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.

class BusinessTransactionAbacus
  attr_reader :prices,
              :by_payment,
              :single_transports,
              :unified_transport,
              :total_retail_price,
              :total_net_price,
              :total_vat,
              :line_item_group

  def self.calculate line_item_group
    abacus = BusinessTransactionAbacus.new(line_item_group)
    abacus.prepare_and_sort_business_transactions
    abacus.calculate_total_retail_price
    abacus.calculate_total_net_price
    abacus.calculate_total_vat
    abacus
  end

  def prepare_and_sort_business_transactions
    line_item_group.business_transactions.each do |bt|
      @prices[bt] = self.class.prices_of(bt)

      prepare_transport_for bt
      prepare_payment_for bt
    end
  end

  def calculate_total_retail_price
    @total_retail_price = @prices.values.map { |prices| prices[:retail_price] }.sum
  end

  def calculate_total_net_price
    @total_net_price = @prices.values.map { |prices| prices[:net_price] }.sum
  end

  def calculate_total_vat
    @total_vat = @total_retail_price - @total_net_price
  end

  private

  def initialize line_item_group
    @line_item_group = line_item_group

    @prices = {}
    @by_payment = {}
    @single_transports = []
    @unified_transport = []
  end

  def self.prices_of business_transaction
    {
      retail_price: retail_price_of(business_transaction),
      net_price: net_price_of(business_transaction),
      quantity: business_transaction.quantity_bought
    }
  end

  # article price * quanity
  def self.retail_price_of business_transaction
    business_transaction.article_price * business_transaction.quantity_bought
  end

  # net article price * quantity
  def self.net_price_of business_transaction
    (business_transaction.article_price / ((100 + business_transaction.article_vat) / 100.0)) * business_transaction.quantity_bought
  end

  def prepare_payment_for business_transaction
    payment = business_transaction.selected_payment.to_sym
    @by_payment[payment] ||= []
    @by_payment[payment].push business_transaction
  end

  def prepare_transport_for business_transaction
    if business_transaction.is_in_unified_transport?
      @unified_transport.push business_transaction
    else
      @single_transports.push business_transaction
    end
  end
end