Attempt to extract class methods to separate class with delegation to this new class

event.rb

class Event < ActiveRecord::Base
  delegate :next_occurrence, :select_events_with_time, :find_category_next_occurences :to => :OccurrenceManager
end

class OccurrenceManager 
  def self.next_occurrence(event_type, begin_time = COLLECTION_TIME_PAST.ago)
    events_with_times = select_events_with_time(event_type: event_type, begin_time: begin_time)

    unless events_with_times.empty?
      events_with_times = events_with_times.sort {|e1, e2| e1.time <=> e2.time }
      events_with_times.first.event.next_occurrence_time_attr = events_with_times.first.time
      events_with_times.first.event
    end    
  end

  def self.select_events_with_time(args)
    event_type  = args.fetch(:event_type)
    begin_time  = args.fetch(:begin_time)

    find_category_next_occurences(event_type, begin_time)
  end

  def self.find_category_next_occurences(event_type, begin_time)
    Event.where(category: event_type).map do |event|
      event.next_event_occurrence_with_time(begin_time)
    end.compact
  end
end