import { builtinModules } from 'node:module';
import { copyFileSync, cpSync, mkdirSync, readFileSync, writeFileSync } from 'node:fs';
import { createHash } from 'node:crypto';
import { build } from 'esbuild';

const out = 'dist';
mkdirSync(out, { recursive: true });

const aliases = {
  '@libsql/client': '@libsql/client-wasm',
  // client-wasm 0.18.0 pins libsql-wasm-experimental 0.0.2, which has no vector functions; 0.0.3 has them.
  '@libsql/libsql-wasm-experimental': './node_modules/@libsql/libsql-wasm-experimental/index.mjs',
  path: 'path-browserify',
};

const builtins = new Set([...builtinModules, ...builtinModules.map(m => `node:${m}`)]);
const stubbed = new Set();
// Node stdlib imports that @mastra/core pulls in for features this demo never touches.
// Each becomes a module with the same export names: globals where the browser has them, inert stubs otherwise.
// The one Node API LibSQLVector itself calls is fs/promises.realpath() (to key its per-file write lock);
// the Wasm database lives in an in-memory filesystem, so the path is returned as is.
const implemented = { 'fs/promises': { realpath: 'async path => path' } };
const stubNodeBuiltins = {
  name: 'stub-node-builtins',
  setup(b) {
    b.onResolve({ filter: /.*/ }, args => {
      if (!builtins.has(args.path) || args.path in aliases) return;
      stubbed.add(args.path);
      return { path: args.path, namespace: 'node-stub' };
    });
    b.onLoad({ filter: /.*/, namespace: 'node-stub' }, async args => {
      const real = await import(args.path);
      const names = Object.keys(real).filter(n => n !== 'default' && /^[A-Za-z_$][\w$]*$/.test(n));
      const contents = [
        'const stub = new Proxy(function () {}, { get: (_t, p) => (p === "prototype" ? {} : p === Symbol.toPrimitive ? () => "" : stub), apply: () => stub, construct: () => ({}) });',
        ...names.map(n => `export const ${n} = ${implemented[args.path]?.[n] ?? `globalThis.${n} ?? stub`};`),
        'export default stub;',
      ].join('\n');
      return { contents, loader: 'js' };
    });
  },
};

const common = {
  bundle: true,
  format: 'esm',
  platform: 'browser',
  target: 'es2022',
  sourcemap: false,
  minify: true,
  legalComments: 'none',
  logLevel: 'warning',
};

await build({
  ...common,
  entryPoints: ['src/worker.js'],
  outfile: `${out}/worker.js`,
  alias: aliases,
  inject: ['./src/shims/process.js'],
  plugins: [stubNodeBuiltins],
  metafile: true,
}).then(r => writeFileSync('worker.meta.json', JSON.stringify(r.metafile)));

await build({ ...common, entryPoints: ['src/main.js'], outfile: `${out}/main.js` });

copyFileSync('node_modules/@libsql/libsql-wasm-experimental/sqlite-wasm/jswasm/sqlite3.wasm', `${out}/sqlite3.wasm`);
cpSync('public', out, { recursive: true });
cpSync('files', `${out}/files`, { recursive: true });
mkdirSync(`${out}/files/demo-src`, { recursive: true });
for (const [from, to] of [
  ['src/worker.js', 'worker.js'],
  ['src/main.js', 'main.js'],
  ['build.mjs', 'build.mjs'],
  ['package.json', 'package.json'],
  ['vendor/libsql-fix/SOURCE.md', 'SOURCE.md'],
]) {
  copyFileSync(from, `${out}/files/demo-src/${to}`);
}

const sha = f => createHash('sha256').update(readFileSync(f)).digest('hex').slice(0, 16);
console.log('stubbed node builtins:', [...stubbed].sort().join(', ') || '(none)');
console.log('worker.js sha256:', sha(`${out}/worker.js`), `${(readFileSync(`${out}/worker.js`).length / 1024).toFixed(0)} KiB`);