[CoursePress] - Alter [course_media] shortcode to enable thumbnail.

cp-add-image-thumbnail.php

<?php
/**
 *
 * Plugin Name: CoursePress - Course Thumbnail
 * Description: Alter [course_media] shortcode to enable thumbnail.
 * Version:     1.0.0
 * Author:      Konstantinos Xenos @ WPMU DEV
 * Author URI:  https://premium.wpmudev.org/
 * License:     GPL-2.0+
 * License URI: http://www.gnu.org/licenses/gpl-2.0.txt
 *
 */

add_action( 'coursepress_course_updated', 'cp_update_thumbnail_id', 10, 2 );
add_action( 'coursepress_course_created', 'cp_update_thumbnail_id', 10, 2 );
function cp_update_thumbnail_id( $course_id, $settings ) {
	global $wpdb;

	$course_image = $settings['listing_image'];

	if ( ! empty( $course_image ) ) {
		$attachment = $wpdb->get_col( $wpdb->prepare( "SELECT ID FROM $wpdb->posts WHERE guid=%s;", $course_image ) );
		update_post_meta( $course_id, '_thumbnail_id', $attachment[0] );
	} else {
		update_post_meta( $course_id, '_thumbnail_id', null );
	}
}

add_action( 'init', 'replace_cp_cm_shortcode', 20 );
function replace_cp_cm_shortcode() {
	remove_shortcode( 'course_media' );
	add_shortcode( 'course_media', 'cp_thumbnail_media_shortcode' );
}

function cp_thumbnail_media_shortcode( $atts ) {
	extract( shortcode_atts( array(
		'course_id' => CoursePress_Helper_Utility::the_course( true ),
		'class'     => '',
		'height'    => CoursePress_Core::get_setting( 'course/image_height' ),
		'list_page' => 'no',
		'priority'  => '', // Gives priority to video (or image).
		'type'      => '', // Default, video, image.
		'width'     => CoursePress_Core::get_setting( 'course/image_width' ),
		'wrapper'   => '',
	), $atts, 'course_media' ) );

	$course_id = (int) $course_id;
	if ( empty( $course_id ) ) {
		return '';
	}

	$type      = sanitize_text_field( $type );
	$priority  = sanitize_text_field( $priority );
	$list_page = cp_is_true( sanitize_html_class( $list_page ) );
	$class     = sanitize_html_class( $class );
	$wrapper   = sanitize_html_class( $wrapper );
	$height    = sanitize_text_field( $height );
	$width     = sanitize_text_field( $width );

	// We'll use pixel if none is set
	if ( ! empty( $width ) && (int) $width == $width ) {
		$width .= 'px';
	}
	if ( ! empty( $height ) && (int) $height == $height ) {
		$height .= 'px';
	}

	if ( ! $list_page ) {
		$type     = empty( $type ) ? CoursePress_Core::get_setting( 'course/details_media_type', 'default' ) : $type;
		$priority = empty( $priority ) ? CoursePress_Core::get_setting( 'course/details_media_priority', 'video' ) : $priority;
	} else {
		$type     = empty( $type ) ? CoursePress_Core::get_setting( 'course/listing_media_type', 'default' ) : $type;
		$priority = empty( $priority ) ? CoursePress_Core::get_setting( 'course/listing_media_priority', 'image' ) : $priority;
	}

	$priority = 'default' != $type ? false : $priority;

	// Saves some overhead by not loading the post again if we don't need to.
	$class = sanitize_html_class( $class );

	$course_video = CoursePress_Data_Course::get_setting( $course_id, 'featured_video' );
	$course_image = CoursePress_Data_Course::get_setting( $course_id, 'listing_image' );

	$content = '';

	if ( 'thumbnail' == $type ) {
		$type     = 'image';
		$priority = 'image';
		$width    = $height = '';
	}

	// If no wrapper and we're specifying a width and height, we need one, so will use div.
	if ( empty( $wrapper ) && ( ! empty( $width ) || ! empty( $height ) ) ) {
		$wrapper = 'div';
	}

	$wrapper_style  = '';
	$wrapper_style .= ! empty( $width ) ? 'width:' . $width . ';' : '';
	$wrapper_style .= ! empty( $width ) ? 'height:' . $height . ';' : '';

	if ( is_singular( 'course' ) ) {
		$wrapper_style = '';
	}

	if ( ( ( 'default' == $type && 'video' == $priority ) || 'video' == $type || ( 'default' == $type && 'image' == $priority && empty( $course_image ) ) ) && ! empty( $course_video ) ) {

		$content = '<div class="video_player course-featured-media course-featured-media-' . $course_id . ' ' . $class . '">';

		$content .= ! empty( $wrapper ) ? '<' . $wrapper . ' style="' . $wrapper_style . '">' : '';

		$video_extension = pathinfo( $course_video, PATHINFO_EXTENSION );

		if ( ! empty( $video_extension ) ) {
			$attr     = array(
				'src' => $course_video,
			);
			$content .= wp_video_shortcode( $attr );
		} else {
			$embed_args = array();

			// Add YouTube filter.
			if ( preg_match( '/youtube.com|youtu.be/', $course_video ) ) {
				add_filter( 'oembed_result', array(
					'CoursePress_Helper_Utility',
					'remove_related_videos',
				), 10, 3 );
			}

			$content .= wp_oembed_get( $course_video, $embed_args );
		}

		$content .= ! empty( $wrapper ) ? '</' . $wrapper . '>' : '';
		$content .= '</div>';
	}

	if ( ( ( 'default' == $type && 'image' == $priority ) || 'image' == $type || ( 'default' == $type && 'video' == $priority && empty( $course_video ) ) ) && ! empty( $course_image ) ) {

		$content .= '<div class="course-thumbnail course-featured-media course-featured-media-' . $course_id . ' ' . $class . '">';
		$content .= ! empty( $wrapper ) ? '<' . $wrapper . ' style="' . $wrapper_style . '">' : '';

		$content .= get_the_post_thumbnail( $course_id );
		$content .= ! empty( $wrapper ) ? '</' . $wrapper . '>' : '';
		$content .= '</div>';
	}

	return $content;
}