<?php

class SurveyRDFReader
{
    protected $model;

    protected $surveyUID;
    protected $filePath;

    public function __construct($surveyUID)
    {
        // Create empty MemModel
        $factory = new ModelFactory();
        $this->model = $factory->getDefaultModel();

        $this->surveyUID = $surveyUID;
        $this->filePath = 'data/surveys/survey_'.$this->surveyUID.'.rdf';
    }

    public function loadSurvey()
    {
        if(file_exists($this->filePath))
        {
            $this->model->load($this->filePath);
            return true;
        }
        else
        {
            return false;
        }
    }

    public function getSurveyInfo()
    {		
        $this->loadSurvey();

        $result = array();
        $result['info'] = $this->readSurveyInfo();				
        $result['questionIDs'] = $this->readSurveyQuestionIDs();

        return $result;
    }

    public function readSurveyInfo()
    {
        $querystring = '
            PREFIX  predicates: <' . SURVEYTOOL_PREDICATES_NAMESPACE . '>
            PREFIX  resources: <' . SURVEYTOOL_RESOURCES_NAMESPACE . '>
            SELECT  ?uid ?title ?description ?creator
            WHERE 	
            {
                    _survey	predicates:resource_type	resources:survey ;
                                predicates:uid			?uid	;
                                predicates:title 		?title 	;
                                predicates:description		?description ;
                                predicates:creator		?creator
            }';

        $result = $this->model->sparqlQuery($querystring);

        return $result;
    }
    
    public function readSurveyQuestionIDs()
    {
        $querystring = '
            PREFIX 	predicates: <' . SURVEYTOOL_PREDICATES_NAMESPACE . '>
            PREFIX	resources: <' . SURVEYTOOL_RESOURCES_NAMESPACE . '>
            SELECT 	?questionID
            WHERE 
            {	
                    _survey	predicates:resource_type	resources:survey ;
                                predicates:has_question		?questionID				
            }';

        $result = $this->model->sparqlQuery($querystring);

        return $result;
    }

    public function getSurveyTitleByID($surveyID)
    {
        // Create empty MemModel
        $factory = new ModelFactory();
        $tempmodel= $factory->getDefaultModel();
        $tempmodel->load('data/surveys/survey_'.$surveyID.'.rdf');

        $querystring = '
            PREFIX  predicates: <' . SURVEYTOOL_PREDICATES_NAMESPACE . '>
            PREFIX  resources: <' . SURVEYTOOL_RESOURCES_NAMESPACE . '>
            SELECT  ?title 
            WHERE 	
            {
                    _survey     predicates:resource_type	resources:survey ;
                                predicates:title 		?title 	
            }';

        $result = $tempmodel->sparqlQuery($querystring);

        return $result;
    }
}
?>