Add signature config

lib/cloudimage/client.rb

@@ -6,12 +6,19 @@ module Cloudimage
   class InvalidConfig < StandardError; end
 
   class Client
-    attr_reader :token
+    attr_reader :token, :salt, :signature_length
 
     API_VERSION = 'v7'
+    DEFAULT_SIGNATURE_LENGTH = 20
 
-    def initialize(token: nil)
+    def initialize(
+      token: nil,
+      salt: nil,
+      signature_length: DEFAULT_SIGNATURE_LENGTH
+    )
       @token = token
+      @salt = salt
+      @signature_length = signature_length
 
       ensure_valid_config
     end
@@ -27,9 +34,21 @@ def base_url_for(token)
     end
 
     def ensure_valid_config
-      return unless token.to_s.strip.empty?
+      ensure_valid_token
+      ensure_valid_signature_length
+    end
+
+    def ensure_valid_token
+      return unless token.nil?
 
       raise InvalidConfig, 'Please specify your Cloudimage customer token.'
     end
+
+    def ensure_valid_signature_length
+      return if salt.nil?
+      return if (6..40).cover? signature_length
+
+      raise InvalidConfig, 'Signature length must be must be 6-40 characters.'
+    end
   end
 end

lib/cloudimage/uri.rb

@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require 'digest'
+
 require_relative 'params'
 require_relative 'custom_helpers'
 
@@ -32,14 +34,22 @@ def initialize(base_url, path)
       alias_method from, to
     end
 
-    def to_url(extra_params = {})
-      url_params = params.merge(extra_params)
-      uri.query_values = url_params if url_params.any?
+    def to_url(**extra_params)
+      set_uri_params(extra_params)
       uri.to_s
     end
 
     private
 
+    def set_uri_params(**extra_params)
+      url_params = params.merge(extra_params)
+      uri.query_values = url_params if url_params.any?
+    end
+
+    def signature
+      Digest::SHA1.hexdigest(salt + uri.request_uri.sub('/v7', ''))
+    end
+
     def ensure_path_format(path)
       path.start_with?('/') ? path : "/#{path}"
     end

spec/cloudimage/client_spec.rb

@@ -6,5 +6,18 @@
       expect { described_class.new }
         .to raise_error Cloudimage::InvalidConfig, /Cloudimage customer token/
     end
+
+    context 'URL signatures' do
+      it 'has a default signature length' do
+        client = described_class.new(token: 'mytoken')
+        expect((6..40)).to cover client.signature_length
+      end
+
+      it 'raises an error when given an invalid signature length' do
+        expect do
+          described_class.new(token: 'token', salt: 'slt', signature_length: 5)
+        end.to raise_error Cloudimage::InvalidConfig, /Signature length must be/
+      end
+    end
   end
 end