Chunked upload endpoint

<?php

namespace App\Http\Controllers;

use Illuminate\Http\JsonResponse;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\Storage;
use Illuminate\Support\Str;

class ChunkedUploadController extends Controller
{
    public function store(Request $request, string $id): JsonResponse
    {
        abort_unless(Str::isUuid($id), 404); // keeps the path safe

        $data = $request->validate([
            'index' => ['required', 'integer', 'min:0', 'max:9999'],
            'chunk' => ['required', 'file', 'max:10240'], // 10 MB per part
        ]);

        // Same index twice simply overwrites: retries are harmless.
        Storage::disk('private')->putFileAs("chunks/{$id}", $data['chunk'], (string) $data['index']);

        return response()->json(['stored' => $data['index']]);
    }

    public function complete(Request $request, string $id): JsonResponse
    {
        abort_unless(Str::isUuid($id), 404);

        $data = $request->validate(['total' => ['required', 'integer', 'min:1', 'max:10000'], 'name' => ['required', 'string', 'max:200']]);
        $disk = Storage::disk('private');

        for ($i = 0; $i < $data['total']; $i++) {
            abort_unless($disk->exists("chunks/{$id}/{$i}"), 422, "Part {$i} is missing.");
        }

        // Stitch the parts together as streams so memory use stays flat.
        $target = fopen('php://temp', 'w+b');
        for ($i = 0; $i < $data['total']; $i++) {
            stream_copy_to_stream($disk->readStream("chunks/{$id}/{$i}"), $target);
        }
        rewind($target);

        $path = 'files/'.Str::random(12).'-'.Str::slug(pathinfo($data['name'], PATHINFO_FILENAME)).'.'.pathinfo($data['name'], PATHINFO_EXTENSION);
        $disk->writeStream($path, $target);
        fclose($target);
        $disk->deleteDirectory("chunks/{$id}");

        return response()->json(['path' => $path], 201);
    }
}