class Cranium::DataImporter

  include Cranium::Logging


  def import(import_definition)
    number_of_items_imported = 0
    Cranium::Database.connection.transaction do
      number_of_items_imported = importer_for_definition(import_definition).import
      Cranium.application.apply_hook(:after_import)
    end

    record_metric import_definition.name, number_of_items_imported.to_s
  end


  private

  def importer_for_definition(import_definition)
    if [!import_definition.merge_fields.empty?, !import_definition.delete_insert_on.empty?, !import_definition.delete_on.empty?, import_definition.truncate_insert].count(true) > 1
      raise StandardError, "Import should not combine merge_on, delete_insert_on, delete_on and truncate_insert settings"
    end

    if !import_definition.merge_fields.empty?
      Cranium::ImportStrategy::Merge.new(import_definition)
    elsif !import_definition.delete_insert_on.empty?
      Cranium::ImportStrategy::DeleteInsert.new(import_definition)
    elsif !import_definition.delete_on.empty?
      Cranium::ImportStrategy::Delete.new(import_definition)
    elsif import_definition.truncate_insert
      Cranium::ImportStrategy::TruncateInsert.new(import_definition)
    else
      Cranium::ImportStrategy::Delta.new(import_definition)
    end
  end

end