// The optional non-commercial symbol sets are never in a build made without
// them (aac-web's nc-symbols feature off): the standard's own build always,
// a deployment's when it does not offer them.
//
//   node tools/symbols/check-no-nc.mjs <site-dir> [<prefix>]
//
// <prefix> is where the app sits in the site: "" for the standard's own
// build (prerender-static.sh, target/site), "app/" for a deployment that
// mounts it at /app/. Fails, naming each file, on:
//   - any symbol-set pack anywhere in the site: a file under models/symbols/,
//     a *.pack file, or a file that starts with a pack's magic bytes, as
//     stored or, for a .br/.gz sidecar, once decompressed;
//   - the service worker (sw.js) precaching anything under models/symbols/
//     or any *.pack;
//   - any file named for a set, in any folder;
//   - any file of the app's own naming the sets, each .gz/.br sidecar
//     decompressed first. Left out of this word scan, and only of it: the
//     third-party data copied in beside the app — voices/, ai/, asr/, ae/,
//     vendor/ and the word lists in models/lang/ (dictionaries hold such
//     words as Italian "sclera", the eye).
// Mirrors aac-aurasense-web scripts/check-nc-off.mjs.
import { closeSync, existsSync, openSync, readdirSync, readFileSync, readSync, realpathSync, statSync } from 'node:fs';
import { join, relative, sep } from 'node:path';
import { pathToFileURL } from 'node:url';
import { brotliDecompressSync, constants, gunzipSync } from 'node:zlib';

export const PACK_MAGIC = Buffer.from('AACSYMP1');
const NAMES = /arasaac|sclera/i;
const THIRD_PARTY = ['voices/', 'ai/', 'asr/', 'ae/', 'vendor/', 'models/lang/'];

// How much of a file is read to find its first bytes: enough for the start of
// any .br/.gz stream; a stream that needs more is read whole.
const PREFIX = 64 * 1024;

function start(path) {
  const fd = openSync(path, 'r');
  try {
    const b = Buffer.alloc(PREFIX);
    return b.subarray(0, readSync(fd, b, 0, b.length, 0));
  } finally {
    closeSync(fd);
  }
}

const inflate = (rel, bytes, partial) =>
  rel.endsWith('.br')
    ? brotliDecompressSync(bytes, partial ? { finishFlush: constants.BROTLI_OPERATION_FLUSH } : {})
    : gunzipSync(bytes, partial ? { finishFlush: constants.Z_SYNC_FLUSH } : {});

/** Does the file begin with a pack's magic bytes, as stored or, for a .br/.gz
 * sidecar, once decompressed? Checked in every folder, third-party ones too. */
function isPackBytes(path, rel) {
  const raw = start(path);
  if (raw.subarray(0, PACK_MAGIC.length).equals(PACK_MAGIC)) return true;
  if (!/\.(br|gz)$/.test(rel)) return false;
  try {
    let out = inflate(rel, raw, true);
    if (out.length < PACK_MAGIC.length && raw.length === PREFIX) out = inflate(rel, readFileSync(path), false);
    return out.subarray(0, PACK_MAGIC.length).equals(PACK_MAGIC);
  } catch {
    return false; // not compressed after all: its stored bytes were checked
  }
}

/** What in `site` breaks the rule: { packs, named, precached }. */
export function check(site, prefix = '') {
  const packs = [];
  const named = [];
  const thirdParty = THIRD_PARTY.map((p) => prefix + p);
  const walk = (dir) => {
    for (const name of readdirSync(dir)) {
      const path = join(dir, name);
      if (statSync(path).isDirectory()) {
        walk(path);
        continue;
      }
      const rel = relative(site, path).split(sep).join('/');
      if (/(^|\/)models\/symbols\//.test(rel) || /\.pack(\.br|\.gz)?$/.test(rel) || isPackBytes(path, rel)) {
        packs.push(rel);
        continue;
      }
      // A file named for a set, in any folder.
      if (NAMES.test(rel)) {
        named.push(rel);
        continue;
      }
      // The content word scan leaves out third-party data.
      if (thirdParty.some((p) => rel.startsWith(p))) continue;
      let bytes = readFileSync(path);
      try {
        if (rel.endsWith('.br')) bytes = brotliDecompressSync(bytes);
        else if (rel.endsWith('.gz')) bytes = gunzipSync(bytes);
      } catch {
        // Not compressed after all: scanned as it is.
      }
      if (NAMES.test(bytes.toString('latin1'))) named.push(rel);
    }
  };
  walk(site);
  let precached = [];
  const sw = join(site, 'sw.js');
  if (existsSync(sw)) {
    // A worker whose list cannot be read cannot be cleared.
    const m = readFileSync(sw, 'utf8').match(/PRECACHE_URLS = (\[.*?\]);/s);
    if (!m) throw new Error(`${sw}: no PRECACHE_URLS list to check`);
    precached = JSON.parse(m[1]).filter((u) => /models\/symbols\/|\.pack$/.test(u));
  }
  return { packs, named, precached };
}

// Run as a command (not imported by the tests)? import.meta.url is the real
// path, percent-encoded: compare it with argv[1] made the same way, so a path
// with a space or through a symlink still runs the check.
function runAsCommand() {
  try {
    return pathToFileURL(realpathSync(process.argv[1])).href === import.meta.url;
  } catch {
    return false;
  }
}

if (runAsCommand()) {
  const [site, prefix = ''] = process.argv.slice(2);
  if (!site) {
    console.error('usage: node tools/symbols/check-no-nc.mjs <site-dir> [<prefix>]');
    process.exit(2);
  }
  const { packs, named, precached } = check(site, prefix);
  if (packs.length) console.error(`✗ a build without the optional symbol sets ships ${packs.length} pack file(s):\n  ${packs.join('\n  ')}`);
  if (named.length) console.error(`✗ a build without the optional symbol sets names them in ${named.length} file(s):\n  ${named.join('\n  ')}`);
  if (precached.length) console.error(`✗ the service worker precaches ${precached.join(', ')}`);
  if (packs.length || named.length || precached.length) process.exit(1);
  console.log(`✓ no symbol pack, and no file of the app's own names the optional symbol sets (word scan leaves out ${THIRD_PARTY.map((p) => prefix + p).join(', ')})`);
}