/**
 * Inline every module into one self-contained HTML file, so the whole tool is a
 * single document that opens straight from the desktop with no install, no
 * server and no internet.
 */
import { readFileSync, writeFileSync, mkdirSync } from 'node:fs';
import { fileURLToPath } from 'node:url';
import { dirname, join } from 'node:path';

const here = dirname(fileURLToPath(import.meta.url));
const root = join(here, '..');

// Dependency order, leaves first.
const MODULES = [
  'src/fonts.js',
  'src/codec/bitfont.mjs',
  'src/codec/td5.mjs',
  'src/codec/tp5.mjs',
  'src/codec/sheet.mjs',
  'app/main.mjs',
];

function strip(src, name) {
  const out = src
    // drop the import lines; every symbol ends up in one shared scope
    .replace(/^\s*import\s+[^;]*?from\s*['"][^'"]+['"];?\s*$/gm, '')
    // `export const X` -> `const X`, `export function f` -> `function f`
    .replace(/^export\s+(const|let|var|function|class|async)\b/gm, '$1')
    // bare re-export statements, if any ever appear
    .replace(/^export\s*\{[^}]*\};?\s*$/gm, '');
  if (/^\s*(import|export)\b/m.test(out)) {
    throw new Error(`${name}: an import/export slipped through the bundler`);
  }
  return `\n// ===== ${name} =====\n${out.trim()}\n`;
}

const code = MODULES.map((m) => strip(readFileSync(join(root, m), 'utf8'), m)).join('\n');

const html = readFileSync(join(root, 'app/index.html'), 'utf8');
if (!html.includes('<script type="module" src="./main.mjs"></script>')) {
  throw new Error('index.html no longer has the expected script tag');
}

const banner = `<!--
  DestoGod — bus destination sign editor.
  Single self-contained file: no install, no internet, nothing to set up.
  Built ${new Date().toISOString().slice(0, 10)} from destogod/src + destogod/app.
-->
`;

const bundled = banner + html.replace(
  '<script type="module" src="./main.mjs"></script>',
  `<script type="module">\n${code}\n</script>`
);

mkdirSync(join(root, 'dist'), { recursive: true });
const outPath = join(root, 'dist/DestoGod.html');
writeFileSync(outPath, bundled);
console.log(`wrote dist/DestoGod.html  (${(bundled.length / 1024).toFixed(0)} KB, ${MODULES.length} modules inlined)`);