<?php
/**
 * A Package decoder 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
 *
 * 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 PackageDecoder extends BaseDecoder implements Decodeable {
	/**
	 * Name for stacker for received packages
	 */
	const STACKER_NAME_DECODED_PACKAGE = 'decoded_package';

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

	/**
	 * Creates an instance of this class
	 *
	 * @param	$stackerInstance	An instance of a Stackable class
	 * @return	$decoderInstance	An instance of a Decodeable class
	 */
	public final static function createPackageDecoder (Stackable $stackerInstance) {
		// Get new instance
		$decoderInstance = new PackageDecoder();

		// Init stacker for received packages
		$stackerInstance->initStacker(self::STACKER_NAME_DECODED_PACKAGE);

		// Set the stacker instance here
		$decoderInstance->setStackerInstance($stackerInstance);

		// Get a singleton network package instance
		$packageInstance = NetworkPackageFactory::createNetworkPackageInstance();

		// And set it in this decoder
		$decoderInstance->setPackageInstance($packageInstance);

		// Return the prepared instance
		return $decoderInstance;
	}

	/**
	 * Checks whether the assoziated stacker for raw package data has some entries left
	 *
	 * @return	$unhandledDataLeft	Whether some unhandled raw package data is left
	 */
	public function ifUnhandledRawPackageDataLeft () {
		// Check it
		$unhandledDataLeft = (!$this->getStackerInstance()->isStackEmpty(ChunkHandler::STACKER_NAME_ASSEMBLED_RAW_DATA));

		// Return it
		return $unhandledDataLeft;
	}

	/**
	 * Handles raw package data by decoding it
	 *
	 * @return	void
	 */
	public function handleRawPackageData () {
		// Assert on it to make sure the next popNamed() call won't throw an exception
		assert($this->ifUnhandledRawPackageDataLeft());

		// "Pop" the next raw package content
		$rawPackageContent = $this->getStackerInstance()->popNamed(ChunkHandler::STACKER_NAME_ASSEMBLED_RAW_DATA);

		// "Decode" the raw package content by using the NetworkPackage instance
		$decodedData = $this->getPackageInstance()->decodeRawContent($rawPackageContent);

		// Next get a recipient-discovery instance
		$discoveryInstance = PackageDiscoveryFactory::createPackageDiscoveryInstance();

		// ... then disover all recipient (might be only one), this package may shall be forwarded
		$discoveryInstance->discoverRawRecipients($decodedData);

		// Check for 'recipient' field (the 'sender' field and others are ignored here)
		if ($discoveryInstance->isRecipientListEmpty()) {
			// The recipient is this node so next stack it on 'decoded_package'
			$this->getStackerInstance()->pushNamed(self::STACKER_NAME_DECODED_PACKAGE, $decodedData);
		} else {
			// Forward the package to the next node
			$this->getPackageInstance()->forwardRawPackage($decodedData);
		}
	}

	/**
	 * Checks whether decoded packages have arrived (for this peer)
	 *
	 * @return	$ifRawPackagesLeft	Whether decoded packages have arrived
	 */
	public function ifDeocedPackagesLeft () {
		// Check it ...
		$ifRawPackagesLeft = (!$this->getStackerInstance()->isStackEmpty(self::STACKER_NAME_DECODED_PACKAGE));

		// ... return it
		return $ifRawPackagesLeft;
	}

	/**
	 * Handles received decoded packages internally (recipient is this node)
	 *
	 * @return	void
	 */
	public function handleDecodedPackage () {
		// Get the next entry (assoziative array)
		$decodedData = $this->getStackerInstance()->popNamed(self::STACKER_NAME_DECODED_PACKAGE);

		// Handle it
		$this->getPackageInstance()->handleRawData($decodedData);
	}
}

// [EOF]
?>