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<?php
//// Returns a quiz variant including quiz data (If the student is registered for the course and the quiz is open)
//// If no quiz variant already assigned to the student a variant will be randomly selected and assigned
//// Parameters: (POST) login, courseName, courseOccasion, quizNr
//// Returns: quizNr
//// quizCourseName
//// quizData
//// quizObjectIDs
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 "../../php/dbconnect.php";
/* Function used to fetch quiz variant data */
function fetchQuizVariant($courseName, $quizNr, $quizVariantNr, $pdo) {
$queryString=" SELECT QuizVariant.quizNr, QuizVariant.quizCourseName, QuizVariant.quizObjectIDs, Quiz.quizData
FROM QuizVariant, Quiz
WHERE QuizVariant.quizNr=Quiz.nr
AND QuizVariant.qVarNr=:VARNR
AND QuizVariant.quizCourseName=:CNAME
AND QuizVariant.quizNr=:QNR;)";
$stmt = $pdo->prepare($queryString);
$stmt->bindParam(':CNAME', $courseName);
$stmt->bindParam(':QNR', $quizNr);
$stmt->bindParam(':VARNR', $quizVariantNr);
$stmt->execute();
$quizVariantData=$stmt->fetch(PDO::FETCH_ASSOC);
$quizVariantData['quizData']=htmlspecialchars_decode($quizVariantData['quizData']);
return $quizVariantData;
}
//Check if the student is a praticipant of the course
$queryString="SELECT COUNT(*)
FROM Student, StudentCourseRegistration
WHERE Student.ssn=StudentCourseRegistration.studentSsn
AND Student.loginName=:LOGINN
AND Student.passw=:PASSW
AND courseName=:CNAME
AND courseOccasion=:COCCASION;";
$stmt = $pdo->prepare($queryString);
$stmt->bindParam(':LOGINN', $_SESSION['loginName']);
$stmt->bindParam(':PASSW', $_SESSION['password']);
$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, Quiz.allowMultipleReplies
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();
$quizData=$stmt->fetch(PDO::FETCH_ASSOC);
if($quizData) {
$now = new DateTime();
$opening = new DateTime($quizData['opening']);
$closing = new DateTime($quizData['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();
}
//Check if student already has been assigned a quiz variant
$queryString="SELECT AssignedQuizzes.qVarNr, AssignedQuizzes.answerHash, AssignedQuizzes.answer
FROM AssignedQuizzes, 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();
$result=$stmt->fetch(PDO::FETCH_ASSOC);
if($result){ //If this quiz is assigned to the student
//if($stmt->rowCount() >= 1){ //If this quiz is assigned to the student
if($result['answerHash']!=NULL && $quizData['allowMultipleReplies']!='1'){ //Student has already answered the quiz
echo json_encode(array('Error' => 'This student has already answered this quiz', 'answerHash'=>$result['answerHash']));
exit();
} else { //Return quiz variant data assigned to student
$quizVariant=$result['qVarNr'];
$quizVariantData=fetchQuizVariant($_POST['courseName'], $_POST['quizNr'], $quizVariant, $pdo);
$quizVariantData['storedAnswer']=$result['answer'];
echo json_encode($quizVariantData);
exit();
}
} else { //This quiz has not been assigned to the student
//Select random variant for requested quiz nr (for a particular course)
//$queryString="SELECT COUNT(QuizVariant.quizNr)
// FROM QuizVariant
// WHERE QuizVariant.quizNr=:QNR AND QuizVariant.quizCourseName=:CNAME;";
//SELECT COUNT(QuizVariant.quizNr) FROM QuizVariant WHERE QuizVariant.quizNr=1 AND QuizVariant.quizCourseName='DA133G Webbutveckling - datorgrafik G1N, 7,5hp (IKI)';
$queryString="SELECT QuizVariant.qVarNr
FROM QuizVariant
WHERE QuizVariant.quizNr=:QNR
AND QuizVariant.quizCourseName=:CNAME;";
$stmt = $pdo->prepare($queryString);
$stmt->bindParam(':QNR', $_POST['quizNr']);
$stmt->bindParam(':CNAME', $_POST['courseName']);
$stmt->execute();
$quizVariants=$stmt->fetchAll(PDO::FETCH_NUM);
if(count($quizVariants)>0) {
$randomIndex=rand(0,count($quizVariants)-1);
$quizVariant=$quizVariants[$randomIndex][0];
$quizVariantData=fetchQuizVariant($_POST['courseName'], $_POST['quizNr'], $quizVariant, $pdo);
//Store selected variant
$insertString="INSERT INTO AssignedQuizzes(ssn, quizNr, qVarNr, quizCourseName, courseOccasion)
VALUES((SELECT Student.ssn FROM Student WHERE Student.loginName=:LOGIN), :QNR, :QVARNR, :CNAME, :COCCASION);";
$insertStmt = $pdo->prepare($insertString);
$insertStmt->bindParam(':LOGIN', $_SESSION['loginName']);
$insertStmt->bindParam(':CNAME', $quizVariantData['quizCourseName']);
$insertStmt->bindParam(':QNR', $quizVariantData['quizNr']);
$insertStmt->bindParam(':QVARNR', $quizVariant);
$insertStmt->bindParam(':COCCASION', $_SESSION['courseOccasion']);
$insertStmt->execute();
echo json_encode($quizVariantData);
exit();
} else {
echo json_encode(array('Error' => 'No quiz variants found'));
exit();
}
}
} else {
//TODO: Store login attempt in log-table
echo json_encode(array('Error' => 'Student not registered for this course'));
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'));
}
?>
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