<?php

class RouterException extends Exception {}

class Router {

    protected $uri = null;
    protected $currentRoute = null;
    protected $params = array();

    public function __construct($defaultController = 'index') {

        $pattern = '@^/@';

        if($_SERVER['PHP_SELF'] !== 'index.php')
            $pattern = '@^.*index.php/@';

        $request = preg_replace($pattern, '', $_SERVER['REQUEST_URI'], 1);

        $this->uri = explode('/', $request);

        if (!isset($this->uri[0]) || trim($this->uri[0]) === '')
            $this->uri[0] = $defaultController;
    }

    public function load(array $routes) {

        if (isset($routes[$this->uri[0]]))
            $this->currentRoute = $routes[$this->uri[0]];

        return $this;
    }

    public function route() {

        if ($this->currentRoute === null)
            throw new RouterException ('[Router] 404 - Page not found');

        $this->parseParams();
        $this->loadGet();
        $this->loadController();
    }

    protected function parseParams() {

        if (!isset($this->currentRoute['params']))
            return false;

        $routeParams = explode('/', $this->currentRoute['params']);
        $uriParams = $this->uri;

        array_shift($routeParams);
        array_shift($uriParams);

        foreach ($routeParams as $key => $param) {

            if (strpos($param, ':') === 0) {

                $param = ltrim($param, ':');

                if (isset($uriParams[$key]) && $this->validParam($param, $uriParams[$key]))
                    $this->params[$param] = $uriParams[$key];
                else
                    throw new RouterException ('[Router] Missing ' . $param . ' param');

            } else {

                $param = ltrim($param, '?');

                if (isset($uriParams[$key]))
                    $this->params[$param] = $uriParams[$key];
                else
                    $this->params[$param] = '';
            }
        }
    }

    protected function validParam($routeParam, $uriValue) {

        if (isset($this->currentRoute['valid'][$routeParam])) {

            return preg_match('@' . $this->currentRoute['valid'][$routeParam] . '@', $uriValue);
        }

        return true;
    }

    protected function loadController() {

        require_once $this->currentRoute['controller'];
    }

    protected function loadGet() {

        global $_GET;

        $_GET = array_merge($this->params, $_GET);
    }
}