/lenasys/0.1

<?php

////Returns a quiz object 

////Parameters: (POST) objectID, quizNr, qVarNr, courseName, courseOccasion, login, password

////Returns: objectData

 

session_start();

//Check if the sent login name is the same as the one stored in the session

if($_POST['loginName']==$_SESSION['loginName'] && $_POST['courseName']==$_SESSION['courseName'] && $_POST['quizNr']==$_SESSION['quizNr']){ 

 

        //Prevents browsers (IE) from caching the response

        header('Cache-Control: no-cache, must-revalidate');

        header('Expires: Mon, 26 Jul 1997 05:00:00 GMT');

        //header('Content-type: application/json');

        header('Content-type: application/json; charset=utf-8'); 

 

        include "dbconnect.php";

 

        //Check if the student is a praticipant of the course

        $queryString="SELECT COUNT(*) 

                                   FROM Student, StudentCourseRegistration 

                                   WHERE Student.ssn=StudentCourseRegistration.studentSsn

                                   AND Student.loginName=:LOGIN

                                   AND courseName=:CNAME 

                                   AND courseOccasion=:COCCASION;";

        $stmt = $pdo->prepare($queryString);

        $stmt->bindParam(':LOGIN', $_POST['loginName']);

        $stmt->bindParam(':CNAME', $_POST['courseName']);

        $stmt->bindParam(':COCCASION', $_POST['courseOccasion']);

        $stmt->execute();

 

        if($stmt->fetchColumn()==1){ //Student is registered for the course - COUNT result read from the first column of the next unread row (i.e. the first row) 

                

                //Check if quiz is open

                $queryString="SELECT Quiz.opening, Quiz.closing

                                           FROM Quiz

                                           WHERE Quiz.nr=:QNR

                                           AND Quiz.courseName=:CNAME;";

                $stmt = $pdo->prepare($queryString);

                $stmt->bindParam(':QNR', $_POST['quizNr']);

                $stmt->bindParam(':CNAME', $_POST['courseName']);

                $stmt->execute();

                $quizDateTimes=$stmt->fetch(PDO::FETCH_ASSOC);

                if($quizDateTimes){

                        $now = new DateTime();

                        $opening = new DateTime($quizDateTimes['opening']);

                        $closing = new DateTime($quizDateTimes['closing']);

 

                        if($now<$opening) { //Quiz is not open yet

                                echo json_encode(array('Error' => 'Requested quiz is not open yet'));

                                exit();

                        } else if($now>$closing) { //Quiz is closed

                                echo json_encode(array('Error' => 'Requested quiz is closed'));

                                exit();

                        } // else continue (Not the best coding practice...)

                        

                } else { //Quiz does not exist

                        echo json_encode(array('Error' => 'Requested quiz does not exist'));

                        exit();

                }

        

                //Fetch quiz variant nr

                $queryString="SELECT AssignedQuizzes.qVarNr 

                                          FROM AssignedQuizzes 

                                          WHERE AssignedQuizzes.ssn=(SELECT Student.ssn FROM Student WHERE Student.ssn=AssignedQuizzes.ssn AND Student.loginName=:LOGIN) 

                                                AND AssignedQuizzes.quizNr=:QNR 

                                                AND AssignedQuizzes.quizCourseName=:CNAME

                                                AND AssignedQuizzes.courseOccasion=:COCCASION;";

                $stmt = $pdo->prepare($queryString);

                $stmt->bindParam(':LOGIN', $_POST['loginName']);

                $stmt->bindParam(':QNR', $_POST['quizNr']);

                $stmt->bindParam(':CNAME', $_POST['courseName']);

                $stmt->bindParam(':COCCASION', $_POST['courseOccasion']);

                $stmt->execute();

 

                $quizAssignmentData=$stmt->fetch(PDO::FETCH_ASSOC);

                $qVarNr=$quizAssignmentData['qVarNr'];

                

                $queryString="SELECT QuizVariantObject.objectData 

                                          FROM QuizVariantObject 

                                          WHERE QuizVariantObject.id=:OID AND QuizVariantObject.quizNr=:QNR AND QuizVariantObject.qVarNr=:QVNR AND QuizVariantObject.quizCourseName=:CNAME;";

                $stmt = $pdo->prepare($queryString);

                $stmt->bindParam(':OID', $_POST['objectID']);

                $stmt->bindParam(':QNR', $_POST['quizNr']);

                $stmt->bindParam(':QVNR', $qVarNr);

                $stmt->bindParam(':CNAME', $_POST['courseName']);

                $stmt->execute();

 

                $quizVariantObject=$stmt->fetch(PDO::FETCH_ASSOC);

 

                if(count($quizVariantObject)>0){

                        $quizVariantObject['objectData']=htmlspecialchars_decode($quizVariantObject['objectData']);

                        echo json_encode($quizVariantObject);

                        exit();

                } else {

                        echo json_encode(array('Error' => 'Object not found'));

                        exit();

                }

        } else {

                echo json_encode(array('Error' => 'Student not registered for this course (or incorrect password was sent)'));

                exit();

        }

} else { //Sent login name does not match the login name stored in the session

        echo json_encode(array('Error' => 'Sent login name does not match stored login name'));

}

?>