<?php
 
function bencode($data) {
	if(is_array($data)) {
		$assoc = false;
		$old_key = -1;
		foreach($data as $key => $value) {
			if(!is_int($key) || $key != ($old_key + 1)) {
				$assoc = true;
				break;
			}
            $old_key = $key;
		}
		if($assoc) {
			$string = 'd';
            ksort($data, SORT_STRING);
			foreach($data as $key => $value) {
				$string .= bencode($key) . bencode($value);
			}
		} else {
			$string = 'l';
			foreach($data as $value) {
				$string .= bencode($value);
			}
		}
        $string .= 'e';
		return $string;
	} elseif(is_int($data)) {
		return 'i' . $data . 'e';
	} elseif(is_string($data)) {
		return strlen($data) . ':' . $data;
	}
}
 
function bdecode(&$string) {
	if($string == "") {
		return null;
	}
	if($string == null) {
		die('Failed to decode' . "\n");
	}
	switch($string[0]) {
		case 'i':
			$end = strpos($string, 'e');
			if($end === false) {
				die('Failed to decode' . "\n");
			}
			$data = (int) substr($string, 1, $end - 1);
			$string = (string) substr($string, $end + 1);
			return $data;
		case 'l':
			$string = substr($string, 1);
			$data = array();
			while($string[0] != 'e') {
				$data[] = bdecode($string);
			}
			$string = (string) substr($string, 1);
			return $data;
		case 'd':
			$string = substr($string, 1);
			$data = array();
			while($string[0] != 'e') {
				$data[bdecode($string)] = bdecode($string);
			}
			$string = (string) substr($string, 1);
			return $data;
		default:
			$end = strpos($string, ':') + 1;
			if($end == 0) {
				die('Failed to decode' . "\n");
			}
			$length = (int) substr($string, 0, $end);
			$string = substr($string, $end);
			if($length > strlen($string)) {
				die('Failed to decode' . "\n");
			}
			$data = substr($string, 0, $length);
			$string = (string)substr($string, $length);
			return $data;
	}
}
 
?>