// I will assume that you use the following for the rest of this guide
import * as fflate from 'fflate';

// However, you should import ONLY what you need to minimize bloat.
// So, if you just need GZIP compression support:
import { gzipSync } from 'fflate';
// Woo! You just saved 20 kB off your bundle with one line.

// Try to avoid this when using fflate in the browser, as it will import
// all of fflate's components, even those that you aren't using.
const fflate = require('fflate');

// Don't use the ?dts Skypack flag; it isn't necessary for Deno support
// The @deno-types comment adds TypeScript typings

// @deno-types="https://cdn.skypack.dev/fflate/lib/index.d.ts"
import * as fflate from 'https://cdn.skypack.dev/fflate?min';

// Again, try to import just what you need

// For the browser:
import * as fflate from 'fflate/esm/browser.js';
// If the standard ESM import fails on Node (i.e. older version):
import * as fflate from 'fflate/esm';

// This is an ArrayBuffer of data
const massiveFileBuf = await fetch('/aMassiveFile').then(
  res => res.arrayBuffer()
);
// To use fflate, you need a Uint8Array
const massiveFile = new Uint8Array(massiveFileBuf);
// Note that Node.js Buffers work just fine as well:
// const massiveFile = require('fs').readFileSync('aMassiveFile.txt');

// Higher level means lower performance but better compression
// The level ranges from 0 (no compression) to 9 (max compression)
// The default level is 6
const notSoMassive = fflate.zlibSync(massiveFile, { level: 9 });
const massiveAgain = fflate.unzlibSync(notSoMassive);
const gzipped = fflate.gzipSync(massiveFile, {
  // GZIP-specific: the filename to use when decompressed
  filename: 'aMassiveFile.txt',
  // GZIP-specific: the modification time. Can be a Date, date string,
  // or Unix timestamp
  mtime: '9/1/16 2:00 PM'
});

const compressed = new Uint8Array(
  await fetch('/GZIPorZLIBorDEFLATE').then(res => res.arrayBuffer())
);
// Above example with Node.js Buffers:
// Buffer.from('H4sIAAAAAAAAE8tIzcnJBwCGphA2BQAAAA==', 'base64');

const decompressed = fflate.decompressSync(compressed);

const buf = fflate.strToU8('Hello world!');

// The default compression method is gzip
// Increasing mem may increase performance at the cost of memory
// The mem ranges from 0 to 12, where 4 is the default
const compressed = fflate.compressSync(buf, { level: 6, mem: 8 });

// When you need to decompress:
const decompressed = fflate.decompressSync(compressed);
const origText = fflate.strFromU8(decompressed);
console.log(origText); // Hello world!

const buf = fflate.strToU8('Hello world!');

// The second argument, latin1, is a boolean that indicates that the data
// is not Unicode but rather should be encoded and decoded as Latin-1.
// This is useful for creating a string from binary data that isn't
// necessarily valid UTF-8. However, binary strings are incredibly
// inefficient and tend to double file size, so they're not recommended.
const compressedString = fflate.strFromU8(
  fflate.compressSync(buf),
  true
);
const decompressed = fflate.decompressSync(
  fflate.strToU8(compressedString, true)
);
const origText = fflate.strFromU8(decompressed);
console.log(origText); // Hello world!

// This example uses synchronous streams, but for the best experience
// you'll definitely want to use asynchronous streams.

let outStr = '';
const gzipStream = new fflate.Gzip({ level: 9 }, (chunk, isLast) => {
  // accumulate in an inefficient binary string (just an example)
  outStr += fflate.strFromU8(chunk, true);
});

// You can also attach the data handler separately if you don't want to
// do so in the constructor.
gzipStream.ondata = (chunk, final) => { ... }

// Since this is synchronous, all errors will be thrown by stream.push()
gzipStream.push(chunk1);
gzipStream.push(chunk2);

...

// You should mark the last chunk by using true in the second argument
// In addition to being necessary for the stream to work properly, this
// will also set the isLast parameter in the handler to true.
gzipStream.push(lastChunk, true);

console.log(outStr); // The compressed binary string is now available

// The options parameter for compression streams is optional; you can
// provide one parameter (the handler) or none at all if you set
// deflateStream.ondata later.
const deflateStream = new fflate.Deflate((chunk, final) => {
  console.log(chunk, final);
});

// If you want to create a stream from strings, use EncodeUTF8
const utfEncode = new fflate.EncodeUTF8((data, final) => {
  // Chaining streams together is done by pushing to the
  // next stream in the handler for the previous stream
  deflateStream.push(data, final);
});

utfEncode.push('Hello'.repeat(1000));
utfEncode.push(' '.repeat(100));
utfEncode.push('world!'.repeat(10), true);

// The deflateStream has logged the compressed data

const inflateStream = new fflate.Inflate();
inflateStream.ondata = (decompressedChunk, final) => { ... };

let stringData = '';

// Streaming UTF-8 decode is available too
const utfDecode = new fflate.DecodeUTF8((data, final) => {
  stringData += data;
});

// Decompress streams auto-detect the compression method, as the
// non-streaming decompress() method does.
const dcmpStrm = new fflate.Decompress((chunk, final) => {
  console.log(chunk, 'was encoded with GZIP, Zlib, or DEFLATE');
  utfDecode.push(chunk, final);
});

dcmpStrm.push(zlibJSONData1);
dcmpStrm.push(zlibJSONData2, true);

// This succeeds; the UTF-8 decoder chained with the unknown compression format
// stream to reach a string as a sink.
console.log(JSON.parse(stringData));

// Note that the asynchronous version (see below) runs in parallel and
// is *much* (up to 3x) faster for larger archives.
const zipped = fflate.zipSync({
  // Directories can be nested structures, as in an actual filesystem
  'dir1': {
    'nested': {
      // You can use Unicode in filenames
      '你好.txt': std('Hey there!')
    },
    // You can also manually write out a directory path
    'other/tmp.txt': new Uint8Array([97, 98, 99, 100])
  },
  // You can also provide compression options
  'myImageData.bmp': [aMassiveFile, {
    level: 9,
    mem: 12,
    // ZIP-specific: mtime works here too, defaults to current time
    mtime: new Date('10/20/2020')
  }],
  // PNG is pre-compressed; no need to waste time
  'superTinyFile.png': [aPNGFile, { level: 0 }]
}, {
  // These options are the defaults for all files, but file-specific
  // options take precedence.
  level: 1,
  // Obfuscate mtime by default
  mtime: 0
});

// If you write the zipped data to myzip.zip and unzip, the folder
// structure will be outputted as:

// myzip.zip (original file)
// dir1
// |-> nested
// |   |-> 你好.txt
// |-> other
// |   |-> tmp.txt
// myImageData.bmp
// superTinyFile.bin

// When decompressing, folders are not nested; all filepaths are fully
// written out in the keys. For example, the return value may be:
// { 'nested/directory/a2.txt': Uint8Array(2) [97, 97] })
const decompressed = fflate.unzipSync(zipped);

// ZIP object
// Can also specify zip.ondata outside of the constructor
const zip = new fflate.Zip((err, dat, final) => {
  if (!err) {
    // output of the streams
    console.log(dat, final);
  }
});

const helloTxt = new fflate.ZipDeflate('hello.txt', {
  level: 9
});

// Always add streams to ZIP archives before pushing to those streams
zip.add(helloTxt);

helloTxt.push(chunk1);
// Last chunk
helloTxt.push(chunk2, true);

// ZipPassThrough is like ZipDeflate with level 0, but allows for tree shaking
const nonStreamingFile = new fflate.ZipPassThrough('test.png');
zip.add(nonStreamingFile);
// If you have data already loaded, just .push(data, true)
nonStreamingFile.push(pngData, true);

// You need to call .end() after finishing
// This ensures the ZIP is valid
zip.end();

// Unzip object
const unzipper = new fflate.Unzip();

// This function will almost always have to be called. It is used to support
// compression algorithms such as BZIP2 or LZMA in ZIP files if just DEFLATE
// is not enough (though it almost always is).
// If your ZIP files are not compressed, this line is not needed.
unzipper.register(fflate.UnzipInflate);

const neededFiles = ['file1.txt', 'example.json'];

// Can specify handler in constructor too
unzipper.onfile = file => {
  // file.name is a string, file is a stream
  if (neededFiles.includes(file.name)) {
    file.ondata = (err, dat, final) => {
      // Stream output here
      console.log(dat, final);
    };
    
    console.log('Reading:', file.name);

    // File sizes are sometimes not set if the ZIP file did not encode
    // them, so you may want to check that file.size != undefined
    console.log('Compressed size', file.size);
    console.log('Decompressed size', file.originalSize);

    // You should only start the stream if you plan to use it to improve
    // performance. Only after starting the stream will ondata be called.
    // This method will throw if the compression method hasn't been registered
    file.start();
  }
};

// Try to keep under 5,000 files per chunk to avoid stack limit errors
// For example, if all files are a few kB, multi-megabyte chunks are OK
// If files are mostly under 100 bytes, 64kB chunks are the limit
unzipper.push(zipChunk1);
unzipper.push(zipChunk2);
unzipper.push(zipChunk3, true);

import {
  gzip, zlib, AsyncGzip, zip, unzip, strFromU8,
  Zip, AsyncZipDeflate, Unzip, AsyncUnzipInflate
} from 'fflate';

// Workers will work in almost any browser (even IE11!)
// However, they fail below Node v12 without the --experimental-worker
// CLI flag, and will fail entirely on Node below v10.

// All of the async APIs use a node-style callback as so:
const terminate = gzip(aMassiveFile, (err, data) => {
  if (err) {
    // The compressed data was likely corrupt, so we have to handle
    // the error.
    return;
  }
  // Use data however you like
  console.log(data.length);
});

if (needToCancel) {
  // The return value of any of the asynchronous APIs is a function that,
  // when called, will immediately cancel the operation. The callback
  // will not be called.
  terminate();
}

// If you wish to provide options, use the second argument.

// The consume option will render the data inside aMassiveFile unusable,
// but can improve performance and dramatically reduce memory usage.
zlib(aMassiveFile, { consume: true, level: 9 }, (err, data) => {
  // Use the data
});

// Asynchronous streams are similar to synchronous streams, but the
// handler has the error that occurred (if any) as the first parameter,
// and they don't block the main thread.

// Additionally, any buffers that are pushed in will be consumed and
// rendered unusable; if you need to use a buffer you push in, you
// should clone it first.
const gzs = new AsyncGzip({ level: 9, mem: 12, filename: 'hello.txt' });
let wasCallbackCalled = false;
gzs.ondata = (err, chunk, final) => {
  // Note the new err parameter
  if (err) {
    // Note that after this occurs, the stream becomes corrupt and must
    // be discarded. You can't continue pushing chunks and expect it to
    // work.
    console.error(err);
    return;
  }
  wasCallbackCalled = true;
}
gzs.push(chunk);

// Since the stream is asynchronous, the callback will not be called
// immediately. If such behavior is absolutely necessary (it shouldn't
// be), use synchronous streams.
console.log(wasCallbackCalled) // false

// To terminate an asynchronous stream's internal worker, call
// stream.terminate().
gzs.terminate();

// This is way faster than zipSync because the compression of multiple
// files runs in parallel. In fact, the fact that it's parallelized
// makes it faster than most standalone ZIP CLIs. The effect is most
// significant for multiple large files; less so for many small ones.
zip({ f1: aMassiveFile, 'f2.txt': anotherMassiveFile }, {
  // The options object is still optional, you can still do just
  // zip(archive, callback)
  level: 6,
  mtime: 0
}, (err, data) => {
  // Save the ZIP file
});

// unzip is the only async function without support for consume option
// Also parallelized, so unzip is also often much faster than unzipSync
unzip(aMassiveZIPFile, (err, unzipped) => {
  // If the archive has data.xml, log it here
  console.log(unzipped['data.xml']);
  // Conversion to string
  console.log(strFromU8(unzipped['data.xml']))
});

// Streaming ZIP archives can accept asynchronous streams. This automatically
// uses multicore compression.
const zip = new Zip();
zip.ondata = (err, chunk, final) => { ... };
// The JSON and BMP are compressed in parallel
const exampleFile = new AsyncZipDeflate('example.json');
exampleFile.push(JSON.stringify({ large: 'object' }), true);
const exampleFile2 = new AsyncZipDeflate('example2.bmp', { level: 9 });
exampleFile.push(ec2a);
exampleFile.push(ec2b);
exampleFile.push(ec2c);
...
exampleFile.push(ec2Final, true);
zip.end();

// Streaming Unzip should register the asynchronous inflation algorithm
// for parallel processing.
const unzip = new Unzip(stream => {
  if (stream.name.endsWith('.json')) {
    stream.ondata = (err, chunk, final) => { ... };
    stream.start();

    if (needToCancel) {
      // To cancel these streams, call .terminate()
      stream.terminate();
    }
  }
});
unzip.register(AsyncUnzipInflate);
unzip.push(data, true);