Challenge - Full PHP app

string with Pending, InProgress, Done cases. The readonly class Task has id, title, status as promoted public properties. statusLabel(TaskStatus $s): string uses match() to return an English label for each case. FiberScheduler adds new Fiber in add(callable); run() starts each fiber and calls resume() while it isSuspended().
Example solution:
<?php
// ETL + Reflection + Performance + Security + Modern: write enum + readonly + match + Fiber

function readRows(array $rows): Generator {
    foreach ($rows as $row) {
        yield $row;
    }
}

function transform(iterable $rows, callable $fn): Generator {
    foreach ($rows as $row) {
        yield $fn($row);
    }
}

function pipeline(array $rows, callable $fn): Generator {
    yield from transform(readRows($rows), $fn);
}

function loadAll(iterable $rows): array {
    $out = [];
    foreach ($rows as $row) {
        $out[] = $row;
    }
    return $out;
}

#[Attribute]
class Field {
    public function __construct(public string $name = "") {}
}

class Product {
    public function __construct(
        #[Field("id")] public int $id,
        #[Field("name")] public string $name,
    ) {}
}

class ReflectionSerializer {
    public function serialize(object $obj): array {
        $rc = new ReflectionClass($obj);
        $out = [];
        foreach ($rc->getProperties() as $prop) {
            $attrs = $prop->getAttributes(Field::class);
            if (empty($attrs)) continue;
            $field = $attrs[0]->newInstance();
            $key = $field->name !== "" ? $field->name : $prop->getName();
            $out[$key] = $prop->getValue($obj);
        }
        return $out;
    }
}

class Cache {
    private array $store = [];
    public function get(string $key, callable $loader) {
        if (!isset($this->store[$key])) {
            $this->store[$key] = $loader();
        }
        return $this->store[$key];
    }
}

function benchmark(callable $fn): array {
    $start = hrtime(true);
    $result = $fn();
    $elapsed = (int)((hrtime(true) - $start) / 1000000);
    $mem = memory_get_usage(true);
    return ["result" => $result, "ms" => $elapsed, "bytes" => $mem];
}

class ReportService {
    private PDO $pdo;
    public function __construct(PDO $pdo) {
        $this->pdo = $pdo;
        $this->pdo->exec("CREATE TABLE products (id INTEGER PRIMARY KEY, name TEXT, category_id INTEGER)");
        $this->pdo->exec("CREATE TABLE categories (id INTEGER PRIMARY KEY, name TEXT)");
        $this->pdo->prepare("INSERT INTO categories (name) VALUES (?)")->execute(["kirtasiye"]);
        $this->pdo->prepare("INSERT INTO products (name, category_id) VALUES (?, ?)")->execute(["kale", 1]);
        $this->pdo->prepare("INSERT INTO products (name, category_id) VALUES (?, ?)")->execute(["defter", 1]);
    }
    public function eagerReport(): array {
        $sql = "SELECT p.name AS product, c.name AS category FROM products p JOIN categories c ON p.category_id = c.id ORDER BY p.id";
        return $this->pdo->query($sql)->fetchAll(PDO::FETCH_ASSOC);
    }
}

class RateLimiter {
    private array $counts = [];
    public function __construct(private int $limit = 3) {}
    public function allow(string $key): bool {
        $this->counts[$key] = ($this->counts[$key] ?? 0) + 1;
        return $this->counts[$key] <= $this->limit;
    }
}

function applyCsp(): void {
    header("Content-Security-Policy: default-src 'self'");
}

class SessionGuard {
    public function regenerate(): void {
        session_regenerate_id(true);
    }
}

function needsRehash(string $hash): bool {
    return password_needs_rehash($hash, PASSWORD_DEFAULT);
}

function validateEmail(string $email): bool {
    return filter_var($email, FILTER_VALIDATE_EMAIL) !== false;
}

enum TaskStatus: string {
    case Pending = "pending";
    case InProgress = "in_progress";
    case Done = "done";
}

readonly class Task {
    public function __construct(
        public int $id,
        public string $title,
        public TaskStatus $status = TaskStatus::Pending,
    ) {}
}

function statusLabel(TaskStatus $s): string {
    return match($s) {
        TaskStatus::Pending => "PENDING",
        TaskStatus::InProgress => "INPROGRESS",
        TaskStatus::Done => "DONE",
    };
}

class FiberScheduler {
    private array $fibers = [];
    public function add(callable $fn): void {
        $this->fibers[] = new Fiber($fn);
    }
    public function run(): void {
        foreach ($this->fibers as $f) {
            $f->start();
            while ($f->isSuspended()) {
                $f->resume();
            }
        }
    }
}

// Demo:
$task = new Task(1, "write summary", TaskStatus::InProgress);
echo "task: " . $task->title . "\n";
echo "status: " . statusLabel($task->status) . "\n";

$sched = new FiberScheduler();
$sched->add(function() {
    echo "fiber1: started\n";
    Fiber::suspend();
    echo "fiber1: resumed\n";
});
$sched->add(function() {
    echo "fiber2: started\n";
});
$sched->run();
echo "php_fpm: ready\n";