<?php

class QuestionRDFReader
{
    protected $model;

    protected $filePath;

    public function __construct()
    {
        // Create empty MemModel
        $factory = new ModelFactory();
        $this->model = $factory->getDefaultModel();

        $this->filePath = 'data/questions/';
        if (!is_dir($this->filePath))
            mkdir($this->filePath);	
    }
    
    public function loadQuestions()
    {
        if(file_exists($this->filePath.'questions.rdf'))
        {
            $this->model->load($this->filePath.'questions.rdf');
            return true;
        }
        else
        {
            return false;
        }
    }
    
    public function readQuestionByID($questionID)
    {        
        $result = array();
        $result['title'] = $this->readQuestionTitle($questionID);				
        $result['description'] = $this->readQuestionDescription($questionID);
        $result['type'] = $this->readQuestionType($questionID);
        $result['code'] = $this->readQuestionCode($questionID);
        $result['category'] = $this->readQuestionCategory($questionID);
        $result['answers'] = $this->readQuestionAnswers($questionID);

        return $result;
    }
    
    public function readQuestionIDs()
    {
        $result = null;
        
        if(file_exists($this->filePath.'questions.rdf'))
        {
            // Create empty MemModel
            $factory = new ModelFactory();
            $tempmodel= $factory->getDefaultModel();
            $tempmodel->load($this->filePath.'questions.rdf');

            $querystring = '
            PREFIX 	predicates: <' . SURVEYTOOL_PREDICATES_NAMESPACE . '>
            PREFIX	resources: <' . SURVEYTOOL_RESOURCES_NAMESPACE . '>
            SELECT 	?questionID
            WHERE 
            {	
                    _question	predicates:resource_type	resources:question ;
                                predicates:uid			?questionID				
            }';
            
            $result = $tempmodel->sparqlQuery($querystring);
        }
        return $result; 
    }
    
    public function readQuestionCodes()
    {
        $result = null;
        
        if(file_exists($this->filePath.'questions.rdf'))
        {
            // Create empty MemModel
            $factory = new ModelFactory();
            $tempmodel= $factory->getDefaultModel();
            $tempmodel->load($this->filePath.'questions.rdf');

            $querystring = '
            PREFIX 	predicates: <' . SURVEYTOOL_PREDICATES_NAMESPACE . '>
            PREFIX	resources: <' . SURVEYTOOL_RESOURCES_NAMESPACE . '>
            SELECT 	?questionCode
            WHERE 
            {	
                    _question	predicates:resource_type	resources:question ;
                                predicates:question_code        ?questionCode				
            }';
            
            $result = $tempmodel->sparqlQuery($querystring);
        }
        return $result; 
    }

    public function readQuestionTitle($questionID)
    {
        $querystring = '
            PREFIX  predicates: <' . SURVEYTOOL_PREDICATES_NAMESPACE . '>
            PREFIX  resources: <' . SURVEYTOOL_RESOURCES_NAMESPACE . '>
            SELECT  ?questionTitle
            WHERE 
            {	
                    _question	predicates:resource_type	resources:question ;
                                predicates:uid			"' . $questionID . '"  ;
                                predicates:title		?questionTitle 		
            }';

        $result = $this->model->sparqlQuery($querystring);

        return $result;
    }

    public function readQuestionDescription($questionID)
    {
        $querystring = '
            PREFIX  predicates: <' . SURVEYTOOL_PREDICATES_NAMESPACE . '>
            PREFIX  resources: <' . SURVEYTOOL_RESOURCES_NAMESPACE . '>
            SELECT  ?questionDescription
            WHERE 
            {	
                    _question	predicates:resource_type	resources:question ;
                                predicates:uid			"' . $questionID . '"  ;
                                predicates:description		?questionDescription 		
            }';

        $result = $this->model->sparqlQuery($querystring);

        return $result;
    }

    public function readQuestionType($questionID)
    {
        $querystring = '
            PREFIX  predicates: <' . SURVEYTOOL_PREDICATES_NAMESPACE . '>
            PREFIX  resources: <' . SURVEYTOOL_RESOURCES_NAMESPACE . '>
            SELECT  ?questionType
            WHERE 
            {	
                    _question	predicates:resource_type	resources:question ;
                                predicates:uid			"' . $questionID . '"  ;
                                predicates:question_type	?questionType				
            }';

        $result = $this->model->sparqlQuery($querystring);

        return $result;
    }
    
    public function readQuestionCode($questionID)
    {
        $querystring = '
            PREFIX  predicates: <' . SURVEYTOOL_PREDICATES_NAMESPACE . '>
            PREFIX  resources: <' . SURVEYTOOL_RESOURCES_NAMESPACE . '>
            SELECT  ?questionCode
            WHERE 
            {	
                    _question	predicates:resource_type	resources:question ;
                                predicates:uid			"' . $questionID . '"  ;
                                predicates:question_code	?questionCode				
            }';

        $result = $this->model->sparqlQuery($querystring);

        return $result;
    }
    
    public function readQuestionCategory($questionID)
    {
        $querystring = '
            PREFIX  predicates: <' . SURVEYTOOL_PREDICATES_NAMESPACE . '>
            PREFIX  resources: <' . SURVEYTOOL_RESOURCES_NAMESPACE . '>
            SELECT  ?questionCategory
            WHERE 
            {	
                    _question	predicates:resource_type	resources:question ;
                                predicates:uid			"' . $questionID . '"  ;
                                predicates:question_category	?questionCategory				
            }';

        $result = $this->model->sparqlQuery($querystring);

        return $result;
    }

    public function readQuestionAnswers($questionID)
    {
        $querystring = '
            PREFIX  predicates: <' . SURVEYTOOL_PREDICATES_NAMESPACE . '>
            PREFIX  resources: <' . SURVEYTOOL_RESOURCES_NAMESPACE . '>
            SELECT  ?answerDescription
            WHERE 
            {
                    _question	predicates:resource_type	resources:question ;
                                predicates:uid			"' . $questionID . '"  ;
                                predicates:has_answer		?answerDescription
            }';

        $result = $this->model->sparqlQuery($querystring);

        return $result;
    }
}

?>