/lenasys/0.1

<?php

////Handels quiz answers 

////Parameters: loginName, courseName, courseOccasion, quizNr, 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 

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']) { 

	include "../../php/dbconnect.php";

	//Store answer and loginName+answer hash

	function storeAnswer($loginName,$courseName,$courseOccasion,$quizNr,$qVarRr,$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 AssignedQuizzes.quizNr=:QNR

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

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

	//TODO: Store ALL answer attempts in answerlog

	// CREATE TABLE AssignedQuizzesAnswerLog(

    // ssn CHAR(11), /*YYMMDD-XXXX*/

	// loginName VARCHAR(50),

    // quizNr INTEGER,

    // qVarNr INTEGER,

    // quizCourseName VARCHAR(200),

	// courseOccasion VARCHAR(25),

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

    // answer TEXT,

	// grade VARCHAR(10),

	// gradeComment TEXT,

	// answeredDateTime TIMESTAMP,

    // userAgent VARCHAR(1024), /*$_SERVER['HTTP_USER_AGENT']*/

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

	// ) ENGINE=INNODB CHARACTER SET utf8 COLLATE utf8_swedish_ci;

	$insertString = "INSERT INTO AssignedQuizzesAnswerLog(

							ssn,

							loginName,

							quizNr,

							qVarNr,

							quizCourseName,

							courseOccasion,

							answerHash,

							answer,

							grade,

							gradeComment,

							answeredDateTime,

							userAgent,

							userIP) 

							VALUES(

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

							:LOGIN,

							:QNR,

							(SELECT AssignedQuizzes.qVarNr 

							 FROM AssignedQuizzes, Student 

							 WHERE Student.ssn=AssignedQuizzes.ssn 	

							   AND AssignedQuizzes.quizNr=:QNR	

							   AND Student.loginName=:LOGIN 

							   AND AssignedQuizzes.quizCourseName=:CNAME

							   AND AssignedQuizzes.courseOccasion=:COCCASION),

							  :CNAME,

							  :COCCASION,

							  :AHASH,

							  :ANSWER,

							  '',

							  '',

							  :ADATETIME,

							  :UAGENT,

							  :UIP);";

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

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

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

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

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

	$stmt->bindParam(':ANSWER', $_POST['quizAnswer']);

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

	$stmt->bindParam(':AHASH', $hashedAnswer);

	$stmt->bindParam(':UAGENT', $_SERVER['HTTP_USER_AGENT']);

	$now=new DateTime();

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

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

	$stmt->bindParam(':UIP', $_SERVER['REMOTE_ADDR']);

	$stmt->execute();

	//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', $_SESSION['loginName']);

	$stmt->bindParam(':PASSW', $_SESSION['password']);

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

	$stmt->bindParam(':COCCASION', $_SESSION['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, 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();

		}

		/*

			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, AssignedQuizzes.qVarNr, AssignedQuizzes.gradeComment 

					  FROM AssignedQuizzes, Student

					  WHERE Student.ssn=AssignedQuizzes.ssn

						AND AssignedQuizzes.quizNr=:QNR 

						AND Student.loginName=:LOGIN

						AND AssignedQuizzes.quizCourseName=:CNAME

						AND AssignedQuizzes.courseOccasion=:COCCASION;";

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

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

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

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

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

		$stmt->execute();

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

		$stmt->closeCursor();

		if($result){ //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 quiz has already been answered', 'answerHash'=>$result['answerHash']));

					exit();

				} else { //check if autoCorrection

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

						$hashedAnswer= substr(md5($_POST['loginName'].$_POST['quizAnswer']),0,8);

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

									   $_POST['courseName'],

									   $_POST['courseOccasion'],

									   $_POST['quizNr'],

									   $result['qVarNr'],

									   $_POST['quizAnswer'],

									   "ungraded",

									   $result['gradeComment']."-",

									   $_SERVER['REMOTE_ADDR'],

									   $_SERVER['HTTP_USER_AGENT'],

									   $pdo)){

							//Stored answer

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

						} else {

							//Failed to store answer

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

						}

						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', $result['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

							$hashedAnswer= substr(md5($_POST['loginName'].$_POST['quizAnswer']),0,8);

							$stmt->closeCursor();

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

									   $_POST['courseName'],

									   $_POST['courseOccasion'],

									   $_POST['quizNr'],

									   $result['qVarNr'],

									   $_POST['quizAnswer'],

									   "Correct",

									   $result['gradeComment']." 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'));

		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')); 

}

?>