AuthChain.php

<?php 
namespace Routing\Auth;

abstract class AuthChecker {
  
  const SKIPPED;
  const SUCCESS;
  const AUTHENTICATION_FAILED;
  const AUTHORIZATION_FAILED;
  
  /**
   * @var AuthChecker|null
   */
  private $next;
  
  abstract protected validatRequest(Request $request, $controllerClass);
  
  public function setNext(AuthChecker $authChecker)
  {
    $this->next = $authChecker;
  }
  
  public function invoke(Request $request, $controllerClass)
  {
    $result = $this->validateRequest($request, $controllerClass);
    if ($result == self::SKIPPED && $this->next) {
      return $this->next->invoke($request, $controllerClass);
    }
    return $result;
  }
}

class AuthChainProvider {
  
  /**
   * @var AuthChecker
   */
  private $firstInChain;
  
  static function getInstance() 
  {
    static $self = null;
    if ($self === null) {
      $self = new self;
    }
    return $self;
  }
  
  private function __construct() {}
  
  public function chain(AuthChecker $authChecker)
  {
    if ($this->firstInChain) {
      $authChecker->setNext($this->firstInChain);
    }
    $this->firstInChain = $authChecker;
  }
  
  public function invoke(Request $request, $controllerClass)
  {
    if ($this->firstInChain) {
      return $this->firstInChain->invoke($request, $controllerClass);
    }
    return null;
  }
}


/*
* EXAMPLE...
*/
$authChainProvider = AuthChainProvider::getInstance();
$authChainProvider->chain(new MainAuthChecker());
$authChainProvider->chain(new WikiDocsAuthChecker());
$authChainProvider->chain(new RestApiAuthChecker());

$authChainProvider->invoke($request, $controllerClass);