// Longest musically-homogeneous stretches in the longplay, from the cached chroma.
// The middle filler only has to look like a battle - the game's own audio is CUT
// under the ums (DUCK=0) - so a long stretch of ANY single battle theme (gym,
// rival, Elite Four) would need one cut in and one out instead of three.
import { readFileSync } from "node:fs";

const b = readFileSync("pk-chroma.f32");
const chroma = new Float32Array(b.buffer, b.byteOffset, b.length / 4);
const nFrames = chroma.length / 12;
const WIN_S = 6, WF = WIN_S * 4;

function profile(f) {
  const p = new Float64Array(12);
  for (let i = 0; i < WF; i += 1) for (let k = 0; k < 12; k += 1) p[k] += chroma[(f + i) * 12 + k];
  let m = 0; for (const x of p) m += x; m /= 12;
  for (let k = 0; k < 12; k += 1) p[k] -= m;
  let e = 0; for (const x of p) e += x * x;
  return { p, e: Math.sqrt(e) || 1 };
}
const cos = (a, b2) => { let d = 0; for (let k = 0; k < 12; k += 1) d += a.p[k] * b2.p[k]; return d / (a.e * b2.e); };

// step 1s; grow a segment while each window still matches the segment's anchor
const STEP = 4, THR = 0.80;
const segs = [];
let f = 0;
while (f + WF < nFrames) {
  const anchor = profile(f);
  let g = f + STEP, miss = 0;
  while (g + WF < nFrames) {
    if (cos(anchor, profile(g)) >= THR) miss = 0;
    else if (++miss >= 3) break;               // tolerate 3s of dropout
    g += STEP;
  }
  const len = (g - f) / 4;
  if (len >= 45) segs.push({ start: f / 4, len });
  f = g > f + STEP ? g : f + STEP;
}
const fmt = (s) => `${Math.floor(s / 60)}:${(s % 60).toFixed(0).padStart(2, "0")}`;
segs.sort((a, b2) => b2.len - a.len);
console.log(`${segs.length} homogeneous segments >=45s. Longest 20:`);
for (const s of segs.slice(0, 20)) console.log(`  ${s.start.toFixed(1)}s (${fmt(s.start)})  len ${s.len.toFixed(1)}s`);