class Xrate::ExchangeRate

Public Class Methods

at(date, from_currency, target_currency) click to toggle source
# File lib/xrate/exchange_rate.rb, line 7
def self.at(date, from_currency, target_currency)
  date_range = (date - fallback_days)..date
  get_latest(date_range, from_currency, target_currency) or
    raise Xrate::UnconvertableCurrencyException
end
calculate_rate(date_range, from_currency, target_currency) click to toggle source
# File lib/xrate/exchange_rate.rb, line 21
def self.calculate_rate(date_range, from_currency, target_currency)
  begin
    base_to_from = Xrate::Rate.where(date: date_range, currency: from_currency).first&.rate
    base_to_target = Xrate::Rate.where(date: date_range, currency: target_currency).first&.rate

    base_to_target / base_to_from
  rescue NoMethodError # handle divide by zero
    nil
  end
end
fallback_days() click to toggle source
# File lib/xrate/exchange_rate.rb, line 32
def self.fallback_days
  ENV.fetch("XRATE_FALLBACK_DAYS").to_i
end
get_latest(date_range, from_currency, target_currency) click to toggle source
# File lib/xrate/exchange_rate.rb, line 13
def self.get_latest(date_range, from_currency, target_currency)
  if from_currency == ENV.fetch("XRATE_BASE_CURRENCY")
    Xrate::Rate.where(date: date_range, currency: target_currency).first&.rate
  else
    calculate_rate(date_range, from_currency, target_currency)
  end
end