void operator()(
            Event const &,
            FSM & fsm,
            SourceState&,
            TargetState&
        )
    {
        namespace instant = mf::api::upload::instant;

        auto request = instant::Request( fsm.filename(), fsm.hash(),
            fsm.filesize());

        switch (fsm.onDuplicateAction())
        {
            case OnDuplicateAction::Fail:
                // This is the default, same as "skip" and doesn't need to be
                // set.
                break;
            case OnDuplicateAction::Replace:
                request.SetActionOnDuplicate(instant::ActionOnDuplicate::Replace);
                break;
            case OnDuplicateAction::AutoRename:
                request.SetActionOnDuplicate(instant::ActionOnDuplicate::Keep);
                break;
            default:
                assert(!"Invalid duplicate action.");
                break;
        }

        UploadTarget target_folder = fsm.targetFolder();
        boost::apply_visitor(TargetSetter(&request), target_folder);

        auto fsmp = fsm.AsFrontShared();

        fsm.GetSessionMaintainer()->Call(
            request,
            [fsmp](const instant::Response & response)
            {
                if (response.error_code)
                {
                    fsmp->ProcessEvent(event::Error{response.error_code,
                        "Failed to instant upload file."});
                }
                else
                {
                    fsmp->ProcessEvent(event::InstantSuccess{ response.quickkey,
                        response.filename });
                }
            });
    }