<?php
/**
 * A class to compare, humanize, and sanitize dates.
 *
 * @package		Time
 * @version		1.0
 * @author		Koa Metter <koa@iamkoa.net>
 * @link		http://iamkoa.net
 * @license		http://www.opensource.org/licenses/bsd-license.php
 */

class Time {
	
	/**
	 * Returns a UNIX timestamp, given either a UNIX timestamp or a valid strtotime() date string.
	 *
	 * @param string $dateString Datetime string
	 * @return string Formatted date string
	 */
	function fromString($dateString)
	{
		if (is_integer($dateString) || is_numeric($dateString)) {
			return intval($dateString);
		} else return strtotime($dateString);
	}

	/**
	 * Returns true if given datetime string was yesterday.
	 *
	 * @param string $dateString Datetime string or Unix timestamp
	 * @return boolean True if datetime string was yesterday
	 */
	function wasYesterday($dateString)
	{
		$date = $this->fromString($dateString);
		$ret = date('Y-m-d', $date) == date('Y-m-d', strtotime('yesterday'));
		return $ret;
	}

	/**
	 * Returns true if given datetime string is today.
	 *
	 * @param string $dateString Datetime string or Unix timestamp
	 * @return boolean True if datetime string is today
	 */
	function isToday($dateString)
	{
		$date = $this->fromString($dateString);
		$ret = date('Y-m-d', $date) == date('Y-m-d', time());
		return $ret;
	}
		
	/**
	 * Returns "morning", "evening" or "night" depending upon date.
	 * @param string $dateString Datetime string or Unix timestamp
	 * @param string $format PHP string format function - strtoupper, ucfirst, ucwords, etc
	 * @return string "morning", "evening" or "night"
	 */
	function timeOfDay($dateString, $format = 'strtolower')
	{
		$date = $this->fromString($dateString);
		$ret = null;
		$now = date('H',$date);

		// morning - midnight through 11am
		if ($now >= 0 && $now <= 11) $ret = $format('morning');
		
		// evening - 6pm through 8pm
		if ($now >= 18 && $now <= 20) $ret = $format('evening');

		// night - 9pm through 11pm
		if ($now >= 21 && $now <= 23) $ret = $format('night');
		
		return $ret;
	}
		
	/**
	 * Returns the difference in seconds between two dates
	 * @param string $then Datetime string or Unix timestamp
	 * @param string $now Datetime string or Unix timestamp
	 * @return int Number of seconds
	 */
	function dateDiff($then, $now = null)
	{
		$then = $this->fromString($then);
		
		// if $now is null, assume we mean today
		if (!$now) $now = strtotime('now');
		$now = $this->fromString($now);
		
		// calculate the difference
		$diff = $now - $then;
		
		return $diff;
	}
		
	/**
	* Returns true if specified datetime was within the interval specified, else false.
	*
	* @param mixed $timeInterval the numeric value with space then time type. Example of valid types: 6 hours, 2 days, 1 minute.
	* @param int $userOffset User's offset from GMT (in hours)
	* @param mixed $dateString the datestring or unix timestamp to compare
	* @return bool
	*/
	function wasWithinLast($timeInterval, $dateString, $userOffset = null)
	{
		$tmp = str_replace(' ', '', $timeInterval);
		if (is_numeric($tmp)) {
			$timeInterval = $tmp.' days';
		}
		
		$date = $this->fromString($dateString, $userOffset);
		$interval = $this->fromString('-'.$timeInterval);

		if ($date >= $interval && $date <= time()) {
			return true;
		}

		return false;
	}

	/**
	* Returns an English humanized date string based on MySQL datetime or UNIX timestamp.
	*
	* @param mixed $dateString the datestring or unix timestamp to compare
	* @param string $default_format the default date() parse; example: 'j M, g:i A'
	* @return mixed "26 July, 2:45 PM", or "Yesterday morning", or "28 minutes ago", etc
	*/
	function timeAgoInWords($dateString = null, $default_format = 'j M, g:i A')
	{
		$date = $this->fromString($dateString);
		
		// what humans like
		$human = null;
		$now = strtotime('now');

		// if $first_date is larger, falsify
		if ($date > $now) return false;
	
		// humanize it
		if ($this->isToday($date))
		{
			// calculate difference
			$diff = $this->dateDiff($date);
			
			// break it down into hours
			$hours = floor($diff/3600);
			$diff = $diff % 3600;
			
			if ($hours >= 1) {
				@$human_hr = $hours > 1 ? "$hours hours " : "$hours hour ";
			}

			// only show minutes if less than one hour
			if ($hours < 1)
			{
				$minutes = floor($diff/60);
				$diff = $diff % 60;
				
				if ($minutes > 0) {
					@$human_hr .= $minutes > 1 ? "$minutes minutes " : "$minutes minute ";
				}
			}

			// only show seconds if less than one minute
			if (isset($minutes) && $minutes < 1)
			{
				$seconds = $diff;
				if ($seconds > 0) {
					@$human_hr .= $seconds > 1 ? "$seconds seconds" : "$seconds second";
				}
			}
			
			// if beyond 5 hours, display $this->timeOfDay()
			if ($hours >= 5) {
				$human = $this->timeOfDay($date) == null ? "Today" : "This ";
				$human .= $this->timeOfDay($date);
			} else {
				// was in the last 5 hours - display hours/minutes/seconds ago
				$human = $human_hr." ago";
			}
			
		} 
		else if ($this->wasYesterday($date))
		{
			$human = $this->timeOfDay($date) == 'night' ? "Last " : "Yesterday ";
			$human .= $this->timeOfDay($date);
		} 
		else if ($this->wasWithinLast('4 days', $date))
		{
			$human = date('l', $date)." ".$this->timeOfDay($date);
		}
		else if ($this->wasWithinLast('10 days', $date))
		{
			$diff = $this->dateDiff($date);
			$days = floor($diff/86400);
			$human = $days > 1 ? $days." days" : $days." day";
			$human .= " ago";
		} 
		else
		{
			$human = date($default_format, $date);
		}

		return $human;

	}
}