line_with_taxes.rb

module LineWithTaxes
  extend ActiveSupport::Concern

  included do
    validates_length_of :label, within: 2..254
    validates_length_of :comment, within: 0..254, allow_blank: true
    validates_numericality_of :amount_with_taxes, :amount_without_taxes
    validates_numericality_of :quantity, minimum: 1, only_integer: true
    validates_numericality_of :ecotax,   minimum: 0

    normalize_attributes :label, with: :squish
    normalize_attributes :comment
  end

  # Amount of taxes for each unit of this line (VAT amount = TVA in France)
  # We don't store percentage to avoid rounding errors
  def taxes
    amount_with_taxes - amount_without_taxes
  end

  # Total amount of VAT for this line
  def total_taxes
    taxes * quantity
  end

  # French "TTC" = "toutes taxes comprises" amount for this line
  def total_with_taxes
    amount_with_taxes * quantity
  end

  # French "HT" = "hors taxes" amount for this line
  def total_without_taxes
    amount_without_taxes * quantity
  end
end