<?php

namespace App\Services;

use App\Models\Category;
use Illuminate\Support\Collection;

class ArticleSelector
{
    public function forCategory(Category $category, int $limit = 10): Collection
    {
        $feeds = $category->feeds()->with([
            'articles' => fn ($q) => $q->orderByDesc('published_at')->limit($limit),
        ])->get();

        // Round robin: take article[0] from every feed, then article[1] from every feed, etc.
        $buckets = $feeds->map(fn ($feed) => $feed->articles->values());
        $maxDepth = $buckets->max(fn ($b) => $b->count()) ?? 0;

        $selected = collect();
        for ($i = 0; $i < $maxDepth && $selected->count() < $limit; $i++) {
            foreach ($buckets as $bucket) {
                if ($selected->count() >= $limit) break;
                if ($bucket->has($i)) $selected->push($bucket[$i]);
            }
        }

        return $selected;
    }
}