Genshin/GAKUEngine

module Gaku
  class SemesterConnector < ActiveRecord::Base
    belongs_to :semester, required: false
    belongs_to :semesterable, polymorphic: true, required: false

    validates :semester_id, :semesterable_type, :semesterable_id, presence: true

    validates :semester_id,
              uniqueness: { scope: %i[semesterable_id semesterable_type], message: I18n.t(:'semester.already') }

    validates :semesterable_type,
              inclusion: { in: %w[Gaku::ClassGroup Gaku::Course], message: '%{value} is not a valid' }

    %w[course class_group].each do |resource|
      define_singleton_method "group_by_semester_#{resource}" do
        where(semesterable_type: extract_model_name(resource)).includes(%i[semester semesterable])
                                                              .group_by(&:semester_id)
      end
    end

    def self.extract_model_name(resource)
      resource.insert(0, 'gaku/').classify
    end
  end
end