<?php
 
 namespace elanpl\L3;
 
 class ViewEngine{
     protected $viewengines; //registered view engines dictionary
 
     public function __construct()
     {
         $this->viewengines = array(); 
     }
 
     public function register($fileExtension, $viewEngine){

         if(!class_exists($viewEngine,true)){
             throw new \Exception("Class \"$viewEngine\" not found!");
         }

         if(!isset(class_implements($viewEngine, true)['elanpl\\L3\\IViewEngine'])){

             throw new \Exception("Class \"$viewEngine\" does not implement IViewEngine interface!");
         }
 
         $this->viewengines[$fileExtension] = $viewEngine;
     }
 
     public function get($fileExtension){
         if(array_key_exists($fileExtension, $this->viewengines)){
             return $this->viewengines[$fileExtension];
         }
         else{
             return null;
         }
     }
 
     public function getRegisteredFileExtensions(){
         return array_keys($this->viewengines);
     }
 
 }