<?php

/**

* CakePHP(tm) : Rapid Development Framework (https://cakephp.org)

* Copyright (c) Cake Software Foundation, Inc. (https://cakefoundation.org)

*

* Licensed under The MIT License

* For full copyright and license information, please see the LICENSE.txt

* Redistributions of files must retain the above copyright notice.

*

* @copyright Copyright (c) Cake Software Foundation, Inc. (https://cakefoundation.org)

* @link https://cakephp.org CakePHP(tm) Project

* @since 3.3.0

* @license https://opensource.org/licenses/mit-license.php MIT License

*/

namespace Cake\Http;

use Cake\Core\App;

use Countable;

use LogicException;

use RuntimeException;

/**

* Provides methods for creating and manipulating a "queue" of middleware callables.

* This queue is used to process a request and response via \Cake\Http\Runner.

*/

class MiddlewareQueue implements Countable

{

/**

* The queue of middlewares.

*

* @var array

*/

protected $queue = [];

/**

* The queue of middleware callables.

*

* @var callable[]

*/

protected $callables = [];

/**

* Constructor

*

* @param array $middleware The list of middleware to append.

*/

public function __construct(array $middleware = [])

{

$this->queue = $middleware;

}

/**

* Get the middleware at the provided index.

*

* @param int $index The index to fetch.

* @return callable|null Either the callable middleware or null

* if the index is undefined.

*/

public function get($index)

{

if (isset($this->callables[$index])) {

return $this->callables[$index];

}

return $this->resolve($index);

}

/**

* Resolve middleware name to callable.

*

* @param int $index The index to fetch.

* @return callable|null Either the callable middleware or null

* if the index is undefined.

*/

protected function resolve($index)

{

if (!isset($this->queue[$index])) {

return null;

}

if (is_string($this->queue[$index])) {

$class = $this->queue[$index];

$className = App::className($class, 'Middleware', 'Middleware');

if (!$className || !class_exists($className)) {

throw new RuntimeException(sprintf(

'Middleware "%s" was not found.',

$class

));

}

$callable = new $className;

} else {

$callable = $this->queue[$index];

}

return $this->callables[$index] = $callable;

}

/**

* Append a middleware callable to the end of the queue.

*

* @param callable|string|array $middleware The middleware(s) to append.

* @return $this

*/

public function add($middleware)

{

if (is_array($middleware)) {

$this->queue = array_merge($this->queue, $middleware);

return $this;

}

$this->queue[] = $middleware;

return $this;

}

/**

* Alias for MiddlewareQueue::add().

*

* @param callable|string|array $middleware The middleware(s) to append.

* @return $this

* @see MiddlewareQueue::add()

*/

public function push($middleware)

{

return $this->add($middleware);

}

/**

* Prepend a middleware to the start of the queue.

*

* @param callable|string|array $middleware The middleware(s) to prepend.

* @return $this

*/

public function prepend($middleware)

{

if (is_array($middleware)) {

$this->queue = array_merge($middleware, $this->queue);

return $this;

}

array_unshift($this->queue, $middleware);

return $this;

}

/**

* Insert a middleware callable at a specific index.

*

* If the index already exists, the new callable will be inserted,

* and the existing element will be shifted one index greater.

*

* @param int $index The index to insert at.

* @param callable|string $middleware The middleware to insert.

* @return $this

*/

public function insertAt($index, $middleware)

{

array_splice($this->queue, $index, 0, [$middleware]);

return $this;

}

/**

* Insert a middleware object before the first matching class.

*

* Finds the index of the first middleware that matches the provided class,

* and inserts the supplied callable before it.

*

* @param string $class The classname to insert the middleware before.

* @param callable|string $middleware The middleware to insert.

* @return $this

* @throws \LogicException If middleware to insert before is not found.

*/

public function insertBefore($class, $middleware)

{

$found = false;

$i = null;

foreach ($this->queue as $i => $object) {

if ((is_string($object) && $object === $class)

|| is_a($object, $class)

) {

$found = true;

break;

}

}

if ($found) {

return $this->insertAt($i, $middleware);

}

throw new LogicException(sprintf("No middleware matching '%s' could be found.", $class));

}

/**

* Insert a middleware object after the first matching class.

*

* Finds the index of the first middleware that matches the provided class,

* and inserts the supplied callable after it. If the class is not found,

* this method will behave like add().

*

* @param string $class The classname to insert the middleware before.

* @param callable|string $middleware The middleware to insert.

* @return $this

*/

public function insertAfter($class, $middleware)

{

$found = false;

$i = null;

foreach ($this->queue as $i => $object) {

if ((is_string($object) && $object === $class)

|| is_a($object, $class)

) {

$found = true;

break;

}

}

if ($found) {

return $this->insertAt($i + 1, $middleware);

}

return $this->add($middleware);

}

/**

* Get the number of connected middleware layers.

*

* Implement the Countable interface.

*

* @return int

*/

public function count()

{

return count($this->queue);

}

}