#!/usr/bin/env node
// Extract `// #region showcase:<name>` … `// #endregion showcase:<name>` blocks from real
// source files into src/app/showcase/snippets.generated.ts (WP-39). The teaching showcase
// renders these, so the code it shows IS the code that ships — it can't drift. A CI drift
// gate (`npm run gen:snippets && git diff --exit-code`) forces a regen after any edit to a
// marked region. Mirrors the gen:api pattern. Run: `npm run gen:snippets`.
import { readFileSync, writeFileSync } from 'node:fs';

// Real source files that carry showcase regions. Add a file here + a #region marker there
// to expose a new snippet; no other change needed.
const SOURCES = [
  'src/app/registratie/domain/registration.ts',
  'src/app/shared/application/remote-data.ts',
  'src/app/registratie/domain/value-objects/postcode.ts',
  'src/app/registratie/domain/change-request.machine.ts',
  'src/app/herregistratie/domain/intake.machine.ts',
];

const START = /\/\/\s*#region showcase:([\w-]+)/;
const END = /\/\/\s*#endregion showcase:/;

/** Remove the shared leading indentation so an extracted, once-nested block reads flush. */
function dedent(lines) {
  const indents = lines.filter((l) => l.trim()).map((l) => l.match(/^\s*/)[0].length);
  const min = indents.length ? Math.min(...indents) : 0;
  return lines
    .map((l) => l.slice(min))
    .join('\n')
    .trim();
}

const snippets = {};
for (const file of SOURCES) {
  const lines = readFileSync(file, 'utf8').split('\n');
  let name = null;
  let buf = [];
  for (const line of lines) {
    const start = line.match(START);
    if (start) {
      name = start[1];
      buf = [];
      continue;
    }
    if (name && END.test(line)) {
      if (snippets[name]) throw new Error(`duplicate showcase region: ${name}`);
      snippets[name] = dedent(buf);
      name = null;
      continue;
    }
    if (name) buf.push(line);
  }
  if (name) throw new Error(`unterminated showcase region "${name}" in ${file}`);
}

const names = Object.keys(snippets).sort();
const body = names.map((n) => `  ${JSON.stringify(n)}: ${JSON.stringify(snippets[n])},`).join('\n');
const out = `// GENERATED by \`npm run gen:snippets\` (scripts/gen-snippets.mjs) — do not edit.
// Source-of-truth code excerpts extracted from real files via // #region showcase:<name>.
export const SNIPPETS: Record<string, string> = {
${body}
};
`;
writeFileSync('src/app/showcase/snippets.generated.ts', out);
console.log(
  `wrote src/app/showcase/snippets.generated.ts (${names.length} snippets: ${names.join(', ')})`,
);