finance_app/app/Http/Controllers/CategoryController.php

<?php

namespace App\Http\Controllers;

use App\Models\Category;
use Illuminate\Foundation\Auth\Access\AuthorizesRequests;
use Illuminate\Http\Request;

class CategoryController extends Controller
{
    use AuthorizesRequests;

    public function store(Request $request)
    {
        $validated = $request->validate([
            'name'  => 'required|string|max:255',
            'color' => 'nullable|string|max:7',
            'icon'  => 'nullable|string|max:50',
        ]);

        Category::create([
            ...$validated,
            'user_id' => auth()->id(),
        ]);

        return redirect()->back();
    }

    public function update(Request $request, Category $category)
    {
        $this->authorize('update', $category);

        $validated = $request->validate([
            'name'  => 'required|string|max:255',
            'color' => 'nullable|string|max:7',
        ]);

        $category->update($validated);
        return redirect()->back();
    }

    public function destroy(Category $category)
    {
        $this->authorize('delete', $category);
        $category->delete();
        return redirect()->back();
    }
}