fairmondo/fairmondo

#   Copyright (c) 2012-2017, Fairmondo eG.  This file is
#   licensed under the GNU Affero General Public License version 3 or later.
#   See the COPYRIGHT file for details.

module BusinessTransactionConcerns
  module Discountable
    extend ActiveSupport::Concern

    included do
      belongs_to :discount, foreign_key: 'discount_id'
      # fields for discounts
      delegate :discount_id, to: :article, prefix: true
      delegate :max_discounted_value_cents, :num_of_discountable_articles, :title, to: :discount, prefix: true
    end

    # Methods
    #
    # Here we have some methods that deal with discounting transactions
    # does this transaction qualify for a discount?
    #
    def discountable?
      discount = Discount.find(self.article_discount_id)
      discount && num_discounted_articles < discount.num_of_discountable_articles && value_discounted_articles < discount.max_discounted_value_cents
    end

    # finds all transactions that where discounted by specific discount
    def discounted
      BusinessTransaction.where(discount: discount).joins(:line_item_group).where('line_item_groups.seller_id' => seller.id)
    end

    # returns the number of articles, that have been discounted for specific discount
    def num_discounted_articles
      discounted.sum(:quantity_bought)
    end

    # returns the value of discounts granted for specific discount
    def value_discounted_articles
      discounted.sum('discount_value_cents * quantity_bought').to_i
    end

    def calculated_discount
      self.quantity_bought * (self.article_calculated_fee_cents / 100.0 * self.discount.percent)
    end

    def remaining_discount
      self.discount.max_discounted_value_cents - self.value_discounted_articles
    end
  end
end