presence [nfc]: Make a Redux selector for getting presence status

Author: chrisbobbe

src/common/PresenceStatusIndicator.js

@@ -6,12 +6,9 @@ import type { ViewStyleProp } from 'react-native/Libraries/StyleSheet/StyleSheet
 
 import { createStyleSheet, ThemeContext } from '../styles';
 import { useSelector } from '../react-redux';
-import { statusFromPresenceAndUserStatus } from '../utils/presence';
-import { getPresence } from '../selectors';
-import { getUserStatus } from '../user-statuses/userStatusesModel';
-import { tryGetUserForId } from '../users/userSelectors';
+import { getPresenceStatusForUserId } from '../utils/presence';
 import { ensureUnreachable } from '../types';
-import type { UserId, UserPresence } from '../types';
+import type { UserId } from '../types';
 
 const styles = createStyleSheet({
   common: {
@@ -126,19 +123,10 @@ type Props = $ReadOnly<{|
  */
 export default function PresenceStatusIndicator(props: Props): Node {
   const { userId, style, hideIfOffline, useOpaqueBackground } = props;
-  const presence = useSelector(getPresence);
-  const user = useSelector(state => tryGetUserForId(state, userId));
-  const userPresence = (user && (presence[user.email]: UserPresence | void)) ?? null;
 
-  const userStatus = useSelector(state => getUserStatus(state, userId));
+  const status = useSelector(state => getPresenceStatusForUserId(state, userId));
 
-  if (!user || !userPresence || !userPresence.aggregated) {
-    return null;
-  }
-
-  const status = statusFromPresenceAndUserStatus(userPresence, userStatus);
-
-  if (hideIfOffline && status === 'offline') {
+  if (status === null || (hideIfOffline && status === 'offline')) {
     return null;
   }
 

src/utils/presence.js

@@ -6,6 +6,11 @@ import formatDistanceToNow from 'date-fns/formatDistanceToNow';
 import type { ClientPresence, UserPresence, PresenceStatus, UserStatus } from '../types';
 import { ensureUnreachable } from '../types';
 import { objectEntries } from '../flowPonyfill';
+import type { PerAccountState } from '../reduxTypes';
+import type { UserId } from '../api/idTypes';
+import { getPresence } from '../directSelectors';
+import { tryGetUserForId } from '../users/userSelectors';
+import { getUserStatus } from '../user-statuses/userStatusesModel';
 
 /** The relation `>=`, where `active` > `idle` > `offline`. */
 const presenceStatusGeq = (a: PresenceStatus, b: PresenceStatus): boolean => {
@@ -118,3 +123,27 @@ export const statusFromPresenceAndUserStatus = (
   userStatus: UserStatus,
 ): PresenceStatus | 'unavailable' =>
   userStatus.away ? 'unavailable' : statusFromPresence(presence);
+
+/**
+ * Get a user's overall presence status, aggregated from all their devices.
+ *
+ * Gives null when we're missing data to determine this, such as when the
+ * user doesn't exist.
+ */
+export const getPresenceStatusForUserId = (
+  state: PerAccountState,
+  userId: UserId,
+): PresenceStatus | 'unavailable' | null => {
+  const presence = getPresence(state);
+  const user = tryGetUserForId(state, userId);
+  if (!user) {
+    return null;
+  }
+  const userPresence = (presence[user.email]: UserPresence | void);
+  if (!userPresence || !userPresence.aggregated) {
+    return null;
+  }
+  const userStatus = getUserStatus(state, userId);
+
+  return statusFromPresenceAndUserStatus(userPresence, userStatus);
+};