Skip loading videos into memory for performance

ts/components/conversation/media-gallery/propTypes/Message.tsx

@@ -2,7 +2,9 @@
  * @prettier
  */
 import is from '@sindresorhus/is';
+import { partition, sortBy } from 'lodash';
 
+import * as MIME from '../../../../types/MIME';
 import { arrayBufferToObjectURL } from '../../../../util/arrayBufferToObjectURL';
 import { Attachment } from '../../../../types/Attachment';
 import { MapAsync } from '../../../../types/MapAsync';
@@ -16,24 +18,55 @@ export type Message = {
 const DEFAULT_CONTENT_TYPE: MIMEType = 'application/octet-stream' as MIMEType;
 
 export const loadWithObjectURL = (loadMessage: MapAsync<Message>) => async (
-  media: Array<Message>
+  messages: Array<Message>
 ): Promise<Array<Message>> => {
   if (!is.function_(loadMessage)) {
     throw new TypeError("'loadMessage' must be a function");
   }
-  if (!is.array(media)) {
-    throw new TypeError("'media' must be a function");
+  if (!is.array(messages)) {
+    throw new TypeError("'messages' must be an array");
   }
 
-  const mediaWithAttachmentData = await Promise.all(media.map(loadMessage));
-  return mediaWithAttachmentData.map(withObjectURL);
+  // Messages with video are too expensive to load into memory, so we don’t:
+  const [messagesWithVideo, messagesWithoutVideo] = partition(
+    messages,
+    hasVideoAttachment
+  );
+  const loadedMessagesWithoutVideo = await Promise.all(
+    messagesWithoutVideo.map(loadMessage)
+  );
+  const loadedMessages = sortBy(
+    [...messagesWithVideo, ...loadedMessagesWithoutVideo],
+    message => -message.received_at
+  );
+
+  return loadedMessages.map(withObjectURL);
 };
 
+const hasVideoAttachment = (message: Message): boolean =>
+  message.attachments.some(
+    attachment =>
+      !is.undefined(attachment.contentType) &&
+      MIME.isVideo(attachment.contentType)
+  );
+
 const withObjectURL = (message: Message): Message => {
   if (message.attachments.length === 0) {
     throw new TypeError('`message.attachments` cannot be empty');
   }
+
   const attachment = message.attachments[0];
+  if (typeof attachment.contentType === 'undefined') {
+    throw new TypeError('`attachment.contentType` is required');
+  }
+
+  if (MIME.isVideo(attachment.contentType)) {
+    return {
+      ...message,
+      objectURL: 'images/video.svg',
+    };
+  }
+
   const objectURL = arrayBufferToObjectURL({
     data: attachment.data,
     type: attachment.contentType || DEFAULT_CONTENT_TYPE,