<?php
/**
 * A NetworkPackage class. This class implements Deliverable and Receivable
 * because all network packages should be deliverable to other nodes and
 * receivable from other nodes. It further provides methods for reading raw
 * content from template engines and feeding it to the stacker for undeclared
 * packages.
 *
 * The factory method requires you to provide a compressor class (which must
 * implement the Compressor interface). If you don't want any compression (not
 * adviceable due to increased network load), please use the NullCompressor
 * class and encode it with BASE64 for a more error-free transfer over the
 * Internet.
 *
 * For performance reasons, this class should only be instanciated once and then
 * used as a "pipe-through" class.
 *
 * @author		Roland Haeder <webmaster@ship-simu.org>
 * @version		0.0.0
 * @copyright	Copyright (c) 2007, 2008 Roland Haeder, 2009 - 2012 Hub Developer Team
 * @license		GNU GPL 3.0 or any newer version
 * @link		http://www.ship-simu.org
 * @todo		Needs to add functionality for handling the object's type
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
class NetworkPackage extends BaseHubSystem implements Deliverable, Receivable, Registerable, Visitable {
	/**
	 * Package mask for compressing package data:
	 * 0: Compressor extension
	 * 1: Raw package data
	 * 2: Tags, seperated by semicolons, no semicolon is required if only one tag is needed
	 * 3: Checksum
	 *                     0  1  2  3
	 */
	const PACKAGE_MASK = '%s%s%s%s%s%s%s';

	/**
	 * Separator for the above mask
	 */
	const PACKAGE_MASK_SEPARATOR = '^';

	/**
	 * Size of an array created by invoking
	 * explode(NetworkPackage::PACKAGE_MASK_SEPARATOR, $content).
	 */
	const PACKAGE_CONTENT_ARRAY_SIZE = 4;

	/**
	 * Separator for checksum
	 */
	const PACKAGE_CHECKSUM_SEPARATOR = '_';

	/**
	 * Array indexes for above mask, start with zero
	 */
	const INDEX_COMPRESSOR_EXTENSION = 0;
	const INDEX_PACKAGE_DATA         = 1;
	const INDEX_TAGS                 = 2;
	const INDEX_CHECKSUM             = 3;

	/**
	 * Array indexes for raw package array
	 */
	const INDEX_PACKAGE_SENDER    = 0;
	const INDEX_PACKAGE_RECIPIENT = 1;
	const INDEX_PACKAGE_CONTENT   = 2;
	const INDEX_PACKAGE_STATUS    = 3;
	const INDEX_PACKAGE_SIGNATURE = 4;

	/**
	 * Size of the decoded data array ('status' is not included)
	 */
	const DECODED_DATA_ARRAY_SIZE = 4;

	/**
	 * Named array elements for decoded package content
	 */
	const PACKAGE_CONTENT_EXTENSION = 'compressor';
	const PACKAGE_CONTENT_MESSAGE   = 'message';
	const PACKAGE_CONTENT_TAGS      = 'tags';
	const PACKAGE_CONTENT_CHECKSUM  = 'checksum';

	/**
	 * Named array elements for package data
	 */
	const PACKAGE_DATA_SENDER    = 'sender';
	const PACKAGE_DATA_RECIPIENT = 'recipient';
	const PACKAGE_DATA_PROTOCOL  = 'protocol';
	const PACKAGE_DATA_CONTENT   = 'content';
	const PACKAGE_DATA_STATUS    = 'status';
	const PACKAGE_DATA_SIGNATURE = 'signature';

	/**
	 * All package status
	 */
	const PACKAGE_STATUS_NEW     = 'new';
	const PACKAGE_STATUS_FAILED  = 'failed';
	const PACKAGE_STATUS_DECODED = 'decoded';

	/**
	 * Constants for message data array
	 */
	const MESSAGE_ARRAY_DATA = 'message_data';
	const MESSAGE_ARRAY_TYPE = 'message_type';

	/**
	 * Tags separator
	 */
	const PACKAGE_TAGS_SEPARATOR = ';';

	/**
	 * Raw package data separator
	 */
	const PACKAGE_DATA_SEPARATOR = '#';

	/**
	 * Network target (alias): 'upper hubs'
	 */
	const NETWORK_TARGET_UPPER_HUBS = 'upper';

	/**
	 * Network target (alias): 'self'
	 */
	const NETWORK_TARGET_SELF = 'self';

	/**
	 * TCP package size in bytes
	 */
	const TCP_PACKAGE_SIZE = 512;

	/**************************************************************************
	 *                    Stacker for out-going packages                      *
	 **************************************************************************/

	/**
	 * Stacker name for "undeclared" packages
	 */
	const STACKER_NAME_UNDECLARED = 'package_undeclared';

	/**
	 * Stacker name for "declared" packages (which are ready to send out)
	 */
	const STACKER_NAME_DECLARED = 'package_declared';

	/**
	 * Stacker name for "out-going" packages
	 */
	const STACKER_NAME_OUTGOING = 'package_outgoing';

	/**************************************************************************
	 *                     Stacker for incoming packages                      *
	 **************************************************************************/

	/**
	 * Stacker name for "incoming" decoded raw data
	 */
	const STACKER_NAME_DECODED_INCOMING = 'package_decoded_data';

	/**
	 * Stacker name for handled decoded raw data
	 */
	const STACKER_NAME_DECODED_HANDLED = 'package_handled_decoded';

	/**
	 * Stacker name for "chunked" decoded raw data
	 */
	const STACKER_NAME_DECODED_CHUNKED = 'package_chunked_decoded';

	/**************************************************************************
	 *                     Stacker for incoming messages                      *
	 **************************************************************************/

	/**
	 * Stacker name for new messages
	 */
	const STACKER_NAME_NEW_MESSAGE = 'package_new_message';

	/**
	 * Stacker name for processed messages
	 */
	const STACKER_NAME_PROCESSED_MESSAGE = 'package_processed_message';

	/**************************************************************************
	 *                   Stacker for other/internal purposes                  *
	 **************************************************************************/

	/**
	 * Stacker name for "back-buffered" packages
	 */
	const STACKER_NAME_BACK_BUFFER = 'package_backbuffer';

	/**
	 * Protected constructor
	 *
	 * @return	void
	 */
	protected function __construct () {
		// Call parent constructor
		parent::__construct(__CLASS__);
	}

	/**
	 * Creates an instance of this class
	 *
	 * @param	$compressorInstance		A Compressor instance for compressing the content
	 * @return	$packageInstance		An instance of a Deliverable class
	 */
	public static final function createNetworkPackage (Compressor $compressorInstance) {
		// Get new instance
		$packageInstance = new NetworkPackage();

		// Now set the compressor instance
		$packageInstance->setCompressorInstance($compressorInstance);

		/*
		 * We need to initialize a stack here for our packages even for those
		 * which have no recipient address and stamp... ;-) This stacker will
		 * also be used for incoming raw data to handle it.
		 */
		$stackerInstance = ObjectFactory::createObjectByConfiguredName('network_package_stacker_class');

		// At last, set it in this class
		$packageInstance->setStackerInstance($stackerInstance);

		// Init all stacker
		$packageInstance->initStackers();

		// Get a visitor instance for speeding up things
		$visitorInstance = ObjectFactory::createObjectByConfiguredName('node_raw_data_monitor_visitor_class', array($packageInstance));

		// Set it in this package
		$packageInstance->setVisitorInstance($visitorInstance);

		// Get crypto instance and set it in this package
		$cryptoInstance = ObjectFactory::createObjectByConfiguredName('crypto_class');
		$packageInstance->setCryptoInstance($cryptoInstance);

		// Get a singleton package assembler instance from factory and set it here
		$assemblerInstance = PackageAssemblerFactory::createAssemblerInstance($packageInstance);
		$packageInstance->setAssemblerInstance($assemblerInstance);

		// Return the prepared instance
		return $packageInstance;
	}

	/**
	 * Initialize all stackers
	 *
	 * @param	$forceReInit	Whether to force reinitialization of all stacks
	 * @return	void
	 */
	protected function initStackers ($forceReInit = false) {
		// Initialize all
		foreach (
			array(
				self::STACKER_NAME_UNDECLARED,
				self::STACKER_NAME_DECLARED,
				self::STACKER_NAME_OUTGOING,
				self::STACKER_NAME_DECODED_INCOMING,
				self::STACKER_NAME_DECODED_HANDLED,
				self::STACKER_NAME_DECODED_CHUNKED,
				self::STACKER_NAME_NEW_MESSAGE,
				self::STACKER_NAME_PROCESSED_MESSAGE,
				self::STACKER_NAME_BACK_BUFFER
			) as $stackerName) {
				// Init this stacker
				$this->getStackerInstance()->initStacker($stackerName, $forceReInit);
		} // END - foreach
	}

	/**
	 * "Getter" for hash from given content
	 *
	 * @param	$content	Raw package content
	 * @return	$hash		Hash for given package content
	 */
	private function getHashFromContent ($content) {
		// Debug message
		//* NOISY-DEBUG: */ $this->debugOutput('NETWORK-PACKAGE: content[md5]=' . md5($content) . ',sender=' . $this->getSessionId() . ',compressor=' . $this->getCompressorInstance()->getCompressorExtension());

		// Create the hash
		// @TODO crc32() is very weak, but it needs to be fast
		$hash = crc32(
			$content .
			self::PACKAGE_CHECKSUM_SEPARATOR .
			$this->getSessionId() .
			self::PACKAGE_CHECKSUM_SEPARATOR .
			$this->getCompressorInstance()->getCompressorExtension()
		);

		// And return it
		return $hash;
	}

	/**
	 * Checks whether the checksum (sometimes called "hash") is the same
	 *
	 * @param	$decodedContent		Package raw content
	 * @param	$decodedData		Whole raw package data array
	 * @return	$isChecksumValid	Whether the checksum is the same
	 */
	private function isChecksumValid (array $decodedContent, array $decodedData) {
		// Get checksum
		$checksum = $this->getHashFromContentSessionId($decodedContent, $decodedData[self::PACKAGE_DATA_SENDER]);

		// Is it the same?
		$isChecksumValid = ($checksum == $decodedContent[self::PACKAGE_CONTENT_CHECKSUM]);

		// Return it
		return $isChecksumValid;
	}

	/**
	 * Change the package with given status in given stack
	 *
	 * @param	$packageData	Raw package data in an array
	 * @param	$stackerName	Name of the stacker
	 * @param	$newStatus		New status to set
	 * @return	void
	 */
	private function changePackageStatus (array $packageData, $stackerName, $newStatus) {
		// Skip this for empty stacks
		if ($this->getStackerInstance()->isStackEmpty($stackerName)) {
			// This avoids an exception after all packages has failed
			return;
		} // END - if

		// Pop the entry (it should be it)
		$nextData = $this->getStackerInstance()->popNamed($stackerName);

		// Compare both signatures
		assert($nextData[self::PACKAGE_DATA_SIGNATURE] == $packageData[self::PACKAGE_DATA_SIGNATURE]);

		// Temporary set the new status
		$packageData[self::PACKAGE_DATA_STATUS] = $newStatus;

		// And push it again
		$this->getStackerInstance()->pushNamed($stackerName, $packageData);
	}

	/**
	 * "Getter" for hash from given content and sender's session id
	 *
	 * @param	$decodedContent		Decoded package content
	 * @param	$sessionId			Session id of the sender
	 * @return	$hash				Hash for given package content
	 */
	public function getHashFromContentSessionId (array $decodedContent, $sessionId) {
		// Debug message
		//* NOISY-DEBUG: */ $this->debugOutput('NETWORK-PACKAGE: content[md5]=' . md5($decodedContent[self::PACKAGE_CONTENT_MESSAGE]) . ',sender=' . $sessionId . ',compressor=' . $decodedContent[self::PACKAGE_CONTENT_EXTENSION]);

		// Create the hash
		// @TODO crc32() is very weak, but it needs to be fast
		$hash = crc32(
			$decodedContent[self::PACKAGE_CONTENT_MESSAGE] .
			self::PACKAGE_CHECKSUM_SEPARATOR .
			$sessionId .
			self::PACKAGE_CHECKSUM_SEPARATOR .
			$decodedContent[self::PACKAGE_CONTENT_EXTENSION]
		);

		// And return it
		return $hash;
	}

	///////////////////////////////////////////////////////////////////////////
	//                   Delivering packages / raw data
	///////////////////////////////////////////////////////////////////////////

	/**
	 * Delivers the given raw package data.
	 *
	 * @param	$packageData	Raw package data in an array
	 * @return	void
	 */
	private function declareRawPackageData (array $packageData) {
		/*
		 * We need to disover every recipient, just in case we have a
		 * multi-recipient entry like 'upper' is. 'all' may be a not so good
		 * target because it causes an overload on the network and may be
		 * abused for attacking the network with large packages.
		 */
		$discoveryInstance = PackageDiscoveryFactory::createPackageDiscoveryInstance();

		// Discover all recipients, this may throw an exception
		$discoveryInstance->discoverRecipients($packageData);

		// Now get an iterator
		$iteratorInstance = $discoveryInstance->getIterator();

		// Rewind back to the beginning
		$iteratorInstance->rewind();

		// ... and begin iteration
		while ($iteratorInstance->valid()) {
			// Get current entry
			$currentRecipient = $iteratorInstance->current();

			// Set the recipient
			$packageData[self::PACKAGE_DATA_RECIPIENT] = $currentRecipient;

			// And enqueue it to the writer class
			$this->getStackerInstance()->pushNamed(self::STACKER_NAME_DECLARED, $packageData);

			// Debug message
			$this->debugOutput('PACKAGE: Package declared for recipient ' . $currentRecipient);

			// Skip to next entry
			$iteratorInstance->next();
		} // END - while

		/*
		 * The recipient list can be cleaned up here because the package which
		 * shall be delivered has already been added for all entries from the
		 * list.
		 */
		$discoveryInstance->clearRecipients();
	}

	/**
	 * Delivers raw package data. In short, this will discover the raw socket
	 * resource through a discovery class (which will analyse the receipient of
	 * the package), register the socket with the connection (handler/helper?)
	 * instance and finally push the raw data on our outgoing queue.
	 *
	 * @param	$packageData	Raw package data in an array
	 * @return	void
	 */
	private function deliverRawPackageData (array $packageData) {
		/*
		 * This package may become big, depending on the shared object size or
		 * delivered message size which shouldn't be so long (to save
		 * bandwidth). Because of the nature of the used protocol (TCP) we need
		 * to split it up into smaller pieces to fit it into a TCP frame.
		 *
		 * So first we need (again) a discovery class but now a protocol
		 * discovery to choose the right socket resource. The discovery class
		 * should take a look at the raw package data itself and then decide
		 * which (configurable!) protocol should be used for that type of
		 * package.
		 */
		$discoveryInstance = SocketDiscoveryFactory::createSocketDiscoveryInstance();

		// Now discover the right protocol
		$socketResource = $discoveryInstance->discoverSocket($packageData);

		// Debug message
		//* NOISY-DEBUG: */ $this->debugOutput('PACKAGE: Reached line ' . __LINE__ . ' after discoverSocket() has been called.');

		// We have to put this socket in our registry, so get an instance
		$registryInstance = SocketRegistry::createSocketRegistry();

		// Get the listener from registry
		$helperInstance = Registry::getRegistry()->getInstance('connection');

		// Debug message
		//* NOISY-DEBUG: */ $this->debugOutput('PACKAGE: stateInstance=' . $helperInstance->getStateInstance());
		//* NOISY-DEBUG: */ $this->debugOutput('PACKAGE: Reached line ' . __LINE__ . ' before isSocketRegistered() has been called.');

		// Is it not there?
		if ((is_resource($socketResource)) && (!$registryInstance->isSocketRegistered($helperInstance, $socketResource))) {
			// Debug message
			$this->debugOutput('PACKAGE: Registering socket ' . $socketResource . ' ...');

			// Then register it
			$registryInstance->registerSocket($helperInstance, $socketResource, $packageData);
		} elseif (!$helperInstance->getStateInstance()->isPeerStateConnected()) {
			// Is not connected, then we cannot send
			$this->debugOutput('PACKAGE: Unexpected peer state ' . $helperInstance->getStateInstance()->__toString() . ' detected.');

			// Shutdown the socket
			$this->shutdownSocket($socketResource);
		}

		// Debug message
		//* NOISY-DEBUG: */ $this->debugOutput('PACKAGE: Reached line ' . __LINE__ . ' after isSocketRegistered() has been called.');

		// Make sure the connection is up
		$helperInstance->getStateInstance()->validatePeerStateConnected();

		// Debug message
		//* NOISY-DEBUG: */ $this->debugOutput('PACKAGE: Reached line ' . __LINE__ . ' after validatePeerStateConnected() has been called.');

		// Enqueue it again on the out-going queue, the connection is up and working at this point
		$this->getStackerInstance()->pushNamed(self::STACKER_NAME_OUTGOING, $packageData);

		// Debug message
		//* NOISY-DEBUG: */ $this->debugOutput('PACKAGE: Reached line ' . __LINE__ . ' after pushNamed() has been called.');
	}

	/**
	 * Sends waiting packages
	 *
	 * @param	$packageData	Raw package data
	 * @return	void
	 */
	private function sendOutgoingRawPackageData (array $packageData) {
		// Init sent bytes
		$sentBytes = 0;

		// Get the right connection instance
		$helperInstance = SocketRegistry::createSocketRegistry()->getHandlerInstanceFromPackageData($packageData);

		// Is this connection still alive?
		if ($helperInstance->isShuttedDown()) {
			// This connection is shutting down
			// @TODO We may want to do somthing more here?
			return;
		} // END - if

		// Sent out package data
		$sentBytes = $helperInstance->sendRawPackageData($packageData);

		// Remember unsent raw bytes in back-buffer, if any
		$this->storeUnsentBytesInBackBuffer($packageData, $sentBytes);
	}

	/**
	 * Generates a signature for given raw package content and sender id
	 *
	 * @param	$content	Raw package data
	 * @param	$senderId	Sender id to generate a signature for
	 * @return	$signature	Signature as BASE64-encoded string
	 */
	private function generatePackageSignature ($content, $senderId) {
		// ash content and sender id together, use md5() as last algo
		$hash = md5($this->getCryptoInstance()->hashString($senderId . $content, $this->getNodeId(), false));

		// Encrypt the content again with the hash as a key
		$encryptedContent = $this->getCryptoInstance()->encryptString($content, $hash);

		// Encode it with BASE64
		$signature = base64_encode($encryptedContent);

		// Return it
		return $signature;
	}

	/**
	 * Checks whether the signature of given package data is 'valid', here that
	 * means it is the same or not.
	 *
	 * @param	$decodedArray		An array with 'decoded' (explode() was mostly called) data
	 * @return	$isSignatureValid	Whether the signature is valid
	 * @todo	Unfinished area, signatures are currently NOT fully supported
	 */
	private function isPackageSignatureValid (array $decodedArray) {
		// Generate the signature of comparing it
		$signature = $this->generatePackageSignature($decodedArray[self::INDEX_PACKAGE_CONTENT], $decodedArray[self::INDEX_PACKAGE_SENDER]);

		// Is it the same?
		//$isSignatureValid = 
		die(__METHOD__.': signature='.$signature.chr(10).',decodedArray='.print_r($decodedArray,true));
	}

	/**
	 * "Enqueues" raw content into this delivery class by reading the raw content
	 * from given helper's template instance and pushing it on the 'undeclared'
	 * stack.
	 *
	 * @param	$helperInstance		An instance of a HelpableHub class
	 * @param	$protocol			Name of used protocol (TCP/UDP)
	 * @return	void
	 */
	public function enqueueRawDataFromTemplate (HelpableHub $helperInstance, $protocolName) {
		// Get the raw content ...
		$content = $helperInstance->getTemplateInstance()->getRawTemplateData();

		// ... and compress it
		$content = $this->getCompressorInstance()->compressStream($content);

		// Add magic in front of it and hash behind it, including BASE64 encoding
		$content = sprintf(self::PACKAGE_MASK,
			// 1.) Compressor's extension
			$this->getCompressorInstance()->getCompressorExtension(),
			// - separator
			self::PACKAGE_MASK_SEPARATOR,
			// 2.) Raw package content, encoded with BASE64
			base64_encode($content),
			// - separator
			self::PACKAGE_MASK_SEPARATOR,
			// 3.) Tags
			implode(self::PACKAGE_TAGS_SEPARATOR, $helperInstance->getPackageTags()),
			// - separator
			self::PACKAGE_MASK_SEPARATOR,
			// 4.) Checksum
			$this->getHashFromContent($content)
		);

		// Now prepare the temporary array and push it on the 'undeclared' stack
		$this->getStackerInstance()->pushNamed(self::STACKER_NAME_UNDECLARED, array(
			self::PACKAGE_DATA_SENDER    => $this->getSessionId(),
			self::PACKAGE_DATA_RECIPIENT => $helperInstance->getRecipientType(),
			self::PACKAGE_DATA_PROTOCOL  => $protocolName,
			self::PACKAGE_DATA_CONTENT   => $content,
			self::PACKAGE_DATA_STATUS    => self::PACKAGE_STATUS_NEW,
			self::PACKAGE_DATA_SIGNATURE => $this->generatePackageSignature($content, $this->getSessionId())
		));
	}

	/**
	 * Checks whether a package has been enqueued for delivery.
	 *
	 * @return	$isEnqueued		Whether a package is enqueued
	 */
	public function isPackageEnqueued () {
		// Check whether the stacker is not empty
		$isEnqueued = (($this->getStackerInstance()->isStackInitialized(self::STACKER_NAME_UNDECLARED)) && (!$this->getStackerInstance()->isStackEmpty(self::STACKER_NAME_UNDECLARED)));

		// Return the result
		return $isEnqueued;
	}

	/**
	 * Checks whether a package has been declared
	 *
	 * @return	$isDeclared		Whether a package is declared
	 */
	public function isPackageDeclared () {
		// Check whether the stacker is not empty
		$isDeclared = (($this->getStackerInstance()->isStackInitialized(self::STACKER_NAME_DECLARED)) && (!$this->getStackerInstance()->isStackEmpty(self::STACKER_NAME_DECLARED)));

		// Return the result
		return $isDeclared;
	}

	/**
	 * Checks whether a package should be sent out
	 *
	 * @return	$isWaitingDelivery	Whether a package is waiting for delivery
	 */
	public function isPackageWaitingForDelivery () {
		// Check whether the stacker is not empty
		$isWaitingDelivery = (($this->getStackerInstance()->isStackInitialized(self::STACKER_NAME_OUTGOING)) && (!$this->getStackerInstance()->isStackEmpty(self::STACKER_NAME_OUTGOING)));

		// Return the result
		return $isWaitingDelivery;
	}

	/**
	 * Delivers an enqueued package to the stated destination. If a non-session
	 * id is provided, recipient resolver is being asked (and instanced once).
	 * This allows that a single package is being delivered to multiple targets
	 * without enqueueing it for every target. If no target is provided or it
	 * can't be determined a NoTargetException is being thrown.
	 *
	 * @return	void
	 * @throws	NoTargetException	If no target can't be determined
	 */
	public function declareEnqueuedPackage () {
		// Make sure this method isn't working if there is no package enqueued
		if (!$this->isPackageEnqueued()) {
			// This is not fatal but should be avoided
			// @TODO Add some logging here
			return;
		} // END - if

		/*
		 * Now there are for sure packages to deliver, so start with the first
		 * one.
		 */
		$packageData = $this->getStackerInstance()->getNamed(self::STACKER_NAME_UNDECLARED);

		// Declare the raw package data for delivery
		$this->declareRawPackageData($packageData);

		// And remove it finally
		$this->getStackerInstance()->popNamed(self::STACKER_NAME_UNDECLARED);
	}

	/**
	 * Delivers the next declared package. Only one package per time will be sent
	 * because this may take time and slows down the whole delivery
	 * infrastructure.
	 *
	 * @return	void
	 */
	public function deliverDeclaredPackage () {
		// Sanity check if we have packages declared
		if (!$this->isPackageDeclared()) {
			// This is not fatal but should be avoided
			$this->debugOutput('PACKAGE: No package has been declared, but ' . __METHOD__ . ' has been called!');
			return;
		} // END - if

		// Get the package
		$packageData = $this->getStackerInstance()->getNamed(self::STACKER_NAME_DECLARED);

		try {
			// And try to send it
			$this->deliverRawPackageData($packageData);

			// And remove it finally
			$this->getStackerInstance()->popNamed(self::STACKER_NAME_DECLARED);
		} catch (InvalidStateException $e) {
			// The state is not excepected (shall be 'connected')
			$this->debugOutput('PACKAGE: Caught ' . $e->__toString() . ',message=' . $e->getMessage());

			// Mark the package with status failed
			$this->changePackageStatus($packageData, self::STACKER_NAME_DECLARED, self::PACKAGE_STATUS_FAILED);
		}
	}

	/**
	 * Sends waiting packages out for delivery
	 *
	 * @return	void
	 */
	public function sendWaitingPackage () {
		// Send any waiting bytes in the back-buffer before sending a new package
		$this->sendBackBufferBytes();

		// Sanity check if we have packages waiting for delivery
		if (!$this->isPackageWaitingForDelivery()) {
			// This is not fatal but should be avoided
			$this->debugOutput('PACKAGE: No package is waiting for delivery, but ' . __METHOD__ . ' was called.');
			return;
		} // END - if

		// Get the package
		$packageData = $this->getStackerInstance()->getNamed(self::STACKER_NAME_OUTGOING);

		try {
			// Now try to send it
			$this->sendOutgoingRawPackageData($packageData);

			// And remove it finally
			$this->getStackerInstance()->popNamed(self::STACKER_NAME_OUTGOING);
		} catch (InvalidSocketException $e) {
			// Output exception message
			$this->debugOutput('PACKAGE: Package was not delivered: ' . $e->getMessage());

			// Mark package as failed
			$this->changePackageStatus($packageData, self::STACKER_NAME_OUTGOING, self::PACKAGE_STATUS_FAILED);
		}
	}

	///////////////////////////////////////////////////////////////////////////
	//                   Receiving packages / raw data
	///////////////////////////////////////////////////////////////////////////

	/**
	 * Checks whether decoded raw data is pending
	 *
	 * @return	$isPending	Whether decoded raw data is pending
	 */
	private function isDecodedDataPending () {
		// Just return whether the stack is not empty
		$isPending = (!$this->getStackerInstance()->isStackEmpty(self::STACKER_NAME_DECODED_INCOMING));

		// Return the status
		return $isPending;
	}

	/**
	 * Checks whether new raw package data has arrived at a socket
	 *
	 * @param	$poolInstance	An instance of a PoolableListener class
	 * @return	$hasArrived		Whether new raw package data has arrived for processing
	 */
	public function isNewRawDataPending (PoolableListener $poolInstance) {
		// Visit the pool. This monitors the pool for incoming raw data.
		$poolInstance->accept($this->getVisitorInstance());

		// Check for new data arrival
		$hasArrived = $this->isDecodedDataPending();

		// Return the status
		return $hasArrived;
	}

	/**
	 * Handles the incoming decoded raw data. This method does not "convert" the
	 * decoded data back into a package array, it just "handles" it and pushs it
	 * on the next stack.
	 *
	 * @return	void
	 */
	public function handleIncomingDecodedData () {
		/*
		 * This method should only be called if decoded raw data is pending,
		 * so check it again.
		 */
		if (!$this->isDecodedDataPending()) {
			// This is not fatal but should be avoided
			// @TODO Add some logging here
			return;
		} // END - if

		// Very noisy debug message:
		/* NOISY-DEBUG: */ $this->debugOutput('PACKAGE: Stacker size is ' . $this->getStackerInstance()->getStackCount(self::STACKER_NAME_DECODED_INCOMING) . ' entries.');

		// "Pop" the next entry (the same array again) from the stack
		$decodedData = $this->getStackerInstance()->popNamed(self::STACKER_NAME_DECODED_INCOMING);

		// Make sure both array elements are there
		assert(
			(is_array($decodedData)) &&
			(isset($decodedData[BaseRawDataHandler::PACKAGE_DECODED_DATA])) &&
			(isset($decodedData[BaseRawDataHandler::PACKAGE_ERROR_CODE]))
		);

		/*
		 * Also make sure the error code is SOCKET_ERROR_UNHANDLED because we
		 * only want to handle unhandled packages here.
		 */
		/* NOISY-DEBUG: */ $this->debugOutput('NETWORK-PACKAGE: errorCode=' . $decodedData[BaseRawDataHandler::PACKAGE_ERROR_CODE]);
		assert($decodedData[BaseRawDataHandler::PACKAGE_ERROR_CODE] == BaseRawDataHandler::SOCKET_ERROR_UNHANDLED);

		// Remove the last chunk SEPARATOR (because it is being added and we don't need it)
		if (substr($decodedData[BaseRawDataHandler::PACKAGE_DECODED_DATA], -1, 1) == PackageFragmenter::CHUNK_SEPARATOR) {
			// It is there and should be removed
			$decodedData[BaseRawDataHandler::PACKAGE_DECODED_DATA] = substr($decodedData[BaseRawDataHandler::PACKAGE_DECODED_DATA], 0, -1);
		} // END - if

		// This package is "handled" and can be pushed on the next stack
		$this->getStackerInstance()->pushNamed(self::STACKER_NAME_DECODED_HANDLED, $decodedData);
	}

	/**
	 * Adds raw decoded data from the given handler instance to this receiver
	 *
	 * @param	$handlerInstance	An instance of a Networkable class
	 * @return	void
	 */
	public function addDecodedDataToIncomingStack (Networkable $handlerInstance) {
		/*
		 * Get the decoded data from the handler, this is an array with
		 * 'decoded_data' and 'error_code' as elements.
		 */
		$decodedData = $handlerInstance->getNextDecodedData();

		// Very noisy debug message:
		//* NOISY-DEBUG: */ $this->debugOutput('PACKAGE: decodedData[' . gettype($decodedData) . ']=' . print_r($decodedData, true));

		// And push it on our stack
		$this->getStackerInstance()->pushNamed(self::STACKER_NAME_DECODED_INCOMING, $decodedData);
	}

	/**
	 * Checks whether incoming decoded data is handled.
	 *
	 * @return	$isHandled	Whether incoming decoded data is handled
	 */
	public function isIncomingDecodedDataHandled () {
		// Determine if the stack is not empty
		$isHandled = (!$this->getStackerInstance()->isStackEmpty(self::STACKER_NAME_DECODED_HANDLED));

		// Return it
		return $isHandled;
	}

	/**
	 * Checks whether the assembler has pending data left
	 *
	 * @return	$isHandled	Whether the assembler has pending data left
	 */
	public function ifAssemblerHasPendingDataLeft () {
		// Determine if the stack is not empty
		$isHandled = (!$this->getAssemblerInstance()->isPendingDataEmpty());

		// Return it
		return $isHandled;
	}

	/**
	 * Handles the attached assemler's pending data queue to be finally
	 * assembled to the raw package data back.
	 *
	 * @return	void
	 */
	public function handleAssemblerPendingData () {
		// Handle it
		$this->getAssemblerInstance()->handlePendingData();
	}

	/**
	 * Assembles incoming decoded data so it will become an abstract network
	 * package again. The assembler does later do it's job by an other task,
	 * not this one to keep best speed possible.
	 *
	 * @return	void
	 */
	public function assembleDecodedDataToPackage () {
		// Make sure the raw decoded package data is handled
		assert($this->isIncomingDecodedDataHandled());

		// Get current package content (an array with two elements; see handleIncomingDecodedData() for details)
		$packageContent = $this->getStackerInstance()->getNamed(self::STACKER_NAME_DECODED_HANDLED);

		// Start assembling the raw package data array by chunking it
		$this->getAssemblerInstance()->chunkPackageContent($packageContent);

		// Remove the package from 'handled_decoded' stack ...
		$this->getStackerInstance()->popNamed(self::STACKER_NAME_DECODED_HANDLED);

		// ... and push it on the 'chunked' stacker
		$this->getStackerInstance()->pushNamed(self::STACKER_NAME_DECODED_CHUNKED, $packageContent);
	}

	/**
	 * Accepts the visitor to process the visit "request"
	 *
	 * @param	$visitorInstance	An instance of a Visitor class
	 * @return	void
	 */
	public function accept (Visitor $visitorInstance) {
		// Debug message
		//* NOISY-DEBUG: */ $this->debugOutput('PACKAGE: ' . $visitorInstance->__toString() . ' has visited - START');

		// Visit the package
		$visitorInstance->visitNetworkPackage($this);

		// Debug message
		//* NOISY-DEBUG: */ $this->debugOutput('PACKAGE: ' . $visitorInstance->__toString() . ' has visited - FINISHED');
	}

	/**
	 * Clears all stacker
	 *
	 * @return	void
	 */
	public function clearAllStacker () {
		// Call the init method to force re-initialization
		$this->initStackers(true);

		// Debug message
		/* DEBUG: */ $this->debugOutput('PACKAGE: All stacker have been re-initialized.');
	}

	/**
	 * Removes the first failed outoging package from the stack to continue
	 * with next one (it will never work until the issue is fixed by you).
	 *
	 * @return	void
	 * @throws	UnexpectedPackageStatusException	If the package status is not 'failed'
	 * @todo	This may be enchanced for outgoing packages?
	 */
	public function removeFirstFailedPackage () {
		// Get the package again
		$packageData = $this->getStackerInstance()->getNamed(self::STACKER_NAME_DECLARED);

		// Is the package status 'failed'?
		if ($packageData[self::PACKAGE_DATA_STATUS] != self::PACKAGE_STATUS_FAILED) {
			// Not failed!
			throw new UnexpectedPackageStatusException(array($this, $packageData, self::PACKAGE_STATUS_FAILED), BaseListener::EXCEPTION_UNEXPECTED_PACKAGE_STATUS);
		} // END - if

		// Remove this entry
		$this->getStackerInstance()->popNamed(self::STACKER_NAME_DECLARED);
	}

	/**
	 * "Decode" the package content into the same array when it was sent.
	 *
	 * @param	$rawPackageContent	The raw package content to be "decoded"
	 * @return	$decodedData		An array with 'sender', 'recipient', 'content' and 'status' elements
	 */
	public function decodeRawContent ($rawPackageContent) {
		// Use the separator '#' to "decode" it
		$decodedArray = explode(self::PACKAGE_DATA_SEPARATOR, $rawPackageContent);

		// Assert on count (should be always 3)
		assert(count($decodedArray) == self::DECODED_DATA_ARRAY_SIZE);

		// Generate the signature of comparing it
		/*
		 * @todo Unsupported feature of "signed" messages commented out
		if (!$this->isPackageSignatureValid($decodedArray)) {
			// Is not valid, so throw an exception here
			die('INVALID SIG! UNDER CONSTRUCTION!' . chr(10));
		} // END - if
		*/

		/*
		 * Create 'decodedData' array with all assoziative array elements,
		 * except signature.
		 */
		$decodedData = array(
			self::PACKAGE_DATA_SENDER    => $decodedArray[self::INDEX_PACKAGE_SENDER],
			self::PACKAGE_DATA_RECIPIENT => $decodedArray[self::INDEX_PACKAGE_RECIPIENT],
			self::PACKAGE_DATA_CONTENT   => $decodedArray[self::INDEX_PACKAGE_CONTENT],
			self::PACKAGE_DATA_STATUS    => self::PACKAGE_STATUS_DECODED
		);

		// And return it
		return $decodedData;
	}

	/**
	 * Handles decoded data for this node by "decoding" the 'content' part of
	 * it. Again this method uses explode() for the "decoding" process.
	 *
	 * @param	$decodedData	An array with decoded raw package data
	 * @return	void
	 * @throws	InvalidDataChecksumException	If the checksum doesn't match
	 */
	public function handleDecodedData (array $decodedData) {
		/*
		 * "Decode" the package's content by a simple explode() call, for
		 * details of the array elements, see comments for constant
		 * PACKAGE_MASK.
		 */
		$decodedContent = explode(self::PACKAGE_MASK_SEPARATOR, $decodedData[self::PACKAGE_DATA_CONTENT]);

		// Assert on array count for a very basic validation
		assert(count($decodedContent) == self::PACKAGE_CONTENT_ARRAY_SIZE);

		/*
		 * Convert the indexed array into an associative array. This is much
		 * better to remember than plain numbers, isn't it?
		 */
		$decodedContent = array(
			// Compressor's extension used to compress the data
			self::PACKAGE_CONTENT_EXTENSION => $decodedContent[self::INDEX_COMPRESSOR_EXTENSION],
			// Package data (aka "message") in BASE64-decoded form but still compressed
			self::PACKAGE_CONTENT_MESSAGE   => base64_decode($decodedContent[self::INDEX_PACKAGE_DATA]),
			// Tags as an indexed array for "tagging" the message
			self::PACKAGE_CONTENT_TAGS      => explode(self::PACKAGE_TAGS_SEPARATOR, $decodedContent[self::INDEX_TAGS]),
			// Checksum of the _decoded_ data
			self::PACKAGE_CONTENT_CHECKSUM  => $decodedContent[self::INDEX_CHECKSUM]
		);

		// Is the checksum valid?
		if (!$this->isChecksumValid($decodedContent, $decodedData)) {
			// Is not the same, so throw an exception here
			throw new InvalidDataChecksumException(array($this, $decodedContent, $decodedData), BaseListener::EXCEPTION_INVALID_DATA_CHECKSUM);
		} // END - if

		/*
		 * The checksum is the same, then it can be decompressed safely. The
		 * original message is at this point fully decoded.
		 */
		$decodedContent[self::PACKAGE_CONTENT_MESSAGE] = $this->getCompressorInstance()->decompressStream($decodedContent[self::PACKAGE_CONTENT_MESSAGE]);

		// And push it on the next stack
		$this->getStackerInstance()->pushNamed(self::STACKER_NAME_NEW_MESSAGE, $decodedContent);
	}

	/**
	 * Checks whether a new message has arrived
	 *
	 * @return	$hasArrived		Whether a new message has arrived for processing
	 */
	public function isNewMessageArrived () {
		// Determine if the stack is not empty
		$hasArrived = (!$this->getStackerInstance()->isStackEmpty(self::STACKER_NAME_NEW_MESSAGE));

		// Return it
		return $hasArrived;
	}

	/**
	 * Handles newly arrived messages
	 *
	 * @return	void
	 * @todo	Implement verification of all sent tags here?
	 */
	public function handleNewlyArrivedMessage () {
		// Get it from the stacker, it is the full array with the decoded message
		$decodedContent = $this->getStackerInstance()->popNamed(self::STACKER_NAME_NEW_MESSAGE);

		// Now get a filter chain back from factory with given tags array
		$chainInstance = PackageFilterChainFactory::createChainByTagsArray($decodedContent[self::PACKAGE_CONTENT_TAGS]);

		/*
		 * Process the message through all filters, note that all other
		 * elements from $decodedContent are no longer needed.
		 */
		$chainInstance->processMessage($decodedContent[self::PACKAGE_CONTENT_MESSAGE], $this);
	}

	/**
	 * Checks whether a processed message is pending for "interpretation"
	 *
	 * @return	$isPending	Whether a processed message is pending
	 */
	public function isProcessedMessagePending () {
		// Check it
		$isPending = (!$this->getStackerInstance()->isStackEmpty(self::STACKER_NAME_PROCESSED_MESSAGE));

		// Return it
		return $isPending;
	}

	/**
	 * Handle processed messages by "interpreting" the 'message_type' element
	 *
	 * @return	void
	 */
	public function handleProcessedMessage () {
		// Get it from the stacker, it is the full array with the processed message
		$messageArray = $this->getStackerInstance()->popNamed(self::STACKER_NAME_PROCESSED_MESSAGE);

		// Create a handler instance from given message type
		$handlerInstance = MessageTypeHandlerFactory::createMessageTypeHandlerInstance($messageArray[self::MESSAGE_ARRAY_TYPE]);

		// Handle message data
		$handlerInstance->handleMessageData($messageArray[self::MESSAGE_ARRAY_DATA], $this);

		die('messageArray='.print_r($messageArray,true));
	}
}

// [EOF]
?>