I love refactoring!

secretfile.rb

# Before Refactoring

def max_refund_exceeded  
  return unless quantity.present?
  job_hours = self.job.number_of_hours
  amendment_hours = self.job.job_items.where(type: ['JobItems::Lateness', 'JobItems::Refund']).map(&:quantity).sum
  errors[:base] << "You've exceeded maximum refund" unless amendment_hours + quantity <= job_hours
end

# After Refactoring #1

def max_refund_exceeded  
  return unless quantity.present?
  job_hours = self.job.number_of_hours
  amendment_hours = self.job.job_items.where(type: ['JobItems::Lateness', 'JobItems::Refund']).map(&:quantity).sum
  errors[:base] << "You've exceeded maximum refund" unless amendment_hours + quantity <= max_refundable_amount
end

def max_refundable_amount
  cancellation_penalty = self.job.job_items.where(type: 'JobItems::CancelationPenalty').first
  late_booking_penalty = self.job.job_items.where(type: 'JobItems::LateBookingPenalty').first
  return self.job.number_of_hours + cancellation_penalty.quantity + late_booking_penalty.quantity if cancellation_penalty.present? && late_booking_penalty.present?
  return self.job.number_of_hours + cancellation_penalty.quantity if cancellation_penalty.present? && late_booking_penalty.blank?
  return self.job.number_of_hours + late_booking_penalty.quantity if late_booking_penalty.present? && cancellation_penalty.blank?
  self.job.number_of_hours
end

# After Refactoring #2

def max_refund_exceeded
  return unless quantity.present?
  amendment_hours = self.job.job_items.where(type: REFUNDABLE_TYPES).map(&:quantity).sum
  amendment_hours -= quantity if self.type == 'JobItems::CancelationPenalty' 
  errors[:base] << "You've exceeded maximum refund" unless amendment_hours + quantity <= max_refundable_hours
end

def max_refundable_hours
  cancellation_penalty = self.job.job_items.where(type: 'JobItems::CancelationPenalty').first
  late_booking_penalty = self.job.job_items.where(type: 'JobItems::LateBookingPenalty').first
  max_refundable_hours = self.job.number_of_hours
  max_refundable_hours += late_booking_penalty.quantity if late_booking_penalty.present?
  max_refundable_hours -= cancellation_penalty.quantity if cancellation_penalty.present?
end