Add rake task to report lost payments

In rare cases, payment records can get lost through database rollbacks.
This new rake task tries to find log entries for lost transactions and
reports them as CSV.

lib/tasks/missing_payments.rake

@@ -0,0 +1,56 @@
+# Find gaps in the sequence of payment ids.
+# If there are gaps then see if there is a log entry with a payment result for
+# the now lost payment. If there are some then you probably want to follow up
+# with the affected enterprise and see if customers need to be refunded.
+#
+# ## Usage
+
+# Report of the last 35 days:
+#   rake ofn:missing_payments[35]
+namespace :ofn do
+  desc 'Find payments that got lost'
+  task :missing_payments, [:days] => :environment do |_task_, args|
+    days = args[:days].andand.to_i || 7
+    payments_sequence = Spree::Payment.where("created_at > ?", days.days.ago).order(:id).pluck(:id)
+    payments_range = (payments_sequence.first..payments_sequence.last).to_a
+    missing_payment_ids = payments_range - payments_sequence
+    puts "Gaps in the payments sequence: #{missing_payment_ids.count}"
+    log_entries = Spree::LogEntry.where(
+      source_type: "Spree::Payment",
+      source_id: missing_payment_ids
+    )
+    return if log_entries.empty?
+
+    CSV do |out|
+      out << headers
+      log_entries.each do |entry|
+        begin
+          details = Psych.load(entry.details)
+        rescue StandardError
+          Logger.new(STDERR).warn(entry)
+          next
+        end
+        out << row(details, details.params)
+      end
+    end
+  end
+
+  def headers
+    [
+      "Created", "Order", "Success", "Message", "Payment ID", "Action",
+      "Amount", "Currencty", "Receipt"
+    ]
+  end
+
+  def row(details, params)
+    [
+      Time.zone.at(params["created"] || 0).to_datetime,
+      params["description"],
+      details.success?,
+      details.message,
+      params["id"],
+      params["object"],
+      params["amount"], params["currency"], params["receipt_url"]
+    ]
+  end
+end