Horizontal swiper gallery like masonry

gallery.php

<?php $gallery_instance = 1;
   if($tpl === 'horizontal_gallery' && $flex['gallery']) { $g = 1; ?>
       <div class="horizontal-gallery row">
           <div class="swiper-container">
               <div class="swiper-wrapper">
                   <?php foreach ($flex['gallery'] as $img) { ?>
                       <div class="swiper-slide <?php echo ($g % 3) == 0?'swiper-slide-fh':''; ?>">
                           <a class="cover" href="<?php echo $img['url']; ?>" data-fancybox="gallery-<?php echo $gallery_instance++; ?>" style="<?php echo image_src($img['ID'], 'large', true); ?>"></a>
                           <div class="e-space"></div>
                           <?php echo ($g % 3) == 0?'</div><div class="swiper-slide swiper-slide-empty">':''; ?>
                       </div>
                   <?php $g++; } ?>
               </div>
               <div class="swiper-button-prev"></div>
               <div class="swiper-button-next"></div>
           </div>
       </div>
   <?php }
?>

h-gallery.js

    $('.horizontal-gallery').each(function(i){
        var h = $('.swiper-container', this)[0];
        setTimeout(function(){
            window.WPASwiper['hg-'+i] = new Swiper( h, {
                navigation: {
                    nextEl          : $('.swiper-button-next', h)[0],
                    prevEl          : $('.swiper-button-prev', h)[0]
                },
                roundLengths                : true,
                observer                    : true,
                observeParents              : true,
                speed                       : 500,
                slidesPerView               : 2,
                slidesPerColumn             : 2,
                spaceBetween                : 6
            });
        }, 1e3*i);
    });

h-gallery.scss

.horizontal-gallery {
    .swiper-slide {
        .e-space {
            &:before {
                padding-bottom: 49.315%;
                display: block;
                content: '';
            }
        }
        > a {
            @include position(absolute);
        }
        &.swiper-slide-fh {
            > a {
                bottom: -102%
            }
        }
    }
}