New Group administration: Add users

ts/groups/toggleSelectedContactForGroupAddition.ts

@@ -0,0 +1,68 @@
+// Copyright 2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import { without } from 'lodash';
+
+export enum OneTimeModalState {
+  NeverShown,
+  Showing,
+  Shown,
+}
+
+export function toggleSelectedContactForGroupAddition(
+  conversationId: string,
+  currentState: Readonly<{
+    maxGroupSize: number;
+    maxRecommendedGroupSize: number;
+    maximumGroupSizeModalState: OneTimeModalState;
+    numberOfContactsAlreadyInGroup: number;
+    recommendedGroupSizeModalState: OneTimeModalState;
+    selectedConversationIds: Array<string>;
+  }>
+): {
+  maximumGroupSizeModalState: OneTimeModalState;
+  recommendedGroupSizeModalState: OneTimeModalState;
+  selectedConversationIds: Array<string>;
+} {
+  const {
+    maxGroupSize,
+    maxRecommendedGroupSize,
+    numberOfContactsAlreadyInGroup,
+    selectedConversationIds: oldSelectedConversationIds,
+  } = currentState;
+  let {
+    maximumGroupSizeModalState,
+    recommendedGroupSizeModalState,
+  } = currentState;
+
+  const selectedConversationIds = without(
+    oldSelectedConversationIds,
+    conversationId
+  );
+  const shouldAdd =
+    selectedConversationIds.length === oldSelectedConversationIds.length;
+  if (shouldAdd) {
+    const newExpectedMemberCount =
+      selectedConversationIds.length + numberOfContactsAlreadyInGroup + 1;
+    if (newExpectedMemberCount <= maxGroupSize) {
+      if (
+        newExpectedMemberCount === maxGroupSize &&
+        maximumGroupSizeModalState === OneTimeModalState.NeverShown
+      ) {
+        maximumGroupSizeModalState = OneTimeModalState.Showing;
+      } else if (
+        newExpectedMemberCount >= maxRecommendedGroupSize &&
+        recommendedGroupSizeModalState === OneTimeModalState.NeverShown
+      ) {
+        recommendedGroupSizeModalState = OneTimeModalState.Showing;
+      }
+      selectedConversationIds.push(conversationId);
+    }
+  }
+
+  return {
+    selectedConversationIds,
+    maximumGroupSizeModalState,
+    recommendedGroupSizeModalState,
+  };
+}