api.rb

module MyApp
  module API
    class Railtie < Rails::Railtie
      class Command
        def initialize(user = nil)
          @user = user || User.first
        end

        %i(get post patch put delete head).each do |method|
          define_method(method) do |path, parameters = {}, headers_or_env = {}|
            app.__send__ method, path, default_params.merge(parameters), default_headers.merge(headers_or_env)
            ActiveSupport::JSON.decode app.response.body
          end
        end

        private

        def default_params
          {
            'api_key' => @user.api_key
          }
        end

        def default_headers
          {
            'Content-Type' => 'application/json',
            'Accept' => 'application/json'
          }
        end

        def app
          TOPLEVEL_BINDING.eval('app')
        end
      end

      module ClassMethods
        def api
          @api ||= Command.new
        end
      end

      console do
        TOPLEVEL_BINDING.eval('self').extend ClassMethods
      end
    end
  end
end