Make the invoice number formattable

README.md

@@ -3,7 +3,7 @@
 [![Build Status](https://travis-ci.org/spree-contrib/spree_print_invoice.svg?branch=master)](https://travis-ci.org/spree-contrib/spree_print_invoice)
 [![Code Climate](https://codeclimate.com/github/spree-contrib/spree_print_invoice/badges/gpa.svg)](https://codeclimate.com/github/spree-contrib/spree_print_invoice)
 
-This extension provides a model `Spree::BookkeepingDocument`, which generates PDFs from any Spree Object with the help of View objects that translate between different object structures and PDF templates. It stores a "number" string as well as first name, last name, email, and amount with each document for convenient searching in the backend.
+This extension provides a model `Spree::BookkeepingDocument`, which generates PDFs from any Spree Object with the help of View objects that translate between different object structures and PDF templates. It stores a `number` string as well as first `name`, `last name`, `email`, and `amount` with each document for convenient searching in the backend.
 
 The Gem contains an example implementation for Invoices for `Spree::Orders`. The basic structure looks like this:
 
@@ -13,6 +13,20 @@ The Gem contains an example implementation for Invoices for `Spree::Orders`. The
 
 In the `Spree::Admin::OrdersController#edit` view, you'll find an additional button `Documents`, where all printable documents will be listed. Additionally, you can find all available Documents in a "Documents" tab in the main menu.
 
+There's also the option of adding a custom `Spree::PrintInvoice::NumberFormatter` class. If that class is present, it will be used to generate a custom string from the next invoice number, complete with (for example) a prefix and padding. Here's what we did:
+
+```
+class Spree::PrintInvoice::NumberFormatter
+  # Generates a number that starts with INV- and pads the invoice number to ten digits
+  def initialize(number)
+    @number = number
+  end
+
+  def to_s
+    "INV-#{'%.10d' % number}"
+  end
+end
+```
 
 ## Installation
 

app/models/spree/printables/invoice/base_view.rb

@@ -54,7 +54,7 @@ def shipping_methods
 
     def number
       if use_sequential_number?
-        Spree::PrintInvoice::Config.next_number
+        formatted_number
       else
         printable.number
       end
@@ -66,6 +66,18 @@ def after_save_actions
 
     private
 
+    def formatted_number
+      if (Object.const_get('::Spree::PrintInvoice::NumberFormatter') rescue false)
+        ::Spree::PrintInvoice::NumberFormatter.new(next_number).to_s
+      else
+        next_number
+      end
+    end
+
+    def next_number
+      Spree::PrintInvoice::Config.next_number
+    end
+
     def increase_invoice_number!
       Spree::PrintInvoice::Config.increase_invoice_number!
     end

spec/controllers/spree/admin/bookkeeping_documents_controller_spec.rb

@@ -1,6 +1,12 @@
 RSpec.describe Spree::Admin::BookkeepingDocumentsController, type: :controller do
   stub_authorization!
 
+  before do
+    reset_spree_preferences
+    user = build(:admin_user)
+    allow(controller).to receive(:try_spree_current_user).and_return(user)
+  end
+
   describe '#show as :pdf' do
     context 'an order invoice' do
       let!(:order) { create(:invoiceable_order) }

spec/controllers/spree/admin/print_invoice_settings_controller_spec.rb

@@ -3,7 +3,7 @@
 
   before do
     reset_spree_preferences
-    user = create(:admin_user)
+    user = build(:admin_user)
     allow(controller).to receive(:try_spree_current_user).and_return(user)
   end
 

spec/models/spree/printables/invoice/base_view_spec.rb

@@ -68,14 +68,17 @@
   end
 
   describe '#number' do
+    before do
+      allow(Spree::PrintInvoice::Config).to receive(:next_number) { 77 }
+    end
+
     context 'when using sequential numbers' do
       before do
         allow(Spree::PrintInvoice::Config).to receive(:use_sequential_number?) { true }
       end
 
-      it 'calls next_number on Spree::PrintInvoice::Config' do
-        expect(Spree::PrintInvoice::Config).to receive(:next_number)
-        base_view.number
+      it 'returns the next number without additional formatting' do
+        expect(base_view.number).to eq(77)
       end
     end
 
@@ -89,5 +92,23 @@
         base_view.number
       end
     end
+
+    context 'when using a NumberFormatter' do
+      before do
+        class Spree::PrintInvoice::NumberFormatter
+          def initialize(number)
+            @number = number
+          end
+
+          def to_s
+            "MY-NICE-INVOICE-#{@number}"
+          end
+        end
+      end
+
+      it 'returns a nicely formatted number' do
+        expect(base_view.number).to eq("MY-NICE-INVOICE-77")
+      end
+    end
   end
 end