Class: Xrate::ExchangeRate

Inherits:
Object
  • Object
show all
Defined in:
lib/xrate/exchange_rate.rb

Class Method Summary collapse

Class Method Details

.at(date, from_currency, target_currency) ⇒ Object 



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# 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) ⇒ Object 



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# 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 ⇒ Object 



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# 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) ⇒ Object 



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# 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