<?php

class XDateTime extends XValue implements Serializable {
	private $timestamp;
	public static function Make($year,$month,$day,$hours=0,$minutes=0,$seconds=0){
		return new static(mktime($hours,$minutes,$seconds,$month,$day,$year));
	}
	public function VarExport() { return '(new '.get_called_class().'('.$this->timestamp.'))'; }
	public function __construct($timestamp = null){
		if ($timestamp instanceof DateTime) $timestamp = $timestamp->getTimestamp();
		$this->timestamp = is_null($timestamp) ? microtime(true) : $timestamp;
	}

	public function MetaType(){ return MetaDateTime::Type(); }
	public function Serialize(){ return serialize( $this->timestamp ); }
	public function Unserialize($data){ $this->timestamp = unserialize( $data ); }

	public static function Now(){ return new XDateTime(); }

	public function GetYear()        { return intval(date('Y',$this->timestamp)); }
	public function GetMonth()       { return intval(date('m',$this->timestamp)); }
	public function GetDay()         { return intval(date('d',$this->timestamp)); }
	public function GetHours()       { return intval(date('H',$this->timestamp)); }
	public function GetMinutes()     { return intval(date('i',$this->timestamp)); }
	public function GetSeconds()     { return intval(date('s',$this->timestamp)); }
	public function GetWeek()        { return intval(date('W',$this->timestamp)); }
	public function GetDayOfWeek($first_day_of_week = 0)   { return ( intval(date('w',$this->timestamp)) + (7-$first_day_of_week) ) % 7; }
	public function GetDaysInMonth() { return intval(date('t',$this->timestamp)); }
	public function GetTimestamp()   { return $this->timestamp; }
	public function GetDate() { return new XDate($this->timestamp); }
	public function GetTime() { return new XTime($this->timestamp); }
	public function AsDate() { return new XDate($this->timestamp); }
	public function AsTime() { return new XTime($this->timestamp); }
	public function AsInt()  { return intval($this->timestamp); }

	public function IsDate(){ return $this->Format('His') === '000000'; }

	public function IsEqualTo( $x ){
		if ($x instanceof XDateTime) return $this->timestamp == $x->timestamp;
		if ($x instanceof DateTime) return $this->timestamp == $x->getTimestamp();
		if (is_int($x)||is_float($x)) return $this->timestamp == $x;
		return parent::IsEqualTo($x);
	}

	public function CompareTo( $x ){
		if ($x instanceof XDateTime) return $this->timestamp - $x->timestamp;
		if ($x instanceof DateTime) return $this->timestamp - $x->getTimestamp();
		if (is_int($x)||is_float($x)) return $this->timestamp - $x;
		return parent::CompareTo($x);
	}

  public function FromLess( XDateTime $that = null ){ return $that === null ? false : $this->timestamp < $that->timestamp; }
  public function FromLessEqual( XDateTime $that = null ){ return $that === null ? false : $this->timestamp <= $that->timestamp; }
  public function TillLess( XDateTime $that = null ){ return $that === null ? true : $this->timestamp < $that->timestamp; }
  public function TillLessEqual( XDateTime $that = null ){ return $that === null ? true : $this->timestamp <= $that->timestamp; }

	/** @return static */ public static function FromMax( XDateTime $x = null, XDateTime $y = null ) { if ($x === null) return $y; if ($y === null) return $x; return $x->CompareTo($y) > 0 ? $x : $y; }
	/** @return static */ public static function FromMin( XDateTime $x = null, XDateTime $y = null ) { if ($x === null || $y === null) return null; return $x->CompareTo($y) < 0 ? $x : $y; }
	/** @return static */ public static function TillMax( XDateTime $x = null, XDateTime $y = null ) { if ($x === null || $y === null) return null; return $x->CompareTo($y) > 0 ? $x : $y; }
	/** @return static */ public static function TillMin( XDateTime $x = null, XDateTime $y = null ) { if ($x === null) return $y; if ($y === null) return $x; return $x->CompareTo($y) < 0 ? $x : $y; }

	/** @return XTimeSpan */
	public function Diff(XDateTime $value){
		return new XTimeSpan(($this->GetTimestamp() - $value->GetTimestamp())*1000);
	}

	/** @return XDateTime */
	public function AddYears($value){
		return new XDateTime(mktime(
			 $this->GetHours()
			,$this->GetMinutes()
			,$this->GetSeconds()
			,$this->GetMonth()
			,$this->GetDay()
			,$this->GetYear() + $value
 			));
	}
	/** @return XDateTime */
	public function AddMonths($value){
		return new XDateTime(mktime(
			 $this->GetHours()
			,$this->GetMinutes()
			,$this->GetSeconds()
			,$this->GetMonth() + $value
			,$this->GetDay()
			,$this->GetYear()
 			));
	}
	/** @return XDateTime */
	public function AddDays($value){
		return new XDateTime(mktime(
			 $this->GetHours()
			,$this->GetMinutes()
			,$this->GetSeconds()
			,$this->GetMonth()
			,$this->GetDay() + $value
			,$this->GetYear()
 			));
	}
	/** @return XDateTime */
	public function AddHours($value){
		return new XDateTime(mktime(
			 $this->GetHours() + $value
			,$this->GetMinutes()
			,$this->GetSeconds()
			,$this->GetMonth()
			,$this->GetDay()
			,$this->GetYear()
 			));
	}
	/** @return XDateTime */
	public function AddMinutes($value){
		return new XDateTime(mktime(
			 $this->GetHours()
			,$this->GetMinutes() + $value
			,$this->GetSeconds()
			,$this->GetMonth()
			,$this->GetDay()
			,$this->GetYear()
 			));
	}
	/** @return XDateTime */
	public function AddSeconds($value){
		return new XDateTime(mktime(
			 $this->GetHours()
			,$this->GetMinutes()
			,$this->GetSeconds() + $value
			,$this->GetMonth()
			,$this->GetDay()
			,$this->GetYear()
 			));
	}
	/** @return XDateTime */
	public function AddTimeSpan(XTimeSpan $value){
		return $this->AddSeconds($value->GetTotalSeconds());
	}




	/** @return static */
	public function ToServerTimeZone() { return $this->ToTimeZone(Oxygen::GetServerTimeZone()); }

	/** @return static */
	public function ToTimeZone($timezone) {
		if ($timezone === null) return $this;
		$current_timezone = Oxygen::GetClientTimeZone();
		if ($timezone === $current_timezone) return $this;
		$z1 = new DateTimeZone($current_timezone);
		$z2 = new DateTimeZone($timezone);
		$d = new DateTime('@'.$this->timestamp);
		$o1 = $z1->getOffset($d);
		$o2 = $z2->getOffset($d);
		return new static( $this->timestamp - $o1 + $o2 );
	}

	/**
	* @param string $value
	* @param string $format  --see date()
	* @return XDateTime
	*/
	public static function Parse($value,$format){
		$d = DateTime::createFromFormat($format,$value);
		if ($d === false) {
			throw new Exception('Invalid date or time.');
		}
		else
		return new static($d->getTimestamp());
	}



	private static $translations = array('%'=>'%%','d'=>'%d','D'=>'%a','j'=>'%d','l'=>'%A','N'=>'%u','S'=>null,'w'=>'%w','z'=>'%j','W'=>'%W','F'=>'%B','m'=>'%m','M'=>'%b','n'=>null,'t'=>null,'L'=>null,'o'=>'%G','Y'=>'%Y','y'=>'%y','a'=>'%P','A'=>'%p','B'=>null,'g'=>'%l','G'=>null,'h'=>'%I','H'=>'%H','i'=>'%M','s'=>'%S','u'=>null,'e'=>null,'I'=>null,'O'=>'%Z','P'=>null,'T'=>null,'Z'=>null,'c'=>'%Y-%m-%dT%H:%M:%S%Z','r'=>'%a, %e %b %Y %H:%M:%S %Z','U'=>null);
	private static $translated_formats_cache = array();
	private static function translate_format($format){
		if (!array_key_exists($format,self::$translated_formats_cache)){
			$f = ''; $escape = false;
			foreach (str_split($format) as $x){
				if ($escape){ $f .= $x; $escape = false; }
				elseif ($x == '\\') { $escape = true; continue; }
				else $f .= array_key_exists($x,self::$translations) ? self::$translations[$x] : $x;
			}
			self::$translated_formats_cache[$format] = $f;
		}
		return self::$translated_formats_cache[$format];
	}
	/**
	* @param string $format  --see date()
	* @return string
	*/
	public function Format($format){
		$r = strftime(self::translate_format($format),$this->timestamp);
		return $r!==false ? Str::ForceUTF8($r) : date($format,$this->timestamp);
	}





	public static function GetTimeZones(){
		return array_filter( timezone_identifiers_list() , function($x){ return $x !== 'UTC'; } );
	}

}