require 'js'

module ::RSpec::Core
  class Example
    # WAS:
    #   def run_after_example
    #     @example_group_class.hooks.run(:after, :example, self)
    #     verify_mocks
    #     assign_generated_description if RSpec.configuration.expecting_with_rspec?
    #   rescue Exception => e
    #     set_exception(e, "in an `after(:example)` hook")
    #   ensure
    #     @example_group_instance.teardown_mocks_for_rspec
    #   end
    # NOW:
    def run_after_example
      @example_group_class.hooks.run(:after, :example, self).then do
        verify_mocks
        assign_generated_description if RSpec.configuration.expecting_with_rspec?
      end.rescue do |e|
        set_exception(e, "in an `after(:example)` hook")
      end.ensure do
        @example_group_instance.teardown_mocks_for_rspec
      end
    end

    def run(example_group_instance, reporter)
      @example_group_instance = example_group_instance
      RSpec.current_example = self

      start(reporter)
      Pending.mark_pending!(self, pending) if pending?

      # WAS:
      #   …
      #     begin
      #       if skipped?
      #         Pending.mark_pending! self, skip
      #       elsif !RSpec.configuration.dry_run?
      #         with_around_example_hooks do
      #           begin
      #             run_before_example
      #             @example_group_instance.instance_exec(self, &@example_block)
      #
      #             if pending?
      #               Pending.mark_fixed! self
      #
      #               raise Pending::PendingExampleFixedError,
      #                     'Expected example to fail since it is pending, but it passed.',
      #                     [location]
      #             end
      #           rescue Pending::SkipDeclaredInExample
      #             # no-op, required metadata has already been set by the `skip`
      #             # method.
      #           rescue Exception => e
      #             set_exception(e)
      #           ensure
      #             run_after_example
      #           end
      #         end
      #       end
      #     rescue Exception => e
      #       set_exception(e)
      #     ensure
      #       @example_group_instance.instance_variables.each do |ivar|
      #         @example_group_instance.instance_variable_set(ivar, nil)
      #       end
      #       @example_group_instance = nil
      #     end
      #
      #     finish(reporter)
      #   ensure
      #     RSpec.current_example = nil
      Promise.value(true).then do
        Promise.value(true).then do
          if skipped?
            Pending.mark_pending! self, skip
          elsif !RSpec.configuration.dry_run?
            with_around_example_hooks do
              # WAS:
              #   with_around_example_hooks do
              #     begin
              #       run_before_example
              #       @example_group_instance.instance_exec(self, &@example_block)
              #
              #       if pending?
              #         Pending.mark_fixed! self
              #
              #         raise Pending::PendingExampleFixedError,
              #               'Expected example to fail since it is pending, but it passed.',
              #               [location]
              #       end
              #     rescue Pending::SkipDeclaredInExample
              #       # no-op, required metadata has already been set by the `skip`
              #       # method.
              #     rescue Exception => e
              #       set_exception(e)
              #     ensure
              #       run_after_example
              #     end
              #   end
              # NOW:
              Promise.value(true).then do
                run_before_example
                .then do
                  # TODO: Use subject! to create a before hook on the fly, might be cleaner than this
                  # Might be a better way to do this, but then you end up with promises around the expectation handlers, which could get ugly
                  begin
                    subj = example_group_instance.subject
                    if subj.is_a? Promise
                      return subj.then do |resolved_subject|
                        # This is a private method, but we're using Opal
                        example_group_instance.__memoized[:subject] = resolved_subject
                      end
                    end
                  rescue StandardError, JS::Error
                    # Exception occurred while checking the subject, might be that the example
                    # group had a described class, was not intending on using it as the subject,
                    # and the initializer for that described class failed
                  end
                  Promise.value(true)
                end
                .then do
                  # WAS:
                  #   @example_group_instance.instance_exec(self, &@example_block)
                  # NOW:
                  Promise.value(@example_group_instance.instance_exec(self, &@example_block)).then do |result|
                    result
                  end.rescue do |ex|
                    case ex
                    when nil then Exception.new 'Async promise failed for unspecified reason'
                    when Exception then ex
                    else Exception.new(ex)
                    end
                  end
                end
                .then do
                  # ORIGINAL:
                  if pending?
                    Pending.mark_fixed! self

                    raise Pending::PendingExampleFixedError,
                          'Expected example to fail since it is pending, but it passed.',
                          [location]
                  end
                end
              end.rescue do |e|
                # WAS:
                #   rescue Pending::SkipDeclaredInExample
                #     # no-op, required metadata has already been set by the `skip`
                #     # method.
                #   rescue Exception => e
                #     set_exception(e)
                #   ensure
                #     run_after_example
                #   end
                # NOW:
                case e
                when Pending::SkipDeclaredInExample
                  # no-op, required metadata has already been set by the `skip`
                  # method.
                when Exception
                  set_exception(e)
                end
              end.ensure do
                run_after_example
              end
            end
          end
        end.rescue do |e|
          set_exception(e)
        end.ensure do
          @example_group_instance.instance_variables.each do |ivar|
            @example_group_instance.instance_variable_set(ivar, nil)
          end
          @example_group_instance = nil
        end
      end.then do
        finish(reporter)
      end.ensure do |result|
        RSpec.current_example = nil
        # promise always/ensure do not behave exactly like ensure, need to be explicit about value being returned
        result
      end
    end
  end
end