class SDG::Goal < ApplicationRecord
  include Comparable
  include SDG::Related

  validates :code, presence: true, uniqueness: true, inclusion: { in: 1..17 }

  has_many :targets, dependent: :destroy
  has_many :local_targets, dependent: :destroy

  def title
    I18n.t("sdg.goals.goal_#{code}.title")
  end

  def title_in_two_lines
    I18n.t("sdg.goals.goal_#{code}.title_in_two_lines")
  end

  def description
    I18n.t("sdg.goals.goal_#{code}.description")
  end

  def <=>(goal_or_target)
    if goal_or_target.class == self.class
      code <=> goal_or_target.code
    elsif goal_or_target.respond_to?(:goal)
      [self, -1] <=> [goal_or_target.goal, 1]
    end
  end

  def self.[](code)
    find_by!(code: code)
  end

  def code_and_title
    "#{code}. #{title}"
  end
end