/**
* Convert MySQL's DATE (YYYY-MM-DD) or DATETIME (YYYY-MM-DD hh:mm:ss) to timestamp
*
* Returns the timestamp equivalent of a given DATE/DATETIME
*
* @todo add regex to validate given datetime
* @author Clemens Kofler <clemens.kofler@chello.at>
* @access    public
* @return    integer
*/
function mysqldatetime_to_timestamp($datetime = "")
{
  // function is only applicable for valid MySQL DATETIME (19 characters) and DATE (10 characters)
  $l = strlen($datetime);
    if(!($l == 10 || $l == 19))
      return 0;

    //
    $date = $datetime;
    $hours = 0;
    $minutes = 0;
    $seconds = 0;

    // DATETIME only
    if($l == 19)
    {
      list($date, $time) = explode(" ", $datetime);
      list($hours, $minutes, $seconds) = explode(":", $time);
    }

    list($year, $month, $day) = explode("-", $date);

    return mktime($hours, $minutes, $seconds, $month, $day, $year);
}

/**
* Convert MySQL's DATE (YYYY-MM-DD) or DATETIME (YYYY-MM-DD hh:mm:ss) to date using given format string
*
* Returns the date (format according to given string) of a given DATE/DATETIME
*
* @author Clemens Kofler <clemens.kofler@chello.at>
* @access    public
* @return    integer
*/
function mysqldatetime_to_date($datetime = "", $format = "d.m.Y, H:i:s")
{
    return date($format, mysqldatetime_to_timestamp($datetime));
}

/**
* Convert timestamp to MySQL's DATE or DATETIME (YYYY-MM-DD hh:mm:ss)
*
* Returns the DATE or DATETIME equivalent of a given timestamp
*
* @author Clemens Kofler <clemens.kofler@chello.at>
* @access    public
* @return    integer
*/
function timestamp_to_mysqldatetime($timestamp = "", $datetime = true)
{
  if(empty($timestamp) || !is_numeric($timestamp)) $timestamp = time();

    return ($datetime) ? date("Y-m-d H:i:s", $timestamp) : date("Y-m-d", $timestamp);
}