WIP on shimming streams in firefox

app/ece.js

@@ -1,4 +1,12 @@
-require('buffer');
+import 'buffer';
+import TransformStream from './transformStream';
+import { ReadableStream as ReadableStreamPony } from 'web-streams-ponyfill';
+try {
+  new ReadableStream().pipeThrough(new TransformStream());
+} catch (e) {
+  // eslint-disable-next-line no-global-assign
+  ReadableStream = ReadableStreamPony;
+}
 
 const NONCE_LENGTH = 12;
 const TAG_LENGTH = 16;
@@ -316,7 +324,7 @@ class StreamSlicer {
 
 /*
 input: a blob or a ReadableStream containing data to be transformed
-key:  Uint8Array containing key of size KEY_LENGTH 
+key:  Uint8Array containing key of size KEY_LENGTH
 mode: string, either 'encrypt' or 'decrypt'
 rs:   int containing record size, optional
 salt: ArrayBuffer containing salt of KEY_LENGTH length, optional

app/serviceWorker.js

@@ -1,5 +1,6 @@
 import Keychain from './keychain';
 import { downloadStream } from './api';
+import TransformStream from './transformStream';
 
 let noSave = false;
 const map = new Map();
@@ -37,8 +38,8 @@ async function decryptStream(request) {
       'Content-Type': file.type,
       'Content-Length': file.size
     };
-
-    return new Response(decrypted, { headers });
+    const body = decrypted.local ? decrypted.nativeReadable : decrypted;
+    return new Response(body, { headers });
   } catch (e) {
     if (noSave) {
       return new Response(null, { status: e.message });

app/transformStream.js

@@ -0,0 +1,25 @@
+/* global TransformStream */
+import { createReadableStreamWrapper } from '@mattiasbuelens/web-streams-adapter';
+import { TransformStream as TransformStreamPony } from 'web-streams-ponyfill';
+
+const toNative = createReadableStreamWrapper(ReadableStream);
+
+class TransformStreamLocal {
+  constructor(transformer) {
+    this.stream = new TransformStreamPony(transformer);
+    this.local = true;
+  }
+  get nativeReadable() {
+    return toNative(this.stream.readable);
+  }
+  get readable() {
+    return this.stream.readable;
+  }
+  get writable() {
+    return this.stream.writable;
+  }
+}
+
+export default (typeof TransformStream === 'function'
+  ? TransformStream
+  : TransformStreamLocal);