/lenasys/0.1

<?php

////Handels quiz answers 

////Parameters: loginName, password, courseName, courseOccasion, quizNr, qVarNr, quizAnswer

////If autoCorrection==false the answer is stored without checking

////Else the quiz answer is checked for correctness, 

////	if incorrect the answer is not stored, else stored 

//Store answer and loginName+answer hash

function storeAnswer($loginName,$password,$courseName,$courseOccasion,$quizNr,$qVarNr,$quizAnswer,$grade,$gradeComment,$ip,$userAgent,$pdo) {

	$updateQuery="UPDATE AssignedQuizzes 

				  SET AssignedQuizzes.answer=:ANSWER, 

					  AssignedQuizzes.answerHash=:ANSWERHASH, 

					  AssignedQuizzes.grade=:GRADE, 

					  AssignedQuizzes.gradeComment=:GRADECOMMENT, 

					  AssignedQuizzes.answeredDateTime=:DATETIME,

					  AssignedQuizzes.userAgent=:AGENT,

					  AssignedQuizzes.userIP=:IP

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

					AND AssignedQuizzes.quizNr=:QNR

					AND AssignedQuizzes.qVarNr=:QVNR

					AND AssignedQuizzes.quizCourseName=:CNAME

					AND AssignedQuizzes.courseOccasion=:COCCASION;";

	$updateStmt = $pdo->prepare($updateQuery);

	$updateStmt->bindParam(':LOGIN', $loginName);

	$updateStmt->bindParam(':CNAME', $courseName);

	$updateStmt->bindParam(':QNR', $quizNr);

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

	$updateStmt->bindParam(':COCCASION', $courseOccasion);

	$updateStmt->bindParam(':ANSWER', $quizAnswer);

	$hashedAnswer= md5($loginName.$quizAnswer);

	$updateStmt->bindParam(':ANSWERHASH', $hashedAnswer);

	$updateStmt->bindParam(':GRADE', $grade);

	$updateStmt->bindParam(':GRADECOMMENT', $gradeComment);

	$now=new DateTime();

	$dateString=$now->format('Y-m-d H:i:s');

	//$updateStmt->bindParam(':DATETIME', new DateTime()->format('Y-m-d H:i:s')); // date and time formated to string e.g. "2012-08-23 08:59:00"

	$updateStmt->bindParam(':DATETIME', $dateString); // date and time formated to string e.g. "2012-08-23 08:59:00"

	$updateStmt->bindParam(':PASSW',$password);

	$updateStmt->bindParam(':IP',$ip);

	$updateStmt->bindParam(':AGENT',$userAgent);

	return $updateStmt->execute();

}

//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; 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 Student.passw=:PASSW

			   AND courseName=:CNAME 

			   AND courseOccasion=:COCCASION;";

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

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

$stmt->bindParam(':PASSW', $_POST['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 (and fetch auto correction setting)

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

				   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();

	}

	/*

		AssignedQuizzes(

    ssn CHAR(11), //YYMMDD-XXXX

    quizNr INTEGER,

    qVarNr INTEGER,

    quizCourseName VARCHAR(200),

	courseOccasion VARCHAR(25) NOT NULL,

    answerHash VARCHAR(255), //Hash of Student login name + answer 

    answer TEXT,

	grade VARCHAR(10),

	gradeComment TEXT,

	answeredDateTime TIMESTAMP,

    userAgent VARCHAR(1024),

    userIP VARCHAR(20), //$_SERVER['REMOTE_ADDR']

	PRIMARY KEY(ssn, qVarNr, quizNr, quizCourseName),

	*/

	//Check if student already has answered the assigned quiz variant

	$queryString="SELECT AssignedQuizzes.answerHash 

				  FROM AssignedQuizzes, Student

				  WHERE Student.ssn=AssignedQuizzes.ssn

					AND AssignedQuizzes.quizNr=:QNR 

					AND AssignedQuizzes.qVarNr=:QVARNR 

					AND Student.loginName=:LOGIN

					AND AssignedQuizzes.quizCourseName=:CNAME

					AND AssignedQuizzes.courseOccasion=:COCCASION;";

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

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

	$stmt->bindParam(':QVARNR', $_POST['qVarNr']);

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

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

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

	$stmt->execute();

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

	if($result) { //If there is a quiz variant assigned to the student

			if($result['answerHash']!=NULL){ //Student has already answered the quiz

				echo json_encode(array('Error' => 'This quiz has already been answered', 'answerHash'=>$result['answerHash']));

				exit();

			} else { //check if autoCorrection

				if($quizData['autoCorrected']=='0') { //Not auto corrected

					if(storeAnswer($_POST['loginName'],

								   $_POST['password'],

								   $_POST['courseName'],

								   $_POST['courseOccasion'],

								   $_POST['quizNr'],

								   $_POST['qVarNr'],

								   $_POST['quizAnswer'],

								   "ungraded",

								   "-",

								   $_SERVER['REMOTE_ADDR'],

								   $_SERVER['HTTP_USER_AGENT'],

								   $pdo)){

				        //Stored answer

						echo json_encode(array('Success' => 'true'));

					} else {

						//Failed to store answer

						echo json_encode(array('Success' => 'false'));

					}

					exit();

				} else { //Is auto corrected - Check if the correct answer was given 

					/*QuizVariant(

					 qVarNr INTEGER,

					quizNr INTEGER,

					quizCourseName VARCHAR(200),

					correctAnswer VARCHAR(255),

					quizObjectIDs TEXT,

					PRIMARY KEY(qVarNr, quizNr, quizCourseName),

					*/

					$queryString = "SELECT QuizVariant.correctAnswer

									FROM QuizVariant

									WHERE QuizVariant.qVarNr=:QVNR

										AND QuizVariant.quizNr=:QNR

										AND QuizVariant.quizCourseName=:CNAME";

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

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

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

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

					$stmt->execute();

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

					$correctAnswer=$qVarData['correctAnswer'];

					if($_POST['quizAnswer']==$correctAnswer){ //Correct answer was given

						$hashedAnswer= md5($_POST['loginName'].$_POST['quizAnswer']);

						if(storeAnswer($_POST['loginName'],

								   $_POST['password'],

								   $_POST['courseName'],

								   $_POST['courseOccasion'],

								   $_POST['quizNr'],

								   $_POST['qVarNr'],

								   $_POST['quizAnswer'],

								   "Correct",

								   "Quiz was corrected automatically",

								   $_SERVER['REMOTE_ADDR'],

								   $_SERVER['HTTP_USER_AGENT'],

								   $pdo)){

							//Stored answer

							echo json_encode(array('Success' => 'true', 'isCorrect' => 'true', 'hashedAnswer' => $hashedAnswer));

						} else {

							//Failed to store answer

							echo json_encode(array('Success' => 'false', 'isCorrect' => 'true', 'hashedAnswer' => $hashedAnswer));

						}

						exit();

					} else { //Answer is incorrect

						echo json_encode(array('isCorrect' => 'false'));

					}

					exit();

				}

			}

	} else {

		echo json_encode(array('Error' => 'This student has not been assigned the quiz'));

		exit();

	}

} else {

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

	exit();

}

?>