Feature: Availability Statuses (#874)

Co-authored-by: Pranav Raj S <pranav@thoughtwoot.com>

lib/online_status_tracker.rb

@@ -1,19 +1,50 @@
 module OnlineStatusTracker
-  def self.add_subscription(channel_id)
-    count = subscription_count(channel_id)
-    ::Redis::Alfred.setex(channel_id, count + 1)
+  PRESENCE_DURATION = 60.seconds
+
+  # presence : sorted set with timestamp as the score & object id as value
+
+  # obj_type: Contact | User
+  def self.update_presence(account_id, obj_type, obj_id)
+    ::Redis::Alfred.zadd(presence_key(account_id, obj_type), Time.now.to_i, obj_id)
   end
 
-  def self.remove_subscription(channel_id)
-    count = subscription_count(channel_id)
-    if count == 1
-      ::Redis::Alfred.delete(channel_id)
-    elsif count != 0
-      ::Redis::Alfred.setex(channel_id, count - 1)
+  def self.get_presence(account_id, obj_type, obj_id)
+    connected_time = ::Redis::Alfred.zscore(presence_key(account_id, obj_type), obj_id)
+    connected_time && connected_time > (Time.zone.now - PRESENCE_DURATION).to_i
+  end
+
+  def self.presence_key(account_id, type)
+    case type
+    when 'Contact'
+      Redis::Alfred::ONLINE_PRESENCE_CONTACTS % account_id
+    else
+      Redis::Alfred::ONLINE_PRESENCE_USERS % account_id
     end
   end
 
-  def self.subscription_count(channel_id)
-    ::Redis::Alfred.get(channel_id).to_i
+  # online status : online | busy | offline
+  # redis hash with obj_id key && status as value
+
+  def self.set_status(account_id, user_id, status)
+    ::Redis::Alfred.hset(status_key(account_id), user_id, status)
+  end
+
+  def self.get_status(account_id, user_id)
+    ::Redis::Alfred.hget(status_key(account_id), user_id)
+  end
+
+  def self.status_key(account_id)
+    Redis::Alfred::ONLINE_STATUS % account_id
+  end
+
+  def self.get_available_contacts(account_id)
+    contact_ids = ::Redis::Alfred.zrangebyscore(presence_key(account_id, 'Contact'), (Time.zone.now - PRESENCE_DURATION).to_i, Time.now.to_i)
+    contact_ids.index_with { |_id| 'online' }
+  end
+
+  def self.get_available_users(account_id)
+    user_ids = ::Redis::Alfred.zrangebyscore(presence_key(account_id, 'User'), (Time.zone.now - PRESENCE_DURATION).to_i, Time.now.to_i)
+    user_availabilities = ::Redis::Alfred.hmget(status_key(account_id), user_ids)
+    user_ids.map.with_index { |id, index| [id, (user_availabilities[index] || 'online')] }.to_h
   end
 end