CI3 flat file session driver used for testing with Codeception

Session_codeception.php

<?php
/**
 * CI3 flat file session driver used for testing with Codeception
 */


/**
 * Class CI_Session_codeception
 */
class CI_Session_codeception extends CI_Session_driver
{

    /**
     * Length of time (in seconds) for sessions to expire
     *
     * @var int
     */
    public $sess_expiration = 7200;

    /**
     * Interval at which to update session
     *
     * @var int
     */
    public $sess_time_to_update = 300;

    /**
     * @var
     */
    public $userdata;
    /**
     * Current time
     *
     * @var int
     */
    public $now;
    /**
     * @var string
     */
    protected $sessionStoreDirectory = '';
    /**
     * @var string
     */
    protected $uId = '';
    /**
     * @var string
     */
    protected $sessFileExt = '_session.json';

    /**
     * Save a session
     */
    public function sess_save()
    {
        // Save current data to storage
        $this->userdata['last_updated'] = $this->now;
        file_put_contents($this->sessFilePath(), json_encode($this->userdata));
    }

    /**
     * Session file path
     * @return string
     */
    private function sessFilePath()
    {
        return $this->sessionStoreDirectory . DIRECTORY_SEPARATOR . $this->uId . $this->sessFileExt;

    }

    /**
     * @param bool $destroy
     */
    public function sess_regenerate($destroy = FALSE)
    {
        if ($destroy) {
            $this->sess_destroy();
            $this->sessCreate();
        } else {
            $this->sessUpdate(true);
        }
    }

    /**
     * Destroy flat file session
     */
    public function sess_destroy()
    {
        unlink($this->sessFilePath());
        $this->userdata = array();
    }

    /**
     *  Create session
     */
    private function sessCreate()
    {

        // Initialize userdata
        $this->userdata = array(
            'session_id' => $this->generateUid(),
            'ip_address' => $this->CI->input->ip_address(),
            'user_agent' => trim(substr($this->CI->input->user_agent(), 0, 120)),
            'last_activity' => $this->now,
        );

        return file_put_contents($this->sessFilePath(), json_encode($this->userdata));


    }

    /**
     * User ID
     * @return string
     */
    private function generateUid()
    {
        return md5($_SERVER['SSH_CLIENT'] . $_SERVER['SSH_CONNECTION'] . implode('-', $_SERVER['argv']));
    }

    /**
     * @param bool $force
     * @return bool|int|null
     */
    private function sessUpdate($force = false)
    {
        // We only update the session every five minutes by default (unless forced)
        if (!$force && ($this->userdata['last_activity'] + $this->sess_time_to_update) >= $this->now) {
            return null;
        }

        $this->userdata = json_decode($this->sessFilePath(), true);

        $this->userdata['last_activity'] = $this->now;
        return file_put_contents($this->sessFilePath(), json_encode($this->userdata));

    }

    /**
     *
     */
    public function &get_userdata()
    {
        return $this->userdata;
    }

    /**
     *
     */
    protected function initialize()
    {


        $this->sessionStoreDirectory = dirname(dirname(APPPATH)) . DIRECTORY_SEPARATOR . 'session_store';
        if (!file_exists($this->sessionStoreDirectory)) {
            mkdir($this->sessionStoreDirectory);
        }

        $this->uid = $this->generateUid();

        $this->now = time();

        if (!$this->sessRead()) {

            $this->sessCreate();

        } else {
            $this->sessUpdate();
        }
    }

    /**
     * Read session from flat file if it exists
     */
    protected function sessRead()
    {

        $filePath = $this->sessFilePath();
        $session = file_exists($filePath);
        if (!$session) {
            return false;
        }

        $sessionRead = json_decode(file_get_contents($filePath), true);

        // Is the session data we unserialized an array with the correct format?
        if (!is_array($sessionRead) OR !isset($sessionRead['session_id'], $sessionRead['ip_address'], $sessionRead['user_agent'], $sessionRead['last_activity'])) {
            $this->sess_destroy();
            return FALSE;
        }

        // Is the session current?
        if (($sessionRead['last_activity'] + $this->sess_expiration) < $this->now OR $session['last_activity'] > $this->now) {
            $this->sess_destroy();
            return FALSE;
        }

        // Session is valid!
        $this->userdata = $session;
        return TRUE;

    }

}