<?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 ResultSet
 */
class ResultSet extends ResearchToolObject{

	private static $filename = 'data/results/resultsets.rdf';

	public $answersets;
	public $playerresults;
	public $groupresults;
	public $periodicresults;

	/**
	 * Constructor for an ResultSet object.
	 * @param type $uid
	 * @param type $answersets;
	 * @param type $playerresults;
	 * @param type $groupresults;
	 * @param type $periodicresults;
	 */
	public function __construct($uid=null, $answersets = null, $playerresults = null, $groupresults = null, $periodicresults = null)
	{
		if(!isset($uid))
		{
			$uid = md5(uniqid(rand(), true));
		}
		
		$this->uid = $uid;
		$this->answersets = $answersets;
		$this->playerresults = $playerresults;
		$this->groupresults = $groupresults;
		$this->periodicresults = $periodicresults;
	}

	/**
	 * funtion evaluate()
	 * evaluates the references of all results
	 */
	public function evaluate()
	{
		if(!empty($this->answersets) && is_string($this->answersets[0]))
		{
			$newAnswerSets = array();
			foreach($this->answersets as $answerSet)
			{
				$result = AnswerSet::get(array("uid" => $answerSet));
				if(!isset($result[0]))
					return false;
				$newAnswerSets[] = $result[0];
			}			
			$this->answersets = $newAnswerSets;
		}
		//TODO: Evaluate the other sets when they are implemented.

		return true;
	}

	/**
	 * function save()
	 * Saves the current object into the database.
	 */
	public function save()
	{
		//If evaluation fails, some references are incorrect.
		//We shouldn't save in this case. Instead - let the user know. This function returns false if the evaluation has failed.
		//TODO: Decide how to fix invalid references graciously.
		if(!$this->evaluate()) 
			return false;
		//Ensure the required folder exists.
		if(!is_dir('data/results/'))
			mkdir('data/results/');

		$model = ResearchToolObject::load(ResultSet::$filename);

		$resourceResultSet = new Resource(RESULTSET . '/' . $this->uid);
		//Remove the old value stored with the given id
		$model->subtract($model->find($resourceResultSet, null, null));

		//Set new values
		$resourceResultSetType = new Resource(RESULTSET);
		$predicateRType = new Resource(RTYPE);
		$model->add(new Statement($resourceResultSet, $predicateRType, $resourceResultSetType));

		$resultSetId = new Literal($this->uid);
		$predicateId = new Resource(UID);
		$model->add(new Statement($resourceResultSet, $predicateId, $resultSetId));

		if(isset($this->answersets))
		{
			foreach($this->answersets as $answerset)
			{
				$answerSetId = new Literal($answerset->uid);
				$predicateAnswerSet = new Resource(HAS_ANSWERSET);
				$model->add(new Statement($resourceResultSet, $predicateAnswerSet, $answerSetId));
			}
		}

		//TODO: store other sets when they are implemented.

		$model->saveAs(ResultSet::$filename, 'rdf');
		return true;
	}

	/**
	 * function get()
	 * @param type $arguments : An array having one or more of the following elements:
	 * 'uid', 'answersets', 'playerresults', 'groupresults', 'periodicresults'
	 */
	public static function get($arguments)
	{
		$model = ResearchToolObject::load(ResultSet::$filename);
		//Build the query string
		$querystring = '
			PREFIX predicates: <' . SURVEYTOOL_PREDICATES_NAMESPACE . '>
			PREFIX resources: <' . SURVEYTOOL_RESOURCES_NAMESPACE . '>
			SELECT DISTINCT ?uid
			WHERE
			{
				_resultset predicates:resource_type resources:resultset ;
				predicates:uid ?uid ;
				' . ResearchToolObject::createArguments($arguments) . '
			}';
		//Query the model
		$results = $model->sparqlQuery($querystring);
		$resultSets = array();
		if(!empty($results))
		{
			foreach($results as $result)
			{
				$answerSets = ResultSet::getAnswerSets($model, $result['?uid']->label);
				$resultSets[] = new ResultSet($result['?uid']->label, $answerSets, array(), array(), array());
			}
		}
		return $resultSets;
	}

	/**
	 * function getAnswerSets()
	 * @param type $uid : The ResultSet uid for which the answerSets should be retrieved.
	 */
	private static function getAnswerSets($model, $uid)
	{
		$result = $model->findRegex("[(".$uid.")]", "[(has_answerset)]" ,null);
		$iterator = $result->getStatementIterator();
		$answersets = array();
		while($iterator->hasNext())
		{
			$element = $iterator->next();
			$answersets[] = $element->getLabelObject();
		}
		return $answersets;
	}



}