<?php
DateTimeUtils::addDate('2012-12-01',1,'y');
DateTimeUtils::getWeekDay('2012/10/01','/');
DateTimeUtils::isLeapYear('2012');
class DateTimeUtils {
	/**
	 * Checks for leap year, returns true if it is. No 2-digit year check. Also
	 * handles julian calendar correctly.
	 * @param integer $year year to check
	 * @return boolean true if is leap year
	 */
	public static function isLeapYear($year)
	{
		$year = self::digitCheck($year);
		if ($year % 4 != 0)
			return false;

		if ($year % 400 == 0)
			return true;
		// if gregorian calendar (>1582), century not-divisible by 400 is not leap
		else if ($year > 1582 && $year % 100 == 0 )
			return false;
		return true;
	}

	/**
	 * Fix 2-digit years. Works for any century.
	 * Assumes that if 2-digit is more than 30 years in future, then previous century.
	 * @param integer $y year
	 * @return integer change two digit year into multiple digits
	 */
	protected static function digitCheck($y)
	{
		if ($y < 100){
			$yr = (integer) date("Y");
			$century = (integer) ($yr /100);

			if ($yr%100 > 50) {
				$c1 = $century + 1;
				$c0 = $century;
			} else {
				$c1 = $century;
				$c0 = $century - 1;
			}
			$c1 *= 100;
			// if 2-digit year is less than 30 years in future, set it to this century
			// otherwise if more than 30 years in future, then we set 2-digit year to the prev century.
			if (($y + $c1) < $yr+30) $y = $y + $c1;
			else $y = $y + $c0*100;
		}
		return $y;
	}

	/**
	 * Returns 4-digit representation of the year.
	 * @param integer $y year
	 * @return integer 4-digit representation of the year
	 */
	public static function get4DigitYear($y)
	{
		return self::digitCheck($y);
	}
	/**
	 * Checks to see if the year, month, day are valid combination.
	 * @param integer $y year
	 * @param integer $m month
	 * @param integer $d day
	 * @return boolean true if valid date, semantic check only.
	 */
	public static function isValidDate($y,$m,$d)
	{
		return checkdate($m, $d, $y);
	}
	public static function checkDate($date, $separator = "-") { //检查日期是否合法日期
		$dateArr = explode ($separator, $date);
		if (is_numeric ( $dateArr [0] ) && is_numeric ( $dateArr [1] ) && is_numeric ( $dateArr [2] )) {
			return checkdate ( $dateArr [1], $dateArr [2], $dateArr [0] );
		}
		return false;
	}
	/**
	 * Checks to see if the hour, minute and second are valid.
	 * @param integer $h hour
	 * @param integer $m minute
	 * @param integer $s second
	 * @param boolean $hs24 whether the hours should be 0 through 23 (default) or 1 through 12.
	 * @return boolean true if valid date, semantic check only.
	 * @since 1.0.5
	 */
	public static function isValidTime($h,$m,$s,$hs24=true)
	{
		if($hs24 && ($h < 0 || $h > 23) || !$hs24 && ($h < 1 || $h > 12)) return false;
		if($m > 59 || $m < 0) return false;
		if($s > 59 || $s < 0) return false;
		return true;
	}
	public static function checkTime($time, $separator = ":") { //检查时间是否合法时间  
		$timeArr = explode ($separator, $time );
		if (is_numeric ( $timeArr [0] ) && is_numeric ( $timeArr [1] ) && is_numeric ( $timeArr [2] )) {
			if (($timeArr [0] >= 0 && $timeArr [0] <= 23) && ($timeArr [1] >= 0 && $timeArr [1] <= 59) && ($timeArr [2] >= 0 && $timeArr [2] <= 59))
				return true;
			else
				return false;
		}
		return false;
	}
	
	public static function addDate($date, $int, $unit = "d") { //日期的增加
		$dateArr = explode ( "-", $date );
		$value [$unit] = $int;
		return date ( "Y-m-d", mktime ( 0, 0, 0, $dateArr [1] + $value ['m'], $dateArr [2] + $value ['d'], $dateArr [0] + $value ['y'] ) );
	
	}
	
	public static function addDayTimestamp($ntime, $aday) { //取当前时间后几天，天数增加单位为1
		$dayst = 3600 * 24;
		$oktime = $ntime + ($aday * $dayst);
		return $oktime;
	}
	
	public static function dateDiff($date1, $date2, $unit = "d") { //时间比较函数，返回两个日期相差几秒、几分钟、几小时或几天  
		switch