SkinbaseNova/app/Services/ArtworkNavigationService.php

<?php

namespace App\Services;

use App\Models\Artwork;
use Illuminate\Support\Str;

final class ArtworkNavigationService
{
    /**
     * Build the public previous/next navigation payload for an already loaded
     * current artwork. No current-artwork lookup is performed here.
     */
    public function navigationFor(Artwork $artwork): array
    {
        $scope = Artwork::published()
            ->select(['id', 'title', 'slug', 'hash', 'file_path', 'file_name'])
            ->where('user_id', $artwork->user_id);

        $prev = (clone $scope)->where('id', '<', $artwork->id)->orderByDesc('id')->first();
        $next = (clone $scope)->where('id', '>', $artwork->id)->orderBy('id')->first();

        if (! $prev) {
            $prev = (clone $scope)->where('id', '!=', $artwork->id)->orderByDesc('id')->first();
        }
        if (! $next) {
            $next = (clone $scope)->where('id', '!=', $artwork->id)->orderBy('id')->first();
        }

        $prevSlug = $this->canonicalSlug($prev);
        $nextSlug = $this->canonicalSlug($next);

        return [
            'prev_id' => $prev?->id,
            'next_id' => $next?->id,
            'prev_url' => $prev ? url('/art/'.$prev->id.'/'.$prevSlug) : null,
            'next_url' => $next ? url('/art/'.$next->id.'/'.$nextSlug) : null,
            'prev_slug' => $prevSlug,
            'next_slug' => $nextSlug,
            'prev_preview' => $this->preview($prev),
            'next_preview' => $this->preview($next),
        ];
    }

    private function canonicalSlug(?Artwork $artwork): ?string
    {
        if (! $artwork) {
            return null;
        }

        return Str::slug($artwork->slug ?: $artwork->title) ?: (string) $artwork->id;
    }

    private function preview(?Artwork $artwork): ?array
    {
        if (! $artwork) {
            return null;
        }

        return [
            'id' => (int) $artwork->id,
            'title' => (string) $artwork->title,
            'slug' => (string) $artwork->slug,
            'thumbs' => [
                'md' => ThumbnailPresenter::present($artwork, 'md'),
                'lg' => ThumbnailPresenter::present($artwork, 'lg'),
            ],
        ];
    }
}