When a group call starts, show an OS notification

ts/state/selectors/calling.ts

@@ -9,16 +9,10 @@ import {
   CallsByConversationType,
   DirectCallStateType,
   GroupCallStateType,
-  isAnybodyElseInGroupCall,
+  getIncomingCall as getIncomingCallHelper,
 } from '../ducks/calling';
-import {
-  CallMode,
-  CallState,
-  GroupCallConnectionState,
-} from '../../types/Calling';
 import { getUserUuid } from './user';
 import { getOwn } from '../../util/getOwn';
-import { missingCaseError } from '../../util/missingCaseError';
 
 export type CallStateType = DirectCallStateType | GroupCallStateType;
 
@@ -62,29 +56,12 @@ export const isInCall = createSelector(
   (call: CallStateType | undefined): boolean => Boolean(call)
 );
 
-// In theory, there could be multiple incoming calls, or an incoming call while there's
-//   an active call. In practice, the UI is not ready for this, and RingRTC doesn't
-//   support it for direct calls.
 export const getIncomingCall = createSelector(
   getCallsByConversation,
   getUserUuid,
   (
     callsByConversation: CallsByConversationType,
     ourUuid: string
-  ): undefined | DirectCallStateType | GroupCallStateType => {
-    return Object.values(callsByConversation).find(call => {
-      switch (call.callMode) {
-        case CallMode.Direct:
-          return call.isIncoming && call.callState === CallState.Ringing;
-        case CallMode.Group:
-          return (
-            call.ringerUuid &&
-            call.connectionState === GroupCallConnectionState.NotConnected &&
-            isAnybodyElseInGroupCall(call.peekInfo, ourUuid)
-          );
-        default:
-          throw missingCaseError(call);
-      }
-    });
-  }
+  ): undefined | DirectCallStateType | GroupCallStateType =>
+    getIncomingCallHelper(callsByConversation, ourUuid)
 );