change rule to display arrow button for type de champ

app/decorators/type_de_champ_decorator.rb

@@ -1,11 +1,37 @@
 
 class TypeDeChampDecorator < Draper::Decorator
   delegate_all
-  def button_up index
-    h.button_tag '', class: %w(btn btn-default form-control fa fa-chevron-up), id: "btn_up_#{index}" unless index == 0
+  def button_up params
+    h.button_tag '', class: up_classes, id: "btn_up_#{params[:index]}", remote: true, method: :post if display_up_button?(params[:index])
   end
 
-  def button_down index
-    h.button_tag '', class: %w(btn btn-default form-control fa fa-chevron-down), id: "btn_down_#{index}" if persisted?
+  def button_down params
+    h.button_tag '', class: down_classes, id: "btn_down_#{params[:index]}", remote: true if display_down_button?(params[:index])
+  end
+
+  private
+
+  def up_classes
+    base_classes << 'fa-chevron-up'
+  end
+
+  def down_classes
+    base_classes << 'fa-chevron-down'
+  end
+
+  def base_classes
+    %w(btn btn-default form-control fa)
+  end
+
+  def display_up_button?(index)
+    !(index == 0 || count_type_de_champ < 2)
+  end
+
+  def display_down_button?(index)
+    (index + 1) < count_type_de_champ
+  end
+
+  def count_type_de_champ
+    @count_type_de_champ ||= procedure.types_de_champ.count
   end
 end

app/views/admin/types_de_champ/_fields.html.haml

@@ -12,10 +12,11 @@
     .form-group
       = ff.hidden_field :order_place, value: ff.index
       = ff.hidden_field :id
-    .form-group
-      %br  
-      = ff.object.button_up(ff.index)
-      = ff.object.button_down(ff.index)
+    - unless ff.object.id.nil?
+      .form-group
+        %br  
+        = ff.object.button_up(index: ff.index)
+        = ff.object.button_down(index: ff.index)
 
     - unless ff.object.id.nil?
       .form-group

spec/views/admin/types_de_champ/show.html.haml_spec.rb

@@ -25,15 +25,23 @@ describe 'admin/types_de_champ/show.html.haml', type: :view do
       render
       rendered
     end
-    context 'when there is only one field' do
+    context 'when there is no field in database' do
       it { expect(subject).not_to have_css('.fa-chevron-down') }
       it { expect(subject).not_to have_css('.fa-chevron-up') }
     end
-    context 'when two fields' do
+    context 'when there is only one field in database' do
       let!(:type_de_champ_0) { create(:type_de_champ, procedure: procedure, order_place: 0) }
-      it { expect(subject).to have_css('#btn_down_0.fa-chevron-down') }
+      it { expect(subject).not_to have_css('#btn_down_0') }
+      it { expect(subject).not_to have_css('#btn_up_0')   }
+      it { expect(subject).not_to have_css('#btn_up_1')   }
+      it { expect(subject).not_to have_css('#btn_down_1') }
+    end
+    context 'when there are 2 fields in database' do
+      let!(:type_de_champ_0) { create(:type_de_champ, procedure: procedure, order_place: 0) }
+      let!(:type_de_champ_1) { create(:type_de_champ, procedure: procedure, order_place: 1) }
+      it { expect(subject).to have_css('#btn_down_0') }
       it { expect(subject).not_to have_css('#btn_up_0') }
-      it { expect(subject).to have_css('#btn_up_1.fa-chevron-up') }
+      it { expect(subject).to have_css('#btn_up_1')   }
       it { expect(subject).not_to have_css('#btn_down_1') }
     end
   end