<?php
/**
 * Fuel
 *
 * Fuel is a fast, lightweight, community driven PHP5 framework.
 *
 * @package    Fuel
 * @version    1.0
 * @author     Fuel Development Team
 * @license    MIT License
 * @copyright  2010 - 2011 Fuel Development Team
 * @link       http://fuelphp.com
 */

namespace Fuel\Core;



// --------------------------------------------------------------------

class Session_File extends Session_Driver {

    /**
     * array of driver config defaults
     */
    protected static $_defaults = array(
        'cookie_name'        => 'fuelfid',                // name of the session cookie for file based sessions
        'path'                =>    '/tmp',                    // path where the session files should be stored
        'gc_probability'    =>    5                        // probability % (between 0 and 100) for garbage collection
    );

    // --------------------------------------------------------------------

    public function __construct($config = array())
    {
        // merge the driver config with the global config
        $this->config = array_merge($config, is_array($config['file']) ? $config['file'] : static::$_defaults);

        $this->config = $this->_validate_config($this->config);
    }

    // --------------------------------------------------------------------

    /**
     * create a new session
     *
     * @access    public
     * @return    void
     */
    public function create()
    {
        // create a new session
        $this->keys['session_id']    = $this->_new_session_id();
        $this->keys['previous_id']    = $this->keys['session_id'];    // prevents errors if previous_id has a unique index
        $this->keys['ip_address']    = \Input::real_ip();
        $this->keys['user_agent']    = \Input::user_agent();
        $this->keys['created']         = $this->time->get_timestamp();
        $this->keys['updated']         = $this->keys['created'];

        // create the session record
        $this->_write_file($this->keys['session_id'], serialize(array()));

        // and set the session cookie
        $this->_set_cookie();
    }

    // --------------------------------------------------------------------

    /**
     * read the session
     *
     * @access    public
     * @param    boolean, set to true if we want to force a new session to be created
     * @return    void
     */
    public function read($force = false)
    {
        // get the session cookie
        $cookie = $this->_get_cookie();

        // if no session cookie was present, create it
        if ($cookie === false or $force)
        {
            $this->create();
        }

        // read the session file
        $payload = $this->_read_file($this->keys['session_id']);

        if ($payload === false)
        {
            // try to find the previous one
            $payload = $this->_read_file($this->keys['previous_id']);

            if ($payload === false)
            {
                // cookie present, but session record missing. force creation of a new session
                $this->read(true);
                return;
            }
        }

        // unpack the payload
        $payload = $this->_unserialize($payload);

        // session referral?
        if (isset($payload['rotated_session_id']))
        {
            $payload = $this->_read_file($payload['rotated_session_id']);
            if ($payload === false)
            {
                // cookie present, but session record missing. force creation of a new session
                $this->read(true);
                return;
            }
            else
            {
                // update the session
                $this->keys['previous_id'] = $this->keys['session_id'];
                $this->keys['session_id'] = $payload['rotated_session_id'];

                // unpack the payload
                $payload = $this->_unserialize($payload);
            }
        }

        if (isset($payload[0])) $this->data = $payload[0];
        if (isset($payload[1])) $this->flash = $payload[1];

        parent::read();
    }

    // --------------------------------------------------------------------

    /**
     * write the session
     *
     * @access    public
     * @return    void
     */
    public function write()
    {
        // do we have something to write?
        if ( ! empty($this->keys))
        {
            parent::write();

            // rotate the session id if needed
            $this->rotate(false);

            // session payload
            $payload = $this->_serialize(array($this->data, $this->flash));

            // create the session file
            $this->_write_file($this->keys['session_id'], $payload);

            // was the session id rotated?
            if ( isset($this->keys['previous_id']) && $this->keys['previous_id'] != $this->keys['session_id'])
            {
                // point the old session file to the new one, we don't want to lose the session
                $payload = $this->_serialize(array('rotated_session_id' => $this->keys['session_id']));
                $this->_write_file($this->keys['previous_id'], $payload);
            }

            $this->_set_cookie();

            // do some garbage collection
            if (mt_rand(0,100) < $this->config['gc_probability'])
            {
                if ($handle = opendir($this->config['path']))
                {
                    $expire = $this->time->get_timestamp() - $this->config['expiration_time'];

                    while (($file = readdir($handle)) !== false)
                    {
                        if (filetype($this->config['path'] . $file) == 'file' &&
                            strpos($file, $this->config['cookie_name'].'_') === 0 &&
                            filemtime($this->config['path'] . $file) < $expire)
                        {
                            @unlink($this->config['path'] . $file);
                        }
                    }
                    closedir($handle);
                }
            }
        }
    }

    // --------------------------------------------------------------------

    /**
     * destroy the current session
     *
     * @access    public
     * @return    void
     */
    public function destroy()
    {
        // do we have something to destroy?
        if ( ! empty($this->keys))
        {
            // delete the session file
            $file = $this->config['path'].$this->config['cookie_name'].'_'.$this->keys['session_id'];
            if (file_exists($file))
            {
                unlink($file);
            }
        }

        // reset the stored session data
        $this->keys = $this->flash = $this->data = array();
    }

    // --------------------------------------------------------------------

    /**
     * Writes the session file
     *
     * @access    private
     * @return  boolean, true if it was an existing session, false if not
     */
    protected function _write_file($session_id, $payload)
    {
        // create the session file
        $file = $this->config['path'].$this->config['cookie_name'].'_'.$session_id;
        $exists = file_exists($file);
        $handle = fopen($file,'c');
        if ($handle)
        {
            // wait for a lock
            while(!flock($handle, LOCK_EX));

            // erase existing contents
            ftruncate($handle, 0);

            // write the session data
            fwrite($handle, $payload);

            //release the lock
            flock($handle, LOCK_UN);

            // close the file
            fclose($handle);
        }

        return $exists;
    }

    // --------------------------------------------------------------------

    /**
     * Reads the session file
     *
     * @access    private
     * @return  mixed, the payload if the file exists, or false if not
     */
    protected function _read_file($session_id)
    {
        $payload = false;

        $file = $this->config['path'].$this->config['cookie_name'].'_'.$session_id;
        if (file_exists($file))
        {
            $handle = fopen($file,'r');
            if ($handle)
            {
                // wait for a lock
                while(!flock($handle, LOCK_EX));

                // read the session data
                $payload = fread($handle, filesize($file));

                //release the lock
                flock($handle, LOCK_UN);

                // close the file
                fclose($handle);

            }
        }
        return $payload;
    }

    // --------------------------------------------------------------------

    /**
     * validate a driver config value
     *
     * @param    array    array with configuration values
     * @access    public
     * @return  array    validated and consolidated config
     */
    public function _validate_config($config)
    {
        $validated = array();

        foreach ($config as $name => $item)
        {
            // filter out any driver config
            if (!is_array($item))
            {
                switch ($name)
                {
                    case 'cookie_name':
                        if ( empty($item) OR ! is_string($item))
                        {
                            $item = 'fuelfid';
                        }
                    break;

                    case 'path':
                        // do we have a path?
                        if ( empty($item) OR ! is_dir($item))
                        {
                            throw new \Fuel_Exception('You have specify a valid path to store the session data files.');
                        }
                        // and can we write to it?
                        if ( ! is_writable($item))
                        {
                            throw new \Fuel_Exception('The webserver doesn\'t have write access to the path to store the session data files.');
                        }
                        // update the path, and add the trailing slash
                        $item = realpath($item).'/';
                    break;

                    case 'gc_probability':
                        // do we have a path?
                        if ( ! is_numeric($item) OR $item < 0 OR $item > 100)
                        {
                            // default value: 5%
                            $item = 5;
                        }
                    break;

                    default:
                        // no config item for this driver
                    break;
                }

                // global config, was validated in the driver
                $validated[$name] = $item;
            }
        }

        // validate all global settings as well
        return parent::_validate_config($validated);
    }

}

/* End of file file.php */