<?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 QuestionConnector
 *
 * @author jkraaijeveld
 */
class QuestionConnector implements IConnector {
    
    protected $model;
    protected $fileName = 'data/questions/questions.rdf';
    
    /**
     * Constructor for QuestionConnector
     */
    public function __construct()
    {
        //Ensure the required folder for this connector exists
        if (!is_dir('data/questions/'))
            mkdir('data/questions/');	
    }
    
    /**
     * 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'); 
    }
    
    /**
     * Get the questions corresponding to the arguments.
	 * @param type $arguments : An array having one ore more of the following elements:
	 * 'uid', 'title', 'type', 'description', 'category', 'has_answer'.
     */
    public function get($arguments)
    {
        $this->load();
        
        $keys = array_keys($arguments);
        //Set default values for arguments
        $uid = ""; $title = ""; $type = ""; $description = ""; $category = ""; $has_answer = "";
        //Set the arguments if they are supplied
        if(in_array("uid", $keys))
            $uid = 'predicates:question_code \''.$arguments["uid"].'\'';
        if(in_array("title", $keys))
            $title = 'predicates:title \''.$arguments["title"].'\'';
        if(in_array("type", $keys))
            $type = 'predicates:type \''.$arguments["type"].'\'';
        if(in_array("description", $keys))
            $description = "predicates:description \"".$arguments["description"]."\"";
        if(in_array("category", $keys))
			$style = "predicates:category \"".$arguments["category"]."\"";
		if(in_array("answers", $keys))
		{
			foreach($arguments["answers"] as $answer)
			{
				$has_answer = $has_answer . 'predicates:has_answer \'' . $answer . '\' ';
			}
		}
           
        $querystring = '
            PREFIX  predicates: <' . SURVEYTOOL_PREDICATES_NAMESPACE . '>
            PREFIX  resources: <' . SURVEYTOOL_RESOURCES_NAMESPACE . '>
            SELECT DISTINCT ?uid, ?title, ?type, ?description, ?category
            WHERE 	
            {
                _question	predicates:resource_type	resources:question ;                
                predicates:question_code ?uid ;
                predicates:title ?title ;
                predicates:question_type ?type ;
                predicates:description ?description ;
                predicates:question_category ?category ;
				'. $uid . $title . $type . $description . $category . $has_answer . '
            }';
        //Create the querystring 
        $results = $this->model->sparqlQuery($querystring);

        
        $questions = array();
        if(!empty($results))
        {
            foreach($results as $result)
            {
                $answers = $this->getAnswers($result['?uid']->label);
                $questions[] = new Question($result['?uid']->label, $result['?title']->label, $result['?type']->label, $result['?description']->label, $result['?category']->label, $answers);
            }
        }
        return $questions;
    }
    
    /**
     * Gets the answers belonging to the given uid.
     * @param type $uid : The uid of the Question in question (haha, pun).
     */
    private function getAnswers($uid)
    {
        $querystring = '
            PREFIX  predicates: <' . SURVEYTOOL_PREDICATES_NAMESPACE . '>
            PREFIX  resources: <' . SURVEYTOOL_RESOURCES_NAMESPACE . '>
            SELECT DISTINCT ?has_answer
            WHERE
            {
                 _question	predicates:resource_type	resources:question ;
                predicates:has_answer ?has_answer ; 
                predicates:question_code \'' . $uid . '\'
            }';

        $answers = $this->model->sparqlQuery($querystring);
        $returnArray = array();
        if(!empty($answers))
        {
            foreach($answers as $answer)
            {
                $returnArray[] = $answer['?has_answer']->label;
            }
        }
        return $returnArray;
    }

    
    /**
     * Save the given ResearchTool object
     * @param type $rToolObject : The ResearchToolObject to be saved.
     */
    public function set($rToolObject)
    {
        $this->load();
        
        $resourceQuestion = new Resource(QUESTION.'/'.$rToolObject->uid);        
        //Remove the old value stored with the given id
        $this->model->subtract($this->model->find($resourceQuestion, null, null));
        
        //Save all the new values
        $resourceQuestionType = new Resource(QUESTION);
        $predicateRType = new Resource(RTYPE);
        $this->model->add(new Statement($resourceQuestion,$predicateRType,$resourceQuestionType));
        
        $questionQCode = new Literal($rToolObject->uid);
        $predicateQCode = new Resource(QCODE);
        $this->model->add(new Statement($resourceQuestion,$predicateQCode,$questionQCode));
        
        $questionTitle = new Literal($rToolObject->title);
        $predicateTitle = new Resource(TITLE);		
        $this->model->add(new Statement($resourceQuestion,$predicateTitle,$questionTitle));	

        $questionDescription = new Literal($rToolObject->description);
        $predicateDescription = new Resource(DESCRIPTION);
        $this->model->add(new Statement($resourceQuestion,$predicateDescription,$questionDescription));		

        $resourceQuestionType = new Literal($rToolObject->type);
        $predicateQType = new Resource(QTYPE);
        $this->model->add(new Statement($resourceQuestion,$predicateQType,$resourceQuestionType));
        
        $questionQCategory = new Literal($rToolObject->category);
        $predicateQCategory = new Resource(QCATEGORY);
        $this->model->add(new Statement($resourceQuestion,$predicateQCategory,$questionQCategory));

        if(isset($rToolObject->answers))
        {
            foreach($rToolObject->answers as $answer)
            {		
                $answerValue = new Literal($answer);
                $predicateAnswer = new Resource(HAS_ANSWER);	
                $this->model->add(new Statement($resourceQuestion,$predicateAnswer,$answerValue));
            }
        }
        $this->save();
    }
}

?>