// SPDX-License-Identifier: Apache-2.0
//
// Metric registry for the browser: display names and `build_spec` ports.
//
// Mirrors `metrics.METRICS`. Computation lives in dsp.js and runs in the
// analysis worker; `buildSpec` is cheap and runs on the main thread whenever the
// view changes, turning computed data into the plot payload the renderer draws —
// the same shape `metrics_json.serialize_spec` used to put on the wire:
// {axes, hlines, annotations, segments (bands), series (curves), heatmap}.

const numbers = (arr) => Array.from(arr, (v) => (Number.isFinite(v) ? v : null));
const extent = (times) => (times.length ? [times[0], times[times.length - 1]] : null);

function payload({ axes, bands = [], curves = [], hlines = [], heatmap = null, annotations = [] }) {
  return {
    title: '',
    axes: {
      x_label: '', y_label: '', y_log: false, x_log: false,
      y_range: null, x_range: null, y_log_allowed: false, x_log_allowed: false,
      ...axes,
    },
    hlines: hlines.map((h) => ({ label: '', color: '#888888', style: 'dot', width: 0.8, ...h })),
    annotations,
    segments: bands.map((b) => ({
      kind: 'band', x: numbers(b.x), lo: numbers(b.lo), hi: numbers(b.hi),
      label: b.label || '', color: null,
    })),
    series: curves.map((c) => ({
      kind: 'line', x: numbers(c.x), y: numbers(c.y),
      label: c.label || '', width: c.width ?? 1.4, color: c.color ?? null,
    })),
    heatmap,
    y_bounds: null,
  };
}

export const METRICS = [
  {
    id: 'rms_power',
    displayName: 'RMS Power',
    buildSpec(data) {
      let peak = 0;
      for (const v of data.rms) if (v > peak) peak = v;
      // Adaptive headroom: loud masters get a taller scale.
      const ymax = data.rms.length && peak > 0.3 ? 0.6 : 0.3;
      return payload({
        axes: { x_label: 'Time (seconds)', y_label: 'Power', y_range: [0.0, ymax], x_range: extent(data.times) },
        bands: [{ x: data.times, lo: new Float64Array(data.rms.length), hi: data.rms, label: 'RMS power' }],
      });
    },
  },
  {
    id: 'waveform',
    displayName: 'Waveform',
    buildSpec(data) {
      return payload({
        axes: { x_label: 'Time (seconds)', y_label: 'Amplitude', y_range: [-1.1, 1.1], x_range: extent(data.times) },
        bands: [{ x: data.times, lo: data.lo, hi: data.hi, label: 'Waveform' }],
      });
    },
  },
  {
    id: 'lufs',
    displayName: 'LUFS',
    buildSpec(data) {
      const hlines = [{ y: -14.0, label: '-14 LUFS (streaming target)', style: 'dot' }];
      const annotations = [];
      if (Number.isFinite(data.integrated)) {
        hlines.push({
          y: data.integrated, label: `Integrated: ${data.integrated.toFixed(1)} LUFS`,
          color: '#e76f51', style: 'dash', width: 1.5,
          perTrack: true,   // differs per track: coloured by track when overlaid
        });
      }
      if (Number.isFinite(data.lra)) annotations.push(`LRA: ${data.lra.toFixed(1)} LU`);
      return payload({
        axes: { x_label: 'Time (seconds)', y_label: 'LUFS', y_range: [-50.0, 0.0], x_range: extent(data.times) },
        curves: [{ x: data.times, y: data.lufs, label: 'Short-term (3 s)' }],
        hlines,
        annotations,
      });
    },
  },
  {
    id: 'crest_factor',
    displayName: 'Crest Factor',
    buildSpec(data) {
      return payload({
        axes: { x_label: 'Time (seconds)', y_label: 'Crest factor (dB)', y_range: [0.0, 25.0], x_range: extent(data.times) },
        curves: [{ x: data.times, y: data.crest_db, label: 'Crest factor (1 s)' }],
        hlines: [
          { y: 12.0, label: '12 dB', style: 'dot' },
          { y: 6.0, label: '6 dB (squashed)', style: 'dot' },
        ],
      });
    },
  },
  {
    id: 'psr',
    displayName: 'PSR',
    buildSpec(data) {
      return payload({
        axes: { x_label: 'Time (seconds)', y_label: 'PSR (LU)', y_range: [0.0, 25.0], x_range: extent(data.times) },
        curves: [{ x: data.times, y: data.psr, label: 'PSR (3 s)' }],
        hlines: [
          { y: 10.0, label: '10 LU (good punch)', style: 'dot' },
          { y: 4.0, label: '4 LU (squashed)', style: 'dot' },
        ],
      });
    },
  },
  {
    id: 'true_peak',
    displayName: 'True Peak',
    buildSpec(data) {
      const annotations = [];
      if (Number.isFinite(data.integrated_tp_db)) annotations.push(`Max: ${data.integrated_tp_db.toFixed(2)} dBTP`);
      return payload({
        axes: { x_label: 'Time (seconds)', y_label: 'dBTP', y_range: [-30.0, 6.0], x_range: extent(data.times) },
        curves: [{ x: data.times, y: data.tp_db, label: 'True Peak (250 ms)', width: 1.0 }],
        hlines: [
          { y: 0.0, label: '0 dBTP (clip)', color: '#000000', style: 'dash', width: 1.0 },
          { y: -1.0, label: '-1 dBTP (typical ceiling)', style: 'dot' },
        ],
        annotations,
      });
    },
  },
  {
    id: 'spectrogram',
    displayName: 'Spectrogram',
    buildSpec(data, view) {
      const yLog = view && view.yLog !== null && view.yLog !== undefined ? view.yLog : true;
      return payload({
        axes: {
          x_label: 'Time (seconds)', y_label: 'Frequency (Hz)',
          y_log: yLog, y_log_allowed: true,
          y_range: [20.0, data.nyquist], x_range: extent(data.times),
        },
        heatmap: {
          x: Array.from(data.times),
          y: data.freqs,
          z: data.s_db,                 // Float32Array, row-major rows x cols
          rows: data.rows,
          cols: data.cols,
          z_min: -80.0,
          z_max: 0.0,
          cmap: 'magma',
          label: 'Power (dB)',
          // Rows are uniform in frequency: the renderer addresses them in Hz,
          // which is what lets it draw a log axis without resampling.
          y0: data.freqs.length ? data.freqs[0] : 0,
          dy: data.freqs.length > 1 ? data.freqs[1] - data.freqs[0] : 1,
        },
      });
    },
  },
];

export const METRIC_BY_ID = Object.fromEntries(METRICS.map((m) => [m.id, m]));
export const DEFAULT_METRIC_ID = 'rms_power';

/**
 * plotspec.apply_x_mode: rewrite a payload's x values to 0-100 % of the
 * dataset's own span. A pure view transform — returns a new payload and leaves
 * the cached one untouched.
 */
export function applyRelativeX(p) {
  const xs = [...p.series.map((s) => s.x), ...p.segments.map((s) => s.x)];
  if (p.heatmap) xs.push(p.heatmap.x);
  const nonEmpty = xs.filter((x) => x.length);
  if (!nonEmpty.length) return p;
  const lo = Math.min(...nonEmpty.map((x) => x[0]));
  const hi = Math.max(...nonEmpty.map((x) => x[x.length - 1]));
  const span = hi - lo || 1.0;
  const rel = (x) => x.map((v) => (v === null ? null : ((v - lo) / span) * 100.0));
  return {
    ...p,
    axes: { ...p.axes, x_label: 'Position (%)', x_range: [0.0, 100.0] },
    series: p.series.map((s) => ({ ...s, x: rel(s.x) })),
    segments: p.segments.map((s) => ({ ...s, x: rel(s.x) })),
    heatmap: p.heatmap ? { ...p.heatmap, x: rel(p.heatmap.x) } : null,
  };
}