From 40f16b98e2fe6303a5d98f7348b6f3565f13e9df Mon Sep 17 00:00:00 2001
From: Fedor Indutny <79877362+indutny-signal@users.noreply.github.com>
Date: Mon, 25 Apr 2022 13:56:59 -0700
Subject: [PATCH] Transcode link preview images

---
 ts/linkPreviews/linkPreviewFetch.ts           | 17 ++++++++++
 .../linkPreviews/linkPreviewFetch_test.ts     | 34 +++++++++----------
 2 files changed, 33 insertions(+), 18 deletions(-)

diff --git a/ts/linkPreviews/linkPreviewFetch.ts b/ts/linkPreviews/linkPreviewFetch.ts
index 2c07ec255..98942f983 100644
--- a/ts/linkPreviews/linkPreviewFetch.ts
+++ b/ts/linkPreviews/linkPreviewFetch.ts
@@ -3,6 +3,7 @@
 
 import type { RequestInit, Response } from 'node-fetch';
 import type { AbortSignal as AbortSignalForNodeFetch } from 'abort-controller';
+import { blobToArrayBuffer } from 'blob-util';
 
 import type { MIMEType } from '../types/MIME';
 import {
@@ -14,6 +15,7 @@ import {
   stringToMIMEType,
 } from '../types/MIME';
 import type { LoggerType } from '../types/Logging';
+import { scaleImageToLevel } from '../util/scaleImageToLevel';
 import * as log from '../logging/log';
 
 const USER_AGENT = 'WhatsApp/2';
@@ -603,5 +605,20 @@ export async function fetchLinkPreviewImage(
     return null;
   }
 
+  // Scale link preview image
+  if (contentType !== IMAGE_GIF) {
+    const dataBlob = new Blob([data], {
+      type: contentType,
+    });
+    const { blob: xcodedDataBlob } = await scaleImageToLevel(
+      dataBlob,
+      contentType,
+      false
+    );
+    const xcodedDataArrayBuffer = await blobToArrayBuffer(xcodedDataBlob);
+
+    data = new Uint8Array(xcodedDataArrayBuffer);
+  }
+
   return { data, contentType };
 }
diff --git a/ts/test-electron/linkPreviews/linkPreviewFetch_test.ts b/ts/test-electron/linkPreviews/linkPreviewFetch_test.ts
index 563e9418b..8681f9407 100644
--- a/ts/test-electron/linkPreviews/linkPreviewFetch_test.ts
+++ b/ts/test-electron/linkPreviews/linkPreviewFetch_test.ts
@@ -1151,15 +1151,14 @@ describe('link preview fetching', () => {
         );
 
         assert.deepEqual(
-          await fetchLinkPreviewImage(
-            fakeFetch,
-            'https://example.com/img',
-            new AbortController().signal
-          ),
-          {
-            data: fixture,
-            contentType: stringToMIMEType(contentType),
-          }
+          (
+            await fetchLinkPreviewImage(
+              fakeFetch,
+              'https://example.com/img',
+              new AbortController().signal
+            )
+          )?.contentType,
+          stringToMIMEType(contentType)
         );
       });
     });
@@ -1238,15 +1237,14 @@ describe('link preview fetching', () => {
       );
 
       assert.deepEqual(
-        await fetchLinkPreviewImage(
-          fakeFetch,
-          'https://example.com/img',
-          new AbortController().signal
-        ),
-        {
-          data: fixture,
-          contentType: IMAGE_JPEG,
-        }
+        (
+          await fetchLinkPreviewImage(
+            fakeFetch,
+            'https://example.com/img',
+            new AbortController().signal
+          )
+        )?.contentType,
+        IMAGE_JPEG
       );
 
       sinon.assert.calledTwice(fakeFetch);