Advent calender displays one new audio piece per day

advent-calendar.php

<?php

/*
 * Display a new item every day of current month (like an Advent calendar).
 * If day has arrived: display the article HTML.
 * If day hasn't arrived, print default HTML.
 * Restrict numbers to total days in current month.
 *
 * Compares an array's key (day number) to current day of  month.
 * Made for Hearing Voices page "Xmas: HV Holiday Stories" (2016).
 * @see https://hearingvoices.com/audio/xmas/
 * 
 * Uses "Cubes Advent Calendar" scripts from Codrops:
 * @see https://tympanus.net/codrops/2016/11/09/cubes-advent-calendar/
 * 
 * Uses these files:
 * @see https://hearingvoices.com/news/wp-content/uploads/2016/12/xmas.css
 * @see https://hearingvoices.com/news/wp-content/uploads/2016/12/xmas.js
 */
// Set timezone; get today's day of month and total days in month.
date_default_timezone_set('America/New_York');
$day_of_month  = (int) date( 'j' );
// $days_in_month = (int) date( 't' );
// $day_of_month = 12; // Define var value to test.
$days_in_month = 25; // Day of Christmas in December.
$month = 'Dec';

// Compare array key (day number) to current day of  month.
foreach ($day_arr as $day => $info) {
	$color = ($day % 2 == 0) ? 'cc0019' : '1c2d3f';

	if ( $day <= $day_of_month ) { // Display article HTML.
?>
	<div class="cube" data-bg-color="#<?php echo $color ?>" data-title="<?php echo $info ?>"></div>
<?php
	} elseif ( $day <= $days_in_month ) { // Display default HTML.
?>
	<div class="cube" data-inactive data-bg-color="#6161616" data-title="Coming <?php echo $month . ' ' . $day ?>"></div>
<?php
	} else {
		break;
	}
}

/*
Above PHP goes inside this div:
<div class="calendar">
<!-- PHP goes here. -->
</div>

<!-- Example of one item: -->
<article class="content__block"><?php $day_arr[21] = 'Homeless: My Name'; ?>
	<h3 class="content__title">Homeless: My Name Is</h3>
	<p class="content__description">Voices in the Minnesota <a href="http://hearingvoices.com/2008/08/land-of-10k-homeless-npr/">&ldquo;Land of 10,000 Homeless&rdquo;</a> series, by <a href="http://www.voicesofthestreets.org/Voices%20of%20the%20Streets/Who%20We%20Are.html">Andrew Turpening</a> and <a href="https://somethingsparks.com/">Danny Burke</a> <small>( <em><a href="http://www.npr.org/templates/story/story.php?storyId=91881310">Day to Day</a></em>)</small>.
	<?php echo do_shortcode( '[audio src="http://download.npr.org/anon.npr-mp3/npr/day/2008/07/20080702_day_05.mp3" preload="metadata"]' ); ?></p>
	<p class="content__meta">by <a href="http://www.voicesofthestreets.org/">Voices in the Streets</a></p>
</article>
*/

?>