<?php

class App
{
    protected $dbLink;
    protected $dbConfig = array(
        'host' => 'localhost',
        'user' => 'user',
        'pass' => 'password',
        'name' => 'mydatabase'
    );

    public function getDbAdapter()
    {
        if (is_null($this->dbLink)) {
            $this->dbLink = new dbAdapter(
                $this->dbConfig
            );
        }

        return $this->dbLink;
    }
}

class dbAdapter
{
    protected $dbHost = '';
    protected $dbUser = '';
    protected $dbPass = '';
    protected $dbName = '';
    protected $link;

    public function __construct($config = array())
    {
        $this->dbHost = $config['host'];
        $this->dbUser = $config['user'];
        $this->dbPass = $config['pass'];
        $this->dbName = $config['name'];
    }

    public function getLink()
    {
        if (is_null($this->link)) {
            $this->link = mysqli_connect($this->dbHost, $this->dbUser, $this->dbPass, $this->dbName);
            if (mysqli_error($this->link)) {
                throw new Exception(mysqli_error($this->link));
            }
            if ($this->link) {
                mysqli_set_charset($this->link, "utf8");
            }
        }
        return $this->link;
    }

    public function runQuery($query)
    {
        return mysqli_query($this->getLink(), $query);
    }
}

final class Core
{
    static private $_app;

    public static function app()
    {
        if (null === self::$_app) {
            self::$_app = new App();
        }

        return self::$_app;
    }
}

abstract class Model
{
    protected $dbAdapter;

    public function __construct()
    {
        $this->dbAdapter = Core::app()->getDbAdapter();
    }

    public function load()
    {
        $this->beforeLoad();
        $this->_load();
        $this->afterLoad();

        return $this;
    }

    protected function beforeLoad()
    {
        return $this;
    }

    protected function afterLoad()
    {
        return $this;
    }

    protected function _load()
    {
        return $this;
    }
}

class User
{

}