php SEO for url variable, utf8 character for url and file

index.php

<?php

private function utf8convert($str) {
                if(!$str) return false;
				
			$ext = substr($str,strrpos($str,'.',-1),strlen($str));  
			$str = substr($str,0,strrpos($str,'.',-1));  

                $utf8 = array(
            'a'=>'á|à|ả|ã|ạ|ă|ắ|ặ|ằ|ẳ|ẵ|â|ấ|ầ|ẩ|ẫ|ậ|Á|À|Ả|Ã|Ạ|Ă|Ắ|Ặ|Ằ|Ẳ|Ẵ|Â|Ấ|Ầ|Ẩ|Ẫ|Ậ',
            'd'=>'đ|Đ',
            'e'=>'é|è|ẻ|ẽ|ẹ|ê|ế|ề|ể|ễ|ệ|É|È|Ẻ|Ẽ|Ẹ|Ê|Ế|Ề|Ể|Ễ|Ệ',
            'i'=>'í|ì|ỉ|ĩ|ị|Í|Ì|Ỉ|Ĩ|Ị',
            'o'=>'ó|ò|ỏ|õ|ọ|ô|ố|ồ|ổ|ỗ|ộ|ơ|ớ|ờ|ở|ỡ|ợ|Ó|Ò|Ỏ|Õ|Ọ|Ô|Ố|Ồ|Ổ|Ỗ|Ộ|Ơ|Ớ|Ờ|Ở|Ỡ|Ợ',
            'u'=>'ú|ù|ủ|ũ|ụ|ư|ứ|ừ|ử|ữ|ự|Ú|Ù|Ủ|Ũ|Ụ|Ư|Ứ|Ừ|Ử|Ữ|Ự',
            'y'=>'ý|ỳ|ỷ|ỹ|ỵ|Ý|Ỳ|Ỷ|Ỹ|Ỵ',
			);
			foreach($utf8 as $ascii=>$uni) $str = preg_replace("/($uni)/i",$ascii,$str);
			$str = strtolower( trim($str, '-') );
			$str = preg_replace(array('`[^a-z0-9]`i','`[-]+`'), '-', $str);
			return $str.$ext;
	}


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//hinh-anh-gau-bong-dep-38.jpg