Enforced Facebook Time Adjustment (Importing into The Events Calendar)

fb-adjustment-tec.php

/**
 * Automates the process of correcting times imported from Facebook by a fixed
 * number of hours (plus or minus).
 *
 * @uses DateTime which introduces a requirement for PHP 5.2 or greater
 */
class FBEventsTimeCorrection {
	protected $negative = false;
	protected $hours = 0;
	protected $modifier = '';
	protected $eventData = array();
	const CORRECTION_FORMAT = '#^([\\+-]?)(\\d{1,2})$#';


	/**
	 * Sets up automated correction of imported Facebook event times.
	 *
	 * The correction should be specified in the form of an optional positive or
	 * negative operator (+/-) followed by an integral number in the range 0-12,
	 * such as +11 or -7.
	 *
	 * If not preceded by a positive/negative operator then positive is assumed.
	 *
	 * @param string $correction
	 * @throws Exception
	 */
	public function __construct($correction) {
		if ($this->setCorrection($correction))
			add_filter('tribe_fb_parse_facebook_event', array($this, 'applyCorrection'));

		else throw new Exception('The specified correction cannot be understood.');
	}


	/**
	 * Tests to see if the specified correction is in an understandable format.
	 *
	 * @param string $correction
	 * @return bool
	 */
	public function setCorrection($correction) {
		$matches = array();

		// Test to see if a basic format of [+/-]n has been specified then try to set
		if (preg_match(self::CORRECTION_FORMAT, $correction, $matches) === 1) {
			if (count($matches) !== 3) return false;
			else return $this->setDirectionAndHours($matches[1], $matches[2]);
		}

		return false;
	}


	/**
	 * Sets the internal variables used to record the correction.
	 *
	 * If the $hours param is out of bounds this method will return bool false.
	 *
	 * @param $direction
	 * @param $hours
	 * @return bool
	 */
	protected function setDirectionAndHours($direction, $hours) {
		// Do we have a negative operator?
		if ($direction === '-') $this->negative = true;

		// Extract the number of hours and ensure they are within range
		$this->hours = (int) $hours;
		if ($this->hours < 0 or $this->hours > 12) return false;

		return true;
	}


	/**
	 * Attempts to adjust the event date/time.
	 *
	 * Although we require the DateTime class (available as of PHP 5.2) we will
	 * degrade gracefully for earlier versions of PHP and give an opportunity
	 * for a replacement class to be used on those versions (ie, from PEAR).
	 *
	 * @param array $eventData
	 * @return array
	 */
	public function applyCorrection($eventData) {
		if (class_exists('DateTime')) {
			$this->correctDateTime('Start', $eventData);
			$this->correctDateTime('End', $eventData);
		}

		return $eventData;
	}


	/**
	 * Performs the correction of event date/time.
	 *
	 * @param $modifier
	 * @param $eventData
	 */
	protected function correctDateTime($modifier, &$eventData) {
		$this->modifier = $modifier;
		$this->eventData = $eventData;

		$datetime = $this->getDateTimeObject();
		$datetime->modify($this->getAdjustment());

		$this->rebuildEventData($datetime);
		$eventData = $this->eventData;
	}


	/**
	 * Creates a DateTime object based on the Start|End date/time. Whether it
	 * is the Start or End is determined by the $modifier property.
	 *
	 * @return DateTime
	 */
	protected function getDateTimeObject() {
		$date = $this->eventData["Event{$this->modifier}Date"];
		$hour = $this->eventData["Event{$this->modifier}Hour"];
		$minute = $this->eventData["Event{$this->modifier}Minute"];
		$meridian = $this->eventData["Event{$this->modifier}Meridian"];

		// Convert hour to 24hr format
		if ($meridian === 'PM') $hour += 12;
		$hour = sprintf('%02d', $hour);
		$minute = sprintf('%02d', $minute);

		return new DateTime("$date $hour:$minute:00");
	}


	/**
	 * Generates a strtotime() compatible modifier string.
	 *
	 * @return string
	 */
	protected function getAdjustment() {
		$adjustment = '';

		if ($this->negative) $adjustment .= '-';
		$adjustment .= $this->hours.' hours';

		return $adjustment;
	}


	/**
	 * Rebuilds the event data array with our adjusted date/time.
	 */
	protected function rebuildEventData(DateTime $datetime) {
		$this->eventData["Event{$this->modifier}Date"] = $datetime->format('Y-m-d');
		$this->eventData["Event{$this->modifier}Hour"] = $datetime->format('g');
		$this->eventData["Event{$this->modifier}Minute"] = $datetime->format('i');
		$this->eventData["Event{$this->modifier}Meridian"] = $datetime->format('A');
	}
}