# frozen_string_literal: true

# ProductCart
# quantity: integer
class ProductCart < ApplicationRecord
  belongs_to :cart
  belongs_to :product

  validates :quantity, presence: true, comparison: { greater_than: 0 }
  validate :sole_product_in_cart
  validate :product_quantity

  def sole_product_in_cart
    return if cart.nil? || cart.products.find_by(id: product_id).nil?

    errors.add(:product_id, "cart already has product with id #{product_id}")
  end

  def product_quantity
    return if product.nil? || product.available_quantity > quantity

    errors.add(:product_id, 'not enough in existence')
  end
end