/**
 * Promisify emscripten modules
 * 
 * idea taken from squoosh app: https://raw.githubusercontent.com/GoogleChromeLabs/squoosh/master/src/codecs/util.ts
 * 
 * usage: 
 * // create a global variable to store the initialized module once
 * let emscriptenModule
 * 
 * // inside an async function:
 * // use the global as cache to the module or initialize it
 * if (!emscriptenModule) emscriptenModule = initEmscriptenModule(importedGlueCode, urlToWasmFile)
 * const module = await emscriptenModule
 */
export function initEmscriptenModule(moduleFactory, wasmUrl) {
  return new Promise (resolve => {
      const module = moduleFactory({
          noInitialRun: true,
          locateFile: (url) => wasmUrl ? wasmUrl : url, 
          onRuntimeInitialized () {
              // hack: deleting then breaks an infinite loop
              // https://github.com/emscripten-core/emscripten/issues/5820
              delete module.then
              resolve(module)
          }
      })
  })
}