first pass at converting to devise strategy

lib/simple_token_authentication.rb

@@ -1,7 +1,20 @@
-require 'simple_token_authentication/acts_as_token_authenticatable'
+require 'devise'
+
+require 'simple_token_authentication/model'
 require 'simple_token_authentication/acts_as_token_authentication_handler'
-require 'simple_token_authentication/configuration'
 
-module SimpleTokenAuthentication
-  extend Configuration
+module Devise
+  mattr_accessor :token_header_names
+  @@header_names = {}
+
+  mattr_accessor :sign_in_token
+  @@sign_in_token = false
 end
+
+Devise.add_module(
+  :simple_token_authentication,
+  route: :session,
+  strategy: true,
+  controller: :session,
+  model: 'simple_token_authentication/model'
+)

lib/simple_token_authentication/model.rb

@@ -0,0 +1,33 @@
+require 'simple_token_authentication/strategy'
+
+module Devise
+  module Models
+    module SimpleTokenAuthentication
+      extend ActiveSupport::Concern
+
+      # Please see https://gist.github.com/josevalim/fb706b1e933ef01e4fb6
+      # before editing this file, the discussion is very interesting.
+
+      included do
+        private :generate_authentication_token
+      end
+
+      def ensure_authentication_token
+        if authentication_token.blank?
+          self.authentication_token = generate_authentication_token
+        end
+      end
+
+      def generate_authentication_token
+        loop do
+          token = Devise.friendly_token
+          break token unless self.class.exists?(authentication_token: token)
+        end
+      end
+
+      module ClassMethods
+        # before_save :ensure_authentication_token
+      end
+    end
+  end
+end

lib/simple_token_authentication/strategy.rb

@@ -0,0 +1,61 @@
+require 'devise/strategies/authenticatable'
+
+module Devise
+  module Strategies
+    class SimpleTokenAuthentication < Authenticatable
+
+      def valid?
+        auth_key.present?
+      end
+
+      def authenticate!
+        resource = mapping.to.find_for_authentication(auth_key)
+
+        if resource && validate(resource) { Devise.secure_compare(resource.authentication_token, token) }
+          success!(resource)
+        else
+          return fail(:invalid)
+        end
+
+      end
+
+      private
+
+      def snake_resource_name
+        mapping.to.name.underscore
+      end
+
+      def login_with
+        @login_with ||= Devise.mappings.find {|k,v| v.class_name == self.class.name}.last.to.authentication_keys.first
+        self[@login_with]
+      end
+
+      # Pass in auth key as resource_name_key e.g. user_email or 
+      def auth_key
+        params["#{snake_resource_name}_#{login_with}"] || lookup_header
+      end
+
+      def token
+        params["#{snake_resource_name}_token"] || token_header
+      end
+
+      def configured_headings
+        ::Devise.token_header_names[.to_sym]
+      end
+
+      def token_header
+        configured_key = configured_headings[:authentication_token]
+        token_key = configured_key.presence ? configured_key : "X-#{mapping.to.name}-Token"
+        return request.headers[token_key]
+      end
+
+      def lookup_header
+        configured_key = configured_headings[login_with.to_sym]
+        lookup_key = configured_key.presence ? configured_key : "X-#{mapping.to.name}-#{login_with.camelize}"
+        return request.headers[lookup_key]
+      end
+    end
+  end
+end
+
+Warden::Strategies.add(:simple_token_authenticatable, Devise::Strategies::SimpleTokenAuthentication)