RecurringSupport.php

<?php
App::uses('CalendarDate', 'Lib');

/**
 * Support class for working with recurring entries
 *
 */
class RecurringSupport {

	protected static $_modelName;

/**
 * Calculate recurrence based on a list of inputs
 *
 * Settings can be the following:
 *  - limit: The max number of expansions to do on each entry (Must be integer) - default is 10 expansions
 *  - skipBefore: Skip all expansions before this date (Must be a CalendarDate object)
 *  - dateInterval: Number of "time" to skip for each expansion test (Must be a DateInterval object) - default is 1 day
 *
 * @param array $entries A list of recurring entries that should be expanded
 * @param array $settings A list of extra configurations for the calculations
 * @return array The expanded list
 */
	public static function calculateRecurrence($entries, $settings = array()) {
		$defaults = array(
			'limit'			=> 10,
			'skipBefore'	=> null,
			'dateInterval'	=> new DateInterval('P1D'),
		);

		$settings = array_merge($defaults, $settings);

		$return = array();
		foreach ($entries as $entry) {
			if (!Hash::get($entry, static::_prefixKey('is_recurrent'))) {
				$return[] = $entry;
				continue;
			}

			$start = new CalendarDate(Hash::get($entry, static::_prefixKey('start_time')));
			$stop  = new CalendarDate(Hash::get($entry, static::_prefixKey('end_time')));

			$expansions = 0;
			for ($date = $start; $date <= $stop; $date->add($settings['dateInterval'])) {
				if ($settings['skipBefore'] && $date < $settings['skipBefore']) {
					continue;
				}

				if (!static::ruleIsTrue($entry, $date)) {
					continue;
				}

				$expansions++;
				$return[] = static::renderEventForDate($entry, clone $date);

				if (is_numeric($settings['limit']) && $expansions >= $settings['limit']) {
					break;
				}
			}
		}

		return $return;
	}

/**
 * Get the next recurring date for an entry or list of entries
 *
 * This method will only expand forward in time, and only find the next recurring date
 *
 * The list must be bare, not containing any model alias key
 *
 * @param array $entries
 * @return array
 */
	public static function getNextDate($entries, $model = null) {
		static::_setModelName($model);

		if (isset($entries[0])) {
			$entries = array($entries);
		}

		$result = static::calculateRecurrence($entries, array('limit' => 1, 'skipBefore' => new CalendarDate()));

		if (empty($result)) {
			return $entries;
		}

		return $entries;
	}

/**
 * Renders a recurring entry for the given date. Does not check to make sure the
 * event occurs on this date (use RecurrenceRule::ruleIsTrue for that).
 *
 * @param array $entry Contains data formatted the same as a retrieved entry from a find.
 * @param DateTime $date A DateTime object in UTC time. This is the date to render the event for.
 * @return array The instance rendered for this recurring event
 */
	public static function renderEventForDate($entry, DateTime $date) {
		$start_date = new CalendarDate(Hash::get($entry, static::_prefixKey('start_time')));
		$end_date   = new CalendarDate(Hash::get($entry, static::_prefixKey('end_time')));

		$interval = $start_date->diff($end_date);
		$interval = new DateInterval("PT{$interval->h}H{$interval->i}M");

		$floating_start_hour = $start_date->format('H');
		$date->setTime($floating_start_hour, $date->format('i'), $date->format('s'));

		$entry = Hash::insert($entry, static::_prefixKey('start_time'), $date->format());

		$date->add($interval);
		$entry = Hash::insert($entry, static::_prefixKey('end_time'), $date->format());

		return $entry;
	}

/**
 * Test if a expansion rule is true
 *
 * It will check the frequency key and check if should be recurring on the date provided as 2nd argument
 *
 * @param array $entry
 * @param DateTime $date
 * @return boolean
 */
	public static function ruleIsTrue($entry, DateTime $date) {
		$itemStart	= new CalendarDate(Hash::get($entry, static::_prefixKey('start_time')));
		$itemEnd	= new CalendarDate(Hash::get($entry, static::_prefixKey('end_time')));
		$frequency	= Hash::get($entry, static::_prefixKey('frequency'));

		if ($frequency == 'weekly') {
			$dayOfWeek = strtolower($itemStart->format('l'));
			return $dayOfWeek == strtolower($date->format('l'));
		}

		if ($frequency === 'daily') {
			return true;
		}

		return false;
	}

/**
 * Optionally prefix a key with a modelName
 *
 * Returns the original key if no prefix is specified
 *
 * @param string $key
 * @return string
 */
	protected static function _prefixKey($key) {
		if (empty(static::$_modelName)) {
			return $key;
		}

		return sprintf('%s.%s', static::$_modelName, $key);
	}

/**
 * Set the prefix for _prefixKey calls
 *
 * @param string $model
 * @return void
 */
	protected static function _setModelName($model) {
		static::$_modelName = $model;
	}
}