module EntriesHelper
	# Berechnet Kilometerpauschale für eine Entry anhand der gespeicherten MileageRate
	# entry: muss attribute `distance_km` und `date` haben
	def kilometrergeld_for(entry)
		rate = MileageRate.for_year(entry.date.year)
		if rate
			(entry.distance_km.to_f * rate).round(2)
		else
			# Fallback: z. B. Standardrate 0.42
			(entry.distance_km.to_f * 0.05).round(2)
		end
	end
	
	# Für Summen: sum_meilen ist Summe der km oder Array von entries
	def total_km_cost_for_year(user, year)
		rate = MileageRate.for_year(year) || 0.42
		total_km = user.entries
		           .where("EXTRACT(YEAR FROM date) = ?", year)
		           .sum(:distance_km).to_f
		(total_km * rate).round(2)
	end
end