class Character < ApplicationRecord
  belongs_to :user
  belongs_to :activity, optional: true
  has_many :character_items
  has_many :items, through: :character_items
  validates :name, presence: true
  validates_length_of :name, maximum: 15, message: "can't be longer than 15 characters"
  validates_uniqueness_of :name, message: "is already being used"
  validates_format_of :name, with: /\A[a-z]+\z/i, message: "must consist of letters only"

  def shift_item(gid, amount)
    CharacterItem.transaction do
      item = self.character_items.find_or_initialize_by(item: Item.find_by_gid(gid))
      item.increment(:quantity, amount)
      item.save
    end
  end
end