Implement currencies endpoint

Gemfile

@@ -4,6 +4,7 @@ source 'http://rubygems.org'
 
 ruby '2.5.1'
 
+gem 'money'
 gem 'oj'
 gem 'ox'
 gem 'rack-cors'

Gemfile.lock

@@ -6,6 +6,7 @@ GEM
     ast (2.4.0)
     builder (3.2.3)
     coderay (1.1.2)
+    concurrent-ruby (1.0.5)
     crack (0.4.3)
       safe_yaml (~> 1.0.0)
     et-orbi (1.1.6)
@@ -15,12 +16,16 @@ GEM
       et-orbi (~> 1.1, >= 1.1.6)
       raabro (~> 1.1)
     hashdiff (0.3.7)
+    i18n (1.1.0)
+      concurrent-ruby (~> 1.0)
     jaro_winkler (1.5.1)
     kgio (2.11.2)
     method_source (0.9.0)
     minitest (5.11.3)
     minitest-around (0.4.1)
       minitest (~> 5.0)
+    money (6.13.0)
+      i18n (>= 0.6.4, <= 2)
     mustermann (1.0.3)
     oj (3.6.11)
     ox (2.10.0)
@@ -64,7 +69,7 @@ GEM
     sass-listen (4.0.0)
       rb-fsevent (~> 0.9, >= 0.9.4)
       rb-inotify (~> 0.9, >= 0.9.7)
-    sequel (5.12.0)
+    sequel (5.13.0)
     sequel_pg (1.11.0)
       pg (>= 0.18.0)
       sequel (>= 4.38.0)
@@ -97,6 +102,7 @@ PLATFORMS
 DEPENDENCIES
   minitest
   minitest-around
+  money
   oj
   ox
   pry

README.md

@@ -32,6 +32,12 @@ Get historical rates for a time period up to the present.
 GET /2010-01-01.. HTTP/1.1
 ```
 
+Get a list of available currency symbols, along with their full names.
+
+```http
+GET /currencies HTTP/1.1
+```
+
 Rates quote against the Euro by default. Quote against a different currency.
 
 ```http

lib/currency_names.rb

@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+require 'currency'
+require 'money/currency'
+
+class CurrencyNames
+  def cache_key
+    Digest::MD5.hexdigest(currencies.first.date.to_s)
+  end
+
+  def formatted
+    iso_codes.each_with_object({}) do |iso_code, result|
+      result[iso_code] = Money::Currency.find(iso_code).name
+    end
+  end
+
+  private
+
+  def iso_codes
+    currencies.map(&:iso_code).append('EUR').sort
+  end
+
+  def currencies
+    @currencies ||= find_currencies
+  end
+
+  def find_currencies
+    Currency.latest.all
+  end
+end

lib/web/server.rb

@@ -6,6 +6,7 @@ require 'redcarpet'
 require 'sass/plugin/rack'
 require 'sinatra'
 
+require 'currency_names'
 require 'query'
 require 'quote'
 
@@ -102,6 +103,12 @@ get '/(?<start_date>\d{4}-\d{2}-\d{2})\.\.(?<end_date>\d{4}-\d{2}-\d{2})?',
   json interval_quote.formatted
 end
 
+get '/currencies' do
+  currency_names = CurrencyNames.new
+  etag currency_names.cache_key
+  json currency_names.formatted
+end
+
 not_found do
   halt 404
 end

spec/currency_names_spec.rb

@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+require_relative 'helper'
+require 'currency_names'
+
+describe CurrencyNames do
+  let(:currency_names) do
+    CurrencyNames.new
+  end
+
+  it 'returns currency codes and names' do
+    currency_names.formatted['USD'].must_equal 'United States Dollar'
+  end
+
+  it 'has a cache key' do
+    currency_names.cache_key.wont_be :empty?
+  end
+end

spec/web/server_spec.rb

@@ -16,25 +16,25 @@ describe 'the server' do
     last_response.must_be :ok?
   end
 
-  it 'returns current quotes' do
+  it 'returns latest quotes' do
-    get '/current'
+    get '/latest'
     last_response.must_be :ok?
   end
 
   it 'sets base currency' do
-    get '/current'
+    get '/latest'
     res = Oj.load(last_response.body)
-    get '/current?from=USD'
+    get '/latest?from=USD'
     json.wont_equal res
   end
 
   it 'sets base amount' do
-    get '/current?amount=10'
+    get '/latest?amount=10'
     json['rates']['USD'].must_be :>, 10
   end
 
   it 'filters symbols' do
-    get '/current?to=USD'
+    get '/latest?to=USD'
     json['rates'].keys.must_equal %w[USD]
   end
 
@@ -50,14 +50,14 @@ describe 'the server' do
   end
 
   it 'returns an ETag' do
-    %w[/current /2012-11-20].each do |path|
+    %w[/latest /2012-11-20].each do |path|
       get path
       headers['ETag'].wont_be_nil
     end
   end
 
   it 'allows cross-origin requests' do
-    %w[/ /current /2012-11-20].each do |path|
+    %w[/ /latest /2012-11-20].each do |path|
       header 'Origin', '*'
       get path
       assert headers.key?('Access-Control-Allow-Methods')
@@ -65,7 +65,7 @@ describe 'the server' do
   end
 
   it 'responds to preflight requests' do
-    %w[/ /current /2012-11-20].each do |path|
+    %w[/ /latest /2012-11-20].each do |path|
       header 'Origin', '*'
       header 'Access-Control-Request-Method', 'GET'
       header 'Access-Control-Request-Headers', 'Content-Type'
@@ -75,7 +75,7 @@ describe 'the server' do
   end
 
   it 'converts an amount' do
-    get '/current?from=GBP&to=USD&amount=100'
+    get '/latest?from=GBP&to=USD&amount=100'
     json['rates']['USD'].must_be :>, 100
   end
 
@@ -92,4 +92,9 @@ describe 'the server' do
     json['end_date'].wont_be :empty?
     json['rates'].wont_be :empty?
   end
+
+  it 'returns currencies' do
+    get '/currencies'
+    json['USD'].must_equal 'United States Dollar'
+  end
 end