chore: Remove stale contact presence records (#5205)

fixes: chatwoot/product#493

spec/lib/online_status_tracker_spec.rb

@@ -21,4 +21,25 @@ describe OnlineStatusTracker do
       expect(described_class.get_available_users(account.id).keys).to contain_exactly(user1.id.to_s, user2.id.to_s)
     end
   end
+
+  context 'when get_available_contacts' do
+    let(:online_contact) { create(:contact, account: account) }
+    let(:offline_contact) { create(:contact, account: account) }
+
+    before do
+      described_class.update_presence(account.id, 'Contact', online_contact.id)
+      # creating a stale record for offline contact presence
+      ::Redis::Alfred.zadd(format(::Redis::Alfred::ONLINE_PRESENCE_CONTACTS, account_id: account.id),
+                           (Time.zone.now - (OnlineStatusTracker::PRESENCE_DURATION + 20)).to_i, offline_contact.id)
+    end
+
+    it 'returns only the online contact ids with presence' do
+      expect(described_class.get_available_contacts(account.id).keys).to contain_exactly(online_contact.id.to_s)
+    end
+
+    it 'flushes the stale records from sorted set after the duration' do
+      described_class.get_available_contacts(account.id)
+      expect(::Redis::Alfred.zscore(format(::Redis::Alfred::ONLINE_PRESENCE_CONTACTS, account_id: account.id), offline_contact.id)).to be_nil
+    end
+  end
 end