shortcodes.php

<?php

/**
 * 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 ];

}