<?php
/**
 * Info about a torrent metadata file
 *
 * @author Charalampos Pournaris
 */
class TorrentInfo {
	/**
	 * Torrent file bdecoder
	 *
	 * @var BDecode
	 */
	private $torrent = null;
	
	/**
	 * All the pieces as a single string
	 *
	 * @var string
	 */
	private $pieces = '';
	
	/**
	 * All pieces length
	 *
	 * @var integer
	 */
	private $pieces_length = 0;
	
	/**
	 * Piece length used to create torrent
	 *
	 * @var integer
	 */
	private $piece_length = 0;
	
	/**
	 * Total length of the torrent data
	 *
	 * @var integer
	 */
	private $total_length = 0;
	
	/**
	 * The info hash string (sha1 hashed)
	 *
	 * @var string
	 */
	private $info_hash = '';
	
	/**
	 * Create a new torrentinfo object
	 *
	 * @param array $torrent
	 */
	public function __construct($torrent = array()) {
		$encoder = new BEncode ( );
		
		if (! empty ( $torrent )) {
			$this->torrent = $torrent;
			$this->pieces = bin2hex ( $torrent->result ['info'] ['pieces'] );
			$this->pieces_length = strlen ( $this->pieces );
			$this->piece_length = $torrent->result ['info'] ['piece length'];
			$this->info_hash = sha1 ( $encoder->encode ( $torrent->result ['info'] ) );
		}
	}
	
	/**
	 * Getter method for pieces field
	 *
	 * @return string
	 */
	public function getPieces() {
		return $this->pieces;
	}
	
	/**
	 * Getter method for info_hash field
	 *
	 * @return string
	 */
	public function getInfoHash() {
		return $this->info_hash;
	}
	
	/**
	 * Getter method for piece_length field
	 *
	 * @return integer
	 */
	public function getPieceLength() {
		return $this->piece_length;
	}
	
	/**
	 * Returns the hash (sha1'd) for a specific piece
	 *
	 * @param integer $piece_index
	 * @return string
	 */
	public function getPieceHash($piece_index) {
		return substr ( $this->pieces, ($piece_index - 1) * 40, 40 );
	}
	
	/**
	 * Checks pieces for equality
	 *
	 * @param integer $piece_index
	 * @param string $hash
	 * @return boolean
	 */
	public function equalPieceHash($piece_index, $hash) {
		return substr_compare ( $this->pieces, $hash, ($piece_index - 1) * 40, 40 ) == 0;
	}
	
	/**
	 * Returns the file list
	 *
	 * @return array
	 */
	public function getFiles() {
		return $this->torrent->result ['info'] ['files'];
	}
	
	/**
	 * Returns the torrent target directory/filename
	 *
	 * @return string
	 */
	public function getName() {
		return $this->torrent->result ['info'] ['name'];
	}
	
	/**
	 * Calculate the total length of the torrent data
	 *
	 * @return integer
	 */
	public function calculateLength() {
		$files = $this->getFiles ();
		
		if ($this->total_length != 0 || empty ( $files ))
			return;
		
		foreach ( $files as $fileinfo ) {
			$this->total_length += $fileinfo ['length'];
		}
		
		return $this->total_length;
	}
	
	/**
	 * Return torrent data total length
	 *
	 * @return integer
	 */
	public function getTotalLength() {
		return $this->total_length;
	}
	
	/**
	 * Returns an array with the filenames (fullpath) and size
	 *
	 * @param string $rootpath
	 * @return array
	 */
	public function getFilePathList($rootpath = null) {
		$filelist = array();
		
		foreach ( $this->getFiles() as $fileinfo ) {
			$filelist[] = array('path'=>(is_null($rootpath) ? $this->getName() : $rootpath) . '/' . implode ( '/', $fileinfo ['path'] ), 'size'=>$fileinfo['length']);
		}
		
		return $filelist;
	}
}
?>