// Magnitude spectrum of the render, log-frequency axis, with the coupled
// modes of the first note overlaid, colored by how much of each mode's
// energy lives in the body. A pizzicato bass spectrum is a comb of slightly
// stretched partials standing on the body resonances; where a string
// partial meets a body mode the overlay shows the pair trading color.

import { magnitudeSpectrum } from '../../lib/fft';
import { useCanvas, drawFrame, PLOT_COLORS } from './canvasUtils';

interface Props {
  y: Float32Array;
  sampleRate: number;
  modeF: Float32Array;
  modeBodyFrac: Float32Array;
}

const F_LO = 30;
const F_HI = 8000;
const DB_RANGE = 80;

function mixColor(t: number, alpha: number): string {
  // cyan (string) -> amber (body)
  const r = Math.round(77 + t * (232 - 77));
  const g = Math.round(208 + t * (163 - 208));
  const b = Math.round(225 + t * (61 - 225));
  return `rgba(${r}, ${g}, ${b}, ${alpha})`;
}

export default function SpectrumPlot({ y, sampleRate, modeF, modeBodyFrac }: Props) {
  const ref = useCanvas(
    (ctx, w, h) => {
      drawFrame(ctx, w, h);
      const padL = 34;
      const padB = 18;
      const pw = w - padL - 6;
      const ph = h - padB - 8;
      const fx = (f: number) =>
        padL + ((Math.log10(f) - Math.log10(F_LO)) / (Math.log10(F_HI) - Math.log10(F_LO))) * pw;

      ctx.font = '10px system-ui';
      ctx.textAlign = 'center';
      for (const f of [30, 50, 100, 200, 500, 1000, 2000, 5000]) {
        const x = fx(f);
        ctx.strokeStyle = PLOT_COLORS.grid;
        ctx.beginPath();
        ctx.moveTo(x, 8);
        ctx.lineTo(x, 8 + ph);
        ctx.stroke();
        ctx.fillStyle = PLOT_COLORS.axis;
        ctx.fillText(f >= 1000 ? `${f / 1000}k` : `${f}`, x, h - 5);
      }
      ctx.textAlign = 'right';
      for (let db = 0; db >= -DB_RANGE; db -= 20) {
        const yy = 8 + (-db / DB_RANGE) * ph;
        ctx.strokeStyle = PLOT_COLORS.grid;
        ctx.beginPath();
        ctx.moveTo(padL, yy);
        ctx.lineTo(padL + pw, yy);
        ctx.stroke();
        ctx.fillStyle = PLOT_COLORS.axis;
        ctx.fillText(`${db}`, padL - 4, yy + 3);
      }

      const { mag, size } = magnitudeSpectrum(y, 65536);
      let peak = 0;
      for (let i = 1; i < mag.length; i++) peak = Math.max(peak, mag[i]);
      if (peak <= 0) return;

      // overlays first so the trace draws on top
      ctx.setLineDash([4, 3]);
      for (let i = 0; i < modeF.length; i++) {
        const f = modeF[i];
        if (f < F_LO || f > F_HI) continue;
        ctx.strokeStyle = mixColor(Math.min(1, modeBodyFrac[i]), 0.45);
        ctx.beginPath();
        ctx.moveTo(fx(f), 8);
        ctx.lineTo(fx(f), 8 + ph);
        ctx.stroke();
      }
      ctx.setLineDash([]);

      ctx.strokeStyle = PLOT_COLORS.trace;
      ctx.beginPath();
      let started = false;
      for (let px = 0; px <= pw; px++) {
        const f = 10 ** (Math.log10(F_LO) + (px / pw) * (Math.log10(F_HI) - Math.log10(F_LO)));
        const bin = Math.min(mag.length - 1, Math.round((f / sampleRate) * size));
        const fNext =
          10 ** (Math.log10(F_LO) + ((px + 1) / pw) * (Math.log10(F_HI) - Math.log10(F_LO)));
        const binNext = Math.min(
          mag.length - 1,
          Math.max(bin + 1, Math.round((fNext / sampleRate) * size)),
        );
        let m = 0;
        for (let b = bin; b < binNext; b++) m = Math.max(m, mag[b]);
        const db = 20 * Math.log10(m / peak + 1e-12);
        const yy = 8 + Math.min(ph, (-db / DB_RANGE) * ph);
        if (!started) {
          ctx.moveTo(padL + px, yy);
          started = true;
        } else {
          ctx.lineTo(padL + px, yy);
        }
      }
      ctx.stroke();

      ctx.textAlign = 'left';
      ctx.fillStyle = mixColor(0, 0.9);
      ctx.fillText('string-dominated modes', padL + 4, 18);
      ctx.fillStyle = mixColor(1, 0.9);
      ctx.fillText('body-dominated modes', padL + 134, 18);
      ctx.fillStyle = PLOT_COLORS.axis;
      ctx.fillText('(first note)', padL + 258, 18);
    },
    [y, sampleRate, modeF, modeBodyFrac],
    200,
  );
  return <canvas ref={ref} />;
}