<?php
// Survey database interface class as intermediate for storing data from the site to the RDF database 
require_once 'rdfConstants.php';
// Include RAP Library to write RDF files
include(RDFAPI_INCLUDE_DIR . "RDFAPI.php");

/**
 * Description of SessionConnector
 *
 * @author jkraaijeveld
 */
class SessionConnector implements IConnector
{
	protected $model;
	protected $fileName = 'data/sessions/sessions.rdf';
	protected $db;

	/**
	 * Constructor for the SessionConnector
	 */
	public function __construct()
	{
		//Ensure the required folder for this connector exists
		if(!is_dir('data/sessions'))
			mkdir('data/sessions');
	}

	/**
	 * function load()
	 * Loads the file into the standard MemModel
	 */
	public function load()
	{
		$this->model = ModelFactory::getDefaultModel();
		if(file_exists($this->fileName))
			$this->model->load($this->fileName);
	}

	/**
	 * fucntion save()
	 * Saves the MemModel into the given file.
	 */
	public function save()
	{
		$this->model->saveAs($this->fileName,'rdf');
	}

	/**
	 * Get the Sessions corresponding to the arguments
	 * @ param type $arguments
	 * Arguments can be one or more of the following:
	 * uid, title, datetime, applications, surveys, answersets
	 * Where applications, surveys and answersets are arrays containing ids
	 */
	public function get($arguments)
	{
		$this->load();

		$keys = array_keys($arguments);
		$uid = ""; $title = ""; $datetime = ""; $applications = ""; $surveys = ""; $answersets = "";
		if(in_array("uid", $keys))
			$uid = 'predicates:uid \''.$arguements["uid"].'\' ';
		if(in_array("title", $keys))
			$title = 'predicates:title \''.$arguments["title"].'\' ';
		if(in_array("datetime", $keys))
			$datetime = 'predicates:datetime \''.$arguments["datetime"].'\' ';
		if(in_array("applications", $keys))
		{
			foreach($arguments["applications"] as $application)
			{
				$applications = $applications . 'predicates:has_application \'' . $application . '\' ';
			}
		}
		if(in_array("surveys", $keys))
		{
			foreach($arguments["surveys"] as $survey)
			{
				$surveys = $surveys . 'predicates:has_survey \'' . $survey . '\' ';
			}
		}
		if(in_array("answersets", $keys))
		{
			foreach($arguments["answersets"] as $answerset)
			{
				$answersets = $answersets . 'predicates:has_answerset \'' . $answerset . '\' ';
			}
		}
	
		//Build the query string
		$querystring = '
			PREFIX predicates: <' . SURVEYTOOL_PREDICATES_NAMESPACE . '>
			PREFIX resources: <' . SURVEYTOOL_RESOURCES_NAMESPACE . '>
			SELECT DISTINCT ?uid, ?title, ?datetime
			WHERE
			{
				_session predicates:resource_type resources:session ;
				predicates:uid ?uid ;
				predicates:title ?title ;
				' . $uid . $title . $datetime . $applications . $surveys . $answersets . '
			}';
		//Query the model
		$results = $this->model->sparqlQuery($querystring);

		$sessions = array();
		if(!empty($results))
		{
			$this->db = new DatabaseInterface();
			foreach($results as $result)
			{
				//Create a session object out of every result, get all required fields as well.
				$pipeline = $this->getPipeline($result['?uid']->label);
				$answersets = $this->getAnswerSets($result['?uid']->label);
				$datetime = new DateTime();
				$datetime->setTimestamp(intval($result['?datetime']));
				$sessions[] = new Session($result['?uid']->label, $result['?title']->label, $datetime, $pipeline, $answersets);
			}
		}
		return $sessions;
	}
	/**
	 * function getPipeline
	 * Get the application and survey objects of the Session in order
	 */
	private function getPipeline($uid)
	{
		$result = $this->model->findRegex("[(".$uid.")]", "[(has_application)|(has_survey)]" ,null);
		$iterator = $result->getStatementIterator();
		$pipeline = array();
		while($iterator->hasNext())
		{
			$element = $iterator->next();
			if(strpos($element->getLabelPredicate(), "has_application") != false)
			{
				$applications = $this->db->get("application", array("uid" => $element->getLabelObject()));
				$pipeline[] = $applications[0];
			}
			else
			{
				$surveys = $this->db->get("survey", array("uid" => $element->getLabelObject()));
				$pipeline[] = $surveys[0];
			}
		}
		return $pipeline;
	}

	/**
	 * function getAnswerSets
	 * Get the answersets belonging to the given session
	 */
	private function getAnswerSets($uid)
	{
		$result = $this->model->findRegex("[(".$uid.")]", "[(has_answerset)]" ,null);
		$iterator = $result->getStatementIterator();
		$answersets = array();
		while($iterator->hasNext())
		{
			$element = $iterator->next();
			$resultsets = $this->db->get("answerset", array("uid" => $element->getLabelObject()));
			$answersets[] = $resultsets[0];
		}
		return $answersets;
	}

	/**
	 * Save the given Session object in the file.
	 * @param type $rToolObjects
	 */
	public function set($rToolObject)
	{
		$this->load();
		$resourceSession = new Resource(SESSION . '/' . $rToolObject->uid);
		//Remove the old value stored with the given id
		$this->model->subtract($this->model->find($resourceSession, null, null));

		//Set the new values
		$resourceSessionType = new Resource(SESSION);
		$predicateType = new Resource(RTYPE);
		$this->model->add(new Statement($resourceSession, $predicateType, $resourceSessionType));

		$sessionId = new Literal($rToolObject->uid);
		$predicateId = new Resource(UID);
		$this->model->add(new Statement($resourceSession, $predicateId, $sessionId));

		$sessionTitle = new Literal($rToolObject->title);
		$predicateTitle = new Resource(TITLE);
		$this->model->add(new Statement($resourceSession, $predicateTitle, $sessionTitle));

		$sessionTimestamp = new Literal($rToolObject->datetime->getTimestamp());
		$predicateTimestamp = new Resource(DATETIME);
		$this->model->add(new Statement($resourceSession, $predicateTimestamp, $sessionTimestamp));

		//Create a sequence to store the different applications and surveys.
		if(isset($rToolObject->pipeline))
		{
			foreach($rToolObject->pipeline as $element)
			{
				$sessionObject = new Literal($element->uid);
				$predicateObject = null;
				if(get_class($element) == "Application")
					$predicateObject = new Resource(HAS_APPLICATION);
				else if(get_class($element) == "Survey")
					$predicateObject = new Resource(HAS_SURVEY);
				if(isset($predicateObject))
					$this->model->add(new Statement($resourceSession, $predicateObject, $sessionObject));
			}
		}

		if(isset($rToolObject->answersets))
		{
			foreach($rToolObject->answersets as $answerset)
			{
				$sessionAnswerSet = new Literal($answerset->uid);
				$predicateAnswerSet = new Resource(HAS_ANSWERSET);
				$this->model->add(new Statement($resourceSession, $predicateAnswerSet, $sessionAnswerSet));
			}
		}

		$this->save();
	}
}
?>