Allow pass a Proc to the setup option when you specify a strategy (#18)

Co-authored-by: Jose Luis Cambero <joseluis.cambero@sngular.com>

README.md

@@ -30,6 +30,26 @@ Rails.application.config.middleware.use OmniAuth::Builder do
 end
 ```
 
+Or using a proc setup with a custom options:
+
+```ruby
+Rails.application.config.middleware.use OmniAuth::Builder do
+  SETUP_PROC = lambda do |env|
+    request = Rack::Request.new(env)
+    organization = Organization.find_by(host: request.host)
+    provider_config = organization.enabled_omniauth_providers[:keycloakopenid]
+
+    env["omniauth.strategy"].options[:client_id] = provider_config[:client_id]
+    env["omniauth.strategy"].options[:client_secret] = provider_config[:client_secret]
+    env["omniauth.strategy"].options[:client_options] = { site: provider_config[:site],  realm: provider_config[:realm] }
+  end
+
+  Rails.application.config.middleware.use OmniAuth::Builder do
+    provider :keycloak_openid, setup: SETUP_PROC
+  end
+end
+```
+
 This will allow a POST request to `auth/keycloak`
 
 ## Devise Usage
@@ -46,7 +66,7 @@ end
 # config/initializers/devise.rb
 config.omniauth :keycloak_openid, "Example-Client-Name", "example-secret-if-configured", client_options: { site: "https://example.keycloak-url.com", realm: "example-realm" }, :strategy_class => OmniAuth::Strategies::KeycloakOpenId
 
-# Below controller assumes callback route configuration following 
+# Below controller assumes callback route configuration following
 # in config/routes.rb
 Devise.setup do |config|
   # ...

lib/omniauth/strategies/keycloak-openid.rb

@@ -16,6 +16,8 @@ module OmniAuth
             attr_reader :certs
 
             def setup_phase
+                super
+
                 if @authorize_url.nil? || @token_url.nil?
                     prevent_site_option_mistake
 

spec/omniauth/strategies/keycloak_spec.rb

@@ -35,7 +35,7 @@ RSpec.describe OmniAuth::Strategies::KeycloakOpenId do
       OmniAuth::Strategies::KeycloakOpenId.new('keycloak-openid', 'Example-Client', 'b53c572b-9f3b-4e79-bf8b-f03c799ba6ec',
         client_options: {site: 'http://localhost:8080/', realm: 'example-realm'})
     end
-    
+
     it 'should have the correct keycloak token url' do
       subject.setup_phase
       expect(subject.token_url).to eq('/auth/realms/example-realm/protocol/openid-connect/token')
@@ -47,6 +47,16 @@ RSpec.describe OmniAuth::Strategies::KeycloakOpenId do
     end
   end
 
+  context 'client setup with a proc' do
+    subject do
+      OmniAuth::Strategies::KeycloakOpenId.new('keycloak-openid', setup: proc { throw :setup_proc_was_called })
+    end
+
+    it 'should call the proc' do
+      expect { subject.setup_phase }.to throw_symbol :setup_proc_was_called
+    end
+  end
+
   describe 'errors processing' do
     context 'when site contains /auth part' do
       subject do