Greeklish file names for uploads

<?php

$greeklish = static function ( string $text ): string {
	$text = mb_strtolower( $text, 'UTF-8' );
	$text = strtr( $text, array( 'ου' => 'ou', 'ού' => 'ou' ) );
	return strtr(
		$text,
		array(
			'α' => 'a', 'ά' => 'a', 'β' => 'v', 'γ' => 'g', 'δ' => 'd', 'ε' => 'e', 'έ' => 'e',
			'ζ' => 'z', 'η' => 'i', 'ή' => 'i', 'θ' => 'th', 'ι' => 'i', 'ί' => 'i', 'ϊ' => 'i',
			'ΐ' => 'i', 'κ' => 'k', 'λ' => 'l', 'μ' => 'm', 'ν' => 'n', 'ξ' => 'x', 'ο' => 'o',
			'ό' => 'o', 'π' => 'p', 'ρ' => 'r', 'σ' => 's', 'ς' => 's', 'τ' => 't', 'υ' => 'y',
			'ύ' => 'y', 'ϋ' => 'y', 'ΰ' => 'y', 'φ' => 'f', 'χ' => 'ch', 'ψ' => 'ps', 'ω' => 'o',
			'ώ' => 'o',
		)
	);
};

add_filter(
	'sanitize_file_name',
	static function ( $filename ) use ( $greeklish ) {
		if ( ! preg_match( '/\p{Greek}/u', (string) $filename ) ) {
			return $filename;
		}
		$filename = preg_replace( '/[^a-z0-9._-]+/', '-', $greeklish( (string) $filename ) );
		return trim( preg_replace( '/-{2,}/', '-', $filename ), '-' );
	},
	5
);