source: Dev/branches/jos-branch/server/classes/models/Session.php @ 285

<?php
require_once 'rdfConstants.php';
// Include RAP Library to write RDF files
include(RDFAPI_INCLUDE_DIR . "RDFAPI.php");
/**
 * Description of Session
 *
 * @author jkraaijeveld
 */

class Session extends ResearchToolObject
{
        private static $filename = 'data/sessions/sessions.rdf';

        public $title;
        public $creator;
        public $creationdate;
        public $pipeline;

        
        /**
         * Constructor for a Session object
         * @param type $uid
         * @param type $title
         * @param type $creator
         * @param type $creationdate
         * @param type $pipeline
         */
        public function __construct($uid = null, $title = null, $creator = null, $creationdate = null, $pipeline = null)
        {
                if(!isset($uid))
                {
                        $uid = md5(uniqid(rand(), true));
                }
                $this->uid = $uid;
                $this->title = $title;
                $this->creator = $creator;
                $this->creationdate = $creationdate;
                $this->pipeline = $pipeline;
        }

        /*
         * function evaluate(()
         * Evaluates all the references of this object.
         */
        public function evaluate()
        {
                if(is_string($this->creator))
                {
                        $result = User::get(array("uid" => $this->creator));
                        if(!isset($result[0]))
                                return false;
                        $this->creator = $result[0];
                }
                if(!empty($this->pipeline) && is_string($this->pipeline[0]))
                {
                        $newPipeline = array();
                        foreach($this->pipeline as $element)
                        {
                                //Check if the element's UID can be found in surveys, if not: 
                                //Check applications. If it isn't in either: invalid reference.
                                $result = Survey::get(array("uid" => $element));
                                if(!isset($result[0]))
                                        $result = Application::get(array("uid" => $element));
                                if(!isset($result[0]))
                                        return false;
                                $newPipeline[] = $result[0];
                        }
                        $this->pipeline = $newPipeline;
                }
                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())
                        throw new Exception('Evaluation failed.');

                //Ensure the required folder exists.
                if(!is_dir('data/sessions/'))
                        mkdir('data/sessions/');

                $model = ResearchToolObject::load(Session::$filename);

                $resourceSession = new Resource(SESSION . '/' . $this->uid);
                //Remove the old value stored with the given id
                $model->subtract($model->find($resourceSession, null, null));

                //Set the new values
                $resourceSessionType = new Resource(SESSION);
                $predicateType = new Resource(RTYPE);
                $model->add(new Statement($resourceSession, $predicateType, $resourceSessionType));

                $sessionId = new Literal($this->uid);
                $predicateId = new Resource(UID);
                $model->add(new Statement($resourceSession, $predicateId, $sessionId));

                $sessionTitle = new Literal($this->title);
                $predicateTitle = new Resource(TITLE);
                $model->add(new Statement($resourceSession, $predicateTitle, $sessionTitle));

                $sessionCreator = new Literal($this->creator->uid);
                $predicateCreator = new Resource(CREATOR);
                $model->add(new Statement($resourceSession, $predicateCreator, $sessionCreator));

                $sessionTimestamp = new Literal($this->creationdate->getTimestamp());
        //      $sessionTimestamp = new Literal($this->datetime);    // Edit of above function, allows for creation of session, but still results in errors...
        $predicateTimestamp = new Resource(CREATIONDATE);
                $model->add(new Statement($resourceSession, $predicateTimestamp, $sessionTimestamp));

                //Create a sequence to store the different applications and surveys.
                if(isset($this->pipeline))
                {
                        foreach($this->pipeline as $element)
                        {
                                $sessionObject = new Literal($element->uid);
                                $predicateObject = null;
                                if(get_class($element) == "Application")
                                        $predicateObject = new Resource(HAS_APPLICATION);
                                else if(get_class($element) == "Survey")
                                        $predicateObject = new Resource(HAS_SURVEY);
                                if(isset($predicateObject))
                                        $model->add(new Statement($resourceSession, $predicateObject, $sessionObject));
                        }
                }

                if(isset($this->answersets))
                {
                        foreach($this->answersets as $answerset)
                        {
                                $sessionAnswerSet = new Literal($answerset->uid);
                                $predicateAnswerSet = new Resource(HAS_ANSWERSET);
                                $model->add(new Statement($resourceSession, $predicateAnswerSet, $sessionAnswerSet));
                        }
                }
                
                return $model->saveAs(Session::$filename, 'rdf');
        }


        /**
         * function get()
         * @param type $arguments : An array containing one or more of the following elements:
         * 'uid', 'title', 'creationdate', 'applications', 'surveys'
         */
        public static function get($arguments)
        {
                $model = ResearchToolObject::load(Session::$filename);
        
                //Build the query string
                $querystring = '
                        PREFIX predicates: <' . SURVEYTOOL_PREDICATES_NAMESPACE . '>
                        PREFIX resources: <' . SURVEYTOOL_RESOURCES_NAMESPACE . '>
                        SELECT DISTINCT ?uid, ?title, ?creator, ?creationdate
                        WHERE
                        {
                                _session predicates:resource_type resources:session ;
                                predicates:uid ?uid ;
                                predicates:title ?title ;
                                predicates:creator ?creator ;
                                predicates:creationdate ?creationdate ;
                                ' . ResearchToolObject::createArguments($arguments) . '
                        }';
                //Query the model
                $results = $model->sparqlQuery($querystring);
                $sessions = array();
                if(!empty($results))
                {
                        foreach($results as $result)
                        {
                                //Create a session object out of every result, get all required fields as well.
                                $pipeline = Session::getPipeline($model, $result['?uid']->label);
                                $creator = $result['?creator']->label;
                                $creationdate = new DateTime();
                                $creationdate->setTimestamp(intval($result['?creationdate']->label));
                                $sessions[] = new Session($result['?uid']->label, $result['?title']->label, $creator, $creationdate, $pipeline);
                        }
                }
                return $sessions;
        }
        /**
         * function getPipeline()
         * param type $uid : The Session uid for which the pipeline should be retrieved.
         */
        private static function getPipeline($model, $uid)
        {
                $result = $model->findRegex("[(".$uid.")]", "[(has_application)|(has_survey)]" ,null);
                $iterator = $result->getStatementIterator();
                $pipeline = array();
                while($iterator->hasNext())
                {
                        $element = $iterator->next();
                        $pipeline[] = $element->getLabelObject();
                }
                return $pipeline;
        }

        /**
         * function toSPSS
         * @param type $location
         * Writes an SPSS parseable file at the given location, named '$datetime_$title.txt'
         * One big note about toSPSS: If this session contains multiple instances of THE SAME Survey,
         * the world burns, people die, etcetera. (or, in a more fortunate case, the latest values
         * are written to the file whilst the others get lost.
         */
        //DO NOT USE - BROKEN AS OF 23/12/2011
        public function toSPSS($location)
        {
                $this->evaluate();
                if(!is_dir($location))
                {
                        mkdir($location);
                }
                //Create the filename, open the file at the given location
                $fileName = $this->datetime->format("d-m-Y") . "_" . $this->title . ".txt";

                //Make a list of all 'column headers', e.g. "respondent" and all the question codes.
                $headers = array();
                $headers[] = "respondent";
                foreach ($this->pipeline as $element)
                {
                        if(get_class($element) == "Survey")
                        {
                                $element->evaluate();
                                foreach($element->questions as $question)
                                {
                                        //TODO: This might need fixing after lazy initialization refactoring.
                                        $headers[] = $element->title . '_' . $question->uid;
                                }
                        }
                }
                //Return if there are no surveys.
                if(count($headers) < 2)
                        return;
                
                //Get the answers for all respondents
                $answers = $this->getAnswers($headers);

                //Create the strings and write to file.
                $headerString = "";
                foreach($headers as $headerElement)
                {
                        $headerString = $headerString . $headerElement . "\t";
                }
                $fileHandler = fopen($location . '/' . $fileName, 'w') or die("File in use");
                fwrite($fileHandler, $headerString . "\n");
                foreach($answers as $entry)
                {
                        $entryString = "";
                        //PHP doesn't automatically sort the indices so I have to do it myself
                        //Entry elements can now be printed in order to match the headers
                        for ($i = 0; $i < count($headers); $i++)
                        {
                                if(in_array($i, array_keys($entry)))
                                        $entryString = $entryString . $entry[$i] . "\t";        
                                else
                                        $entryString = $entryString . "\t";
                        }
                        fwrite($fileHandler, $entryString . "\n");      
                }
        }

        /*
         * function getAnswers
         * @param type $headers
         * Based on the questions specified in the headers array, matches the answers of every
         * respondent to the correct questions and returns an array containing a list of answers per 
         * respondent
         */
        private function getAnswers($headers)
        {
                //Add the answers per survey per respondent. Requires some extra looping to assure proper ordering.
                //Keeps a list of respondents which have already been used. If an answerset exists for a respondent which
                //already exists within the answers-array, use the index of the respondent. Else: make a new row.
                $respondentsUsed = array();
                $answers = array();
                foreach($this->answersets as $answerset)
                {
                        $entryIndex;
                        if(in_array($answerset->respondent->name, $respondentsUsed))
                        {
                                $entryIndex = array_search($answerset->respondent->name, $respondentsUsed);
                                $entry = $answers[$entryIndex];
                        }
                        else
                        {
                                $entry = array();
                                $entry[0] = $answerset->respondent->name;
                                $entryIndex = count($respondentsUsed);
                                $respondentsUsed[] = $answerset->respondent->name;
                        }
                        foreach ($answerset->answers as $answer)
                        {
                                $index = array_search($answerset->survey->title . '_' . $answer->question->uid, $headers);
                                //Index has to be a good number, else the answer doesn't belong in this session
                                //Causes might be a missing question or having a wrong survey
                                if($index != 0)
                                {
                                        $value = "";
                                        foreach ($answer->values as $val)
                                        {
                                                $value = $value . $val . ",";
                                        }
                                        //We all hate trailing commas
                                        if (strlen($value) > 0) { $value = substr($value, 0, strlen($value)-1); }
                                        $entry[$index] = $value;
                                }
                        }
                        $answers[$entryIndex] = $entry;
                }
                return $answers;
        }

    public static function create($obj) {
        return new Session($obj->uid, $obj->title, $obj->creator,
                $obj->creationdate, $obj->pipeline);
    }

}       

?>