require 'rails/generators'
require 'active_support/core_ext'
require 'rspec/rails/adapters'
require 'rspec/rails/example/rails_example_group'

module Ammeter
  module RSpec
    module Rails
      # Delegates to Rails::Generators::TestCase to work with RSpec.
      module GeneratorExampleGroup
        extend ActiveSupport::Concern
        include ::RSpec::Rails::RailsExampleGroup

        DELEGATED_METHODS = [:generator, :capture, :prepare_destination,
                             :destination_root, :current_path, :generator_class]
        module ClassMethods
          mattr_accessor :test_unit_test_case_delegate
          delegate :default_arguments, :to => :'self.test_unit_test_case_delegate'
          DELEGATED_METHODS.each do |method|
            delegate method,  :to => :'self.test_unit_test_case_delegate'
          end
          delegate :destination, :arguments, :to => :'self.test_unit_test_case_delegate.class'

          def initialize_delegate
            self.test_unit_test_case_delegate = ::Rails::Generators::TestCase.new 'pending'
            self.test_unit_test_case_delegate.class.tests(describes)
          end

          def run_generator(given_args=self.default_arguments, config={})
            args, opts = Thor::Options.split(given_args)
            capture(:stdout) { generator(args, opts, config).invoke_all }
          end
        end

        module InstanceMethods
          def invoke_task name
            capture(:stdout) { generator.invoke_task(generator_class.all_tasks[name.to_s]) }
          end
        end

        included do
          delegate :run_generator, :destination, :arguments, :to => :'self.class'
          DELEGATED_METHODS.each do |method|
            delegate method,  :to => :'self.class'
          end
          def destination_root_is_set? #:nodoc:
            raise "You need to configure your Rails::Generators::TestCase destination root." unless destination_root
          end
          def ensure_current_path #:nodoc:
            # cd current_path
          end
          initialize_delegate

          subject { generator }

          before do
            self.class.initialize_delegate
            destination_root_is_set?
            ensure_current_path
          end
          after do
            ensure_current_path
          end
          metadata[:type] = :generator
        end

        def file relative
          File.expand_path(relative, destination_root)
        end
      end
    end
  end
end