<?php

namespace App\Http\Controllers;

use App\Http\Resources\CategoryResource;
use App\Models\Category;
use App\Models\Product;
use Illuminate\Database\Eloquent\Collection;
use Illuminate\Http\Resources\Json\AnonymousResourceCollection;

class CategoryController extends Controller
{
    public function index(): AnonymousResourceCollection
    {
        /** @var Collection<int, Category> $categories */
        $categories = Category::query()
            ->where('active', true)
            ->select(['id', 'parent_id', 'name', 'slug', 'description', 'sort_order'])
            ->orderBy('sort_order')
            ->orderBy('name')
            ->get();

        $directProductCounts = Product::query()
            ->active()
            ->whereNotNull('published_at')
            ->selectRaw('category_id, COUNT(*) as aggregate')
            ->groupBy('category_id')
            ->pluck('aggregate', 'category_id');

        $childrenByParent = [];

        foreach ($categories as $category) {
            if ($category->parent_id === null) {
                continue;
            }

            $childrenByParent[$category->parent_id][] = (int) $category->id;
        }

        $totalCountsByCategory = [];

        $countWithDescendants = function (int $categoryId) use (&$countWithDescendants, &$totalCountsByCategory, $childrenByParent, $directProductCounts): int {
            if (isset($totalCountsByCategory[$categoryId])) {
                return $totalCountsByCategory[$categoryId];
            }

            $total = (int) ($directProductCounts[$categoryId] ?? 0);

            foreach ($childrenByParent[$categoryId] ?? [] as $childId) {
                $total += $countWithDescendants($childId);
            }

            $totalCountsByCategory[$categoryId] = $total;

            return $total;
        };

        $categories->each(function (Category $category) use ($countWithDescendants): void {
            $category->setAttribute('products_count', $countWithDescendants((int) $category->id));
        });

        return CategoryResource::collection($categories);
    }
}