PHPOOP_classes/User.php

<?php
class User
{
	private $_db,
			$_data,
			$_sessionName,
			$_isLoggedIn;

	public function __construct($user = null)
	{
		$this->_db = DB::getInstance();
		$this->_sessionName = Config::get('session/session_name');

		if(!$user)
		{
			if(Session::exists($this->_sessionName))
			{
				$user = Session::get($this->_sessionName);

				if($this->find($user))
				{
					$this->_isLoggedIn = true;
				}
				else
				{
					//process logout
				}
			}
			else
			{
				$this->find($user);
			}
		}
	}

	public function create($table, $fields = array())
	{
		if(!$this->_db->insert($table, $fields))
		{
			throw new Exception("There was a problem creating an account.");
		}
	}

	public function find($user = null)
	{
		if($user)
		{
			$field = (is_numeric($user)) ? 'id' : 'username';
			$data = $this->_db->get('users', array($field, '=', $user));

			if($data->count())
			{
				$this->_data = $data->first();
				return true;
			}
		}
		return false;
	}

	public function login($username = null, $password = null)
	{
		$user = $this->find($username);

		if($user)
		{
			if($this->data()->password === Hash::make($password, $this->data()->salt))
			{
				Session::put($this->_sessionName, $this->data()->id);
				return true;
			}
		}

		return false;
	}

	public function logout()
	{
		Session::delete($this->_sessionName);
	}

	public function data()
	{
		return $this->_data;
	}

	public function isLoggedIn()
	{
		return $this->_isLoggedIn;
	}
}