Split string based on number of words, returning before and after (similar to wp_trim_words -- but passed words after instead of discarding)

functions.php

<?php
if( ! function_exists( 'smyles_wp_split_words' ) ){
	/**
	 * Split a string based on word count
	 *
	 * This is similar to WordPress wp_trim_words function, but instead of just trimming after a certain amount of
	 * words, this function returns an array with 'before' and 'after' keys -- providing you the string of text up
	 * to the number of words (in before key), and the words after (in the after key).  After key will be empty string
	 * if there are less words in the passed string than number of words to split on.
	 *
	 *
	 * @param string    $text
	 * @param int       $num_words
	 *
	 * @return array    Array with `before` and `after` keys. The `before` key contains all words up to $num_words, the
	 *                  `after` key contains the words after $num_words (or empty string if passed string has less words
	 *                  than passed in $text)
	 *
	 */
	function smyles_wp_split_words( $text, $num_words = 55 ) {

		$text = wp_strip_all_tags( $text );

		/*
		 * translators: If your word count is based on single characters (e.g. East Asian characters),
		 * enter 'characters_excluding_spaces' or 'characters_including_spaces'. Otherwise, enter 'words'.
		 * Do not translate into your own language.
		 */
		if ( strpos( _x( 'words', 'Word count type. Do not translate!' ), 'characters' ) === 0 && preg_match( '/^utf\-?8$/i', get_option( 'blog_charset' ) ) ) {
			$text = trim( preg_replace( "/[\n\r\t ]+/", ' ', $text ), ' ' );
			preg_match_all( '/./u', $text, $words_array_matches );
			$words_array = $words_array_matches[0];
			$sep         = '';
		} else {
			$words_array = preg_split( "/[\n\r\t ]+/", $text, -1, PREG_SPLIT_NO_EMPTY );
			$sep         = ' ';
		}

		if ( count( $words_array ) > $num_words ) {
			$before = implode( $sep, array_slice( $words_array, 0, $num_words ) );
			$after  = implode( $sep, array_slice( $words_array, $num_words, count( $words_array ) - 1 ) );
		} else {
			$before = implode( $sep, $words_array );
		}

		$results = array(
			'before' => $before,
			'after' => isset( $after ) ? $after : ''
		);

		return $results;
	}
}