Proof of concept on how we could implement the new metrics on the Flow::Statistics class

statistics.rb

class Flow::Statistics
  def patients_messaged
    CacheCounter.get_fast_count_for(Flow::FlowPatient, flow.provider_id, :patients) -
      pre_filtered_flow_patients.where.not(state: %w(duplicated incomplete)).count
  end

  def need_review
    pre_filtered_flow_patients.last_response_flagged("invalid").count
  end

  def opt_out_rate
    pre_filtered_flow_patients.opted_out.count / patients_messaged
  end
end