<?php

namespace GuzzleHttp\Promise;

final class Create
{
/**
* Creates a promise for a value if the value is not a promise.
*
* @param mixed $value Promise or value.
*
* @return PromiseInterface
*/
public static function promiseFor($value)
{
if ($value instanceof PromiseInterface) {
return $value;
}

// Return a Guzzle promise that shadows the given promise.
if (is_object($value) && method_exists($value, 'then')) {
$wfn = method_exists($value, 'wait') ? [$value, 'wait'] : null;
$cfn = method_exists($value, 'cancel') ? [$value, 'cancel'] : null;
$promise = new Promise($wfn, $cfn);
$value->then([$promise, 'resolve'], [$promise, 'reject']);
return $promise;
}

return new FulfilledPromise($value);
}

/**
* Creates a rejected promise for a reason if the reason is not a promise.
* If the provided reason is a promise, then it is returned as-is.
*
* @param mixed $reason Promise or reason.
*
* @return PromiseInterface
*/
public static function rejectionFor($reason)
{
if ($reason instanceof PromiseInterface) {
return $reason;
}

return new RejectedPromise($reason);
}

/**
* Create an exception for a rejected promise value.
*
* @param mixed $reason
*
* @return \Exception|\Throwable
*/
public static function exceptionFor($reason)
{
if ($reason instanceof \Exception || $reason instanceof \Throwable) {
return $reason;
}

return new RejectionException($reason);
}

/**
* Returns an iterator for the given value.
*
* @param mixed $value
*
* @return \Iterator
*/
public static function iterFor($value)
{
if ($value instanceof \Iterator) {
return $value;
}

if (is_array($value)) {
return new \ArrayIterator($value);
}

return new \ArrayIterator([$value]);
}
}