museways/abilities

module Chi
  module Authorization
    class Policies

      attr_reader :user

      def initialize(user, &block)
        @user = user
        Proxy.new self, &block
      end

      def can?(action, resource)
        id = normalize_id(resource)
        if id != :any && can?(action, :any)
          true
        elsif actions = registry[id]
          if policy = (actions[action] || actions[:manage])
            policy.call resource
          else
            false
          end
        else
          false
        end
      end

      def cannot?(*args)
        !can? *args
      end

      def add(actions, resources, &block)
        unless actions.is_a?(Array)
          actions = [actions]
        end
        unless resources.is_a?(Array)
          resources = [resources]
        end
        resources.each do |resource|
          actions.each do |action|
            id = normalize_id(resource)
            registry[id] ||= {}
            registry[id][action] = block
          end
        end
      end

      private

      def registry
        @registry ||= {}
      end

      def normalize_id(resource)
        case resource
        when :any
          resource
        when Class
          resource.name.underscore.to_sym
        else
          resource.class.name.underscore.to_sym
        end
      end

    end
  end
end