Revert "Revert "Permission phase 2""

This reverts commit 8b9244b079.

frontend/src/lib/fn/array.ts

@@ -13,3 +13,22 @@ export const groupBy = <T, Key extends string | number | symbol>(
     acc[groupId].push(item);
     return acc;
   }, {} as Record<Key, T[]>);
+
+/**
+ * Given a list of items returns a new list with only
+ * unique items. Accepts an optional identity function
+ * to convert each item in the list to a comparable identity
+ * value
+ */
+export const unique = <T, K extends string | number | symbol>(
+  array: readonly T[],
+  toKey?: (item: T) => K
+): T[] => {
+  const valueMap = array.reduce((acc, item) => {
+    const key = toKey ? toKey(item) : (item as unknown as string | number | symbol);
+    if (acc[key]) return acc;
+    acc[key] = item;
+    return acc;
+  }, {} as Record<string | number | symbol, T>);
+  return Object.values(valueMap);
+};

frontend/src/lib/fn/object.ts

@@ -0,0 +1,20 @@
+/**
+ * Omit a list of properties from an object
+ * returning a new object with the properties
+ * that remain
+ */
+export const omit = <T, TKeys extends keyof T>(obj: T, keys: TKeys[]): Omit<T, TKeys> => {
+  if (!obj) return {} as Omit<T, TKeys>;
+  if (!keys || keys.length === 0) return obj as Omit<T, TKeys>;
+  return keys.reduce(
+    (acc, key) => {
+      // Gross, I know, it's mutating the object, but we
+      // are allowing it in this very limited scope due
+      // to the performance implications of an omit func.
+      // Not a pattern or practice to use elsewhere.
+      delete acc[key];
+      return acc;
+    },
+    { ...obj }
+  );
+};