import wasmWorker from 'wasm-worker';

// supposing an "add.wasm" module that exports a single function "add"
wasmWorker('add.wasm')
  .then(module => {
    return module.exports.add(1, 2);
  })
  .then(sum => {
    console.log('1 + 2 = ' + sum);
  })
  .catch(ex => {
    // ex is a string that represents the exception
    console.error(ex);
  });

// you can also run js functions inside the worker
// to access importObject for example
wasmWorker('add.wasm')
  .then(module => {
    return module.run(({
      // module,
      // importObject,
      instance,
      params
    }) => {
      // here is sync
      const sum = instance.exports.add(...params);
      return '1 + 2 = ' + sum;
    }, [1, 2]);
  })
  .then(result => {
    console.log(result);
  });

type JsCallback = (context: {
  module: WebAssembly.Module,
  instance: WebAssembly.Instance,
  importObject: importObject,
  params: any,
}) => any;

type WasmWorkerModule = {
  exports: {
    [export: string]: (...any: Array<any>) => Promise<any>
  },
  // run a js function inside the worker and provides it the given params
  // ⚠️ Caveat: the function you pass cannot rely on its surrounding scope, since it is executed in an isolated context.
  // Please use the "params" parameter to provide some values to the callback
  run: (callback: JsCallback, params?: any) => Promise<any>
};

type Options = {
  // the first 3 properties are used to create the Web Worker
  // https://developer.mozilla.org/en-US/docs/Web/API/Worker/Worker#Parameters
  name: string,
  type: 'classic' | 'module',
  credentials: 'omit' | 'same-origin' | 'include',
  
  // the getImportObject function is used to get the options to instantiate the WebAssembly Module
  // ⚠️ Caveat: the function you pass cannot rely on its surrounding scope, since it is executed in an isolated context.
  // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WebAssembly/instantiate#Primary_overload_%E2%80%94_taking_wasm_binary_code
  getImportObject: () => importObject,
};

wasmWorker(url: string, options?: Options): Promise<WasmWorkerModule> // browser only
wasmWorker(bufferSource: TypedArray | ArrayBuffer, options?: Options): Promise<WasmWorkerModule>

if (!window.fetch || !window.Worker || !window.WebAssembly) {
    ...
} else {
    ...
}