<?php
/**
* Copyright © Magento, Inc. All rights reserved.
* See COPYING.txt for license details.
*/

declare(strict_types=1);

namespace Magento\Framework\Async;

/**
* Executes given callback when get() is used.
*/
class CallbackDeferred implements CancelableDeferredInterface
{
/**
* @var callable
*/
private $callback;

/**
* @var bool
*/
private $canceled = false;

/**
* @var bool
*/
private $done = false;

/**
* @var mixed
*/
private $value;

/**
* @var \Throwable
*/
private $exception;

/**
* CallbackDeferred constructor.
* @param callable $callback
*/
public function __construct(callable $callback)
{
$this->callback = $callback;
}

/**
* @inheritDoc
*/
public function cancel(bool $force = false): void
{
if ($this->isDone()) {
throw new CancelingDeferredException('Already executed');
}
if ($this->isCancelled()) {
throw new CancelingDeferredException('Already canceled');
}

$this->canceled = true;
}

/**
* @inheritDoc
*/
public function isCancelled(): bool
{
return $this->canceled;
}

/**
* Return deferred value.
*
* @return mixed
* @throws \Throwable
*/
private function returnResults()
{
if ($this->exception) {
throw $this->exception;
}

return $this->value;
}

/**
* @inheritDoc
*/
public function get()
{
if ($this->isCancelled()) {
throw new CancelingDeferredException('Deferred operation is canceled');
}

if (!$this->isDone()) {
try {
$this->value = ($this->callback)();
} catch (\Throwable $exception) {
$this->exception = $exception;
}
$this->done = true;
}

return $this->returnResults();
}

/**
* @inheritDoc
*/
public function isDone(): bool
{
return $this->done;
}
}