<?php

namespace Leenooks\OpenPGP;

/**
 * OpenPGP Compressed Data packet (tag 8).
 *
 * @see http://tools.ietf.org/html/rfc4880#section-5.6
 */
class CompressedDataPacket extends Packet implements \IteratorAggregate, \ArrayAccess
{
	protected $tag = 8;
	public $algorithm;

	/* see http://tools.ietf.org/html/rfc4880#section-9.3 */
	static $algorithms = [
		0 => 'Uncompressed',
		1 => 'ZIP',
		2 => 'ZLIB',
		3 => 'BZip2',
	];

	// IteratorAggregate interface

	function getIterator()
	{
		return new \ArrayIterator($this->data->packets);
	}

	// ArrayAccess interface

	function offsetExists($offset) {
		return isset($this->data[$offset]);
	}

	function offsetGet($offset) {
		return $this->data[$offset];
	}

	function offsetSet($offset, $value) {
		return is_null($offset) ? $this->data[] = $value : $this->data[$offset] = $value;
	}

	function offsetUnset($offset) {
		unset($this->data[$offset]);
	}

	function body()
	{
		$body = chr($this->algorithm);

		switch($this->algorithm) {
			case 0:
				$body .= $this->data->to_bytes();
				break;

			case 1:
				$body .= gzdeflate($this->data->to_bytes());
				break;

			case 2:
				$body .= gzcompress($this->data->to_bytes());
				break;

			case 3:
				$body .= bzcompress($this->data->to_bytes());
				break;

			default:
				/* @todo error? */
		}

		return $body;
	}

	function read()
	{
		$this->algorithm = ord($this->read_byte());
		$this->data = $this->read_bytes($this->length);

		switch($this->algorithm) {
			case 0:
				$this->data = OpenPGP\Message::parse($this->data);
				break;

			case 1:
				$this->data = OpenPGP\Message::parse(gzinflate($this->data));
				break;

			case 2:
				$this->data = OpenPGP\Message::parse(gzuncompress($this->data));
				break;

			case 3:
				$this->data = OpenPGP\Message::parse(bzdecompress($this->data));
				break;

			default:
				/* TODO error? */
		}
	}
}