/**
 * Runs helpdeco for johnmcm.com's /hlp-viewer, one help file per message,
 * each in a fresh instance.
 *
 * Messages in:  { id, name: string (file name inside the decompiler), bytes: Uint8Array }
 * Messages out: { id, code, files: { name, data }[], log } or { id, error }.
 *
 * Written for johnmcm.com (2026); part of the module published at /source/helpdeco/.
 */

import createHelpdeco from './helpdeco.mjs';
import { decompile } from './run.mjs';

let compiled = null;

function wasmModule() {
  // A failed fetch or compile is not kept, so the next file tries again.
  compiled ??= WebAssembly.compileStreaming(fetch(new URL('./helpdeco.wasm', import.meta.url))).catch((err) => {
    compiled = null;
    throw err;
  });
  return compiled;
}

self.onmessage = async (e) => {
  const { id, name, bytes } = e.data;
  try {
    const module = await wasmModule();
    // If instantiating fails, the factory never settles; this lets the failure through.
    let failed;
    const instantiateFailed = new Promise((_, reject) => (failed = reject));
    const out = await Promise.race([
      decompile(createHelpdeco, name, bytes, {
        instantiateWasm(imports, done) {
          WebAssembly.instantiate(module, imports).then((i) => done(i)).catch(failed);
          return {};
        },
      }),
      instantiateFailed,
    ]);
    self.postMessage({ id, ...out }, out.files.map((f) => f.data.buffer));
  } catch (err) {
    self.postMessage({ id, error: String(err?.message || err) });
  }
};