<?php
/** 
* Loader is used to route parameters from input url and set parameters for controller.
* The routing is done by the RewriteRule written in .htaccess file.
*/

class Loader {
	private $controller;
	private $action;
	private $urlvalues;
	private $postdata = 0;

	public function __construct($urlvalues, $postdata) {
		/** 
		* It stores the URL values on object creation.
		* For example, the URL structure is like this: some_domain_name/Extractapp/TaggingText. 
		* The controller is "Extractapp" and the action is "TaggingText".
		* For the "Extractapp" controller, there is a corresponding "extractapp.php" in "./controllers" folder.
		* For the action "TaggingText", there is a corresponding "TaggingText.php" in "./views/Extractapp" folder.
		* Under "./view" folder, the first level is named by the controller. Each action belongs to the controller is named by its action name.
		*/

		$this->urlvalues = $urlvalues;
		$this->postdata = $postdata;
		if ($this->urlvalues['controller'] == "") {
			$this->controller = "Extractapp";	// the default controller

		} else {
			$this->controller = $this->urlvalues['controller'];
		}

		if ($this->urlvalues['action'] == "") {
			$this->action = "TaggingText";	// the default action

		} else {
			$this->action = $this->urlvalues['action'];
		}
	}
	
	public function CreateController() {
		/** 
		* Establish the requested controller as an object, and check if the query is valid.
		* The queried controller, which should be extended from BaseController, exists and the queried action should be one of its method.
		*/

		//does the class exist?
		if (class_exists($this->controller)) {
			$parents = class_parents($this->controller);
			//does the class extend the controller class?
			if (in_array("BaseController",$parents)) {
				//does the class contain the requested method?
				if (method_exists($this->controller,$this->action)) {
					return new $this->controller($this->action,$this->urlvalues,$this->postdata);
				} else {
					//bad method error
					return new Error("badUrl",$this->urlvalues);
				}
			} else {
				//bad controller error
				return new Error("badUrl",$this->urlvalues);
			}
		} else {
			//bad controller error
			return new Error("badUrl",$this->urlvalues);
		}
	}
}

?>