Moves DraftAttachments into redux

ts/util/writeDraftAttachment.ts

@@ -0,0 +1,29 @@
+// Copyright 2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import { omit } from 'lodash';
+import { AttachmentType } from '../types/Attachment';
+
+export async function writeDraftAttachment(
+  attachment: AttachmentType
+): Promise<AttachmentType> {
+  if (attachment.pending) {
+    throw new Error('writeDraftAttachment: Cannot write pending attachment');
+  }
+
+  const result: AttachmentType = {
+    ...omit(attachment, ['data', 'screenshotData']),
+    pending: false,
+  };
+  if (attachment.data) {
+    result.path = await window.Signal.Migrations.writeNewDraftData(
+      attachment.data
+    );
+  }
+  if (attachment.screenshotData) {
+    result.screenshotPath = await window.Signal.Migrations.writeNewDraftData(
+      attachment.screenshotData
+    );
+  }
+  return result;
+}