class Admission < ApplicationRecord
  belongs_to :country, inverse_of: :admissions
  belongs_to :person, inverse_of: :admissions
  belongs_to :previous, class_name: name, inverse_of: :next, optional: true
  has_one :next, class_name: name, foreign_key: :previous_id, inverse_of: :previous

  scope :ordered, -> { order(:arrived_on, :previous_id) }
  scope :before, -> (date) { where("#{table_name}.arrived_on <= ?", date) }
  scope :after, -> (date) { where("#{table_name}.arrived_on >= ?", date) }
  
  around_create :set_previous
  before_destroy :update_nexts_previous

  def set_previous
    self.previous ||= person.admissions.ordered.before(arrived_on).last
    future_next = previous&.reload_next
    yield
    future_next&.update(previous: self)
  end

  def update_nexts_previous
    self.next&.update(previous: previous)
  end
end