Repack app

I'm moving my company's server to a private location now that I have sold the domain. While prepping for this, I've done some cleanup and also threw in changes I had lingering on my hard drive.

- Run a single database query instead of two
- Fold the gem into the app and use Ox instead of REXML
- Simplify error handling logic
- Relax throttling

.env.example

@@ -1,5 +1,5 @@
+APP_ENV=production
 HTTPS_METHOD=noredirect
 LETSENCRYPT_EMAIL=foo@bar.com
 LETSENCRYPT_HOST=example.com,www.example.com
-RACK_ENV=production
 VIRTUAL_HOST=example.com,www.example.com

.travis.yml

@@ -1,10 +1,11 @@
-before_install:
+language: ruby
-  - gem update --system
+sudo: false
-  - gem install bundler
+
-  - psql -c 'create database fixer_test;' -U postgres
-  - cd app
-env:
-  - RACK_ENV=test
 rvm:
   - 2.5.0
-sudo: false
+env:
+  - APP_ENV=test
+
+bundler_args: "--without development"
+before_install:
+  - "psql -c 'create database fixer_test;' -U postgres"

Gemfile

@@ -4,8 +4,8 @@ source 'http://rubygems.org'
 
 ruby '2.5.0'
 
-gem 'fixer'
 gem 'oj'
+gem 'ox'
 gem 'rack-cors'
 gem 'rake'
 gem 'rufus-scheduler'
@@ -14,8 +14,14 @@ gem 'sinatra'
 gem 'unicorn'
 
 group :development do
+  gem 'pry'
+end
+
+group :test do
   gem 'minitest'
   gem 'minitest-around'
   gem 'rack-test'
   gem 'rubocop'
+  gem 'vcr'
+  gem 'webmock'
 end

Gemfile.lock

@@ -1,33 +1,44 @@
 GEM
   remote: http://rubygems.org/
   specs:
-    ast (2.3.0)
+    addressable (2.5.2)
-    et-orbi (1.0.8)
+      public_suffix (>= 2.0.2, < 4.0)
+    ast (2.4.0)
+    coderay (1.1.2)
+    crack (0.4.3)
+      safe_yaml (~> 1.0.0)
+    et-orbi (1.0.9)
       tzinfo
-    fixer (1.0.0)
+    hashdiff (0.3.7)
-    kgio (2.11.1)
+    kgio (2.11.2)
-    minitest (5.11.1)
+    method_source (0.9.0)
-    minitest-around (0.4.0)
+    minitest (5.11.3)
+    minitest-around (0.4.1)
       minitest (~> 5.0)
-    mustermann (1.0.1)
+    mustermann (1.0.2)
-    oj (3.3.10)
+    oj (3.5.0)
+    ox (2.8.4)
     parallel (1.12.1)
-    parser (2.4.0.2)
+    parser (2.5.0.3)
-      ast (~> 2.3)
+      ast (~> 2.4.0)
-    pg (0.21.0)
+    pg (1.0.0)
     powerpack (0.1.1)
-    rack (2.0.3)
+    pry (0.11.3)
+      coderay (~> 1.1.0)
+      method_source (~> 0.9.0)
+    public_suffix (3.0.2)
+    rack (2.0.4)
     rack-cors (1.0.2)
-    rack-protection (2.0.0)
+    rack-protection (2.0.1)
       rack
-    rack-test (0.8.2)
+    rack-test (0.8.3)
       rack (>= 1.0, < 3)
     rainbow (3.0.0)
     raindrops (0.19.0)
     rake (12.3.0)
-    rubocop (0.52.1)
+    rubocop (0.53.0)
       parallel (~> 1.10)
-      parser (>= 2.4.0.2, < 3.0)
+      parser (>= 2.5)
       powerpack (~> 0.1)
       rainbow (>= 2.2.2, < 4.0)
       ruby-progressbar (~> 1.7)
@@ -35,32 +46,39 @@ GEM
     ruby-progressbar (1.9.0)
     rufus-scheduler (3.4.2)
       et-orbi (~> 1.0)
-    sequel (5.4.0)
+    safe_yaml (1.0.4)
+    sequel (5.6.0)
     sequel_pg (1.8.1)
       pg (>= 0.18.0)
       sequel (>= 4.34.0)
-    sinatra (2.0.0)
+    sinatra (2.0.1)
       mustermann (~> 1.0)
       rack (~> 2.0)
-      rack-protection (= 2.0.0)
+      rack-protection (= 2.0.1)
       tilt (~> 2.0)
     thread_safe (0.3.6)
     tilt (2.0.8)
-    tzinfo (1.2.4)
+    tzinfo (1.2.5)
       thread_safe (~> 0.1)
     unicode-display_width (1.3.0)
     unicorn (5.4.0)
       kgio (~> 2.6)
       raindrops (~> 0.7)
+    vcr (4.0.0)
+    webmock (3.3.0)
+      addressable (>= 2.3.6)
+      crack (>= 0.3.2)
+      hashdiff
 
 PLATFORMS
   ruby
 
 DEPENDENCIES
-  fixer
   minitest
   minitest-around
   oj
+  ox
+  pry
   rack-cors
   rack-test
   rake
@@ -69,6 +87,8 @@ DEPENDENCIES
   sequel_pg
   sinatra
   unicorn
+  vcr
+  webmock
 
 RUBY VERSION
    ruby 2.5.0p0

README.md

@@ -4,8 +4,6 @@
 
 Fixer is a free API for current and historical foreign exchange rates [published by the European Central Bank](https://www.ecb.europa.eu/stats/policy_and_exchange_rates/euro_reference_exchange_rates/html/index.en.html).
 
-A public instance of the API lives at [https://api.fixer.io](https://api.fixer.io). Alternatively, you can run  privately with the provided [Docker image](https://hub.docker.com/r/hakanensari/fixer/).
-
 Rates are updated around 4PM CET every working day.
 
 ## Usage
@@ -22,16 +20,22 @@ Get historical rates for any day since 1999.
 GET /2000-01-03
 ```
 
-Rates are quoted against the Euro by default. Quote against a different currency by setting the base parameter in your request.
+Rates quote against the Euro by default. Quote against a different currency.
 
 ```http
-GET /latest?base=USD
+GET /latest?from=USD
 ```
 
-Request specific exchange rates by setting the symbols parameter.
+Request specific exchange rates.
 
 ```http
-GET /latest?symbols=USD,GBP
+GET /latest?to=GBP
+```
+
+Change the amount requested.
+
+```http
+GET /latest?amount=100
 ```
 
 The primary use case is client side. For instance, with [money.js](https://openexchangerates.github.io/money.js/) in the browser
@@ -42,7 +46,7 @@ let demo = () => {
   alert("£1 = $" + rate.toFixed(4))
 }
 
-fetch('https://api.fixer.io/latest')
+fetch('https://api.example.com/latest')
   .then((resp) => resp.json())
   .then((data) => fx.rates = data.rates)
   .then(demo)
@@ -50,8 +54,6 @@ fetch('https://api.fixer.io/latest')
 
 ## Installation
 
-I have included a sample Docker Compose configuration in the repo.
-
 To build locally, type
 
 ```bash
@@ -64,7 +66,7 @@ Now you can access the API at
 http://localhost:8080
 ```
 
-In production, create a [`.env`](.env.example) file in the project root and run with
+In production, create a [`.env`](.env.example) file and run with
 
 ```bash
 docker-compose -f docker-compose.yml -f docker-compose.prod.yml up -d

app/lib/currency.rb

@@ -1,25 +0,0 @@
-# frozen_string_literal: true
-
-class Currency < Sequel::Model
-  dataset_module do
-    def recent
-      order(Sequel.desc(:date))
-    end
-
-    def before(value)
-      where { date <= value }
-    end
-
-    def current_date
-      recent.first&.date
-    end
-
-    def current_date_before(value)
-      before(value).current_date
-    end
-  end
-
-  def to_h
-    { iso_code => rate }
-  end
-end

app/lib/quote.rb

@@ -1,80 +0,0 @@
-# frozen_string_literal: true
-
-require 'currency'
-
-class Quote
-  Invalid = Class.new(StandardError)
-
-  DEFAULT_AMOUNT = 1
-  DEFAULT_BASE = 'EUR'
-
-  attr_reader :amount, :base, :date, :symbols
-
-  def initialize(params = {})
-    self.amount = params['amount']
-    self.base = params.values_at(:base, :from).compact.first
-    self.symbols = params.values_at(:symbols, :to).compact.first
-    self.date = params[:date]
-  end
-
-  def rates
-    @rates ||= find_rates
-  end
-
-  def attributes
-    { base: base, date: date, rates: rates }
-  end
-
-  alias to_h attributes
-
-  private
-
-  attr_writer :symbols
-
-  def amount=(value)
-    @amount = (value || DEFAULT_AMOUNT).to_f
-    raise Invalid, 'Invalid amount' if @amount.zero?
-  end
-
-  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
-  end
-
-  def find_rates
-    rates = quoted_against_default_base? ? find_default_rates : find_rebased_rates
-    symbols ? rates.keep_if { |k, _| symbols.include?(k) } : rates
-  end
-
-  def quoted_against_default_base?
-    base == DEFAULT_BASE
-  end
-
-  def find_default_rates
-    Currency.where(date: date).order(:iso_code).reduce({}) do |rates, currency|
-      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 => amount).delete(base)
-    raise Invalid, 'Invalid base' unless denominator
-    rates
-      .map { |(iso_code, rate)| [iso_code, round_rate(amount * rate / denominator)] }
-      .sort_by(&:first)
-      .to_h
-  end
-
-  # I'm mimicking the apparent convention of the ECB here.
-  def round_rate(rate)
-    Float(format('%.5g', rate))
-  end
-end

app/spec/currency_spec.rb

@@ -1,35 +0,0 @@
-# frozen_string_literal: true
-
-require_relative 'helper'
-require 'currency'
-
-describe Currency do
-  around do |test|
-    Currency.db.transaction do
-      test.call
-      raise Sequel::Rollback
-    end
-  end
-
-  before do
-    Currency.dataset.delete
-    @first = Currency.create(date: '2014-01-01')
-    @last = Currency.create(date: '2015-01-01')
-  end
-
-  it 'returns current date' do
-    Currency.current_date.must_equal @last.date
-  end
-
-  it 'returns current date before given date' do
-    Currency.current_date_before(@last.date - 1).must_equal @first.date
-  end
-
-  it 'returns nil if there is no current date before given date' do
-    Currency.current_date_before(@first.date - 1).must_be_nil
-  end
-
-  it 'casts to hash' do
-    @first.to_h.must_be_kind_of Hash
-  end
-end

app/spec/helper.rb

@@ -1,5 +0,0 @@
-# frozen_string_literal: true
-
-require './config/environment'
-require 'minitest/autorun'
-require 'minitest/around/spec'

app/spec/quote_spec.rb

@@ -1,104 +0,0 @@
-# frozen_string_literal: true
-
-require_relative 'helper'
-require 'quote'
-
-describe Quote do
-  def stub_rates(default_rates = {})
-    quote.stub :find_default_rates, default_rates do
-      yield quote
-    end
-  end
-
-  describe 'by default' do
-    let(:quote) { Quote.new }
-
-    it 'quotes rates against the euro' do
-      stub_rates 'USD' => 1.25 do |quote|
-        rate = quote.rates['USD']
-        rate.must_equal 1.25
-      end
-    end
-
-    it 'does not quote the euro' do
-      stub_rates do |quote|
-        quote.rates.keys.wont_include 'EUR'
-      end
-    end
-
-    it 'casts to hash' do
-      stub_rates do |quote|
-        %i[base date rates].each do |key|
-          quote.to_h.keys.must_include key
-        end
-      end
-    end
-  end
-
-  describe 'when given a custom base' do
-    let(:quote) { Quote.new(base: 'FOO') }
-
-    it 'quotes rates against that currency' do
-      stub_rates 'FOO' => 2 do |quote|
-        quote.rates.keys.must_include 'EUR'
-      end
-    end
-
-    it 'does not quote the base currency' do
-      stub_rates 'FOO' => 2 do |quote|
-        quote.rates.keys.wont_include 'FOO'
-      end
-    end
-
-    it 'rounds to five significant digits' do
-      stub_rates 'FOO' => 0.6995 do |quote|
-        rate = quote.rates['EUR']
-        rate.must_equal 1.4296
-      end
-    end
-
-    it 'returns the currencies sorted' do
-      stub_rates 'BAZ' => 1.5, 'FOO' => 2, 'BAR' => 3, 'QUX' => 4 do |quote|
-        quote.rates.keys.must_equal quote.rates.keys.sort
-      end
-    end
-  end
-
-  describe 'when given an invalid base' do
-    let(:quote) { Quote.new(base: 'FOO') }
-
-    it 'raises validation error' do
-      proc { quote.to_h }.must_raise Quote::Invalid
-    end
-  end
-
-  describe 'when given a date that is too old' do
-    let(:quote) { Quote.new(date: '1900-01-01') }
-
-    it 'raises validation error' do
-      Currency.stub :current_date_before, nil do
-        proc { quote }.must_raise Quote::Invalid
-      end
-    end
-  end
-
-  describe 'when given a bad date' do
-    let(:quote) { Quote.new(date: '2000-31-01') }
-
-    it 'raises validation error' do
-      proc { quote }.must_raise Quote::Invalid
-    end
-  end
-
-  describe 'when given custom symbols' do
-    let(:quote) { Quote.new(symbols: 'FOO,BAR') }
-
-    it 'quotes rates only for given symbols' do
-      stub_rates 'FOO' => 1, 'BAR' => 2, 'BAZ' => 3 do |quote|
-        quote.rates.keys.must_include 'FOO'
-        quote.rates.keys.must_include 'BAR'
-        quote.rates.keys.wont_include 'BAZ'
-      end
-    end
-  end
-end

config/app.rb

@@ -6,7 +6,7 @@ require 'pathname'
 module App
   class << self
     def env
-      ENV['RACK_ENV'] || 'development'
+      ENV['APP_ENV'] || 'development'
     end
 
     def root

docker-compose.override.yml

@@ -1,15 +1,13 @@
 version: '3'
 services:
   web:
-    build:
+    build: .
-      context: ./app
     environment:
-      RACK_ENV: development
+      APP_ENV: development
       VIRTUAL_HOST: localhost
     ports:
       - "8080:8080"
   scheduler:
-    build:
+    build: .
-      context: ./app
     environment:
-      RACK_ENV: development
+      APP_ENV: development

gem/.rubocop.yml

@@ -1,5 +0,0 @@
-AllCops:
-  TargetRubyVersion: 2.5
-Metrics/BlockLength:
-  Exclude:
-    - 'spec/**/*'

gem/Gemfile

@@ -1,4 +0,0 @@
-# frozen_string_literal: true
-
-source 'https://rubygems.org'
-gemspec

gem/Gemfile.lock

@@ -1,52 +0,0 @@
-PATH
-  remote: .
-  specs:
-    fixer (1.0.0)
-
-GEM
-  remote: https://rubygems.org/
-  specs:
-    addressable (2.5.2)
-      public_suffix (>= 2.0.2, < 4.0)
-    ast (2.3.0)
-    crack (0.4.3)
-      safe_yaml (~> 1.0.0)
-    hashdiff (0.3.7)
-    minitest (5.10.3)
-    parallel (1.12.1)
-    parser (2.4.0.2)
-      ast (~> 2.3)
-    powerpack (0.1.1)
-    public_suffix (3.0.1)
-    rainbow (3.0.0)
-    rake (12.3.0)
-    rubocop (0.52.1)
-      parallel (~> 1.10)
-      parser (>= 2.4.0.2, < 3.0)
-      powerpack (~> 0.1)
-      rainbow (>= 2.2.2, < 4.0)
-      ruby-progressbar (~> 1.7)
-      unicode-display_width (~> 1.0, >= 1.0.1)
-    ruby-progressbar (1.9.0)
-    safe_yaml (1.0.4)
-    unicode-display_width (1.3.0)
-    vcr (4.0.0)
-    webmock (3.1.1)
-      addressable (>= 2.3.6)
-      crack (>= 0.3.2)
-      hashdiff
-
-PLATFORMS
-  ruby
-
-DEPENDENCIES
-  bundler
-  fixer!
-  minitest
-  rake
-  rubocop
-  vcr
-  webmock
-
-BUNDLED WITH
-   1.16.1

gem/README.md

@@ -1,9 +0,0 @@
-# Fixer
-
-Fixer wraps the XML feeds of Euro foreign exchange reference provided by the European Central Bank:
-
-```ruby
-Fixer.current
-Fixer.ninety_days
-Fixer.historical
-```

gem/Rakefile

@@ -1,14 +0,0 @@
-# frozen_string_literal: true
-
-require 'bundler/gem_tasks'
-require 'rake/testtask'
-require 'rubocop/rake_task'
-
-Rake::TestTask.new do |t|
-  t.ruby_opts += ['-W1']
-  t.pattern = 'spec/**/*_spec.rb'
-end
-
-RuboCop::RakeTask.new
-
-task default: %i[test rubocop]

gem/fixer.gemspec

@@ -1,26 +0,0 @@
-# frozen_string_literal: true
-
-lib = File.expand_path('../lib', __FILE__)
-$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
-require 'fixer/version'
-
-Gem::Specification.new do |spec|
-  spec.name          = 'fixer'
-  spec.version       = Fixer::VERSION
-  spec.author        = ['Hakan Ensari']
-  spec.email         = ['hakanensari@gmail.com']
-  spec.summary       = <<-SUMMARY
-    A wrapper to the exchange rate feeds of the European Central Bank
-  SUMMARY
-  spec.homepage      = 'https://github.com/hakanensari/fixer'
-  spec.license       = 'MIT'
-  spec.files         = Dir.glob('lib/**/*') + %w[README.md]
-  spec.require_paths = ['lib']
-
-  spec.add_development_dependency 'bundler'
-  spec.add_development_dependency 'minitest'
-  spec.add_development_dependency 'rake'
-  spec.add_development_dependency 'rubocop'
-  spec.add_development_dependency 'vcr'
-  spec.add_development_dependency 'webmock'
-end

gem/lib/fixer.rb

@@ -1,17 +0,0 @@
-# frozen_string_literal: true
-
-require 'fixer/feed'
-
-# ECB exchange rate datasets
-#
-# The three available short hands here are `.current`, `.ninety_days`, and
-# `.historical`.
-module Fixer
-  class << self
-    Feed::SCOPES.each_key do |scope|
-      define_method(scope) do
-        Feed.new(scope)
-      end
-    end
-  end
-end

gem/lib/fixer/feed.rb

@@ -1,48 +0,0 @@
-# frozen_string_literal: true
-
-require 'net/http'
-require 'rexml/document'
-
-module Fixer
-  # Wraps ECB's data feed
-  class Feed
-    include Enumerable
-
-    SCOPES = {
-      current: 'daily',
-      ninety_days: 'hist-90d',
-      historical: 'hist'
-    }.freeze
-
-    def initialize(scope = :current)
-      @scope = SCOPES.fetch(scope) { raise ArgumentError }
-    end
-
-    def each
-      REXML::XPath.each(document, '/gesmes:Envelope/Cube/Cube[@time]') do |day|
-        date = Date.parse(day.attribute('time').value)
-        REXML::XPath.each(day, './Cube') do |currency|
-          yield(
-            date: date,
-            iso_code: currency.attribute('currency').value,
-            rate: Float(currency.attribute('rate').value)
-          )
-        end
-      end
-    end
-
-    private
-
-    def document
-      REXML::Document.new(xml)
-    end
-
-    def xml
-      Net::HTTP.get(url)
-    end
-
-    def url
-      URI("http://www.ecb.europa.eu/stats/eurofxref/eurofxref-#{@scope}.xml")
-    end
-  end
-end

gem/lib/fixer/version.rb

@@ -1,5 +0,0 @@
-# frozen_string_literal: true
-
-module Fixer
-  VERSION = '1.0.0'
-end

gem/spec/fixer_spec.rb

@@ -1,34 +0,0 @@
-# frozen_string_literal: true
-
-require_relative 'helper'
-
-describe Fixer do
-  before do
-    @mock = MiniTest::Mock.new
-  end
-
-  after do
-    @mock.verify
-  end
-
-  it 'returns current rates' do
-    @mock.expect(:call, nil, [:current])
-    Fixer::Feed.stub(:new, @mock) do
-      Fixer.current
-    end
-  end
-
-  it 'returns ninety-day rates' do
-    @mock.expect(:call, nil, [:ninety_days])
-    Fixer::Feed.stub(:new, @mock) do
-      Fixer.ninety_days
-    end
-  end
-
-  it 'returns historical rates' do
-    @mock.expect(:call, nil, [:historical])
-    Fixer::Feed.stub(:new, @mock) do
-      Fixer.historical
-    end
-  end
-end

lib/api.rb

@@ -3,7 +3,9 @@
 require 'oj'
 require 'sinatra'
 require 'rack/cors'
-require 'quote'
+
+require 'query'
+require 'quotation'
 
 use Rack::Cors do
   allow do
@@ -20,13 +22,20 @@ configure :production do
   disable :dump_errors
 end
 
+configure :test do
+  set :raise_errors, false
+end
+
 helpers do
-  def quote
+  def quotation
-    @quote ||= Quote.new(params)
+    @quotation ||= begin
+      query = Query.new(params)
+      Quotation.new(query.to_h)
+    end
   end
 
   def jsonp(data)
-    json = encode_json(data)
+    json = Oj.dump(data, mode: :compat)
     callback = params.delete('callback')
     if callback
       content_type :js
@@ -36,10 +45,6 @@ helpers do
       json
     end
   end
-
-  def encode_json(data)
-    Oj.dump(data, mode: :compat)
-  end
 end
 
 options '*' do
@@ -52,23 +57,23 @@ get '*' do
 end
 
 get '/' do
-  jsonp details: 'http://fixer.io'
+  jsonp source: 'https://github.com/hakanensari/fixer'
 end
 
 get '/latest' do
-  last_modified quote.date
+  last_modified quotation.date
-  jsonp quote.to_h
+  jsonp quotation.quote
 end
 
 get '/(?<date>\d{4}-\d{2}-\d{2})', mustermann_opts: { type: :regexp } do
-  last_modified quote.date
+  last_modified quotation.date
-  jsonp quote.to_h
+  jsonp quotation.quote
 end
 
 not_found do
-  halt 404, encode_json(error: 'Not found')
+  halt 404
 end
 
-error Quote::Invalid do |ex|
+error do
-  halt 422, encode_json(error: ex.message)
+  halt 422
 end

lib/bank.rb

@@ -1,20 +1,19 @@
 # frozen_string_literal: true
 
 require 'currency'
-require 'fixer'
+require 'bank/feed'
 
 module Bank
   def self.fetch_all_rates!
     Currency.db.transaction do
       Currency.dataset.delete
-      data = Fixer.historical
+      Currency.multi_insert(Feed.historical.to_a)
-      Currency.multi_insert(data.to_a)
     end
   end
 
   def self.fetch_current_rates!
     Currency.db.transaction do
-      Fixer.current.each do |hsh|
+      Feed.current.each do |hsh|
         Currency.find_or_create(hsh)
       end
     end

lib/bank/feed.rb

@@ -0,0 +1,53 @@
+# frozen_string_literal: true
+
+require 'net/http'
+require 'ox'
+
+module Bank
+  class Feed
+    include Enumerable
+
+    def self.current
+      new('daily')
+    end
+
+    def self.ninety_days
+      new('hist-90d')
+    end
+
+    def self.historical
+      new('hist')
+    end
+
+    def initialize(scope)
+      @scope = scope
+    end
+
+    def each
+      document.locate('gesmes:Envelope/Cube/Cube').each do |day|
+        date = Date.parse(day['time'])
+        day.locate('Cube').each do |record|
+          yield(
+            date: date,
+            iso_code: record['currency'],
+            rate: Float(record['rate'])
+          )
+        end
+      end
+    end
+
+    private
+
+    def document
+      Ox.load(xml)
+    end
+
+    def xml
+      Net::HTTP.get(url)
+    end
+
+    def url
+      URI("http://www.ecb.europa.eu/stats/eurofxref/eurofxref-#{@scope}.xml")
+    end
+  end
+end

lib/currency.rb

@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+class Currency < Sequel::Model
+  dataset_module do
+    def latest(date = Date.today)
+      where(date: select(:date).where(Sequel.lit('date <= ?', date))
+                               .order(Sequel.desc(:date))
+                               .limit(1))
+    end
+  end
+end

lib/query.rb

@@ -0,0 +1,27 @@
+# frozen_string_literal: true
+
+class Query
+  def initialize(params = {})
+    @params = params
+  end
+
+  def amount
+    @params[:amount].to_f if @params[:amount] # rubocop:disable Style/SafeNavigation
+  end
+
+  def base
+    @params.values_at(:base, :from).compact.first&.upcase
+  end
+
+  def symbols
+    @params.values_at(:symbols, :to).compact.first&.split(',')
+  end
+
+  def date
+    @params[:date]
+  end
+
+  def to_h
+    { amount: amount, base: base, date: date, symbols: symbols }.compact
+  end
+end

lib/quotation.rb

@@ -0,0 +1,61 @@
+# frozen_string_literal: true
+
+require 'currency'
+
+class Quotation
+  DEFAULT_BASE = 'EUR'
+
+  def initialize(amount: 1.0,
+                 base: DEFAULT_BASE,
+                 date: Date.today.to_s,
+                 symbols: nil)
+    @amount = amount
+    @base = base
+    @date = date
+    @symbols = symbols
+  end
+
+  def quote
+    { date: date, rates: calculate_rates }
+  end
+
+  def date
+    currencies.first[:date].to_s
+  end
+
+  private
+
+  def calculate_rates # rubocop:disable Metrics/AbcSize
+    rates = currencies.each_with_object({}) do |currency, hsh|
+      hsh[currency[:iso_code]] = currency[:rate]
+    end
+
+    return rates if @base == DEFAULT_BASE && @amount == 1.0
+
+    if @symbols.nil? || @symbols.include?(DEFAULT_BASE)
+      rates.update(DEFAULT_BASE => 1.0)
+    end
+    divisor = rates.delete(@base)
+
+    rates.sort.map! { |ic, rate| [ic, round(@amount * rate / divisor)] }.to_h
+  end
+
+  def currencies
+    @currencies ||= begin
+      scope = Currency.latest(@date)
+      scope = scope.where(iso_code: @symbols + [@base]) if @symbols
+
+      scope.order(:iso_code).naked
+    end
+  end
+
+  # To paraphrase Wikipedia, most currency pairs are quoted to four decimal
+  # places. An exception to this is exchange rates with a value of less than
+  # 1.000, which are quoted to five or six decimal places. Exchange rates
+  # greater than around 20 are usually quoted to three decimal places and
+  # exchange rates greater than 80 are quoted to two decimal places.
+  # Currencies over 5000 are usually quoted with no decimal places.
+  def round(rate)
+    Float(format('%.5g', rate))
+  end
+end

limit_req.conf

@@ -1,3 +1,3 @@
-limit_req_zone $binary_remote_addr zone=api:10m rate=1r/s;
+limit_req_zone $binary_remote_addr zone=api:10m rate=50r/s;
 limit_req_status 429;
-limit_req zone=api burst=50 nodelay;
+limit_req zone=api burst=500 nodelay;

spec/api_spec.rb

@@ -22,8 +22,10 @@ describe 'the API' do
   end
 
   it 'sets base currency' do
+    get '/latest'
+    res = Oj.load(last_response.body)
     get '/latest?base=USD'
-    json['base'].must_equal 'USD'
+    json.wont_equal res
   end
 
   it 'sets base amount' do
@@ -36,16 +38,6 @@ describe 'the API' do
     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?

spec/bank/feed_spec.rb

@@ -1,47 +1,49 @@
 # frozen_string_literal: true
 
 require_relative '../helper'
+require 'bank/feed'
 
-module Fixer
+module Bank
   describe Feed do
-    before { VCR.insert_cassette 'fixer' }
+    before do
-    after  { VCR.eject_cassette }
+      VCR.insert_cassette 'feed'
+    end
+
+    after do
+      VCR.eject_cassette
+    end
+
+    it 'fetches current rates' do
+      feed = Feed.current
+      feed.count.must_be :<, 40
+    end
+
+    it 'fetches rates for the past 90 days' do
+      feed = Feed.ninety_days
+      feed.count.must_be :>, 33 * 60
+    end
+
+    it 'fetches historical rates' do
+      feed = Feed.historical
+      feed.count.must_be :>, 33 * 3000
+    end
 
     it 'parses the date of a currency' do
-      feed = Feed.new(:current)
+      feed = Feed.current
       currency = feed.first
       currency[:date].must_be_kind_of Date
     end
 
     it 'parse the ISO code of a currency' do
-      feed = Feed.new(:current)
+      feed = Feed.current
       currency = feed.first
       currency[:iso_code].must_be_kind_of String
     end
 
     it 'parses the rate of a currency' do
-      feed = Feed.new(:current)
+      feed = Feed.current
       currency = feed.first
       currency[:rate].must_be_kind_of Float
     end
-
-    it 'fetches current rates' do
-      feed = Feed.new(:current)
-      feed.count.must_be :<, 40
-    end
-
-    it 'fetches rates for the past 90 days' do
-      feed = Feed.new(:ninety_days)
-      feed.count.must_be :>, 33 * 60
-    end
-
-    it 'fetches historical rates' do
-      feed = Feed.new(:historical)
-      feed.count.must_be :>, 33 * 3000
-    end
-
-    it 'raises error when scope is not valid' do
-      -> { Feed.new(:invalid) }.must_raise ArgumentError
-    end
   end
 end

spec/bank_spec.rb

@@ -12,9 +12,19 @@ describe Bank do
   end
 
   before do
+    VCR.insert_cassette 'feed'
     Currency.dataset.delete
   end
 
+  after do
+    VCR.eject_cassette
+  end
+
+  it 'fetches all rates' do
+    Bank.fetch_all_rates!
+    Currency.count.must_be :positive?
+  end
+
   it 'fetches current rates' do
     Bank.fetch_current_rates!
     Currency.count.must_be :positive?

spec/currency_spec.rb

@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+require_relative 'helper'
+require 'currency'
+
+describe Currency do
+  around do |test|
+    Currency.db.transaction do
+      test.call
+      raise Sequel::Rollback
+    end
+  end
+
+  before do
+    Currency.dataset.delete
+    @earlier = [
+      Currency.create(iso_code: 'EUR', rate: 1, date: '2014-01-01'),
+      Currency.create(iso_code: 'USD', rate: 2, date: '2014-01-01')
+    ]
+    @later = [
+      Currency.create(iso_code: 'EUR', rate: 1, date: '2015-01-01'),
+      Currency.create(iso_code: 'USD', rate: 2, date: '2015-01-01')
+    ]
+  end
+
+  it 'returns latest rates' do
+    data = Currency.latest.to_a
+    data.sample.date.must_equal @later.sample.date
+  end
+
+  it 'returns latest rates before given date' do
+    data = Currency.latest(@later.sample.date - 1).to_a
+    data.sample.date.must_equal @earlier.sample.date
+  end
+
+  it 'returns nothing if there are no rates before given date' do
+    data = Currency.latest(@earlier.sample.date - 1).to_a
+    data.must_be_empty
+  end
+end

spec/edge_cases_spec.rb

@@ -13,42 +13,31 @@ describe 'the API' do
   it 'handles unfound pages' do
     get '/foo'
     last_response.status.must_equal 404
-    json.wont_be_empty
   end
 
   it 'will not process an invalid date' do
     get '/2010-31-01'
     last_response.must_be :unprocessable?
-    json.wont_be_empty
   end
 
   it 'will not process a date before 2000' do
     get '/1999-01-01'
     last_response.must_be :unprocessable?
-    json.wont_be_empty
   end
 
   it 'will not process an invalid base' do
     get '/latest?base=UAH'
     last_response.must_be :unprocessable?
-    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?
-    json.wont_be_empty
   end
 
   it 'returns fresh dates' do
     Currency.db.transaction do
-      new_date = Currency.current_date + 1
+      new_date = Currency.order(Sequel.desc(:date)).first.date + 1
       Currency.create(date: new_date, iso_code: 'FOO', rate: 1)
       get '/latest'
       json['date'].must_equal new_date.to_s

spec/helper.rb

@@ -1,12 +1,16 @@
 # frozen_string_literal: true
 
-$LOAD_PATH.unshift(File.expand_path('../../lib', __FILE__))
+require_relative '../config/environment'
 
 require 'minitest/autorun'
+require 'minitest/around/spec'
 require 'vcr'
 require 'webmock'
 
-require 'fixer'
+begin
+  require 'pry'
+rescue LoadError # rubocop:disable Lint/HandleExceptions
+end
 
 VCR.configure do |c|
   c.cassette_library_dir = 'spec/vcr_cassettes'

spec/query_spec.rb

@@ -0,0 +1,56 @@
+# frozen_string_literal: true
+
+require_relative 'helper'
+require 'query'
+
+describe Query do
+  it 'returns given amount' do
+    query = Query.new(amount: '100')
+    query.amount.must_equal 100.0
+  end
+
+  it 'defaults amount to nothin' do
+    query = Query.new
+    query.amount.must_be_nil
+  end
+
+  it 'returns given base' do
+    query = Query.new(base: 'USD')
+    query.base.must_equal 'USD'
+  end
+
+  it 'defaults base to nothing' do
+    query = Query.new
+    query.base.must_be_nil
+  end
+
+  it 'aliases base as from' do
+    query = Query.new(from: 'USD')
+    query.base.must_equal 'USD'
+  end
+
+  it 'returns given symbols' do
+    query = Query.new(symbols: 'USD,GBP')
+    query.symbols.must_equal %w[USD GBP]
+  end
+
+  it 'aliases symbols to to' do
+    query = Query.new(to: 'USD')
+    query.symbols.must_equal ['USD']
+  end
+
+  it 'defaults symbols to nothing' do
+    query = Query.new
+    query.symbols.must_be_nil
+  end
+
+  it 'returns given date' do
+    query = Query.new(date: '2014-01-01')
+    query.date.must_equal '2014-01-01'
+  end
+
+  it 'defaults date to nothing' do
+    query = Query.new
+    query.date.must_be_nil
+  end
+end

spec/quotation_spec.rb

@@ -0,0 +1,45 @@
+# frozen_string_literal: true
+
+require_relative 'helper'
+require 'quotation'
+
+describe Quotation do
+  describe 'by default' do
+    it 'quotes against the Euro' do
+      quotation = Quotation.new
+      rates = quotation.quote[:rates]
+      rates.keys.wont_include 'EUR'
+    end
+  end
+
+  describe 'when given a base' do
+    it 'quotes against that base' do
+      quotation = Quotation.new(base: 'USD')
+      rates = quotation.quote[:rates]
+      rates.keys.wont_include 'USD'
+    end
+
+    it 'sorts rates' do
+      quotation = Quotation.new(base: 'USD')
+      rates = quotation.quote[:rates]
+      rates.keys.must_equal rates.keys.sort
+    end
+  end
+
+  describe 'when given symbols' do
+    it 'quotes rates only for given symbols' do
+      quotation = Quotation.new(symbols: ['USD'])
+      rates = quotation.quote[:rates]
+      rates.keys.must_include 'USD'
+      rates.keys.wont_include 'GBP'
+    end
+  end
+
+  describe 'when given an amount' do
+    it 'quotes for that amount' do
+      quotation = Quotation.new(amount: 100)
+      rates = quotation.quote[:rates]
+      rates['USD'].must_be :>, 10
+    end
+  end
+end