More work on permission utils and eager permission checks

backend/src/utils/getPermissionNames.ts

@@ -0,0 +1,29 @@
+import { Constants } from "eris";
+
+const camelCaseToTitleCase = str =>
+  str
+    .replace(/([a-z])([A-Z])/g, "$1 $2")
+    .split(" ")
+    .map(w => w[0].toUpperCase() + w.slice(1))
+    .join(" ");
+
+const permissionNumberToName: Map<bigint, string> = new Map();
+const ignoredPermissionConstants = ["all", "allGuild", "allText", "allVoice"];
+
+for (const key in Constants.Permissions) {
+  if (ignoredPermissionConstants.includes(key)) continue;
+  permissionNumberToName.set(BigInt(Constants.Permissions[key]), camelCaseToTitleCase(key));
+}
+
+/**
+ * @param permissions Bitmask of permissions to get the names for
+ */
+export function getPermissionNames(permissions: number | bigint): string[] {
+  const permissionNames = [];
+  for (const [permissionNumber, permissionName] of permissionNumberToName.entries()) {
+    if (BigInt(permissions) & permissionNumber) {
+      permissionNames.push(permissionName);
+    }
+  }
+  return permissionNames;
+}