[lib] Update permissionsToBitmask to permissionsToBitmaskHex

Summary:
Summmary:
Was initially planning (and drafting) to encode the `BigInt` as `base64` to be included in stringified JSON. However, as I jotted down ([ENG-5373 : Use "bitmask" approach to encoding ThreadPermissions and Role permissions blobs](https://linear.app/comm/issue/ENG-5373/use-bitmask-approach-to-encoding-threadpermissions-and-role)), decided to encode as hex instead.

Update `permissionsToBitmask` and corresponding `hasPermission` to return and accept `string` instead of `bigint`.

Test Plan: Unit test, will add a few more.

Reviewers: ashoat, ginsu, tomek, rohan

Reviewed By: tomek

Subscribers: wyilio

Differential Revision: https://phab.comm.dev/D9589

lib/permissions/minimally-encoded-thread-permissions.js

@@ -34,9 +34,9 @@ const minimallyEncodedThreadPermissions = Object.freeze({
   manage_invite_links: BigInt(1) << BigInt(20),
 });
 
-// TODO (atul): Update flow to `194.0.0` for bigint support
-// $FlowIssue bigint-unsupported
-const permissionsToBitmask = (permissions: ThreadPermissionsInfo): bigint => {
+const permissionsToBitmaskHex = (
+  permissions: ThreadPermissionsInfo,
+): string => {
   let bitmask = BigInt(0);
   for (const [key, permission] of entries(permissions)) {
     if (permission.value && key in minimallyEncodedThreadPermissions) {
@@ -49,15 +49,14 @@ const permissionsToBitmask = (permissions: ThreadPermissionsInfo): bigint => {
       bitmask |= minimallyEncodedThreadPermissions[key];
     }
   }
-  return bitmask;
+  return bitmask.toString(16);
 };
 
 const hasPermission = (
-  // TODO (atul): Update flow to `194.0.0` for bigint support
-  // $FlowIssue bigint-unsupported
-  permissionsBitmask: bigint,
+  permissionsBitmaskHex: string,
   permission: ThreadPermission,
 ): boolean => {
+  const permissionsBitmask = BigInt(`0x${permissionsBitmaskHex}`);
   if (!(permission in minimallyEncodedThreadPermissions)) {
     return false;
   }
@@ -73,6 +72,6 @@ const hasPermission = (
 
 export {
   minimallyEncodedThreadPermissions,
-  permissionsToBitmask,
+  permissionsToBitmaskHex,
   hasPermission,
 };

lib/permissions/minimally-encoded-thread-permissions.test.js

@@ -2,7 +2,7 @@
 
 import {
   hasPermission,
-  permissionsToBitmask,
+  permissionsToBitmaskHex,
 } from './minimally-encoded-thread-permissions.js';
 
 describe('minimallyEncodedThreadPermissions', () => {
@@ -28,8 +28,8 @@ describe('minimallyEncodedThreadPermissions', () => {
   };
 
   it('should encode ThreadPermissionsInfo as bitmask', () => {
-    const permissionsBitmask = permissionsToBitmask(permissions);
-    expect(permissionsBitmask.toString(2)).toBe('110111001111111111');
+    const permissionsBitmask = permissionsToBitmaskHex(permissions);
+    expect(permissionsBitmask).toBe('373ff');
     expect(hasPermission(permissionsBitmask, 'know_of')).toBe(true);
     expect(hasPermission(permissionsBitmask, 'visible')).toBe(true);
     expect(hasPermission(permissionsBitmask, 'voiced')).toBe(true);