sample_code.rb

class MirandaService::ActualData

  attr_reader :contacts

  attr_reader :new_data
  attr_reader :renamed_data
  attr_reader :old_data

  attr_reader :actual_contacts
  attr_reader :new_contacts
  attr_reader :renamed_contacts
  attr_reader :old_contacts

  def initialize model: Credential, default_attrs: {}
    miranda_connect!

    @model         = model
    @default_attrs = default_attrs

    make_data
  end

  private

  def miranda_connect!
    if defined? BlatherInitializer
      Object.send(:remove_const, :BlatherInitializer)
    end

    load File.expand_path('blather/initializer.rb', __dir__)
    BlatherInitializer.run
  end

  def make_data
    @contacts         = contacts_by_key "contact"

    @actual_data      = actual_data_by_key "contact"
    @new_data         = get_new_data
    @renamed_data     = get_renamed_data
    @old_data         = get_old_data

    @actual_contacts  = get_actual_contacts
    @new_contacts     = get_new_contacts
    @renamed_contacts = get_renamed_contacts
    @old_contacts     = get_old_contacts
  end

  def get_actual_contacts
    to_contacts @actual_data, @default_attrs
  end

  def get_new_contacts
    to_contacts @new_data, @default_attrs
  end

  def get_renamed_contacts
    to_contacts @renamed_data, @default_attrs
  end

  def get_old_contacts
    to_contacts @old_data, @default_attrs
  end

  def get_new_data
    @actual_data.slice(*(@actual_data.keys - @contacts.keys)).select do |contact, data|
      old?(data)
    end
  end

  def get_renamed_data
    @actual_data.select do |contact, data|
      @contacts[contact] && (
        diff_fio?(contact, data) && ! old?(data)
      )
    end
  end

  def get_old_data
    @actual_data.select do |contact, data|
      @contacts[contact] && (
        diff_fio?(contact, data) && old?(data)
      )
    end
  end

  def contacts_by_key key
    to_keyed_hash @model.all.map{|cr| cr.attributes }, key
  end

  def actual_data_by_key key
    to_keyed_hash to_data(BlatherService.users), key
  end

  def to_data data_rows, default={}
    attrs = []
    data_rows.each do |data|
      name = data.keys.first
      contact = data.values.first[:contact] 
      if name && contact
        attrs << default.merge({ "fio" => name, "contact" => contact })
      end
    end
    attrs
  end

  def to_contacts data_rows, default={}
    data_rows.merge(data_rows) do |contact, data|
      default.merge data
    end
  end

  def to_keyed_hash arr, key
    arr.map{|e| [e[key], e] }.to_h
  end

  def old? data
    data["fio"] =~ /^old_/
  end
  
  def diff_fio? contact, data
    @contacts[contact]["fio"] != data["fio"]
  end
end