// Hello world with zip.js (and Streams)

import { ZipWriter, ZipReader, BlobReader } from "https://deno.land/x/zipjs/index.js";

// ----
// Write the zip file
// ----

// Creates a TransformStream object where the zip content will be written.
const zipStream = new TransformStream();
// Creates a Promise object resolved to the zip content returned as a Blob object.
const zipBlobPromise = new Response(zipStream.readable).blob();
// Creates a ReadableStream object containing the text of the entry to add in the zip.
const helloWorldReadable = new Blob(["Hello world!"], { type: "text/plain" }).stream();


// Creates a ZipWriter object writing data via zipStream, adds the file "hello.txt" containing
// the text "Hello world!" via helloWorldReadable in the zip, and closes the writer.
const zipWriter = new ZipWriter(zipStream);
await zipWriter.add("hello.txt", { readable: helloWorldReadable });
await zipWriter.close();


// Retrieves the Blob object containing the zip content.
const zipBlob = await zipBlobPromise;

// Uncomment the following code to download the zip file (in a browser)
// 
// const anchorElement = document.createElement("a");
// anchorElement.href = URL.createObjectURL(zipBlob);
// anchorElement.download = "hello.zip";
// anchorElement.click();
// 


// ----
// Read the zip file
// ----

// Creates a TransformStream object where the content of the first entry in the zip will be written.
const contentStream = new TransformStream();
// Creates a Promise object resolved to the first entry content returned as text.
const contentTextPromise = new Response(contentStream.readable).text();


// Reads zipBlob via a BlobReader object, retrieves metadata (name, dates, etc.) of the first entry, 
// retrieves its content via contentStream, and closes the reader.
// Note: it is *not* possible to use a ReadableStream object to read a zip because random access 
// to data is required to fetch entries reliably and efficiently.
const zipReader = new ZipReader(new BlobReader(zipBlob));
const firstEntry = (await zipReader.getEntries()).shift();
await firstEntry.getData(contentStream);
await zipReader.close();


// Displays "Hello world!".
const contentText = await contentTextPromise;
console.log(contentText);