#!/usr/bin/env node
// Apply the trims exported by mk-hooks.html, writing a NEW hook directory.
//
//   node apply-hook-trims.mjs <trims.json> [outDir]
//
// The originals are never touched: separation bleed is a judgement call and a
// trim that turns out too tight has to be undoable by re-exporting, not by
// re-separating the stem.
//
// Hooks with no entry in the export are COPIED THROUGH unchanged, so the output
// directory is always complete and can be pointed at directly with
// HOOKDIR=<outDir> in mk-mix-hooks.mjs.
import { readFileSync, mkdirSync, copyFileSync, readdirSync, existsSync } from "node:fs";
import { execFileSync } from "node:child_process";
import path from "node:path";

import { SONG_DATA } from "./paths.mjs";
const DIR = path.resolve(path.dirname(new URL(import.meta.url).pathname));
const [TRIMS, OUTDIR = "mkvocals/hooks-trim"] = process.argv.slice(2);
const SRCDIR = process.env.HOOKDIR ?? "mkvocals/hooks";
if (!TRIMS) { console.error("usage: node apply-hook-trims.mjs <trims.json> [outDir]"); process.exit(1); }

const trims = JSON.parse(readFileSync(TRIMS, "utf8"));
const byFile = new Map(trims.map((t) => [t.file, t]));
const src = path.join(SONG_DATA, SRCDIR), out = path.join(SONG_DATA, OUTDIR);
mkdirSync(out, { recursive: true });

// A hard cut at a zero-crossing-free point clicks, and a click is more obvious
// than the leak being removed. 8ms is short enough not to soften the shout.
const FADE = Number(process.env.FADE ?? 0.008);

// An entry may instead name a SOURCE to cut from:
//   {"file":"hook-22.wav","source":"stem","start":97.08,"end":98.06}
// with start/end in STEM seconds. Some catalogue windows begin mid-word -- the
// hook-22 "Scorpion!" window opens at 97.54 when the word starts at 97.10, so
// the clip is a fragment and no amount of trimming inside it can recover the
// syllable. Re-cutting from the stem is the only fix.
//   {"file":"hook-22.wav","source":"hook-35.wav"}
// substitutes another hook's audio wholesale, keeping the placement.
const STEM = path.join(SONG_DATA, "mkvocals/stem48.wav");

let cut = 0, recut = 0, copied = 0;
for (const f of readdirSync(src).filter((f) => f.endsWith(".wav"))) {
  const t = byFile.get(f);
  const dst = path.join(out, f);
  if (!t) { copyFileSync(path.join(src, f), dst); copied += 1; continue; }
  if (t.source) {
    const from = t.source === "stem" ? STEM : path.join(src, t.source);
    const d = +(t.end - t.start).toFixed(4);
    const fd = Math.min(FADE, d / 4);
    execFileSync("ffmpeg", ["-v", "error", "-y", "-ss", String(t.start), "-t", String(d), "-i", from,
      "-af", `afade=t=in:st=0:d=${fd},afade=t=out:st=${(d - fd).toFixed(4)}:d=${fd}`,
      "-ar", "48000", "-ac", "1", dst]);
    console.log(`  ${f}  <- ${t.source} ${t.start}-${t.end}s  (${d.toFixed(3)}s)`);
    recut += 1; continue;
  }
  const dur = +(t.end - t.start).toFixed(4);
  const fade = Math.min(FADE, dur / 4);
  execFileSync("ffmpeg", ["-v", "error", "-y", "-i", path.join(src, f),
    "-af", `atrim=${t.start}:${t.end},asetpts=PTS-STARTPTS,` +
      `afade=t=in:st=0:d=${fade},afade=t=out:st=${(dur - fade).toFixed(4)}:d=${fade}`,
    "-ar", "48000", "-ac", "1", dst]);
  console.log(`  ${f}  ${t.start.toFixed(3)}-${t.end.toFixed(3)}s  (${dur.toFixed(3)}s)`);
  cut += 1;
}

// The catalogue travels with the hooks: mk-mix-hooks.mjs reads durations from
// the files, but place-vocals-full.mjs reads this to place them.
const catSrc = path.join(SONG_DATA, "mkvocals/hooks-verb/mk-vocals.json");
if (existsSync(catSrc)) copyFileSync(catSrc, path.join(out, "mk-vocals.json"));

console.log(`\n${cut} trimmed, ${recut} re-cut from source, ${copied} copied through -> ${OUTDIR}`);
console.log(`use it with:  HOOKDIR=${OUTDIR} node mk-mix-hooks.mjs …`);