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import {  createSubscribeFn,  defer,  Observer,  SubscribeFn,} from "../core/runtime/async/observer.ts";
export interface ProgressResult {  originalResponse: Response;  response: Response;  subscribeProgress: SubscribeFn<Progress>;}export interface Progress {  current: number;  total: number;}export function progressResponse(originalResponse: Response): ProgressResult {  const deferredStart = defer<void>();  const subscribeReader = readerToSubscribeFn(    originalResponse.body?.getReader()!,    deferredStart,  );  const contentLength = +originalResponse.headers.get("content-length")! | 0;  let loaded = 0;  let progressObserver: Observer<Progress> | null = null;  const subscribeProgress: SubscribeFn<Progress> = (observer) => {    progressObserver = observer;    return () => {      progressObserver = null;      observer.complete();    };  };  const response = new Response(    new ReadableStream({      start(controller) {        subscribeReader({          next({ value }) {            if (!value) return;            controller.enqueue(value);            loaded += value.byteLength | 0;            progressObserver?.next({              current: loaded,              total: contentLength,            });          },          error(err) {            controller.error(err);            progressObserver?.error(err);          },          complete() {            controller.close();            progressObserver?.complete();          },        });        deferredStart.resolve();      },    }),  );  return { originalResponse, response, subscribeProgress };}
function readerToSubscribeFn<T>(  reader: ReadableStreamDefaultReader<T>,  wait = Promise.resolve(),): SubscribeFn<ReadableStreamReadResult<T>> {  return createSubscribeFn(async () => {    const readResult = await reader.read();    return [readResult, readResult.done];  }, wait);}