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

app/services/auto_assignment/inbox_round_robin_service.rb

@@ -0,0 +1,62 @@
+class AutoAssignment::InboxRoundRobinService
+  pattr_initialize [:inbox!]
+
+  # called on inbox delete
+  def clear_queue
+    ::Redis::Alfred.delete(round_robin_key)
+  end
+
+  # called on inbox member create
+  def add_agent_to_queue(user_id)
+    ::Redis::Alfred.lpush(round_robin_key, user_id)
+  end
+
+  # called on inbox member delete
+  def remove_agent_from_queue(user_id)
+    ::Redis::Alfred.lrem(round_robin_key, user_id)
+  end
+
+  def reset_queue
+    clear_queue
+    add_agent_to_queue(inbox.inbox_members.map(&:user_id))
+  end
+
+  # end of queue management functions
+
+  # allowed member ids = [assignable online agents supplied by the assignement service]
+  # the values of allowed member ids should be in string format
+  def available_agent(allowed_agent_ids: [])
+    reset_queue unless validate_queue?
+    user_id = get_member_from_allowed_agent_ids(allowed_agent_ids)
+    inbox.inbox_members.find_by(user_id: user_id)&.user if user_id.present?
+  end
+
+  private
+
+  def get_member_from_allowed_agent_ids(allowed_agent_ids)
+    return nil if allowed_agent_ids.blank?
+
+    user_id = queue.intersection(allowed_agent_ids).pop
+    pop_push_to_queue(user_id)
+    user_id
+  end
+
+  def pop_push_to_queue(user_id)
+    return if user_id.blank?
+
+    remove_agent_from_queue(user_id)
+    add_agent_to_queue(user_id)
+  end
+
+  def validate_queue?
+    return true if inbox.inbox_members.map(&:user_id).sort == queue.map(&:to_i).sort
+  end
+
+  def queue
+    ::Redis::Alfred.lrange(round_robin_key)
+  end
+
+  def round_robin_key
+    format(::Redis::Alfred::ROUND_ROBIN_AGENTS, inbox_id: inbox.id)
+  end
+end