Adds all contact methods to co-authors-plus plugin guest authors screen

co-authors-plus-contactmethods.php

<?php

// Adds all contact methods to co-authors-plus plugin guest authors screen

add_filter( 'coauthors_guest_author_fields', 'coauthors_contactmethods', 10, 2 );
function coauthors_contactmethods( $fields, $groups ) {

	if ( ! in_array( 'contact-info', $groups ) && $groups[ 0 ] !== 'all' )
		return $fields;

	$contact_methods = apply_filters( 'user_contactmethods', array() );

	$existing_keys = array_map( function( $item ) {
		return $item[ 'key' ];
		}, $fields );

	foreach( $contact_methods as $key => $label ) {
		if ( $index = array_search( $key, $existing_keys ) )
			unset( $fields[ $index ] );
		$fields[] = array(
			'key' => $key,
			'label' => $label,
			'group' => 'contact-info',
			'sanitize_function' => 'sanitize_text_field'
		);
	}

	return array_values( $fields );
}