;
    case TYPE_NOTCH:
      b0 = 1;
      b1 = -2 * cos_w;
      b2 = 1;
      a0 = 1 + alpha;
      a1 = -2 * cos_w;
      a2 = 1 - alpha;
      break;
    case TYPE_ALLPASS:
      b0 = 1 - alpha;
      b1 = -2 * cos_w;
      b2 = 1 + alpha;
      a0 = b2;
      a1 = b1;
      a2 = b0;
      break;
    default:
      b0 = 1;
      b1 = 0;
      b2 = 0;
      a0 = 1;
      a1 = 0;
      a2 = 0;
      break;
  }

  const coeff = new Coeff();
  coeff.setB0(b0 / a0);
  coeff.setB1(b1 / a0);
  coeff.setB2(b2 / a0);
  coeff.setA0(a0 / a0);
  coeff.setA1(a1 / a0);
  coeff.setA2(a2 / a0);
  return coeff;
}

/**
 * Visualize frequency response
 * Returns [xValues, yValues] for the overall response
 */
export function visualizeResponse(coeffList: Coeff[], fs: number): [number[], number[]] {
  const n = 349;
  const startF = 20;
  const logStep = (Math.log10(20000) - Math.log10(20)) / n;
  const f = new Array(n);
  const step = Math.pow(10, logStep);

  for (let i = 0; i < n; i++) {
    f[i] = startF * Math.pow(step, i);
  }

  const semilogf = new Array(n);
  // Only calculate first 200 points for x-axis
  for (let i = 0; i < 200; i++) {
    semilogf[i] = Math.log10(f[i]);
  }

  const validCoeffList: Coeff[] = [];
  coeffList.forEach((coeff) => {
    if (
      !Number.isNaN(coeff.getB0()) &&
      !Number.isNaN(coeff.getB1()) &&
      !Number.isNaN(coeff.getB2()) &&
      !Number.isNaN(coeff.getA0()) &&
      !Number.isNaN(coeff.getA1()) &&
      !Number.isNaN(coeff.getA2())
    ) {
      validCoeffList.push(coeff);
    }
  });

  if (validCoeffList.length === 0) {
    const flat = f.map(() => 0);
    return [semilogf, flat];
  }

  const overall = getFreqznList(validCoeffList, fs, f);
  return [semilogf, overall];
}

/** Same log-spaced grid as visualizeResponse (20 Hz … 20 kHz, 349 points). */
export function getPeqLogSpacedFreqs(): number[] {
  const n = 349;
  const startF = 20;
  const logStep = (Math.log10(20000) - Math.log10(20)) / n;
  const step = Math.pow(10, logStep);
  const f: number[] = [];
  for (let i = 0; i < n; i++) {
    f.push(startF * Math.pow(step, i));
  }
  return f;
}

export type PeqBandForResponse = {
  enabled: boolean;
  gain: number;
  freq: number;
  q: number;
  type: string | number;
};

/**
 * Combined magnitude response (dB) per band — same pipeline as legacy:
 * getSectionsMatrix(...) per filter, then cascade via getFreqznList.
 */
export function computePeqMagnitudeDb(bands: PeqBandForResponse[], fs: number): number[] {
  const f = getPeqLogSpacedFreqs();
  const list: Coeff[] = [];
  bands.forEach((b) => {
    if (!b.enabled) return;
    list.push(getSectionsMatrix(b.gain, b.freq, b.q, getFilterType(b.type), false, fs));
  });
  if (list.length === 0) {
    return f.map(() => 0);
  }
  return getFreqznList(list, fs, f);
}

export type PeqSvgCurveData = {
  points: Array<{ x: number; y: number; gainDb: number; freq: number }>;
  pathD: string;
  fillD: string;
};

/**
 * Build reusable SVG curve data (`points`, `pathD`, `fillD`) for PEQ response rendering.
 * Any page can call this and render with SVG `<path d={pathD} />`.
 */
export function buildPeqSvgCurveData(args: {
  bands: PeqBandForResponse[];
  width: number;
  height: number;
  fs?: number;
  yDbMax?: number;
  minFreq?: number;
  maxFreq?: number;
  paddingY?: number;
}): PeqSvgCurveData {
  const {
    bands,
    width,
    height,
    fs = 48000,
    yDbMax = 20,
    minFreq = 20,
    maxFreq = 20000,
    paddingY = 10,
  } = args;

  const safeW = Math.max(1, width);
  const safeH = Math.max(1, height);

  const logMin = Math.log10(minFreq);
  const logMax = Math.log10(maxFreq);
  const freqToX = (f: number) =>
    ((Math.log10(Math.max(minFreq, Math.min(maxFreq, f))) - logMin) / (logMax - logMin)) * safeW;
  const gainToY = (g: number) => safeH / 2 - (g / yDbMax) * (safeH / 2 - paddingY);

  const freqs = getPeqLogSpacedFreqs();
  const db = computePeqMagnitudeDb(bands, fs);
  const points = freqs.map((f, i) => {
    const gainDb = db[i] ?? 0;
    return { x: freqToX(f), y: gainToY(gainDb), gainDb, freq: f };
  });

  const pathD = points
    .map((p, i) => `${i === 0 ? "M" : "L"} ${p.x.toFixed(1)} ${p.y.toFixed(1)}`)
    .join(" ");
  const fillD = pathD ? `${pathD} L ${safeW} ${safeH / 2} L 0 ${safeH / 2} Z` : "";
  return { points, pathD, fillD };
}

/**
 * Get ECharts options for frequency response chart
 */
export function getChartOps(
  dataSet: [number[], number[]],
  yMax: number,
  yMin: number,
  lineColor: string
) {
  const labelsToShow = [0, 43, 85, 116, 160, 200, 233, 281, 320, 348];
  const labelMap: { [key: number]: string } = {
    0: '20',
    43: '50',
    85: '100',
    116: '200',
    160: '500',
    200: '1K',
    233: '2K',
    281: '5K',
    320: '10K',
    348: '20K',
  };

  return {
    xAxis: {
      type: 'category' as const,
      data: dataSet[0],
      axisLabel: {
        formatter: (value: any, index: number) => {
          if (labelsToShow.includes(index)) {
            return labelMap[index] || '';
          }
          return '';
        },
        interval: (index: number) => labelsToShow.includes(index),
        fontSize: 14,
        color: '#999',
      },
      splitLine: {
        show: true,
        lineStyle: {
          type: 'solid',
          color: '#3A4348',
        },
      },
      axisLine: {
        lineStyle: {
          color: '#3A4348',
        },
      },
    },
    yAxis: {
      type: 'value' as const,
      min: yMin,
      max: yMax,
      interval: 5,
      axisLabel: {
        fontSize: 14,
        color: '#999',
      },
      splitLine: {
        show: true,
        lineStyle: {
          type: 'solid',
          color: '#3A4348',
        },
      },
      axisLine: {
        lineStyle: {
          color: '#3A4348',
        },
      },
    },
    legend: {
      show: true,
      top: 15,
      data: [
        {
          name: 'Equalizer',
          icon: 'circle',
          textStyle: { color: lineColor },
          itemStyle: {
            color: lineColor,
            borderColor: lineColor,
          },
        },
        {
          name: 'Raw',
          icon: 'circle',
          textStyle: { color: '#ffffff' },
          itemStyle: {
            color: '#ffffff',
            borderColor: '#ffffff',
          },
        },
        {
          name: 'Equalized',
          icon: 'circle',
          textStyle: { color: '#23d2fe' },
          itemStyle: {
            color: '#23d2fe',
            borderColor: '#23d2fe',
          },
        },
      ],
      textStyle: {
        fontSize: 13,
      },
    },
    series: [
      {
        name: 'Equalizer',
        data: dataSet[1],
        type: 'line' as const,
        showSymbol: false,
        lineStyle: {
          color: lineColor,
        },
        areaStyle: {
          opacity: 0.3,
          color: new echarts.graphic.LinearGradient(0, 0, 0, 1, [
            { offset: 0, color: '#578400' },
            { offset: 1, color: '#578400' },
          ]),
        },
      },
    ],
  };
}