#!/usr/bin/env node
/**
 * Bundle size gate — TASK-DEBT-015
 * Fails the build if initial JS bundle exceeds 200KB gzipped.
 * Measures: index-*.js + vendor-react-*.js (critical path for first paint).
 */
import { readdirSync, readFileSync } from 'fs';
import { createGzip } from 'zlib';
import { dirname, join } from 'path';
import { fileURLToPath } from 'url';

const __dirname = dirname(fileURLToPath(import.meta.url));
const DIST = join(__dirname, '../dist_verification/assets');
const MAX_COMBINED_KB = 200;

function gzipSize(bytes) {
  return new Promise((resolve, reject) => {
    const chunks = [];
    const gzip = createGzip();
    gzip.on('data', (chunk) => chunks.push(chunk));
    gzip.on('end', () => resolve(Buffer.concat(chunks).length));
    gzip.on('error', reject);
    gzip.end(bytes);
  });
}

async function main() {
  let dir;
  try {
    dir = readdirSync(DIST);
  } catch (e) {
    console.error('Run "npm run build" first. dist_verification/assets not found.');
    process.exit(1);
  }

  const indexFile = dir.find((f) => f.startsWith('index-') && f.endsWith('.js'));
  const vendorReactFile = dir.find((f) => f.startsWith('vendor-react-') && f.endsWith('.js'));

  let totalGzip = 0;
  const results = [];

  for (const file of [indexFile, vendorReactFile]) {
    if (!file) continue;
    const path = join(DIST, file);
    const bytes = readFileSync(path);
    const sizeGzip = await gzipSize(bytes);
    totalGzip += sizeGzip;
    results.push({ file, kb: (sizeGzip / 1024).toFixed(1) });
  }

  const totalKb = totalGzip / 1024;
  console.log('Bundle size (gzipped):');
  results.forEach((r) => console.log(`  ${r.file}: ${r.kb} kB`));
  console.log(`  Total (index + vendor-react): ${totalKb.toFixed(1)} kB`);

  if (totalKb > MAX_COMBINED_KB) {
    console.error(`\nFAIL: Initial bundle exceeds ${MAX_COMBINED_KB} kB (target: ORIGIN_PERFORMANCE_TARGETS §3.2)`);
    process.exit(1);
  }
  console.log(`\nPASS: Bundle under ${MAX_COMBINED_KB} kB limit.`);
}

main().catch((e) => {
  console.error(e);
  process.exit(1);
});