class LifePex::Level
  LEVEL_BY_XP = -> (xp) { ((xp / 100.0)**(1.0 / 1.1)).floor + 1 }
  XP_BY_LEVEL = -> (level) { (level - 1)**(1.1) * 100.0 }

  SERIALIZABLE_ATTRIBUTES = [:current_xp, :current_level, :next_xp, :next_level, :xp_from_current_level, :xp_to_next_level, :xp_for_complete_level, :progress]

  attr_reader *SERIALIZABLE_ATTRIBUTES

  def initialize(current_xp = 0)
    @current_xp = current_xp
    @current_level = LEVEL_BY_XP.call(@current_xp)
    @next_level = @current_level + 1
    @next_xp = XP_BY_LEVEL.call(next_level)
    @xp_for_complete_level = XP_BY_LEVEL.call(@next_level) - XP_BY_LEVEL.call(@current_level)
    @xp_to_next_level = XP_BY_LEVEL.call(@next_level) - @current_xp
    @xp_from_current_level = @xp_for_complete_level - @xp_to_next_level
    @progress = @xp_from_current_level / @xp_for_complete_level
  end

  def to_h
    SERIALIZABLE_ATTRIBUTES.map { |attr| [attr, self.send(attr)] }.to_h
  end
end