<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');

define('FLASHDATA_KEY', 'flash');
define('FLASHDATA_NEW', ':new:');
define('FLASHDATA_OLD', ':old:');
define('FLASHDATA_EXP', ':exp:');

_flashdata_sweep();
_flashdata_mark();


function get_session($item = null)
{
    if(!is_null($item))
        return isset($_SESSION[$item]) ? $_SESSION[$item] : false;
    else
    {
        if(!isset($_SESSION))
            my_session_start();
        return $_SESSION;
    }
}

function unset_session()
{
    if(isset($_SESSION))
        session_destroy();
}

function unset_session_item($item)
{
    unset($_SESSION[$item]);
}

function set_session($data, $val = '')
{
    if(is_string($data))
        $data = array($data => $val);

    if(is_array($data))
    {
        foreach($data as $key => $val)
            $_SESSION[$key] = $val;
    }
    else
        return false;
}

function set_flashdata($newdata = array(), $newval = '')
{
    // Wrap item as array if singular
    if (is_string($newdata))
    {
        $newdata = array($newdata => $newval);
    }

    // Prepend each key name and set value
    if (count($newdata) > 0)
    {
        foreach ($newdata as $key => $val)
        {
            $flashdata_key = FLASHDATA_KEY.FLASHDATA_NEW.$key;
            set_session($flashdata_key, $val);
        }
    }
}

function flashdata($key)
{
    // Prepend key and retrieve value
    $flashdata_key = FLASHDATA_KEY.FLASHDATA_OLD.$key;
    return get_session($flashdata_key);
}

/**
 * Removes all flashdata marked as 'old'
 *
 * @access	protected
 * @return	void
 */
function _flashdata_sweep()
{
    $userdata = get_session();
    foreach ($userdata as $key => $value)
    {
        if (strpos($key, FLASHDATA_OLD))
        {
            unset_session_item($key);
        }
    }
}

function _flashdata_mark()
{
    $userdata = get_session();
    foreach ($userdata as $name => $value)
    {
        $parts = explode(FLASHDATA_NEW, $name);
        if (is_array($parts) && count($parts) === 2)
        {
            $new_name = FLASHDATA_KEY.FLASHDATA_OLD.$parts[1];
            set_session($new_name, $value);
            unset_session_item($name);
        }
    }
}

function all_flashdata()
{
    $out = array();

    // loop through all userdata
    foreach (get_session() as $key => $val)
    {
        // if it contains flashdata, add it
        if (strpos($key, FLASHDATA_KEY.FLASHDATA_OLD) !== FALSE)
        {
            $key = str_replace(FLASHDATA_KEY.FLASHDATA_OLD, '', $key);
            $out[$key] = $val;
        }
    }
    return $out;
}

function keep_flashdata($key)
{
    // 'old' flashdata gets removed. Here we mark all flashdata as 'new' to preserve it from _flashdata_sweep()
    // Note the function will return NULL if the $key provided cannot be found
    $old_flashdata_key = FLASHDATA_KEY.FLASHDATA_OLD.$key;
    $value = get_session($old_flashdata_key);

    $new_flashdata_key = FLASHDATA_KEY.FLASHDATA_NEW.$key;
    set_session($new_flashdata_key, $value);
}

function my_session_start()
{
    static $my_session_started = FALSE;

    // Check if session already started
    if ($my_session_started && session_id())
        return;

    session_cache_limiter(FALSE);

    // Check session id
    $my_session_id = NULL;
    if (isset($_COOKIE['PHPSESSID']))
        $my_session_id = $_COOKIE['PHPSESSID'];
    elseif (isset($_GET['PHPSESSID']))
        $my_session_id = $_GET['PHPSESSID'];

    if (empty($my_session_id) || !preg_match('/^[a-z0-9]{16,32}$/', $my_session_id))
    {
        // Create new session id
        $my_session_id = my_random_key(32, FALSE, TRUE);
        session_id($my_session_id);
    }

    session_start();
    if (!isset($_SESSION['initiated']))
    {
        session_regenerate_id();
        $_SESSION['initiated'] = TRUE;
    }

    $my_session_started = TRUE;
}

// Generate a random key of length $len
function my_random_key($len, $readable = false, $hash = false)
{
    $key = '';

    if ($hash)
        $key = substr(sha1(uniqid(rand(), true)), 0, $len);
    else if ($readable)
    {
        $chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';

        for ($i = 0; $i < $len; ++$i)
            $key .= substr($chars, (mt_rand() % strlen($chars)), 1);
    }
    else
        for ($i = 0; $i < $len; ++$i)
            $key .= chr(mt_rand(33, 126));

    return $key;
}