Chore: Refactor round robin logic (#1015)

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

app/services/round_robin/assignment_service.rb

@@ -0,0 +1,24 @@
+class RoundRobin::AssignmentService
+  pattr_initialize [:conversation]
+
+  def perform
+    # online agents will get priority
+    new_assignee = round_robin_manage_service.available_agent(priority_list: online_agents)
+    conversation.update(assignee: new_assignee) if new_assignee
+  end
+
+  private
+
+  def online_agents
+    online_agents = OnlineStatusTracker.get_available_users(conversation.account_id)
+    online_agents.select { |_key, value| value.eql?('online') }.keys if online_agents.present?
+  end
+
+  def round_robin_manage_service
+    @round_robin_manage_service ||= RoundRobin::ManageService.new(inbox: conversation.inbox)
+  end
+
+  def round_robin_key
+    format(::Redis::Alfred::ROUND_ROBIN_AGENTS, inbox_id: conversation.inbox_id)
+  end
+end

app/services/round_robin/manage_service.rb

@@ -0,0 +1,56 @@
+class RoundRobin::ManageService
+  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 available_agent(priority_list: [])
+    reset_queue unless validate_queue?
+    user_id = get_agent_via_priority_list(priority_list)
+    # incase priority list was empty or inbox members weren't present
+    user_id ||= ::Redis::Alfred.rpoplpush(round_robin_key, round_robin_key)
+    inbox.inbox_members.find_by(user_id: user_id)&.user if user_id.present?
+  end
+
+  def reset_queue
+    clear_queue
+    add_agent_to_queue(inbox.inbox_members.map(&:user_id))
+  end
+
+  private
+
+  def get_agent_via_priority_list(priority_list)
+    return if priority_list.blank?
+
+    user_id = queue.intersection(priority_list.map(&:to_s)).pop
+    if user_id.present?
+      remove_agent_from_queue(user_id)
+      add_agent_to_queue(user_id)
+    end
+    user_id
+  end
+
+  def validate_queue?
+    return true if inbox.inbox_members.map(&:user_id).sort == queue.sort.map(&:to_i)
+  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