Refactor and improve invoices

- `runner 'Invoice.cancel_overdue_invoices'` in `schedule.rb` is
changed to `rake 'invoices:cancel_overdue'`.
- `invoices.payment_term` database column is removed and its value is
hardcoded in UI.
- `invoices.paid_at` is removed as unused
- `invoices.due_date` column's type is now `date`.
- `Invoice#invoice_items` renamed to `Invoice#items` and `Invoice`
interface to get a list of items is unified.
- Default date format in UI.
- Default translations are used.
- Tests improved.
- Specs converted to tests and removed along with factories.
- Database structure improved.

app/models/bank_transaction.rb

@@ -41,9 +41,7 @@ class BankTransaction < ActiveRecord::Base
     return unless registrar
     return unless invoice_num
     return unless invoice
-
-    return if invoice.binded?
-    return if invoice.cancelled?
+    return unless invoice.payable?
 
     return if invoice.total != sum
     create_activity(registrar, invoice)
@@ -62,7 +60,7 @@ class BankTransaction < ActiveRecord::Base
       return
     end
 
-    if invoice.binded?
+    if invoice.paid?
       errors.add(:base, I18n.t('invoice_is_already_binded'))
       return
     end

app/models/concerns/invoice/cancellable.rb

@@ -0,0 +1,28 @@
+module Concerns
+  module Invoice
+    module Cancellable
+      extend ActiveSupport::Concern
+
+      included do
+        scope :non_cancelled, -> { where(cancelled_at: nil) }
+      end
+
+      def cancellable?
+        unpaid? && not_cancelled?
+      end
+
+      def cancel
+        raise 'Invoice cannot be cancelled' unless cancellable?
+        update!(cancelled_at: Time.zone.now)
+      end
+
+      def cancelled?
+        cancelled_at
+      end
+
+      def not_cancelled?
+        !cancelled?
+      end
+    end
+  end
+end

app/models/concerns/invoice/payable.rb

@@ -0,0 +1,28 @@
+module Concerns
+  module Invoice
+    module Payable
+      extend ActiveSupport::Concern
+
+      included do
+        scope :unpaid, -> { where('id NOT IN (SELECT invoice_id FROM account_activities WHERE' \
+                              ' invoice_id IS NOT NULL)') }
+      end
+
+      def payable?
+        unpaid? && not_cancelled?
+      end
+
+      def paid?
+        account_activity
+      end
+
+      def receipt_date
+        account_activity.created_at.to_date
+      end
+
+      def unpaid?
+        !paid?
+      end
+    end
+  end
+end

app/models/directo.rb

@@ -3,7 +3,7 @@ class Directo < ActiveRecord::Base
   belongs_to :item, polymorphic: true
 
   def self.send_receipts
-    new_trans = Invoice.where(in_directo: false).where(cancelled_at: nil)
+    new_trans = Invoice.where(in_directo: false).non_cancelled
     total     = new_trans.count
     counter   = 0
     Rails.logger.info("[DIRECTO] Will try to send #{total} invoices")
@@ -26,7 +26,7 @@ class Directo < ActiveRecord::Base
             xml.invoice(
                 "SalesAgent"  => Setting.directo_sales_agent,
                 "Number"      => num,
-                "InvoiceDate" => invoice.created_at.strftime("%Y-%m-%d"),
+                "InvoiceDate" => invoice.issue_date.strftime("%Y-%m-%d"),
                 "PaymentTerm" => Setting.directo_receipt_payment_term,
                 "Currency"    => invoice.currency,
                 "CustomerCode"=> invoice.buyer.accounting_customer_code

app/models/invoice.rb

@@ -1,16 +1,16 @@
 class Invoice < ActiveRecord::Base
   include Versions
+  include Concerns::Invoice::Cancellable
+  include Concerns::Invoice::Payable
+
   belongs_to :seller, class_name: 'Registrar'
   belongs_to :buyer, class_name: 'Registrar'
   has_one  :account_activity
-  has_many :invoice_items
+  has_many :items, class_name: 'InvoiceItem', dependent: :destroy
   has_many :directo_records, as: :item, class_name: 'Directo'
 
-  accepts_nested_attributes_for :invoice_items
+  accepts_nested_attributes_for :items
 
-  scope :unbinded, lambda {
-    where('id NOT IN (SELECT invoice_id FROM account_activities where invoice_id IS NOT NULL)')
-  }
   scope :all_columns,                    ->{select("invoices.*")}
   scope :sort_due_date_column,           ->{all_columns.select("CASE WHEN invoices.cancelled_at is not null THEN
                                                                 (invoices.cancelled_at + interval '100 year') ELSE
@@ -24,11 +24,14 @@ class Invoice < ActiveRecord::Base
   scope :sort_by_sort_receipt_date_asc,  ->{sort_receipt_date_column.order("sort_receipt_date ASC")}
   scope :sort_by_sort_receipt_date_desc, ->{sort_receipt_date_column.order("sort_receipt_date DESC")}
 
+  scope :overdue, -> { unpaid.non_cancelled.where('due_date < ?', Time.zone.today) }
+
   attr_accessor :billing_email
   validates :billing_email, email_format: { message: :invalid }, allow_blank: true
 
+  validates :issue_date, presence: true
   validates :due_date, :currency, :seller_name,
-            :seller_iban, :buyer_name, :invoice_items, presence: true
+            :seller_iban, :buyer_name, :items, presence: true
   validates :vat_rate, numericality: { greater_than_or_equal_to: 0, less_than: 100 },
             allow_nil: true
 
@@ -56,35 +59,6 @@ class Invoice < ActiveRecord::Base
     false
   end
 
-  class << self
-    def cancel_overdue_invoices
-      STDOUT << "#{Time.zone.now.utc} - Cancelling overdue invoices\n" unless Rails.env.test?
-
-      cr_at = Time.zone.now - Setting.days_to_keep_overdue_invoices_active.days
-      invoices = Invoice.unbinded.where(
-        'due_date < ? AND cancelled_at IS NULL', cr_at
-      )
-
-      unless Rails.env.test?
-        invoices.each do |m|
-          STDOUT << "#{Time.zone.now.utc} Invoice.cancel_overdue_invoices: ##{m.id}\n"
-        end
-      end
-
-      count = invoices.update_all(cancelled_at: Time.zone.now)
-
-      STDOUT << "#{Time.zone.now.utc} - Successfully cancelled #{count} overdue invoices\n" unless Rails.env.test?
-    end
-  end
-
-  def binded?
-    account_activity.present?
-  end
-
-  def receipt_date
-    account_activity.try(:created_at)
-  end
-
   def to_s
     I18n.t('invoice_no', no: number)
   end
@@ -119,25 +93,6 @@ class Invoice < ActiveRecord::Base
     "invoice-#{number}.pdf"
   end
 
-  def cancel
-    if binded?
-      errors.add(:base, I18n.t('cannot_cancel_paid_invoice'))
-      return false
-    end
-
-    if cancelled?
-      errors.add(:base, I18n.t('cannot_cancel_cancelled_invoice'))
-      return false
-    end
-
-    self.cancelled_at = Time.zone.now
-    save
-  end
-
-  def cancelled?
-    cancelled_at.present?
-  end
-
   def forward(html)
     return false unless valid?
     return false unless billing_email.present?
@@ -146,12 +101,8 @@ class Invoice < ActiveRecord::Base
     true
   end
 
-  def items
-    invoice_items
-  end
-
   def subtotal
-    invoice_items.map(&:item_sum_without_vat).reduce(:+)
+    items.map(&:item_sum_without_vat).reduce(:+)
   end
 
   def vat_amount
@@ -164,6 +115,10 @@ class Invoice < ActiveRecord::Base
     read_attribute(:total)
   end
 
+  def each
+    items.each { |item| yield item }
+  end
+
   private
 
   def apply_default_vat_rate

app/models/invoice_item.rb

@@ -3,6 +3,6 @@ class InvoiceItem < ActiveRecord::Base
   belongs_to :invoice
 
   def item_sum_without_vat
-    (amount * price).round(2)
+    (price * quantity).round(2)
   end
 end

app/models/registrar.rb

@@ -51,8 +51,8 @@ class Registrar < ActiveRecord::Base
 
   def issue_prepayment_invoice(amount, description = nil)
     invoices.create(
-      due_date: (Time.zone.now.to_date + Setting.days_to_keep_invoices_active.days).end_of_day,
-      payment_term: 'prepayment',
+      issue_date: Time.zone.today,
+      due_date: (Time.zone.now + Setting.days_to_keep_invoices_active.days).to_date,
       description: description,
       currency: 'EUR',
       seller_name: Setting.registry_juridical_name,
@@ -82,11 +82,11 @@ class Registrar < ActiveRecord::Base
       buyer_url: website,
       buyer_email: email,
       reference_no: reference_no,
-      invoice_items_attributes: [
+      items_attributes: [
         {
           description: 'prepayment',
           unit: 'piece',
-          amount: 1,
+          quantity: 1,
           price: amount
         }
       ]