Popescu Alexandru Interview

Gemfile

@@ -20,3 +20,11 @@ end
 
 # Windows does not include zoneinfo files, so bundle the tzinfo-data gem
 gem 'tzinfo-data', platforms: %i[mingw mswin x64_mingw jruby]
+
+gem 'csv'
+gem 'httparty'
+gem 'pry'
+gem 'rack'
+gem 'rack-test'
+gem 'rackup'
+gem 'sinatra'

Gemfile.lock

@@ -2,18 +2,48 @@ GEM
   remote: https://rubygems.org/
   specs:
     ast (2.4.2)
+    base64 (0.2.0)
+    bigdecimal (3.1.9)
     byebug (11.1.3)
+    coderay (1.1.3)
+    csv (3.3.2)
     diff-lcs (1.5.1)
+    httparty (0.22.0)
+      csv
+      mini_mime (>= 1.0.0)
+      multi_xml (>= 0.5.2)
     json (2.9.1)
     language_server-protocol (3.17.0.3)
+    logger (1.6.5)
+    method_source (1.1.0)
+    mini_mime (1.1.5)
+    multi_xml (0.7.1)
+      bigdecimal (~> 3.1)
+    mustermann (3.0.3)
+      ruby2_keywords (~> 0.0.1)
     nio4r (2.7.4)
     parallel (1.26.3)
     parser (3.3.7.0)
       ast (~> 2.4.1)
       racc
+    pry (0.15.2)
+      coderay (~> 1.1)
+      method_source (~> 1.0)
     puma (6.5.0)
       nio4r (~> 2.0)
     racc (1.8.1)
+    rack (3.1.8)
+    rack-protection (4.1.1)
+      base64 (>= 0.1.0)
+      logger (>= 1.6.0)
+      rack (>= 3.0.0, < 4)
+    rack-session (2.1.0)
+      base64 (>= 0.1.0)
+      rack (>= 3.0.0)
+    rack-test (2.2.0)
+      rack (>= 1.3)
+    rackup (2.2.1)
+      rack (>= 3)
     rainbow (3.1.1)
     regexp_parser (2.10.0)
     rspec (3.13.0)
@@ -42,6 +72,15 @@ GEM
     rubocop-ast (1.37.0)
       parser (>= 3.3.1.0)
     ruby-progressbar (1.13.0)
+    ruby2_keywords (0.0.5)
+    sinatra (4.1.1)
+      logger (>= 1.6.0)
+      mustermann (~> 3.0)
+      rack (>= 3.0.0, < 4)
+      rack-protection (= 4.1.1)
+      rack-session (>= 2.0.0, < 3)
+      tilt (~> 2.0)
+    tilt (2.6.0)
     unicode-display_width (3.1.4)
       unicode-emoji (~> 4.0, >= 4.0.4)
     unicode-emoji (4.0.4)
@@ -52,9 +91,16 @@ PLATFORMS
 
 DEPENDENCIES
   byebug
+  csv
+  httparty
+  pry
   puma (~> 6.5)
+  rack
+  rack-test
+  rackup
   rspec (~> 3.10)
   rubocop
+  sinatra
   tzinfo-data
 
 RUBY VERSION

README.md

@@ -1,33 +1,47 @@
-# Backend Interview Starting Point
+<details>
+  <summary><i>Local setup</i></summary>
 
-This repo will serve as a starting point for your code challenge. Feel free to change anything in order to complete it: Change framework, other tests, new gems etc.
+  1. Install ruby: `$ rvm install 3.4.1`
+  2. `$ cd .` or `$ cd <path_to_project>` to auto-create the rvm gemset
+  3. Install bundler: `$ gem install bundler`
+  4. Install the dependencies with bundler: `$ bundle install`
+</details>
 
-## Get this repo
+### Code Structure and Purpose
 
-- Fork this repo
-- Clone your fork
+- **Controller to Service**: When a request is received, the controller delegates the task to the appropriate service. **Sinatra** is used to handle HTTP requests and responses in a lightweight manner.
+- **Service to External API**: The `CoffeeShopFinderService` interacts with an external API to retrieve data about coffee shops. It processes this data to find the closest coffee shops based on the provided coordinates.
+- **Response Handling**: After processing the request, the service returns the result to the controller, which then formats the response and sends it back to the client.
 
-## Prerequisites
-- Have RVM installed: https://letmegooglethat.com/?q=install+rvm+on+ubuntu
+### Testing
 
-## Local setup
-1. Install ruby: `$ rvm install 3.4.1`
-2. `$ cd .` or `$ cd <path_to_project>` to auto-create the rvm gemset
-3. Install bundler: `$ gem install bundler`
-4. Install the dependencies with bundler: `$ bundle install`
+- **Unit Tests**: The project is thoroughly tested using the `rspec` gem.
+- Run tests ➡️ `$ bundle exec rspec`
 
-## Run sample CLI command
-`$ bin/ruby-interview`
 
-## Run tests
-`$ bundle exec rspec`
 
-## Tools
 
-- Write HTTP APIs [rails](https://rubyonrails.org/) or [roda](https://roda.jeremyevans.net/documentation.html) or others
-- Write CLI tools [thor](http://whatisthor.com/) or [tty](https://ttytoolkit.org/) or others (including [rake](https://github.com/ruby/rake))
-- Test your code with [rspec](https://rspec.info/)
+# Usage
+#### Run CLI command to start the server
+`$ bin/start`
 
----
+#### Choose a provider to call the endpoind, I choose [Thunder Client](https://www.thunderclient.com/) inside VS Code. (Postman, Insomnia)
+`http://localhost:9292/api/closest_shops?lat=47.6&lon=-122.4`
+#### Should see a reponse similar to:
+![image](https://github.com/user-attachments/assets/7b3f7d83-4b94-4e7a-b2c0-ad2452a09f84)
 
-Good luck!
+
+#### It can be also tested using the terminal
+```curl "http://localhost:9292/api/closest_shops?lat=47.6&lon=-122.4"```
+```
+Coffee shops nearest (47.6, -122.4) by distance:
+
+0.0645 <--> Starbucks Seattle2
+0.0861 <--> Starbucks Seattle
+10.0793 <--> Starbucks SF'
+```
+
+### Disclaimers
+
+- I thought about setting up a DB, querying the endpoint to seed it and then seeding it periodically.
+- But taking into the consideration the size of the csv file, the minimal number of requests I choose to prioritize always having the latest data and calling the endpoint through my CoffeeShopFinderService on each request."

app.rb

@@ -0,0 +1,3 @@
+# frozen_string_literal: true
+
+require_relative 'config/environment'

app/controllers/coffee_shop_controller.rb

@@ -0,0 +1,79 @@
+# frozen_string_literal: true
+
+require 'sinatra/base'
+require 'json'
+require_relative '../services/coffee_shop_finder_service'
+
+class CoffeeShopController < Sinatra::Base
+  configure do
+    set :protection, except: [:host_authorization]
+    set :show_exceptions, false
+    set :raise_errors, true
+    enable :logging
+  end
+
+  before do
+    content_type :json
+  end
+
+  get '/closest_shops' do
+    content_type 'text/plain'
+    lat, lon = validate_coordinates!(params)
+
+    shops_with_distances = coffee_shop_finder_service.closest_shops(lat, lon)
+    format_response(shops_with_distances, lat, lon)
+  rescue StandardError => e
+    handle_error(e)
+  end
+
+  private
+
+  # Format shops into "Name --> distance <-- (user-lat, user_lon)" strings
+  def format_response(shops_with_distances, user_lat, user_lon)
+    header = "Coffee shops nearest (#{user_lat}, #{user_lon}) by distance:\n\n"
+
+    header + shops_with_distances.map do |shops_with_distance|
+      shop = shops_with_distance[:shop]
+      distance = shops_with_distance[:distance]
+
+      "#{distance} <--> #{shop.name}"
+    end.join("\n")
+  end
+
+  def validate_coordinates!(parameters)
+    error!(400, 'Invalid coordinates') unless parameters[:lat] && parameters[:lon]
+    error!(400, 'Coordinates must be numeric') unless numeric?(parameters[:lat]) && numeric?(parameters[:lon])
+
+    lat = parameters[:lat].to_f
+    lon = parameters[:lon].to_f
+    error!(400, 'Invalid coordinates') unless lat.between?(-90, 90) && lon.between?(-180, 180)
+
+    [lat, lon]
+  end
+
+  def numeric?(str)
+    return false unless str =~ /\A[-+]?[0-9]*\.?[0-9]+\Z/
+
+    Float(str)
+  end
+
+  # Handle errors with appropriate HTTP status codes
+  def handle_error(error)
+    status_code = case error.message
+                  when /Invalid CSV/ then 400
+                  when /Failed to fetch CSV/ then 502
+                  else 500
+                  end
+
+    status status_code
+    { error: error.message }.to_json
+  end
+
+  def error!(code, message)
+    halt code, { error: message }.to_json
+  end
+
+  def coffee_shop_finder_service
+    CoffeeShopFinderService.new
+  end
+end

app/models/coffee_shop.rb

@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+class CoffeeShop
+  class InvalidCoordinatesError < StandardError; end
+
+  attr_reader :name, :latitude, :longitude
+
+  def initialize(name, latitude, longitude)
+    @name = validate_name(name)
+    @latitude = validate_coordinate(latitude.to_f, -90..90, 'Latitude')
+    @longitude = validate_coordinate(longitude.to_f, -180..180, 'Longitude')
+  end
+
+  def distance_to(user_lat, user_lon)
+    user_lat = validate_coordinate(user_lat.to_f, -90..90, 'User Latitude')
+    user_lon = validate_coordinate(user_lon.to_f, -180..180, 'User Longitude')
+
+    Math.sqrt(((user_lat - latitude)**2) + ((user_lon - longitude)**2)).round(4)
+  end
+
+  private
+
+  def validate_name(name)
+    name = name.to_s.strip
+    raise ArgumentError, 'Name cannot be empty' if name.empty?
+
+    name
+  end
+
+  def validate_coordinate(coord, range, name)
+    raise InvalidCoordinatesError, "#{name} must be a number" unless coord.is_a?(Numeric)
+    raise InvalidCoordinatesError, "#{name} out of range" unless range.include?(coord)
+
+    coord
+  end
+end

app/services/coffee_shop_finder_service.rb

@@ -0,0 +1,50 @@
+# frozen_string_literal: true
+
+require 'csv'
+require 'httparty'
+
+class CoffeeShopFinderService
+  def closest_shops(user_lat, user_lon, limit = 3)
+    coffee_shops = fetch_and_parse_coffee_shops
+
+    # Used for faster distance retrieval
+    distances = Hash.new { |h, shop| h[shop] = shop.distance_to(user_lat, user_lon) }
+    closest_shops = coffee_shops.min_by(limit) { |shop| distances[shop] }
+
+    closest_shops.map { |shop| { shop: shop, distance: distances[shop] } }
+  end
+
+  private
+
+  def fetch_and_parse_coffee_shops
+    response = fetch_csv
+    parse_coffee_shops(response)
+  end
+
+  def parse_coffee_shops(response)
+    CSV.parse(response.body, headers: headers).map do |row|
+      validate_csv_row!(row)
+      CoffeeShop.new(row['Name'], row['Lat Coordinate'], row['Lon Coordinate'])
+    end
+  rescue CSV::MalformedCSVError => e
+    raise "Malformed CSV: #{e.message}"
+  end
+
+  def fetch_csv
+    url = ENV['CSV_URL'] || APP_CONFIG[:csv_url]
+    response = HTTParty.get(url)
+    raise "Failed to fetch CSV: #{response.code}" unless response.success?
+
+    response
+  end
+
+  # Validate CSV row structure
+  def validate_csv_row!(row)
+    missing = headers.reject { |h| row[h] }
+    raise "Invalid CSV headers: #{missing.join(', ')}" if missing.any?
+  end
+
+  def headers
+    ['Name', 'Lat Coordinate', 'Lon Coordinate']
+  end
+end

bin/ruby-interview → bin/start

@@ -1,4 +1,4 @@
 #!/usr/bin/env ruby
 # frozen_string_literal: true
 
-puts 'Good luck!'
+system('bundle exec rackup config.ru')

config.ru

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+require_relative 'app'
+
+map '/api' do
+  run CoffeeShopController
+end

config/environment.rb

@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+require 'yaml'
+require 'logger'
+
+APP_CONFIG = YAML.load_file(File.join(__dir__, 'settings.yml')).transform_keys(&:to_sym)
+APP_LOGGER = Logger.new($stdout)
+
+Dir[File.join(__dir__, '../app/**/*.rb')].each { |file| require file }

config/settings.yml

@@ -0,0 +1 @@
+csv_url: 'https://raw.githubusercontent.com/Agilefreaks/test_oop/master/coffee_shops.csv'