<?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 - 2011 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 BaseFrameworkSystem implements Deliverable, Receivable, Registerable {
	/**
	 * 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';

	/**
	 * Seperator for the above mask
	 */
	const PACKAGE_MASK_SEPERATOR = ':';

	/**
	 * Seperator for checksum
	 */
	const PACKAGE_CHECKSUM_SEPERATOR = ':';

	/**
	 * 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;

	/**
	 * Named array elements for package data
	 */
	const PACKAGE_DATA_SENDER    = 'sender';
	const PACKAGE_DATA_RECIPIENT = 'recipient';
	const PACKAGE_DATA_CONTENT   = 'content';

	/**
	 * Tags seperator
	 */
	const PACKAGE_TAGS_SEPERATOR = ';';

	/**
	 * Raw package data seperator
	 */
	const PACKAGE_DATA_SEPERATOR = '#';

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

	/**
	 * 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;

	/**
	 * 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);

		// Return the prepared instance
		return $packageInstance;
	}

	/**
	 * Initialize all stackers
	 *
	 * @return	void
	 */
	protected function initStackers () {
		// 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_BACK_BUFFER
			) as $stackerName) {
			// Init this stacker
			$this->getStackerInstance()->initStacker($stackerName);
		} // END - foreach
	}

	/**
	 * "Getter" for hash from given content and helper instance
	 *
	 * @param	$content	Raw package content
	 * @param	$helperInstance		An instance of a HelpableHub class
	 * @param	$nodeInstance		An instance of a NodeHelper class
	 * @return	$hash	Hash for given package content
	 * @todo	$helperInstance is unused
	 */
	private function getHashFromContent ($content, HelpableHub $helperInstance, NodeHelper $nodeInstance) {
		// Create the hash
		// @TODO crc32() is not very strong, but it needs to be fast
		$hash = crc32(
			$content .
			self::PACKAGE_CHECKSUM_SEPERATOR .
			$nodeInstance->getSessionId() .
			self::PACKAGE_CHECKSUM_SEPERATOR .
			$this->getCompressorInstance()->getCompressorExtension()
		);

		// 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();

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

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

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

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

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

		// Clean-up 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('NETWORK-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('NETWORK-PACKAGE: Reached line ' . __LINE__ . ' before isSocketRegistered() has been called.');

		// Is it not there?
		if ((is_resource($socketResource)) && (!$registryInstance->isSocketRegistered($helperInstance, $socketResource))) {
			// Then register it
			$registryInstance->registerSocket($helperInstance, $socketResource, $packageData);
		} // END - if

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

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

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

		// We enqueue it again, but now in the out-going queue
		$this->getStackerInstance()->pushNamed(self::STACKER_NAME_OUTGOING, $packageData);
	}

	/**
	 * 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);
	}

	/**
	 * "Enqueues" raw content into this delivery class by reading the raw content
	 * from given template instance and pushing it on the 'undeclared' stack.
	 *
	 * @param	$helperInstance		An instance of a HelpableHub class
	 * @param	$nodeInstance		An instance of a NodeHelper class
	 * @return	void
	 */
	public function enqueueRawDataFromTemplate (HelpableHub $helperInstance, NodeHelper $nodeInstance) {
		// 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
			$this->getCompressorInstance()->getCompressorExtension(),
			// 2.) Raw package content, encoded with BASE64
			base64_encode($content),
			// 3.) Tags
			implode(self::PACKAGE_TAGS_SEPERATOR, $helperInstance->getPackageTags()),
			// 4.) Checksum
			$this->getHashFromContent($content, $helperInstance, $nodeInstance)
		);

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

	/**
	 * Checks wether a package has been enqueued for delivery.
	 *
	 * @return	$isEnqueued		Wether a package is enqueued
	 */
	public function isPackageEnqueued () {
		// Check wether 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 wether a package has been declared
	 *
	 * @return	$isDeclared		Wether a package is declared
	 */
	public function isPackageDeclared () {
		// Check wether 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 wether a package should be sent out
	 *
	 * @return	$isWaitingDelivery	Wether a package is waiting for delivery
	 */
	public function isPackageWaitingForDelivery () {
		// Check wether 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 we know for sure there are packages to deliver, we can 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
			// @TODO Add some logging here
			return;
		} // END - if

		// Get the package again
		$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 exception ' . $e->__toString() . ' with message=' . $e->getMessage());
		}
	}

	/**
	 * 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 again
		$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());
		}
	}

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

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

		// Return the status
		return $isPending;
	}

	/**
	 * Checks wether new raw package data has arrived at a socket
	 *
	 * @param	$poolInstance	An instance of a PoolableListener class
	 * @return	$hasArrived		Wether 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.
		 */
		assert($decodedData[BaseRawDataHandler::PACKAGE_ERROR_CODE] == BaseRawDataHandler::SOCKET_ERROR_UNHANDLED);

		// Remove the last chunk seperator (because it is being added and we don't need it)
		if (substr($decodedData[BaseRawDataHandler::PACKAGE_DECODED_DATA], -1, 1) == PackageFragmenter::CHUNK_SEPERATOR) {
			// 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 wether incoming decoded data is handled.
	 *
	 * @return	$isHandled	Wether 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;
	}

	/**
	 * Assembles incoming decoded data so it will become an abstract network
	 * package again.
	 *
	 * @return	void
	 */
	public function assembleDecodedDataToPackage () {
		$this->partialStub('Please implement this method.');
	}

	/**
	 * Checks wether a new package has arrived
	 *
	 * @return	$hasArrived		Wether a new package has arrived for processing
	 */
	public function isNewPackageArrived () {
		// @TODO Add some content here
	}
}

// [EOF]
?>