Fold conversion into quote

lib/api.rb

@@ -4,7 +4,6 @@ require 'oj'
 require 'sinatra'
 require 'rack/cors'
 require 'quote'
-require 'converter'
 
 configure :development do
   set :show_exceptions, :after_handler
@@ -32,12 +31,8 @@ helpers do
     end
   end
 
-  def converter
-    @converter ||= Converter.new(params)
-  end
-
   def symbols
-    @symbols ||= params.values_at('symbols', 'currencies').first
+    @symbols ||= params.values_at('symbols', 'to').compact.first
   end
 
   def jsonp(data)
@@ -83,11 +78,6 @@ get(/(?<date>\d{4}-\d{2}-\d{2})/) do
   jsonp quote_attributes
 end
 
-get '/converter' do
-  params[:base] = params[:from]
-  jsonp Hash(amount: converter.convert(quote))
-end
-
 not_found do
   halt 404, encode_json(error: 'Not found')
 end

lib/converter.rb

@@ -1,32 +0,0 @@
-# frozen_string_literal: true
-
-require 'bigdecimal'
-require 'quote'
-
-class Converter
-  attr_reader :to, :from
-
-  def initialize(params = {})
-    @amount = params[:amount]
-    @from   = params[:from]
-    @to     = params[:to]
-  end
-
-  # Converts an amount into a new currency
-  # @param quote [Quote] the quote object
-  # @return amount [BigDecimal] the converted amount
-  def convert(quote = latest_quote)
-    return amount if quote.base == to
-    amount * quote.rates.fetch(to) { raise Quote::Invalid, 'Invalid to' }
-  end
-
-  def amount
-    BigDecimal(@amount.to_s)
-  end
-
-  private
-
-  def latest_quote
-    @latest_quote ||= Quote.new(base: from)
-  end
-end

lib/quote.rb

@@ -5,12 +5,14 @@ require 'currency'
 class Quote
   Invalid = Class.new(StandardError)
 
+  DEFAULT_AMOUNT = 1
   DEFAULT_BASE = 'EUR'
 
-  attr_reader :base, :date
+  attr_reader :amount, :base, :date
 
   def initialize(params = {})
-    self.base = params[:base]
+    self.amount = params['amount']
+    self.base = params.values_at(:base, :from).compact.first
     self.date = params[:date]
   end
 
@@ -26,14 +28,18 @@ class Quote
 
   private
 
-  def base=(base)
-    @base = base&.upcase || DEFAULT_BASE
+  def amount=(value)
+    @amount = (value || DEFAULT_AMOUNT).to_f
+    raise Invalid, 'Invalid amount' if @amount.zero?
   end
 
-  def date=(date)
-    current_date = date ? Currency.current_date_before(date) : Currency.current_date
-    raise Invalid, 'Date too old' unless current_date
-    @date = current_date
+  def base=(value)
+    @base = value&.upcase || DEFAULT_BASE
+  end
+
+  def date=(value)
+    @date = value ? Currency.current_date_before(value) : Currency.current_date
+    raise Invalid, 'Date too old' unless @date
   rescue Sequel::DatabaseError => ex
     raise Invalid, 'Invalid date' if ex.wrapped_exception.is_a?(PG::DataException)
     raise
@@ -49,16 +55,16 @@ class Quote
 
   def find_default_rates
     Currency.where(date: date).reduce({}) do |rates, currency|
-      rates.update(currency.to_h)
+      rates.update(Hash[currency.to_h.map { |k, v| [k, round_rate(v * amount)] }])
     end
   end
 
   def find_rebased_rates
     rates = find_default_rates
-    denominator = rates.update(DEFAULT_BASE => 1.0).delete(base)
+    denominator = rates.update(DEFAULT_BASE => amount).delete(base)
     raise Invalid, 'Invalid base' unless denominator
     rates.each do |iso_code, rate|
-      rates[iso_code] = round_rate(rate / denominator)
+      rates[iso_code] = round_rate(amount * rate / denominator)
     end
 
     rates

spec/api_spec.rb

@@ -26,11 +26,26 @@ describe 'the API' do
     json['base'].must_equal 'USD'
   end
 
+  it 'sets base amount' do
+    get '/latest?amount=10'
+    json['rates']['USD'].must_be :>, 10
+  end
+
   it 'filters symbols' do
     get '/latest?symbols=USD'
     json['rates'].keys.must_equal %w(USD)
   end
 
+  it 'aliases base as from' do
+    get '/latest?from=USD'
+    json['base'].must_equal 'USD'
+  end
+
+  it 'aliases symbols as to' do
+    get '/latest?to=USD'
+    json['rates'].keys.must_equal %w(USD)
+  end
+
   it 'returns historical quotes' do
     get '/2012-11-20'
     json['rates'].wont_be :empty?
@@ -67,8 +82,8 @@ describe 'the API' do
     end
   end
 
-  it 'returns converted amount' do
-    get '/converter?to=USD&amount=100'
-    json['amount'].wont_be :nil?
+  it 'converts an amount' do
+    get '/latest?from=GBP&to=USD&amount=100'
+    json['rates']['USD'].must_be :>, 100
   end
 end

spec/converter_spec.rb

@@ -1,47 +0,0 @@
-# frozen_string_literal: true
-
-require_relative 'helper'
-require 'converter'
-
-describe Converter do
-  let(:to) { 'USD' }
-  let(:from) { 'EUR' }
-  let(:amount) { '100.0' }
-
-  let(:converter) { Converter.new to: to, from: from, amount: amount }
-  let(:quote) { Quote.new }
-
-  describe '#amount' do
-    it 'casts to BigDecimal' do
-      converter.amount.must_be_kind_of BigDecimal
-    end
-  end
-
-  describe '#convert' do
-    it 'should return the amount' do
-      quote.stub :base, to do
-        converter.convert(quote).must_equal BigDecimal(amount)
-      end
-    end
-
-    it 'should use the rates to convert' do
-      quote.stub :rates, Hash(to => 1.2) do
-        converter.convert(quote).must_equal BigDecimal('120.0')
-      end
-    end
-
-    it 'should raise with invalid currency' do
-      quote.stub :rates, {} do
-        -> { converter.convert(quote) }.must_raise Quote::Invalid, 'Invalid to'
-      end
-    end
-
-    it 'should use latest quote as default' do
-      quote.stub :rates, Hash(to => 1.3) do
-        converter.stub :latest_quote, quote do
-          converter.convert.must_equal 130.0
-        end
-      end
-    end
-  end
-end

spec/edge_cases_spec.rb

@@ -34,6 +34,12 @@ describe 'the API' do
     json.wont_be_empty
   end
 
+  it 'will not process an invalid amount' do
+    get '/latest?amount=foo'
+    last_response.must_be :unprocessable?
+    json.wont_be_empty
+  end
+
   it 'handles malformed queries' do
     get '/latest?base=USD?callback=?'
     last_response.must_be :unprocessable?