<?php

/**
 * Description of AnswerSetConnector
 *
 * @author jkraaijeveld
 */
class AnswerSetConnector implements IConnector{
    protected $model;
    protected $fileName = 'data/answers/answersets.rdf';
    protected $db;

	/**
	 * Constructor for the AnswerSetConnector
	 */
	public function __construct()
	{
		//Ensure the required folder for this connector exists
		if(!is_dir('data/answers'))
			mkdir('data/answers');
	}

	/**
	 * function load()
	 * Loads the file into the standard MemModel
	 */
	public function load()
	{
	    //Get the Memory Model from the ModelFactory
        $this->model = ModelFactory::getDefaultModel();
        
        //Ensure the required file exists before loading
        if(file_exists($this->fileName))
            $this->model->load($this->fileName);
	}

	/**
     * function save()
     * Saves the MemModel into the given file.
     */
    public function save() {
        $this->model->saveAs($this->fileName,'rdf'); 
	}

	/**
	 * function get()
	 * @param type $arguments : An array having one ore more of the following elements:
	 * 'uid', 'survey', 'respondent', 'answers'.
	 */
	public function get($arguments)
	{
		$this->load();
		
		$keys = array_keys($arguments);
		$uid = ""; $survey = ""; $respondent = ""; $answers = "";
		if(in_array("uid", $keys))
			$uid = 'predicates:uid \''.$arguments["uid"].'\' ';
		if(in_array("survey", $keys))
			$survey = 'predicates:for_survey \''.$arguments["survey"].'\' ';
		if(in_array("respondent", $keys))
			$respondent = 'predicates:by_respondent \''.$arguments["respondent"].'\' ';
		if(in_array("answers", $keys))
		{
			foreach ($arguments["answers"] as $answer)
			{
				$answers = $answers . 'predicates:given_answer \'' . $answer . '\' ';
			}
		}

		//Build the query string
		$querystring = '
			PREFIX predicates: <' . SURVEYTOOL_PREDICATES_NAMESPACE . '>
			PREFIX resources: <' . SURVEYTOOL_RESOURCES_NAMESPACE . '>
			SELECT DISTINCT ?uid, ?for_survey, ?by_respondent
			WHERE
			{
				_answerset	predicates:resource_type	resources:answerset ;
				predicates:uid ?uid ;
				predicates:for_survey ?for_survey ;
				predicates:by_respondent ?by_respondent ;
				' . $uid . $survey . $respondent . $answers . '
			}';

		//Query the model
		$results = $this->model->sparqlQuery($querystring);
		$answerSets = array();
		if(!empty($results))
		{
			$this->db = new DatabaseInterface();
			foreach($results as $result)
			{
				$survey = $this->db->get("survey", array("uid" => $result['?for_survey']->label));
				$respondent = $this->db->get("respondent", array("uid" => $result['?by_respondent']->label));
				$answers = 	$this->getAnswers($result['?uid']->label);
				$answerSets[] = new AnswerSet($result['?uid']->label, $survey[0], $respondent[0], $answers);
			}
		}
		return $answerSets;
	}

	/**
	 * function getAnswers()
	 * @param type $uid : the uid for which the answers should be retrieved.
	 */
	private function getAnswers($uid)
	{
		$querystring = '
			PREFIX predicates: <' . SURVEYTOOL_PREDICATES_NAMESPACE .'>
			PREFIX resources: <' . SURVEYTOOL_RESOURCES_NAMESPACE .'>
			SELECT DISTINCT ?given_answer
			WHERE
			{
				_answerset predicates:resource_type resources:answerset ;
				predicates:given_answer ?given_answer ;
				predicates:uid \'' . $uid . '\'
			}';
		$answers = $this->model->sparqlQuery($querystring);
		$returnArray = array();
		if(!empty($answers))
		{
			foreach($answers as $answer)
			{
				$answerR = $this->db->get("answer", array("uid" => $answer["?given_answer"]->label));
				$returnArray[] = $answerR[0];
			}
		}
		return $returnArray;
	}

	/**
	 * function set()
	 * @param type $rToolObject : The ResearchToolObject to be saved.
	 */
	public function set($rToolObject)
	{
		$this->load();
		$resourceAnswerSet = new Resource(ANSWERSET . '/' . $rToolObject->uid);
		//Remove the old value stored with the given id
		$this->model->subtract($this->model->find($resourceAnswerSet, null, null));

		//Set the new values
		$resourceAnswerSetType = new Resource(ANSWERSET);
		$predicateRType = new Resource(RTYPE);
		$this->model->add(new Statement($resourceAnswerSet, $predicateRType, $resourceAnswerSetType));

		$answerSetId = new Literal($rToolObject->uid);
		$predicateId = new Resource(UID);
		$this->model->add(new Statement($resourceAnswerSet, $predicateId, $answerSetId));

		$surveyId = new Literal($rToolObject->survey->uid);
		$predicateSurvey = new Resource(FOR_SURVEY);
		$this->model->add(new Statement($resourceAnswerSet, $predicateSurvey, $surveyId));

		$respondentId = new Literal($rToolObject->respondent->uid);
		$predicateRespondent = new Resource(BY_RESPONDENT);
		$this->model->add(new Statement($resourceAnswerSet, $predicateRespondent, $respondentId));
		
		if(isset($rToolObject->answers))
		{
			foreach($rToolObject->answers as $answer)
			{
				$answerId = new Literal($answer->uid);
				$predicateAnswer = new Resource(GIVEN_ANSWER);
				$this->model->add(new Statement($resourceAnswerSet, $predicateAnswer, $answerId));
			}
		}
		$this->save();
	}
}