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61 lines
1.3 KiB
Ruby
61 lines
1.3 KiB
Ruby
# frozen_string_literal: true
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require 'virtus'
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require 'currency'
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class Quote
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include Virtus.value_object
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DEFAULT_BASE = 'EUR'
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values do
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attribute :base, String, default: DEFAULT_BASE
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attribute :date, Date, default: proc { Currency.current_date }
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attribute :rates, Hash, default: :find_rates, lazy: true
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end
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private
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def base=(base)
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base.upcase!
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super base
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end
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def date=(date)
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current_date = Currency.current_date_before(date)
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fail ArgumentError, 'Date too old' unless current_date
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super current_date
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end
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def find_rates
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quoted_against_default_base? ? find_default_rates : find_rebased_rates
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end
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def quoted_against_default_base?
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base == DEFAULT_BASE
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end
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def find_default_rates
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Currency.where(date: date).reduce({}) do |rates, currency|
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rates.update(currency.to_h)
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end
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end
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def find_rebased_rates
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rates = find_default_rates
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denominator = rates.update(DEFAULT_BASE => 1.0).delete(base)
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fail ArgumentError, 'Invalid base' unless denominator
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rates.each do |iso_code, rate|
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rates[iso_code] = round_rate(rate / denominator)
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end
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rates
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end
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# I'm mimicking the apparent convention of the ECB here.
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def round_rate(rate)
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Float("%.#{5}g" % rate)
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end
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end
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