New attachment storage system

ts/util/getLocalAttachmentUrl.ts

@@ -0,0 +1,57 @@
+// Copyright 2024 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import type { AttachmentType } from '../types/Attachment';
+import { strictAssert } from './assert';
+
+export enum AttachmentDisposition {
+  Attachment = 'attachment',
+  Temporary = 'temporary',
+  Draft = 'draft',
+  Sticker = 'sticker',
+  AvatarData = 'avatarData',
+}
+
+export type GetLocalAttachmentUrlOptionsType = Readonly<{
+  disposition?: AttachmentDisposition;
+}>;
+
+export function getLocalAttachmentUrl(
+  attachment: Partial<
+    Pick<
+      AttachmentType,
+      'version' | 'path' | 'localKey' | 'size' | 'contentType'
+    >
+  >,
+  {
+    disposition = AttachmentDisposition.Attachment,
+  }: GetLocalAttachmentUrlOptionsType = {}
+): string {
+  strictAssert(attachment.path != null, 'Attachment must be downloaded first');
+
+  // Fix Windows paths
+  const path = attachment.path.replace(/\\/g, '/');
+
+  let url: URL;
+  if (attachment.version !== 2) {
+    url = new URL(`attachment://v1/${path}`);
+  } else {
+    url = new URL(`attachment://v${attachment.version}/${path}`);
+    if (attachment.localKey != null) {
+      url.searchParams.set('key', attachment.localKey);
+    }
+  }
+
+  if (attachment.size != null) {
+    url.searchParams.set('size', attachment.size.toString());
+  }
+
+  if (attachment.contentType != null) {
+    url.searchParams.set('contentType', attachment.contentType);
+  }
+
+  if (disposition !== AttachmentDisposition.Attachment) {
+    url.searchParams.set('disposition', disposition);
+  }
+  return url.toString();
+}