feat: Enable Capacity Config UI (#5164)

- Enables Capacity Config in UI
- Rewrite auto assignment Logic to consider only online agents

fixes: #4990

app/services/auto_assignment/agent_assignment_service.rb

@@ -0,0 +1,38 @@
+class AutoAssignment::AgentAssignmentService
+  # Allowed agent ids: array
+  # This is the list of agents from which an agent can be assigned to this conversation
+  # examples: Agents with assignment capacity, Agents who are members of a team etc
+  pattr_initialize [:conversation!, :allowed_agent_ids!]
+
+  def find_assignee
+    round_robin_manage_service.available_agent(allowed_agent_ids: allowed_online_agent_ids)
+  end
+
+  def perform
+    new_assignee = find_assignee
+    conversation.update(assignee: new_assignee) if new_assignee
+  end
+
+  private
+
+  def online_agent_ids
+    online_agents = OnlineStatusTracker.get_available_users(conversation.account_id)
+    online_agents.select { |_key, value| value.eql?('online') }.keys if online_agents.present?
+  end
+
+  def allowed_online_agent_ids
+    # We want to perform roundrobin only over online agents
+    # Hence taking an intersection of online agents and allowed member ids
+
+    # the online user ids are string, since its from redis, allowed member ids are integer, since its from active record
+    @allowed_online_agent_ids ||= online_agent_ids & allowed_agent_ids&.map(&:to_s)
+  end
+
+  def round_robin_manage_service
+    @round_robin_manage_service ||= AutoAssignment::InboxRoundRobinService.new(inbox: conversation.inbox)
+  end
+
+  def round_robin_key
+    format(::Redis::Alfred::ROUND_ROBIN_AGENTS, inbox_id: conversation.inbox_id)
+  end
+end