#!/usr/bin/env node
/**
 * Capabilities Codegen
 *
 * Projects `packages/capabilities/index.js` (ESM, the source of truth) into
 * a checked-in CommonJS module at `apps/server/capabilities.js`.
 *
 * apps/server/ is subtree-split and deployed standalone, so it can't import
 * packages/ at runtime (see the comment atop apps/server/db.js) — same
 * constraint `packages/schema/codegen.js` works around by generating
 * apps/server/schema.json from packages/schema/v1.json. That precedent
 * projects *data*; this one projects *logic*, because resolveCapabilities()
 * and validateTileManifest() are code the server needs to run, not read.
 * The projection is a mechanical ESM→CommonJS syntax rewrite — index.js has
 * no imports and no capability is added, widened, narrowed or removed by it.
 *
 * Usage:
 *   node packages/capabilities/codegen.js
 *   yarn capabilities:codegen
 */

import { readFileSync, writeFileSync } from 'fs';
import { dirname, join } from 'path';
import { fileURLToPath } from 'url';

const __filename = fileURLToPath(import.meta.url);
const __dirname = dirname(__filename);

/**
 * Rewrite `index.js`'s ESM export syntax to CommonJS and collect the
 * exported names, so the projection can end with a single `module.exports`
 * rather than one `exports.x =` per declaration (keeps the body a literal
 * copy of the source instead of another place per-export logic could
 * drift).
 */
export function generateServerCapabilities(sourceJs) {
  const exportedNames = [];
  const body = sourceJs
    .replace(/^export function (\w+)/gm, (_match, name) => {
      exportedNames.push(name);
      return `function ${name}`;
    })
    .replace(/^export const (\w+)/gm, (_match, name) => {
      exportedNames.push(name);
      return `const ${name}`;
    });

  const banner = [
    '/**',
    ' * Generated by packages/capabilities/codegen.js from packages/capabilities/index.js.',
    ' * DO NOT EDIT - regenerate with: yarn capabilities:codegen',
    ' *',
    ' * apps/server/ is subtree-split and deployed standalone, so it can\'t import',
    ' * packages/ at runtime and carries its own copy instead (see the comment atop',
    ' * apps/server/db.js). This file is a straight ESM->CommonJS syntax rewrite of',
    ' * packages/capabilities/index.js — no capability is added, widened, narrowed',
    ' * or removed by the projection.',
    ' */',
    '',
    '\'use strict\';',
    '',
  ].join('\n');

  const footer = `\nmodule.exports = { ${exportedNames.join(', ')} };\n`;

  return banner + body + footer;
}

function main() {
  console.log('[capabilities-codegen] Reading packages/capabilities/index.js...');

  const sourcePath = join(__dirname, 'index.js');
  const sourceJs = readFileSync(sourcePath, 'utf-8');

  const generated = generateServerCapabilities(sourceJs);

  const serverPath = join(__dirname, '..', '..', 'apps', 'server', 'capabilities.js');
  writeFileSync(serverPath, generated);

  console.log('[capabilities-codegen] Wrote apps/server/capabilities.js');
}

// Only run when invoked directly (node packages/capabilities/codegen.js),
// not when imported by check-freshness.js to reuse generateServerCapabilities.
const isMain = process.argv[1] === __filename;
if (isMain) {
  main();
}