<?php
// SPDX-License-Identifier: GPL-3.0-or-later
declare(strict_types=1);

namespace Aiwend\Provider;

/**
 * Cooperative cancellation. The checker is consulted between streamed chunks;
 * in WordPress it reads a short-lived cancel flag set by the cancel endpoint
 * or detects a closed client connection.
 */
final class CancellationToken
{
    private bool $cancelled = false;

    /** @param (callable(): bool)|null $checker */
    public function __construct(private $checker = null)
    {
    }

    public static function none(): self
    {
        return new self();
    }

    public function cancel(): void
    {
        $this->cancelled = true;
    }

    public function isCancelled(): bool
    {
        if (!$this->cancelled && $this->checker !== null && ($this->checker)()) {
            $this->cancelled = true;
        }
        return $this->cancelled;
    }
}