added registrar credit changing functionality

app/controllers/admin/accounts_controller.rb

@@ -0,0 +1,46 @@
+module Admin
+  class AccountsController < BaseController
+    load_and_authorize_resource
+
+    def index
+      @q = Account.includes(:registrar).search(params[:q])
+      @accounts = @q.result.page(params[:page])
+      @accounts = @accounts.per(params[:results_per_page]) if params[:results_per_page].to_i.positive?
+
+      render_by_format('admin/accounts/index', 'accounts')
+    end
+
+    def show; end
+
+    def edit; end
+
+    def update
+      if @account.valid?
+        @sum = params[:account][:balance].to_f - @account.balance
+        redirect_to admin_accounts_path, notice: t('.updated') if create_activity
+      else
+        render 'edit'
+      end
+    end
+
+    private
+
+    def create_activity
+      activity = AccountActivity.new(account: @account,
+                                     sum: @sum,
+                                     currency: @account.currency,
+                                     description: params[:description],
+                                     activity_type: AccountActivity::ADD_CREDIT)
+
+      if activity.save
+        true
+      else
+        false
+      end
+    end
+
+    def account_params
+      params.require(:account).permit(:id, :currency, :balance)
+    end
+  end
+end