Use the new credentials API in Rails 5.2 (#63)

* Use the new credentials API in Rails 5.2

Rails.application.secrets will soon be deprecated. Let's leverage the
new credentials way of doing things that comes with Rails 5.2

* Loop over providers from service.rb

README.md

@@ -29,6 +29,37 @@ Or if you have downloaded this repo, you can reference template.rb locally:
 rails new myapp -d postgresql -m template.rb
 ```
 
+#### Authenticate with social networks
+
+We use the encrypted Rails Credentials for app_id and app_secrets when it comes to omniauth authentication. Edit them as so:
+
+```
+EDITOR=vim rails credentials:edit
+```
+
+Make sure your file follow this structure:
+
+```
+secret_key_base: [your-key]
+development:
+  github:
+    app_id: something
+    app_secret: something
+    options:
+      scope: 'user:email'
+      whatever: true
+production:
+  github:
+    app_id: something
+    app_secret: something
+    options:
+      scope: 'user:email'
+      whatever: true
+```
+
+With the environment, the service and the app_id/app_secret. If this is done correctly, you should see login links
+for the services you have added to the encrypted credentials using `EDITOR=vim rails credentials:edit`
+
 #### Cleaning up
 
 ```bash

app/models/service.rb

@@ -1,7 +1,9 @@
 class Service < ApplicationRecord
   belongs_to :user
 
-  %w{ facebook twitter github }.each do |provider|
+  PROVIDERS = %w{ facebook twitter github }
+
+  PROVIDERS.each do |provider|
     scope provider, ->{ where(provider: provider) }
   end
 

template.rb

@@ -184,17 +184,12 @@ def add_multiple_authentication
     generate "model Service user:references provider uid access_token access_token_secret refresh_token expires_at:datetime auth:text"
 
     template = """
-  if Rails.application.secrets.facebook_app_id.present? && Rails.application.secrets.facebook_app_secret.present?
-    config.omniauth :facebook, Rails.application.secrets.facebook_app_id, Rails.application.secrets.facebook_app_secret, scope: 'email,user_posts'
-  end
-
-  if Rails.application.secrets.twitter_app_id.present? && Rails.application.secrets.twitter_app_secret.present?
-    config.omniauth :twitter, Rails.application.secrets.twitter_app_id, Rails.application.secrets.twitter_app_secret
-  end
-
-  if Rails.application.secrets.github_app_id.present? && Rails.application.secrets.github_app_secret.present?
-    config.omniauth :github, Rails.application.secrets.github_app_id, Rails.application.secrets.github_app_secret
-  end
+    env_creds = Rails.application.credentials[Rails.env.to_sym]
+    Service::PROVIDERS.each do |provider|
+      if options = env_creds[provider]
+        confg.omniauth provider, options[:app_id], options[:app_secret], options.fetch(:options, {})
+      end
+    end
     """.strip
 
     insert_into_file "config/initializers/devise.rb", "  " + template + "\n\n",