/lenasys/trunk

<?php

	Class User extends CI_Model {

		/*

		 *	Constructor

		 */

		function __construct() {

			parent::__construct();

			//Load required libraries

			$this->load->database();

			$this->load->library('session');

		}

		/*

		 *	This function logs the user in (returns FALSE on fail).

		 */ 

		public function login($username, $password)

		{			

			//Generate a salted hash

			$hash = $this->getSaltedHash($password);

			//Query-structure

			$this->db->select('userName, name, passwd, userType, ssn');

			$this->db->from('Users');

			$this->db->where('userName', $username);

			$this->db->where('passwd', $hash);

			$this->db->limit(1);

			//Execute query

			$query = $this->db->get();

			$result = $query->result();

			//If a matching DB record is found.

			if($result) {

				//Prepare session data

				$userDetails = array();

				foreach($result as $row) {

					$userDetails = array(

						'username' => $row->userName,

						'name' => $row->name,

						'usertype' => $row->userType,

						'ssn' => $row->ssn

					);

				}

				//Set session data

				$this->session->set_userdata('authenticated', $userDetails);

				//Return success

				return TRUE;

			}

			//Return fail

			return FALSE;	

		}

		/*

		 *	This function logs the user out.

		 */ 

		public function logout() {		

			//Unset session data

			$this->session->unset_userdata('authenticated');

		}

		/*

		 *	This function return TRUE if the user is logged in and FALSE otherwise.

		 */ 

		public function isLoggedIn() {	

			if ($this->session->userdata('authenticated')) {

				return TRUE;

			}

			return FALSE;

		}

		/*

		 *	This function returns the users type (or FALSE if user isn't logged in).

		 */ 

		public function getUserType() {	

			if($this->isLoggedIn()) {

				$temp = $this->session->userdata('authenticated');

				return $temp['usertype'];

			}

			return FALSE;

		}

		/*

		 *	This function returns the username (or FALSE if user isn't logged in).

		 */ 

		public function getUserName() {	

			if($this->isLoggedIn()) {

				$temp = $this->session->userdata('authenticated');

				return $temp['username'];

			}

			return FALSE;

		}

		/*

		 *	This function returns the users password hint (or FALSE if user isn't logged in).

		 */ 

		public function getPasswordHint($user) {

			$hint = '';

			//Query-structure

			$this->db->select('passwdHint');

			$this->db->from('Users');

			$this->db->where('userName', $user);

			$this->db->limit(1);

			//Execute query

			$query = $this->db->get();

			$result = $query->result();

			//If a matching DB record is found.

			if($result) {

			    foreach($result as $row) {

			    	$hint = $row->passwdHint;

			    	return $hint;

			    }

			}

			return FALSE;

		}

		/*

		 *	This function registers user into the database.

		 */

		public function addUser($userName, $name, $ssn, $password, $userType, $pwdHint) {

			//Check that a user is logged in and has the right privileges (is teacher)

			if($this->isLoggedIn() && $this->getUserType() === 'Teacher') {

				//Generate a salted hash

				$hash = $this->getSaltedHash($password);

				//Query-structure (All values are escaped automatically by codeigninte, producing safer queries.)

				$this->db->set('userName', $userName);

				$this->db->set('name', $name);

				$this->db->set('ssn', $ssn);

				$this->db->set('passwd', $password);

				$this->db->set('userType', $userType);

				$this->db->set('passwdHint', $pwdHint);

				$result = $this->db->insert('Users');

				//Check for my-sql error

				if($result) {

					//Return success

					return TRUE;

				} 

			}

			//Return error

			return FALSE;

		}

		/*

		 *	This function changes the users password.

		 */ 

		public function changePassword($pwdOld, $pwdNew, $pwdHint) {

			//Check that a user is logged in.

			if($this->isLoggedIn()) {

				$user = $this->getUserName();

				$oldHash = $this->getSaltedHash($pwdOld);

				$newHash = $this->getSaltedHash($pwdNew);

				//Validate

				$this->db->select('userName');

				$this->db->from('Users');

				$this->db->where('userName', $user);

				$this->db->where('passwd', $oldHash);

				$this->db->limit(1);

				$query = $this->db->get();

				$result = $query->result();

				//If a matching DB record is found, update database with new info.

				if($result) {

					$data = array(

						'passwd' => $newHash,

						'passwdHint' => $pwdHint

					);

					$this->db->where('userName', $user);

					$this->db->update('Users', $data);

					//Return Success!

					return TRUE;							

				}

			}

			//Return error

			return FALSE;

		}

		/*

		 *	This function removes users from the database.

		 */ 

		public function removeUser($userName) {

			//Check that a user is logged in, has the right privileges (is teacher) and not is the users own username.

			if($this->isLoggedIn() && $this->getUserType() === 'Teacher' && $this->getUserName() != $userName) {

				//Query-structure

				$this->db->where('userName', $userName);

				$result = $this->db->delete('Users');		 

				//Check for my-sql error

				if($result) {

					//Return success

					return TRUE;

				} 

			}

			//Return error

			return FALSE;

		}

		/*

		 *	Generates a password hash using a user-unique salt.

		 */		

		private function getSaltedHash($pwd)

		{	

			/* Salt algorithm:

			 * Step 1: Get encryption key

			 * Step 2: Salt is set to password (reversed)

			 * Step 3: Salt is encrypted with MD5

			 * Step 4: Salt is reversed (again)

			 * Step 5: Salt is encrypted with SHA1

			 */

			$salt = '';

			//UNCOMMENT TO ACTIVATE SALT LATER IN DEVELOPMENT!!!

			//$salt = sha1(strrev(md5(strrev($this->config->item('encryption_key')))));

			//Generate SHA1 hash using salt

			$hash = sha1($salt.$pwd);

			return $hash;

		}

	}

?>