add feature flag stuff

Signed-off-by: Katalina Okano <git@kat.cafe>

packages/api/utils/feature-flags.ts

@@ -0,0 +1,38 @@
+import { hasFeature } from '@roleypoly/misc-utils/hasFeature';
+import { Features, Guild, GuildData } from '@roleypoly/types';
+
+const flagPercents: Record<Features, { percent: number; rotation: number }> = {
+  [Features.AuditLogging]: { percent: 0, rotation: 0 },
+  [Features.AccessControl]: { percent: 0, rotation: 33 },
+};
+
+const testingGroup: Guild['id'][] = [
+  '386659935687147521', // Roleypoly
+];
+
+const ONE_HUNDRED = BigInt(100);
+
+export const getFeatureFlags = (
+  feature: Features,
+  guildData: GuildData
+): Record<Features, boolean> => {
+  const flags = Object.entries(flagPercents).map(([flag, value]) => {
+    const intFlag = Number(flag);
+    const intGuildID = BigInt(guildData.id);
+    const rotation = BigInt(value.rotation);
+    const percent = BigInt(value.percent);
+
+    if (testingGroup.includes(guildData.id)) {
+      return [intFlag, true];
+    }
+
+    const percentValue = (intGuildID + rotation) % ONE_HUNDRED;
+    if (percentValue >= percent) {
+      return [intFlag, true];
+    }
+
+    return [intFlag, hasFeature(feature, intFlag)];
+  });
+
+  return Object.fromEntries(flags);
+};

packages/misc-utils/hasFeature.spec.ts

@@ -0,0 +1,8 @@
+import { Features } from '@roleypoly/types';
+import { hasFeature } from './hasFeature';
+
+it('correctly matches against features', () => {
+  const features = Features.LegacyGuild;
+  expect(hasFeature(Features.LegacyGuild, features)).toBe(true);
+  expect(hasFeature(Features.LegacyGuild, Features.None)).toBe(false);
+});

packages/misc-utils/hasFeature.ts

@@ -0,0 +1,5 @@
+import { Features } from '@roleypoly/types';
+
+export const hasFeature = (feature: Features, features: number): boolean => {
+  return (features & feature) === feature;
+};

packages/types/Guild.ts

@@ -13,6 +13,8 @@ export enum Features {
   None = 0,
   Preview = None,
   LegacyGuild = 1 << 1,
+  AccessControl = 1 << 2,
+  AuditLogging = 1 << 3,
 }
 
 export type GuildData = {