Date validation for Codeigniter 2

I wrote a tutorial here about the CI date. At that post I used the HTML <select> for the input of date. Sometime our client can want to use text box for the date input. We need the validation for this date. I have found this code from here. It is for CI 1.7.* and PHP 5.2.*. So I change some code for the CI 2.0.* and PHP 5.3.*.

To use, copy the class below into your application/libraries folder named MY_Form_validation.php, then in your controller use it like any other rule.

Form

This validation rule validates an input text box only right now.

<input type="text" name="date" value="<?php echo set_value('date'); ?>" size="10" />

Controller Usage

UK

$this->form_validation->set_rules('date', 'date', 'trim|required|valid_date[d/m/y,/]');

US

$this->form_validation->set_rules('date', 'date', 'trim|required|valid_date[m/d/y,/]');

Database

$this->form_validation->set_rules('date', 'date', 'trim|required|valid_date[y-m-d,-]');

Code

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

class MY_Form_validation extends CI_Form_validation {

 function __construct(){
  parent::__construct();
 }

 /**
 * @desc Validates a date format
 * @params format,delimiter
 * e.g. d/m/y,/ or y-m-d,-
 */
 function valid_date($str, $params)
 {
  // setup
  $CI =&get_instance();
  $params = explode(',', $params);
  $delimiter = $params[1];
  $date_parts = explode($delimiter, $params[0]);

  // get the index (0, 1 or 2) for each part
  $di = $this->valid_date_part_index($date_parts, 'd');
  $mi = $this->valid_date_part_index($date_parts, 'm');
  $yi = $this->valid_date_part_index($date_parts, 'y');

  // regex setup
  $dre =   "(0?1|0?2|0?3|0?4|0?5|0?6|0?7|0?8|0?9|10|11|12|13|14|15|16|17|18|19|20|21|22|23|24|25|26|27|28|29|30|31)";
  $mre = "(0?1|0?2|0?3|0?4|0?5|0?6|0?7|0?8|0?9|10|11|12)";
  $yre = "([0-9]{4})";
  $red = ''.$delimiter; // escape delimiter for regex
  $rex = "/^[0]{$red}[1]{$red}[2]/";

  // do replacements at correct positions
  $rex = str_replace("[{$di}]", $dre, $rex);
  $rex = str_replace("[{$mi}]", $mre, $rex);
  $rex = str_replace("[{$yi}]", $yre, $rex);

  if (preg_match($rex, $str, $matches))
  {
   // skip 0 as it contains full match, check the date is logically valid
   if (checkdate($matches[$mi + 1], $matches[$di + 1], $matches[$yi + 1]))
   {
    return true;
   }
   else
   {
    // match but logically invalid
    $CI->form_validation->set_message('valid_date', "The date is invalid.");
    return false;
   }
  }

  // no match
  $CI->form_validation->set_message('valid_date', "The date format is invalid. Use {$params[0]}");
  return false;
 }

 function valid_date_part_index($parts, $search)
 {
  for ($i = 0; $i <= count($parts); $i++)
  {
   if ($parts[$i] == $search)
   {
    return $i;
   }
  }
 }
}
?>

`