#!/usr/bin/env node
// Bundle size budget (Gitea #96). The CI "Report bundle sizes" step printed
// numbers with nothing to compare them against, so a bundle could balloon
// silently. This script compares dist/assets gzip sizes against a small
// checked-in budget (scripts/bundle-budget.json) and prints the same report.
//
// Mode is passed via argv: `pull_request` fails the build over budget,
// anything else (e.g. `push`) only warns — a push has already merged, so
// blocking it can't prevent the regression, only delay the deploy of an
// otherwise-good commit; the pull_request gate is where this should be caught.
import { appendFileSync, readFileSync, readdirSync, statSync } from 'node:fs';
import { gzipSync } from 'node:zlib';
import path from 'node:path';
import { fileURLToPath } from 'node:url';

const __dirname = path.dirname(fileURLToPath(import.meta.url));
const mode = process.argv[2] || 'push';
const distAssetsDir = path.join(__dirname, '..', 'dist', 'assets');
const budgetPath = path.join(__dirname, 'bundle-budget.json');

function formatKb(bytes) {
  return `${(bytes / 1024).toFixed(1)} kB`;
}

function main() {
  const budget = JSON.parse(readFileSync(budgetPath, 'utf-8'));

  const jsFiles = readdirSync(distAssetsDir)
    .filter((f) => f.endsWith('.js') && !f.endsWith('.map'))
    .sort();

  if (jsFiles.length === 0) {
    console.error(
      `[check-bundle-size] No .js files found in ${distAssetsDir} — did the build run?`,
    );
    process.exitCode = 1;
    return;
  }

  const rows = jsFiles.map((name) => {
    const filePath = path.join(distAssetsDir, name);
    const size = statSync(filePath).size;
    const gzipSize = gzipSync(readFileSync(filePath)).length;
    return { name, size, gzipSize };
  });

  const totalGzipBytes = rows.reduce((sum, r) => sum + r.gzipSize, 0);
  const largest = rows.reduce((max, r) => (r.gzipSize > max.gzipSize ? r : max), rows[0]);

  const summaryLines = [
    '### Bundle sizes',
    '',
    '| File | Size | Gzip |',
    '|------|------|------|',
    ...rows.map((r) => `| ${r.name} | ${formatKb(r.size)} | ${formatKb(r.gzipSize)} |`),
    '',
    `**Total gzip:** ${formatKb(totalGzipBytes)} (budget ${formatKb(budget.totalGzipBytes)})`,
    `**Largest chunk gzip:** ${largest.name} — ${formatKb(largest.gzipSize)} (budget ${formatKb(
      budget.largestChunkGzipBytes,
    )})`,
  ];

  const summaryText = summaryLines.join('\n');
  console.log(summaryText);
  if (process.env.GITHUB_STEP_SUMMARY) {
    // Gitea Actions/act_runner honors the same GITHUB_STEP_SUMMARY convention.
    appendFileSync(process.env.GITHUB_STEP_SUMMARY, `${summaryText}\n`);
  }

  const overBudget = [];
  if (totalGzipBytes > budget.totalGzipBytes) {
    overBudget.push(
      `total gzip ${formatKb(totalGzipBytes)} exceeds budget ${formatKb(budget.totalGzipBytes)}`,
    );
  }
  if (largest.gzipSize > budget.largestChunkGzipBytes) {
    overBudget.push(
      `largest chunk (${largest.name}) gzip ${formatKb(largest.gzipSize)} exceeds budget ${formatKb(
        budget.largestChunkGzipBytes,
      )}`,
    );
  }

  if (overBudget.length > 0) {
    const message = `[check-bundle-size] Over budget: ${overBudget.join('; ')}`;
    if (mode === 'pull_request') {
      console.error(message);
      process.exitCode = 1;
    } else {
      console.warn(`${message} (warning only on "${mode}")`);
    }
  } else {
    console.log('[check-bundle-size] Within budget.');
  }
}

main();