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);
+};