Restzeiten mit PHP berechnen (OOP)

Da mir zur Zeit extrem langweilig ist, habe ich mich an eine Klasse zur Berechnung von Zeitunteschieden (Restzeit ;)) gemacht. Sie ist nicht die beste, hat aber die wichtigsten Funktionen eingebaut. Die Parameter sollten selbsterklärend sein….

resttime.class.php

define("SECONDS_PER_MINUTE", 60);
define("SECONDS_PER_MINUTE", 60);
define("SECONDS_PER_HOUR", SECONDS_PER_MINUTE*60);
define("SECONDS_PER_DAY", SECONDS_PER_HOUR*24);
define("SECONDS_PER_MONTH", SECONDS_PER_DAY*30);
define("SECONDS_PER_WEEK", SECONDS_PER_DAY*7);
define("SECONDS_PER_YEAR", SECONDS_PER_MONTH*12);

/**
  Klasse zur Berechnung von Restzeiten
*/
class resttime
{
  private $start_timestamp;         //start of the period
  private $end_timestamp; 		    //end of the period
  private $difference;              //difference between start and end
  private $rest;                    //temporary variable for calculations
  private $days;                    //amount of days
  private $hours; 					//amount of hours
  private $minutes; 				//amount of minuts
  private $seconds;					//amount of seconds
  private $years;					//amount of years
  private $months;					//amount of months
  private $weeks;					//amount of weeks

  /**
    Constructor initializes properities
  */
  public function __construct($start = 0, $end = 0)            //Start and end can be defined in the constructor (it's no must)
  {
    $this->start_timestamp  = 0;
    $this->end_timestamp    = 0;
    $this->difference       = 0;
	$this->rest 		    = 0;
    $this->days 			= 0;
    $this->hours 			= 0;
    $this->minutes 			= 0;
    $this->seconds 			= 0;
    $this->years 			= 0;
	$this->months           = 0;
    $this->weeks 			= 0;

	/**
	  That's the default value, wich can be changed by calling $class->set_timezone()
	*/
	$this->set_timezone("Europe/Berlin");

	/**
	  To ensure that a start is defined in any case, set_start is called
	*/
	$this->set_start($start);

	/**
	  To ensure that a end is defined in any case, set_end is called
	*/
	$this->set_end($end);
  }   

  /**
    Destructor deletes the variables
  */
  public function __destruct()
  {
    unset($this->start_timestamp);
    unset($this->end_timestamp);
    unset($this->difference);
	unset($this->rest);
    unset($this->days);
    unset($this->hours);
    unset($this->minutes);
	unset($this->seconds);
    unset($this->years);
	unset($this->months);
    unset($this->weeks);
  } 

  /**
    This function is only used when this class has to work with a date, wich is no timestamp
  */
  public function set_timezone($zone)
  {
    date_default_timezone_set($zone);
  }

  /**
    Sets the beginning of the time to calculate
  */
  public function set_start($timestamp)
  {
   if(is_numeric($timestamp)) //no datetime, so there's no need to convert the date to a timestamp
   {
    $this->start_timestamp = $timestamp;
   }
   else
   {
    $this->start_timestamp = strtotime($timestamp);	//convert the date to a timestamp
   }
   $this->calculate_difference();                   //update the difference in this object
  }

  /**
    Returns a timestamp
  */
  public function get_start()
  {
    return $this->start_timestamp;
  }

  /**
    Sets the end of the time to calculate
  */
  public function set_end($timestamp)
  {
   if(is_numeric($timestamp)) //no datetime, so there's no need to convert the date to an timestamp
   {
    $this->end_timestamp = $timestamp;
   }
   else
   {
    $this->end_timestamp = strtotime($timestamp);	//convert the date to a timestamp
   }
   $this->calculate_difference();                   //update the difference in this object
  }

  /**
    Returns a timestamp
  */
  public function get_end()
  {
    return $this->end_timestamp;
  }

  /**
    This private function calculates the difference between the end and the start of the period
  */
  private function calculate_difference()
  {
    $this->difference = $this->end_timestamp - $this->start_timestamp;
  }

  /**
    Returns the calculated difference as integer (in seconds)
  */
  public function get_difference()
  {
    return (int)$this->difference;
  }

  /**
    Returns the calculated difference as an array / a string
  */
  public function get_difference_formated($array 	= true,
  										  $year		= array(true, true),       //1. parameter means: Yes, i want to have it
										  $month	= array(true, true),       //2. parameter means: Yes, i want to have it even when it's zero
										  $week		= array(true, true),
										  $day		= array(true, true),
										  $hour		= array(true, true),
										  $minute	= array(true, true),
										  $second	= array(true, true))
  {
    $this->rest = $this->difference;
	if($year[0] == true)
	{
	  $this->years = floor($this->rest / SECONDS_PER_YEAR);
	  $this->rest = $this->rest - ($this->years * SECONDS_PER_YEAR);
	}

	if($month[0] == true)
	{
	  $this->months = floor($this->rest / SECONDS_PER_MONTH);
	  $this->rest = $this->rest - ($this->months * SECONDS_PER_MONTH);
	}

	if($week[0] == true)
	{
	  $this->weeks = floor($this->rest / SECONDS_PER_WEEK);
	  $this->rest = $this->rest - ($this->weeks * SECONDS_PER_WEEK);
	}

	if($day[0] == true)
	{
	  $this->days = floor($this->rest / SECONDS_PER_DAY);
	  $this->rest = $this->rest - ($this->days * SECONDS_PER_DAY);
	}

	if($hour[0] == true)
	{
	  $this->hours = floor($this->rest / SECONDS_PER_HOUR);
	  $this->rest = $this->rest - ($this->hours * SECONDS_PER_HOUR);
	}

	if($minute[0] == true)
	{
	  $this->minutes = floor($this->rest / SECONDS_PER_MINUTE);
	  $this->rest = $this->rest - ($this->minutes * SECONDS_PER_MINUTE);
	}

	if($second[0] == true)
	{
	  $this->seconds = $this->rest;
	}	

	if($array != true)
	{          //when it's not 0   OR  when you want to have it even when it's 0
	  return (($this->years   != 0 || $year[1]) ? $this->years." Years, " : "").
	       	 (($this->months  != 0 || $month[1]) ? $this->months." Months " : "").
		     (($this->weeks   != 0 || $week[1]) ? $this->weeks." Weeks " : "").
		     (($this->days    != 0 || $day[1]) ? $this->days." Days " : "").
		     (($this->hours   != 0 || $hour[1]) ? $this->hours." Hours " : "").
		     (($this->minutes != 0 || $minute[1]) ? $this->minutes." Minutes " : "").
		     (($this->seconds != 0 || $second[1]) ? $this->seconds." Seconds " : "0 Seconds");    //falls Unterschied 0 ist, soll kein leerer string returned werden
	}
	else
	{
	   return array("years"   => $this->years,
	                "months"  => $this->months,
					"weeks"   => $this->weeks,
					"days"    => $this->days,
					"hours"   => $this->hours,
					"minutes" => $this->minutes,
					"seconds" => $this->seconds);
	}
  }
}

Und hier ein Beispiel zur Verwendung der Klasse:
index.php

error_reporting(E_ALL | E_STRICT);
error_reporting(E_ALL | E_STRICT);
require_once("resttime.class.php");

for($i = 0; $i < 30; $i++)
{
  $test[$i] = new Resttime;
}

for($i = 0; $i < 30; $i++)
{
  $test[$i]->set_start(date("d.m.Y H:i:s", time()-mt_rand(1, 9999999)*20));
  $test[$i]->set_end("04.02.2009 23:00:00");
  echo "
".$test[$i]->get_difference_formated(false, array(true, true),
                                              array(true, true),
											  array(true, true),
											  array(true, true),
											  array(true, true),
											  array(true, true),
											  array(true, true));

}