Add location alert fields to homepage widget

** Why are these changes being introduced:

* There is an upcoming closure to the Hayden library, and we want to
  enable UXWS staff to be able to add alerts to the homepage for cases
  like this without asking for EngX to modify static templates.

** Relevant ticket(s):

* https://mitlibraries.atlassian.net/browse/pw-93

** How does this address that need:

* This adds a function to the homepage locations widget (part of the
  hours plugin), to check each location's record to see if there are any
  location alerts. If either the alert title or alert content field has
  been populated, they are shown to the user below that location's
  entry on the homepage.

** Document any side effects to this change:

* The alert_title and alert_content fields already exist as part of the
  location record type. Those fields are currently shown on the location
  page and the hours page, but only if the title is populated (the
  content field alone being populated does not suffice). This change
  hooks into those fields and displays them in a new location, which may
  have an impact on how UXWS handles these fields.

* This does not get us entirely away from mixing code and content, as
  the homepage hours widget still has hard-coded values for other
  location information (location names, which locations are shown, and
  in what order, etc).

* The old CSS styles for the hayden renovation alert have been renamed
  to be just 'location-alert'.

web/app/plugins/mitlib-pull-hours/templates/display-widget-frontpage.php

@@ -6,6 +6,52 @@
  * @since 0.6.0
  */
 
+/**
+ * This function accepts the post ID of a location record, which will be used
+ * to check if that location has its alert populated. If either of the two
+ * fields for the location alert (alert_title or alert_content) are populated,
+ * that content will be shown in a div.
+ *
+ * The function does not return anything.
+ *
+ * @param string $location_id The ID of a location record to look up.
+ *
+ * @return none
+ */
+function location_alert( $location_id ) {
+	$allowed_html = array(
+		'a' => array(
+			'href' => array(),
+		),
+		'br' => array(),
+		'em' => array(),
+		'p' => array(),
+		'strong' => array(),
+	);
+
+	$query_args = array(
+		'post_type' => 'location',
+		'p' => $location_id,
+		'post_status' => 'publish',
+		'meta_key' => 'primary_location',
+		'meta_value' => 1,
+		'orderby' => 'title',
+		'order' => 'ASC',
+		'ignore_sticky_posts' => 1,
+	);
+	$locations = new \WP_Query($query_args);
+	while ( $locations->have_posts() ) {
+		$locations->the_post();
+		$alert_title = get_field( 'alert_title' );
+		$alert_content = get_field( 'alert_content' );
+		if ( $alert_title || $alert_content ) {
+			echo '<div class="location-alert">';
+			echo wp_kses( $alert_title, $allowed_html );
+			echo wp_kses( $alert_content, $allowed_html );
+			echo '</div>';
+		}
+	}
+}
 ?>
 
 <div class="location">
@@ -14,18 +60,30 @@
 		<h3><a class="name-location" href="/barker">Barker Library</a></h3><div class="hours"><span data-location-hours="Barker Library"></span> today</div><div class="location-info"><a href="/locations/#!barker-library" class="map-location">10-500</a><a href="tel:617-253-0968" class="phone"><span class="number">617-253-0968</span></a></div>
 	</div>
 </div>
+<?php
+	// Load location alerts for Barker (post 322).
+	location_alert( 322 );
+?>
 <div class="location">
 	<a href="/dewey" aria-labelledby="dewey" class="img-loc dewey"><span class="sr" id="dewey">Dewey Library</span></a>
 	<div class="wrap-loc-info">
 		<h3><a class="name-location" href="/dewey">Dewey Library</a></h3><div class="hours"><span data-location-hours="Dewey Library"></span> today</div><div class="location-info"><a href="/locations/#!dewey-library" class="map-location">E53-100</a><a href="tel:617-253-5676" class="phone"><span class="number">617-253-5676</span></a></div>
 	</div>
 </div>
+<?php
+	// Load location alerts for Dewey (post 313).
+	location_alert( 313 );
+?>
 <div class="location">
 	<a href="/hayden" aria-labelledby="hayden" class="img-loc hayden"><span class="sr" id="hayden">Hayden Library</span></a>
 	<div class="wrap-loc-info">
 		<h3><a class="name-location" href="/hayden">Hayden Library</a></h3><div class="hours"><span data-location-hours="Hayden Library"></span> today</div> <div class="location-info"><a href="/locations/#!hayden-library" class="map-location">14S-100</a><a href="tel:617-253-5671" class="phone"><span class="number">617-253-5671</span></a></div>
 	</div>
 </div>
+<?php
+	// Load location alerts for Hayden (post 452).
+	location_alert( 452 );
+?>
 <a href="#0" class="show-more hidden-non-mobile">
 	<svg class="icon-arrow-down" version="1.1" xmlns="http://www.w3.org/2000/svg" x="0" y="0" width="16.3" height="9.4" viewBox="2.7 8.3 16.3 9.4" enable-background="new 2.7 8.3 16.3 9.4" xml:space="preserve"><path d="M18.982 9.538l-8.159 8.159L2.665 9.538l1.284-1.283 6.875 6.875 6.875-6.875L18.982 9.538z"/></svg>Show 3 More
 </a>
@@ -35,16 +93,28 @@
 		<h3><a class="name-location" href="/rotch">Rotch Library</a></h3><div class="hours"><span data-location-hours="Rotch Library"></span> today</div><div class="location-info"><a href="/locations/#!rotch-library" class="map-location">7-238</a><a href="tel:617-258-5592" class="phone"><span class="number">617-258-5592</span></a></div>
 	</div>
 </div>
+<?php
+	// Load location alerts for Rotch (post 359).
+	location_alert( 359 );
+?>
 <div class="location hidden-mobile inactive-mobile">
 	<a href="/distinctive-collections" aria-labelledby="dc" class="img-loc archives"><span class="sr" id="dc">Distinctive Collections Reading Room</span></a>
 	<div class="wrap-loc-info">
 		<h3><a class="name-location" href="/distinctive-collections">Distinctive Collections Reading Room</a></h3><div class="hours"><span data-location-hours="Distinctive Collections"></span> today</div><div class="location-info"><a href="/locations/#!distinctive-collections" class="map-location">14N-118</a><a href="tel:617-253-5690" class="phone"><span class="number">617-253-5690</span></a></div>
 	</div>
 </div>
+<?php
+	// Load location alerts for Distinctive Collections (post 504).
+	location_alert( 504 );
+?>
 <div class="location hidden-mobile inactive-mobile">
 	<a href="/music" aria-labelledby="lewis" class="img-loc lewis"><span class="sr" id="lewis">Lewis Music Library</span></a>
 	<div class="wrap-loc-info">
 		<h3><a class="name-location" href="/music">Lewis Music Library</a></h3><div class="hours"><span data-location-hours="Lewis Music Library"></span> today</div><div class="location-info"><a href="/locations/#!lewis-music-library" class="map-location">14E-109</a><a href="tel:617-253-5689" class="phone"><span class="number">617-253-5689</span></a></div>
 	</div>
 </div>
+<?php
+	// Load location alerts for Lewis (post 473).
+	location_alert( 473 );
+?>
 <a href="/hours" class="button-primary--green full add-margin link-hours">All hours &amp; locations</a>

web/app/themes/mitlib-parent/css/scss/partials/_home.scss

@@ -199,7 +199,7 @@ body.page-home {
 			}
 		}
 
-		.location-hayden-reno {
+		.location-alert {
 			padding: .5rem 1em;
 			color: #008700;
 			margin: 0;