refactor: uses rubocop for style

Author: Insmael

Gemfile

@@ -1,4 +1,13 @@
 # frozen_string_literal: true
 source "https://rubygems.org"
 
-gem 'rest-client'
+gem 'rest-client'
+gem 'openssl'
+gem 'eventmachine'
+gem 'faye-websocket'
+
+
+group :test do
+  gem 'test-unit'
+  gem 'rubocop'
+end

Gemfile.lock

@@ -1,29 +1,40 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    domain_name (0.5.20190701)
-      unf (>= 0.0.5, < 1.0.0)
+    domain_name (0.6.20240107)
+    eventmachine (1.2.7)
+    faye-websocket (0.11.3)
+      eventmachine (>= 0.12.0)
+      websocket-driver (>= 0.5.1)
     http-accept (1.7.0)
-    http-cookie (1.0.4)
+    http-cookie (1.0.5)
       domain_name (~> 0.5)
-    mime-types (3.4.1)
+    mime-types (3.5.2)
       mime-types-data (~> 3.2015)
-    mime-types-data (3.2022.0105)
+    mime-types-data (3.2024.0206)
     netrc (0.11.0)
+    openssl (3.2.0)
+    power_assert (2.0.3)
     rest-client (2.1.0)
       http-accept (>= 1.7.0, < 2.0)
       http-cookie (>= 1.0.2, < 2.0)
       mime-types (>= 1.16, < 4.0)
       netrc (~> 0.8)
-    unf (0.1.4)
-      unf_ext
-    unf_ext (0.0.8)
+    test-unit (3.6.2)
+      power_assert
+    websocket-driver (0.7.6)
+      websocket-extensions (>= 0.1.0)
+    websocket-extensions (0.1.5)
 
 PLATFORMS
   x86_64-linux
 
 DEPENDENCIES
+  eventmachine
+  faye-websocket
+  openssl
   rest-client
+  test-unit
 
 BUNDLED WITH
-   2.3.8
+   2.3.5

lib/cryptomarket/CredentialFactory.rb

@@ -0,0 +1,50 @@
+require 'net/http'
+require 'uri'
+require 'json'
+require 'base64'
+require 'rest-client'
+require 'date'
+require_relative 'exceptions'
+
+module Cryptomarket
+  # Builds a credential used by the cryptomarket server
+  class CredentialFactory
+    def initialize(api_key:, api_secret:, window: nil)
+      @api_key = api_key
+      @api_secret = api_secret
+      @window = window
+    end
+
+    def get_credential(http_method, method, params)
+      timestamp = DateTime.now.strftime('%Q')
+      msg = build_credential_message(http_method, method, timestamp, params)
+      digest = OpenSSL::Digest.new 'sha256'
+      signature = OpenSSL::HMAC.hexdigest digest, @api_secret, msg
+      signed = "#{@api_key}:#{signature}:#{timestamp}"
+      signed += ":#{@window}" unless @window.nil?
+      encoded = Base64.encode64(signed).delete "\n"
+      "HS256 #{encoded}"
+    end
+
+    def build_credential_message(http_method, method, timestamp, params)
+      msg = http_method + @@api_version + method
+      msg += if http_method.upcase == 'POST'
+               params
+             else
+               not_post_params(http_method, params)
+             end
+      msg += timestamp
+      msg += @window unless @window.nil?
+      msg
+    end
+
+    def not_post_params(http_method, params)
+      msg = ''
+      if !params.nil? && params.keys.any?
+        msg += '?' if http_method.upcase == 'GET'
+        msg += URI.encode_www_form(params)
+      end
+      msg
+    end
+  end
+end