#!/usr/bin/env node
// Hold the FINAL note of a cut longer, before arranging.
//
// A tune cut at `TIME_LIMIT` stops on whatever note happens to be last, at whatever
// length the sequencer wrote it -- 0.218s for Mario RPG's lead, 0.106s for its bass.
// That is a stop, not an ending.
//
// The extension has to happen in the LEAD file rather than in the finished plan,
// because the arranger sizes its pick to the note: lengthening a slot afterwards
// leaves the chosen clip too short and the extra slot is simply silence. Asking for a
// long note up front makes it choose a clip that can hold it.
//
//   node hold-last.mjs <lead.json> <TL> <extraSeconds> <out.json>
//
// TL is in the lead file's own units (raw MIDI seconds), the same units TIME_LIMIT
// filters on -- so "the last note of the cut" is the last note with t < TL, which is
// not the last note of the file.
import { readFileSync, writeFileSync } from "node:fs";
import path from "node:path";
import { SONG_DATA } from "./paths.mjs";

const [IN, TLs, EXTRAs, OUT] = process.argv.slice(2);
if (!OUT) throw new Error("usage: hold-last.mjs <lead.json> <TL> <extraSeconds> <out.json>");
const TL = Number(TLs), EXTRA = Number(EXTRAs);
const abs = (f) => (path.isAbsolute(f) ? f : path.join(SONG_DATA, f));

const notes = JSON.parse(readFileSync(abs(IN), "utf8"));
const kept = notes.filter((n) => n.t < TL);
if (!kept.length) throw new Error(`no notes before TL=${TL} in ${IN}`);
const lastT = Math.max(...kept.map((n) => n.t));
// A final CHORD is several notes at the same onset; all of them are held, or the
// remaining one sticks out as a lone voice over the rest.
let n = 0;
for (const note of notes) {
  if (Math.abs(note.t - lastT) < 1e-6) {
    note.dur = (note.dur ?? 0) + EXTRA;
    n += 1;
  }
}
writeFileSync(abs(OUT), JSON.stringify(notes));
console.log(`${path.basename(IN)}: ${kept.length} notes before TL=${TL}; held ${n} note(s) at ` +
  `t=${lastT.toFixed(3)} by +${EXTRA}s -> ${path.basename(OUT)}`);