<?php
/**
 * Describes a torrent piece
 *
 * @author Charalampos Pournaris
 */
class TorrentPiece {
	/**
	 * The offset that this piece starts in a file
	 *
	 * @var integer
	 */
	private $start_offset = 0;
	
	/**
	 * The offset that this piece ends in a file
	 *
	 * @var integer
	 */
	private $end_offset = 0;
	
	/**
	 * Piece id (incremental index)
	 *
	 * @var integer
	 */
	private $piece_id = 0;
	
	/**
	 * If it's a shared piece, remaining bytes to complete a piece
	 *
	 * @var integer
	 */
	private $remaining = 0;
	
	/**
	 * This piece length size in bytes
	 *
	 * @var integer
	 */
	private $piece_length = 0;
	
	/**
	 * It is a full piece
	 *
	 * @var boolean
	 */
	private $is_full = false;
	
	/**
	 * It is a partial piece
	 *
	 * @var boolean
	 */
	private $is_shared = false;
	
	/**
	 * Piece size used to create the torrent file
	 *
	 * @var integer
	 */
	public static $piece_size = 0;
	
	/**
	 * Create a new torrent piece object
	 *
	 * @param integer $piece_id
	 * @param integer $start_offset
	 * @param integer $end_offset
	 * @param boolean $is_full
	 * @param boolean $is_shared
	 */
	public function __construct($piece_id, $start_offset, $end_offset, $is_full=false, $is_shared=false) {
		$this->start_offset = $start_offset;
		$this->end_offset = $end_offset;
		$this->piece_id = $piece_id;
		$this->is_full = $is_full;
		$this->is_shared = $is_shared;
		$this->piece_length = $end_offset - $start_offset;
		$this->remaining = self::$piece_size - $this->piece_length;
	}
	
	/**
	 * Returns if this is a full piece
	 *
	 * @return boolean
	 */
	public function isFullPiece() {
		return $this->is_full;
	}
	
	/**
	 * Returns if this a partial piece
	 *
	 * @return boolean
	 */
	public function isPartialPiece() {
		return $this->is_shared;
	}
	
	/**
	 * Set the number of bytes remaining to complete a piece
	 *
	 * @param integer $remaining
	 */
	public function setRemaining($remaining) {
		$this->remaining = $remaining;
	}	
	
	/**
	 * Returns this piece's id
	 *
	 * @return integer
	 */
	public function getPieceId() {
		return $this->piece_id;
	}
	
	/**
	 * Return the start offset
	 *
	 * @return integer
	 */
	public function getStartOffset() {
		return $this->start_offset;
	}
	
	/**
	 * Return the end offset
	 *
	 * @return integer
	 */
	public function getEndOffset() {
		return $this->end_offset;
	}
	
	/**
	 * Get the number of bytes remaining to complete a piece
	 *
	 * @return integer
	 */
	public function getRemaining() {
		return $this->remaining;
	}
	
	/**
	 * Get this piece's length size in bytes
	 *
	 * @return integer
	 */
	public function getPieceLength() {
		return $this->piece_length;
	}
}
?>