<?php
function disable_emojis(){
	remove_action('wp_head', 'print_emoji_detection_script', 7);
	remove_action('admin_print_scripts', 'print_emoji_detection_script');
	remove_action('wp_print_styles', 'print_emoji_styles');
	remove_action('admin_print_styles', 'print_emoji_styles');
	remove_filter('the_content_feed', 'wp_staticize_emoji');
	remove_filter('comment_text_rss', 'wp_staticize_emoji');
	remove_filter('wp_mail', 'wp_staticize_emoji_for_email');
	add_filter('tiny_mce_plugins', 'disable_emojis_tinymce');
	add_filter('wp_resource_hints', 'disable_emojis_remove_dns_prefetch', 10, 2);
}

add_action('init', 'disable_emojis');

/**
 * Filter function used to remove the tinymce emoji plugin.
 *
 * @param array $plugins
 *
 * @return array Difference betwen the two arrays
 */
function disable_emojis_tinymce($plugins){
	if(is_array($plugins)) {
		return array_diff($plugins, array( 'wpemoji' ));
	} else {
		return array();
	}
}

/**
 * Remove emoji CDN hostname from DNS prefetching hints.
 *
 * @param array  $urls          URLs to print for resource hints.
 * @param string $relation_type The relation type the URLs are printed for.
 *
 * @return array Difference betwen the two arrays.
 */
function disable_emojis_remove_dns_prefetch($urls, $relation_type){
	if('dns-prefetch' == $relation_type) {
		/** This filter is documented in wp-includes/formatting.php */
		$emoji_svg_url = apply_filters('emoji_svg_url', 'https://s.w.org/images/core/emoji/2/svg/');

		$urls = array_diff($urls, array( $emoji_svg_url ));
	}

	return $urls;
}