#!/usr/bin/env node
// Build exported instrument bundles (format numbl-instrument-v1) for one
// instrument repository. Run from the repo root:
//
//   node scripts/build-exports.mjs
//
// For each export-src/<name>/export.json, the bundle's files are that
// directory's .m sources (the drivers, render_note.m required) plus every
// matlab/*.m of the repo, and the result is written to exports/<id>.json.
// The canonical copy of this script lives in
// simulated_instruments/instrument-format; instrument repos carry a copy so
// they build standalone.

import { mkdirSync, readdirSync, readFileSync, writeFileSync, existsSync } from 'node:fs';
import { join } from 'node:path';

const ID_RE = /^[a-z0-9][a-z0-9-]*$/;
const SRC = 'export-src';
const OUT = 'exports';

function fail(msg) {
  console.error(`build-exports: ${msg}`);
  process.exit(1);
}

function checkKnobs(id, knobs) {
  if (!Array.isArray(knobs)) fail(`${id}: 'knobs' must be an array`);
  for (const k of knobs) {
    if (typeof k.key !== 'string' || typeof k.label !== 'string') fail(`${id}: knobs need key and label`);
    if (typeof k.min !== 'number' || typeof k.max !== 'number' || typeof k.default !== 'number' || !(k.min < k.max)) {
      fail(`${id}: knob '${k.key}' needs min < max and a default`);
    }
    if (k.default < k.min || k.default > k.max) fail(`${id}: knob '${k.key}' default outside its range`);
    if (k.step !== undefined && !(k.step > 0)) fail(`${id}: knob '${k.key}' step must be > 0`);
    if (k.scale !== undefined && k.scale !== 'log') fail(`${id}: knob '${k.key}' has unknown scale`);
    if (k.scale === 'log' && k.min <= 0) fail(`${id}: knob '${k.key}' log scale needs min > 0`);
  }
}

function mfilesIn(dir) {
  if (!existsSync(dir)) return [];
  return readdirSync(dir)
    .filter((f) => f.endsWith('.m'))
    .sort()
    .map((name) => ({ name, content: readFileSync(join(dir, name), 'utf8') }));
}

if (!existsSync(SRC)) fail(`no ${SRC}/ directory here; run from the instrument repo root`);
const shared = mfilesIn('matlab');
const dirs = readdirSync(SRC, { withFileTypes: true }).filter((d) => d.isDirectory()).map((d) => d.name).sort();
if (dirs.length === 0) fail(`${SRC}/ has no instrument directories`);
mkdirSync(OUT, { recursive: true });

for (const dir of dirs) {
  const metaPath = join(SRC, dir, 'export.json');
  if (!existsSync(metaPath)) fail(`${metaPath} is missing`);
  const meta = JSON.parse(readFileSync(metaPath, 'utf8'));
  const id = meta.id;
  if (typeof id !== 'string' || !ID_RE.test(id)) fail(`${metaPath}: 'id' must match ${ID_RE}`);
  if (typeof meta.name !== 'string' || meta.name === '') fail(`${id}: missing 'name'`);
  checkKnobs(id, meta.knobs ?? []);
  const drivers = mfilesIn(join(SRC, dir));
  if (!drivers.some((f) => f.name === 'render_note.m')) fail(`${id}: no render_note.m in ${SRC}/${dir}/`);
  const names = new Set(drivers.map((f) => f.name));
  const clash = shared.find((f) => names.has(f.name));
  if (clash) fail(`${id}: driver file '${clash.name}' collides with matlab/${clash.name}`);
  const bundle = {
    format: 'numbl-instrument-v1',
    id,
    name: meta.name,
    ...(meta.description ? { description: meta.description } : {}),
    ...(meta.source ? { source: meta.source } : {}),
    knobs: meta.knobs ?? [],
    files: [...drivers, ...shared],
  };
  const outPath = join(OUT, `${id}.json`);
  writeFileSync(outPath, JSON.stringify(bundle, null, 2) + '\n');
  console.log(`wrote ${outPath} (${bundle.files.length} files, ${bundle.knobs.length} knobs)`);
}