1 files changed, 83 insertions, 0 deletions
diff --git a/src/utils/messages.ts b/src/utils/messages.ts
new file mode 100644
index 00000000..d63f2b7a
--- /dev/null
+++ b/src/utils/messages.ts
@@ -0,0 +1,83 @@
+import moment from 'moment';
+import {RootState} from '../store/rootReducer';
+import {ChannelGroupedType} from '../types';
+
+/**
+ * Finds the difference in time in minutes
+ * @param lastActive given time e.g. "2021-04-08T19:07:09.361300983Z"
+ * @returns diff in minutes
+ */
+const _diffInMinutes = (lastActive: string | undefined) => {
+  if (!lastActive) {
+    return undefined;
+  }
+  return moment().diff(moment(lastActive), 'minutes');
+};
+
+/**
+ * Formats the last activity status.
+ *  - "Active now"          (≤ 5 minutes)
+ *  - "Seen X minutes ago"  (5 > x ≥ 59 minutes)
+ *  - "Seen X hours ago"    (x = [1, 2])
+ *  - "Offline"
+ * @param lastActive given time e.g. "2021-04-08T19:07:09.361300983Z"
+ * @returns
+ */
+export const formatLastSeenText = (lastActive: string | undefined) => {
+  const diff = _diffInMinutes(lastActive);
+  if (!diff) {
+    return 'Offline';
+  }
+  if (diff <= 5) {
+    return 'Active now';
+  }
+  if (diff <= 59) {
+    return `Seen ${diff} minutes ago`;
+  }
+  if (diff <= 180) {
+    const hours = Math.floor(diff / 60);
+    return `Seen ${hours} hours ago`;
+  }
+  return 'Offline';
+};
+
+/**
+ * Checks if a lastActive timestamp is considered Online or not.
+ *
+ * A user is online if last active is ≤ 15 minutes.
+ *
+ * @param lastActive given time e.g. "2021-04-08T19:07:09.361300983Z"
+ * @returns True if active
+ */
+export const isOnline = (lastActive: string | undefined) => {
+  if (!lastActive) {
+    return false;
+  }
+  const diff = _diffInMinutes(lastActive);
+  if (!diff) {
+    return false;
+  }
+  return diff <= 15;
+};
+
+/**
+ * Gets the other member in the channel.
+ * @param channel the current chat channel
+ * @param state the current redux state
+ * @returns other member or undefined
+ */
+export const getMember = (
+  channel: ChannelGroupedType | undefined,
+  state: RootState,
+) => {
+  if (!channel) {
+    return undefined;
+  }
+  const loggedInUserId = state.user.user.userId;
+  const otherMembers = channel
+    ? Object.values(channel.state.members).filter(
+        (member) => member.user?.id !== loggedInUserId,
+      )
+    : [];
+  return otherMembers.length === 1 ? otherMembers[0] : undefined;
+};