implement paid cancel

app/controllers/admin/invoices_controller.rb

@@ -20,6 +20,23 @@ module Admin
       end
     end
 
+    def cancel_paid
+      invoice_id = params[:invoice_id]
+      invoice = Invoice.find(invoice_id)
+
+      account_activity = AccountActivity.find_by(invoice_id: invoice_id)
+      account_activity_dup = account_activity.dup
+      account_activity_dup.sum = -account_activity.sum
+
+      if account_activity_dup.save and invoice.update(cancelled_at: Time.zone.today)
+        flash[:notice] = t(:payment_was_cancelled)
+        redirect_to admin_invoices_path
+      else
+        flash[:alert] = t(:failed_to_payment_cancel)
+        redirect_to admin_invoices_path
+      end
+    end
+
     def index
       @q = Invoice.includes(:account_activity).search(params[:q])
       @q.sorts = 'number desc' if @q.sorts.empty?

app/views/admin/invoices/show.haml

@@ -6,6 +6,10 @@
     %h1.text-right.text-center-xs
       - if @invoice.unpaid?
         = link_to(t(:payment_received), new_admin_bank_statement_path(invoice_id: @invoice.id), class: 'btn btn-default')
+
+      - if @invoice.paid? and !@invoice.cancelled?
+        = link_to(t(:cancel_payment), cancel_paid_admin_invoices_path(invoice_id: @invoice.id), method: 'post', data: { confirm: t(:are_you_sure) }, class: 'btn btn-warning')
+
       = link_to(t('.download_btn'), download_admin_invoice_path(@invoice), class: 'btn btn-default')
       = link_to(t('.deliver_btn'), new_admin_invoice_delivery_path(@invoice), class: 'btn btn-default')
       - if @invoice.cancellable?