Allow deletion of financial transactions

app/models/financial_transaction.rb

@@ -5,11 +5,14 @@ class FinancialTransaction < ApplicationRecord
   belongs_to :user
   belongs_to :financial_link
   belongs_to :financial_transaction_type
+  belongs_to :reverts, class_name: 'FinancialTransaction', foreign_key: 'reverts_id'
+  has_one :reverted_by, class_name: 'FinancialTransaction', foreign_key: 'reverts_id'
 
   validates_presence_of :amount, :note, :user_id, :ordergroup_id
   validates_numericality_of :amount, greater_then: -100_000,
     less_than: 100_000
 
+  scope :visible, -> { joins('LEFT JOIN financial_transactions r ON financial_transactions.id = r.reverts_id').where('r.id IS NULL').where(reverts: nil) }
   scope :without_financial_link, -> { where(financial_link: nil) }
 
   localize_input_of :amount
@@ -23,6 +26,21 @@ class FinancialTransaction < ApplicationRecord
     ordergroup.add_financial_transaction! amount, note, user, financial_transaction_type
   end
 
+  def revert!(user)
+    transaction do
+      rt = dup
+      rt.amount = -rt.amount
+      rt.reverts = self
+      rt.user = user
+      rt.save!
+      ordergroup.update_balance!
+    end
+  end
+
+  def hidden?
+    reverts.present? || reverted_by.present?
+  end
+
   protected
 
   def initialize_financial_transaction_type

app/models/ordergroup.rb

@@ -84,8 +84,7 @@ class Ordergroup < Group
     transaction do
       t = FinancialTransaction.new(ordergroup: self, amount: amount, note: note, user: user, financial_transaction_type: transaction_type, financial_link: link)
       t.save!
-      self.account_balance = financial_transactions.sum('amount')
-      save!
+      update_balance!
       # Notify only when order group had a positive balance before the last transaction:
       if t.amount < 0 && self.account_balance < 0 && self.account_balance - t.amount >= 0
         Resque.enqueue(UserNotifier, FoodsoftConfig.scope, 'negative_balance', self.id, t.id)
@@ -103,6 +102,10 @@ class Ordergroup < Group
     update_attribute(:stats, {:jobs_size => jobs, :orders_sum => orders_sum})
   end
 
+  def update_balance!
+    update_attribute :account_balance, financial_transactions.sum('amount')
+  end
+
   def avg_jobs_per_euro
     stats[:jobs_size].to_f / stats[:orders_sum].to_f rescue 0
   end