override the Sufia::Analytics module to load config with ERB parsing (#1468)

Author: weiweishi

app/services/sufia/analytics.rb

@@ -0,0 +1,50 @@
+require 'google/api_client'
+require 'oauth2'
+require 'legato'
+
+module Sufia
+  module Analytics
+    # Loads configuration options from config/analytics.yml. Expected structure:
+    # `analytics:`
+    # `  app_name: GOOGLE_OAUTH_APP_NAME`
+    # `  app_version: GOOGLE_OAUTH_APP_VERSION`
+    # `  privkey_path: GOOGLE_OAUTH_PRIVATE_KEY_PATH`
+    # `  privkey_secret: GOOGLE_OAUTH_PRIVATE_KEY_SECRET`
+    # `  client_email: GOOGLE_OAUTH_CLIENT_EMAIL`
+    # @return [Hash] A hash containing five keys: 'app_name', 'app_version', 'client_email', 'privkey_path', 'privkey_secret'
+    def self.config
+      @config ||= YAML.load(ERB.new(File.read(File.join(Rails.root, 'config', 'analytics.yml'))).result)['analytics']
+    end
+
+    # Generate an OAuth2 token for Google Analytics
+    # @return [OAuth2::AccessToken] An OAuth2 access token for GA
+    def self.token
+      scope = 'https://www.googleapis.com/auth/analytics.readonly'
+      client = Google::APIClient.new(application_name: self.config['app_name'],
+        application_version: self.config['app_version'])
+      key = Google::APIClient::PKCS12.load_key(self.config['privkey_path'],
+        self.config['privkey_secret'])
+      service_account = Google::APIClient::JWTAsserter.new(self.config['client_email'], scope,
+        key)
+      client.authorization = service_account.authorize
+      oauth_client = OAuth2::Client.new('', '', {
+          authorize_url: 'https://accounts.google.com/o/oauth2/auth',
+          token_url: 'https://accounts.google.com/o/oauth2/token'})
+      OAuth2::AccessToken.new(oauth_client, client.authorization.access_token)
+    end
+
+    # Return a user object linked to a Google Analytics account
+    # @return [Legato::User] A user account wit GA access
+    def self.user
+      Legato::User.new(self.token)
+    end
+
+    # Return a Google Analytics profile matching specified ID
+    # @ return [Legato::Management::Profile] A user profile associated with GA
+    def self.profile
+      self.user.profiles.detect do |profile|
+        profile.web_property_id == Sufia.config.google_analytics_id
+      end
+    end
+  end
+end