shortcodes.php

<?php
/**
 * YouTube Gallery
 *
 * @package      CoreFunctionality
 * @author       Bill Erickson
 * @since        1.0.0
 * @license      GPL-2.0+
**/

/**
 * Youtube Gallery
 */
function ea_youtube_gallery_shortcode( $atts = array() ) {

	$atts = shortcode_atts( array(
		'user' => false
	), $atts, 'ea_youtube_gallery' );
	
	// Only run if user is specified 
	if( empty( $atts['user'] ) ) {
		return;
	}
	
	// Get Videos
	$data = ea_get_youtube_videos( $user );

	$output = '<div class="youtube-gallery">';

	// Video Player
	$output .= '<div class="youtube-gallery--player">';
	$output .= '<h4>Video goes here</h4>';
	$output .= '</div>';

	// Video Listing
	$output .= '<div class="youtube-gallery--listing">';
	for( $i = 0; $i < 24; $i++ ) {
		$class = 0 == $i ? 'item active' : 'item';
		$output .= '<a href="#main-content" class="' . $class . '">';
		$output .= '<span class="title">thumbnail goes here</span>';
		$output .= '</a>';
	}
	$output .= '</div>';

	$output .= '</div>';

	return $output;
}
add_shortcode( 'ea_youtube_gallery', 'ea_youtube_gallery_shortcode' );

/**
 * Get Youtube Videos
 *
 */
function ea_get_youtube_videos( $user = '' ) {

	if( empty( $user ) )
		return;

	$key = 'ea_youtube_gallery_' . sanitize_text_field( $user );

	$data = get_transient( $key );
	if( false === $data ) {

		$channel = ea_get_youtube_channel( $user );

		$url = add_query_arg( array(
			'part'       => 'snippet',
			'channelId'  => $channel,
			'order'      => 'date',
			'maxResults' => 24,
			'key'        => EA_YOUTUBE_API_KEY,
		), 'https://www.googleapis.com/youtube/v3/search' );

		$data = wp_remote_retrieve_body( wp_remote_get( $url ) );
		set_transient( $key, $data, DAY_IN_SECONDS );
	}

	return $data;
}

/**
 * Get Youtube Channel
 *
 */
function ea_get_youtube_channel( $user = '' ) {

	if( empty( $user ) )
		return;

	$channels = get_option( 'ea_youtube_gallery_channels' );
	if( empty( $channels ) || empty( $channels[ $user ] ) ) {

		$url = add_query_arg(
			array(
				'forUsername' => esc_attr( $user ),
				'part'        => 'id',
				'key'         => EA_YOUTUBE_API_KEY,
			),
			'https://www.googleapis.com/youtube/v3/channels'
		);

		$response = wp_remote_get( $url );
		$data = json_decode( wp_remote_retrieve_body( $response ) );
		if( !empty( $data->items ) )
			$channels[ $user ] = $data->items[0]->id;
		else
			$channels[ $user ] = false;

		update_option( 'ea_youtube_gallery_channels', $channels );
	}

	return $channels[ $user ];

}