#!/usr/bin/env node
// golden-baseline.mjs — regenerate the v8 Phase 5 golden baseline artifacts.
//
//   node scripts/golden-baseline.mjs            # print a summary, write nothing
//   node scripts/golden-baseline.mjs --write    # (re-)bless the artifacts
//
// Re-blessing is a deliberate act. During Phase 5, a diff here means the
// table swap under test changed observable behaviour — the correct response
// is to roll the swap back, not to re-run this with --write.

import { mkdirSync, writeFileSync, existsSync, readFileSync, readdirSync } from 'node:fs';
import { resolve, dirname } from 'node:path';
import { fileURLToPath } from 'node:url';
import {
  buildPatternDump,
  buildReferenceRun,
  buildSuiteCounts,
  serialize,
} from './lib/golden-dump.mjs';

const ROOT = resolve(dirname(fileURLToPath(import.meta.url)), '..');
const GOLDEN_DIR = resolve(ROOT, 'tests/golden');
const write = process.argv.includes('--write');
// Opt-in: one node process per test file, sequentially. Minutes, not seconds.
const withSuite = process.argv.includes('--suite');

const artifacts = [
  ['patterns.json', await buildPatternDump(ROOT)],
  ['reference-run.json', await buildReferenceRun(ROOT)],
];

/** `fs.globSync` is Node 22+; package.json promises >=18, so walk by hand. */
function findTestFiles(dir, acc = []) {
  for (const e of readdirSync(dir, { withFileTypes: true }).sort((a, b) =>
    a.name.localeCompare(b.name)
  )) {
    const full = resolve(dir, e.name);
    if (e.isDirectory()) findTestFiles(full, acc);
    else if (e.name.endsWith('.test.mjs')) acc.push(full);
  }
  return acc;
}

if (withSuite) {
  artifacts.push([
    'suite-counts.json',
    buildSuiteCounts(ROOT, findTestFiles(resolve(ROOT, 'tests'))),
  ]);
}

mkdirSync(GOLDEN_DIR, { recursive: true });

let drift = false;
for (const [name, data] of artifacts) {
  const path = resolve(GOLDEN_DIR, name);
  const next = serialize(data);
  const prev = existsSync(path) ? readFileSync(path, 'utf8') : null;
  const status = prev === null ? 'new' : prev === next ? 'unchanged' : 'CHANGED';
  if (status === 'CHANGED') drift = true;

  if (write) writeFileSync(path, next);
  console.log(`${write ? 'wrote' : 'checked'}  tests/golden/${name}  [${status}]`);
}

const [, dump] = artifacts[0];
const [, run] = artifacts[1];
console.log(
  `\n  regex records : ${dump.counts.regex}` +
    `\n  table records : ${dump.counts.table}` +
    `\n  file digests  : ${dump.counts.file}` +
    `\n  reference run : ${run.summary.total} cases, ` +
    `${run.summary.matchingExpectation} match expectation` +
    `\n  reachability  : ${run.coverage.patternsReachable}/${run.coverage.patternsTotal} patterns` +
    ` (STATIC probe, not observed coverage — see tests/golden/README.md)`
);

const suite = artifacts.find(([n]) => n === 'suite-counts.json');
if (suite) {
  const [, s] = suite;
  console.log(
    `  suite         : ${s.totals.pass} pass / ${s.totals.fail} fail across ${s.totals.files} files`
  );
}

if (!write && drift) {
  console.error('\nBaseline drift detected. Investigate before re-blessing with --write.');
  process.exit(1);
}