/speakers
/speaker/{slug}
/2017/speakers
/2017/speaker/{slug}
/2016/speakers
/2016/speaker/{slug}

Route::group(['middleware' => ['web']], function() {
    $routeGen = function($decorator) {
        Route::get('/speakers', 'SpeakerController@all')->name($decorator('speakers'));
        Route::get('/speaker/{slug}', 'SpeakerController@show')->name($decorator('speaker'));
    };

    // current conference
    Route::group(['middleware' => ['yearVerifier']], function() use ($routeGen) {
        $routeGen(function($name) { return 'currentYear.'.$name;});
    });

    // previous conferences
    Route::group(['prefix' => '{year}', 'middleware' => ['yearVerifier']], function() use ($routeGen) {
        $routeGen(function($name) {return $name;});
    });
});

public function handle($request, Closure $next, $guard = null)
{
    $years = Cache::remember('conferenceyears.list', 5, function() {
        return ConferenceYear::all('year')->map(function($conferenceYear) {
            return $conferenceYear->year;
        })->toArray();
    });

    // TODO: probably this is not the best way to make this info globally available
    $request->merge(['nextConferenceYear' => max($years)]);

    if (is_null($request->year)) {
        $request->merge(['year' => $request->nextConferenceYear]);
    } else {
        if ($request->year == $request->nextConferenceYear) {
            return redirect('/');
        }
    }

    if (!in_array($request->year, $years)) {
        return redirect('/');
    }

    // TODO: probably this is also not the right way to make this info globally available in the views
    view()->share('nextConferenceYear', $request->nextConferenceYear);
    view()->share('currentConferenceYear', $request->year);

    return $next($request);
}

@if ($nextConferenceYear == $currentConferenceYear)
    {{ route('currentYear.speaker', ['slug' => $speakerSlug]) }}
@else
    {{ route('speaker', ['slug' => $speakerSlug, 'year' => $currentConferenceYear]) }}
@endif