Lachenzelg/config/function.php

<?php
session_start();

require 'dbcon.php';

function validate($inputData){
    global $conn;
    $validatedData = mysqli_real_escape_string($conn, $inputData);
    return trim($validatedData);
}

function redirect($url, $status, $alertLevel="secondary")
{
    $_SESSION['status'] = $status;
    $_SESSION['alertLevel'] = $alertLevel;
    header('Location: '.$url);
    exit(0);

}

function logoutSession(){
    unset($_SESSION['auth']);
    unset($_SESSION['loggedInUserID']);
    unset($_SESSION['loggedInUserRole']);
}

function alertMessage($level="info")
{
    if(isset($_SESSION['status']))
    {
        echo '<div class="alert alert-'.$_SESSION['alertLevel'].'" role="alert">'.$_SESSION['status'].'
        </div>';
        unset($_SESSION['status']);
    }
}

function checkParamId($paramType)
{
    if(isset($_GET[$paramType]))
    {
        if($_GET[$paramType] != null)
        {
           return $_GET[$paramType];
        }
        else
        {
            return 'keine ID gefunden';
        }
    }
    else
    {
        return 'keine ID angegeben';
    }
}

function getAll($columnname,$tablename,$conditionvalue = "")
{
    global $conn;
    $column = validate($columnname);
    $table = validate($tablename);
    //$condition = validate($conditionvalue); 
    $query = "SELECT $column FROM $table $conditionvalue";
    $result = mysqli_query($conn, $query);
    return $result;
}

function saveResetToken($userId, $token, $expiry) {
    global $conn;
    $userId = validate($userId);
    $token = validate($token);
    $expiry = validate($expiry);

    $query = "UPDATE users SET reset_token='$token', reset_token_expiry='$expiry' WHERE userid='$userId'";
    $result = mysqli_query($conn, $query);

    return $result;
}

function getById($tableName, $id)
{
    global $conn;
    $table = validate($tableName);
    $id = validate($id);

    $query = "SELECT * FROM $table WHERE id='$id' LIMIT 1";
    $result = mysqli_Query($conn, $query);

    if($result)
    {
        if(mysqli_num_rows($result) == 1)
        {
            $row = mysqli_fetch_array($result, MYSQLI_ASSOC);
            $response = [
                'status' => 200,
                'message' => 'Daten konnten abgerufen werden',
                'data' => $row
            ];
            return $response;
        }
        else
        {
            $response = [
                'status' => 404,
                'message' => 'Keinen Eintrag gefunden'
            ];
            return $response;
        }
    }
    else
    {
        $response = [
            'status' => 500,
            'message' => 'Ein Fehler ist aufgetreten'
        ];
        return $response;
    }
}

function getByCategoryId($tableName, $id)
{
    global $conn;
    $table = validate($tableName);
    $id = validate($id);

    $query = "SELECT * FROM $table WHERE id='$id' LIMIT 1";
    $result = mysqli_Query($conn, $query);

    if($result)
    {
        if(mysqli_num_rows($result) == 1)
        {
            $row = mysqli_fetch_array($result, MYSQLI_ASSOC);
            $response = [
                'status' => 200,
                'message' => 'Daten konnten abgerufen werden',
                'data' => $row
            ];
            return $response;
        }
        else
        {
            $response = [
                'status' => 404,
                'message' => 'Keinen Eintrag gefunden'
            ];
            return $response;
        }
    }
    else
    {
        $response = [
            'status' => 500,
            'message' => 'Ein Fehler ist aufgetreten'
        ];
        return $response;
    }
}

function archiveQuery($tablename, $id)
{
    global $conn;

    $table = validate($tablename);
    $id = validate($id);

    $query = "UPDATE $table SET status='archived' WHERE id='$id' LIMIT 1";
    $result = mysqli_query($conn, $query);
    return $result;
}

function reactivateQuery($tablename, $id)
{
    global $conn;

    $table = validate($tablename);
    $id = validate($id);

    $query = "UPDATE $table SET status='active' WHERE id='$id' LIMIT 1";
    $result = mysqli_query($conn, $query);
    return $result;
}

function deleteQuery($tablename, $id, $limit = "")
{
    global $conn;

    $table = validate($tablename);
    $id = validate($id);
    
    $query = "DELETE FROM $table WHERE id='$id' '$limit'";
    $result = mysqli_query($conn, $query);
    return $result;
}

function getAllClasses($status)
{
    global $conn;
    if(!$status) {$querystatus = "";}
    elseif($status){$querystatus = "WHERE status='$status'";}
    $query = "SELECT id, CONCAT(sek, ' ', type, ' - ', name) AS display_name FROM tbl_classes $querystatus ORDER BY display_name ASC";
    $result = mysqli_query($conn, $query);

    $classOptions = array();

    if ($result) {
        while ($row = mysqli_fetch_assoc($result)) {
            $classOptions[$row['id']] = $row['display_name'];
        }
    }

    return $classOptions;
}

function getStudentCountsPerClass() {
    global $conn;

    $classOptions = getAllClasses('active');
    $classCounts = array();

    if (!empty($classOptions)) {
        foreach ($classOptions as $classID => $className) {
            $query = "SELECT COUNT(*) as count FROM tbl_students WHERE class = $classID AND (status='active' OR status='disabled')";
            $result = mysqli_query($conn, $query);

            if ($result) {
                $row = mysqli_fetch_assoc($result);
                $count = $row['count'];
            } else {
                $count = 0;
            }
            $classCounts[$classID] = $count;
        }
    }

    return $classCounts;
}

function createEnumSelect($tableName, $columnName, $selectedValue = '', $valueLabels = [])
{
    global $conn;

    $query = "SHOW COLUMNS FROM $tableName LIKE '$columnName'";
    $result = mysqli_query($conn, $query);

    if ($result) {
        $row = mysqli_fetch_assoc($result);
        $enumStr = $row['Type'];

        $enumValues = explode(",", str_replace("'", "", substr($enumStr, 5, -1)));
        foreach ($enumValues as $enumValue) {
            $enumLabel = isset($valueLabels[$enumValue]) ? $valueLabels[$enumValue] : ucfirst($enumValue);
            $selected = ($enumValue == $selectedValue) ? 'selected' : '';
            echo "<option value='$enumValue' $selected>$enumLabel</option>";
        }
    } else {
        echo "<select name='$columnName' required class='form-select'><option value=''>Fehler beim Abrufen der Werte</option></select>";
    }
}

function createEnumSelectFiltered($tableName, $columnName, $selectedValue = '', $valueLabels = []) {
    global $conn;

    $query = "SHOW COLUMNS FROM $tableName LIKE '$columnName'";
    $result = mysqli_query($conn, $query);

    if ($result) {
        $row = mysqli_fetch_assoc($result);
        $enumStr = $row['Type'];

        $enumValues = explode(",", str_replace("'", "", substr($enumStr, 5, -1)));
        foreach ($enumValues as $enumValue) {
            if (isset($valueLabels[$enumValue])) {
                $enumLabel = $valueLabels[$enumValue];
                $selected = ($enumValue == $selectedValue) ? 'selected' : '';
                echo "<option value='$enumValue' $selected>$enumLabel</option>";
            }
        }
    } else {
        echo "<select name='$columnName' required class='form-select'><option value=''>Fehler beim Abrufen der Werte</option></select>";
    }
}

function getArchivedStudentsWithActiveClasses() {
    global $conn;
    $query = "SELECT 
                tbl_students.id AS student_id,
                tbl_students.firstname AS student_firstname,
                tbl_students.lastname AS student_lastname,
                tbl_students.userid AS student_userid,
                CONCAT(tbl_classes.sek, ' ', tbl_classes.type, ' - ', tbl_classes.name) AS display_name
              FROM tbl_students
              INNER JOIN tbl_classes ON tbl_students.class = tbl_classes.id
              WHERE tbl_students.status = 'archived' AND tbl_classes.status != 'archived'";
    
    $result = mysqli_query($conn, $query);

    $students = array();

    while ($row = mysqli_fetch_assoc($result)) {
        $students[] = $row;
    }

    return $students;
}

function deleteArchivedStudentsWithActiveClasses($students) {
    global $conn;

    foreach ($students as $student) {
        $student_id = $student['student_id'];
        $query = "DELETE FROM tbl_students WHERE id='$student_id'";
        $result = mysqli_query($conn, $query);
        
        
    }
    return $result;
}

function reactivateArchivedStudentsWithActiveClasses($students) {
    global $conn;

    foreach ($students as $student) {
        $student_id = $student['student_id'];
        $query = "UPDATE tbl_students SET status='active' WHERE id='$student_id'";
        $result = mysqli_query($conn, $query);
        
        
    }
    return $result;
}

function getArchivedClasses() {
    global $conn;
    $query = "SELECT 
                tbl_classes.id AS class_id,
                CONCAT(tbl_classes.sek, ' ', tbl_classes.type, ' - ', tbl_classes.name) AS display_name,
                GROUP_CONCAT(
                    CONCAT(tbl_students.firstname, ' ', tbl_students.lastname, ' (ID: ', tbl_students.userid, ')') 
                    SEPARATOR '<br>'
                ) AS students
              FROM tbl_classes
              LEFT JOIN tbl_students ON tbl_classes.id = tbl_students.class
              WHERE tbl_classes.status = 'archived' AND tbl_students.status = 'archived'
              GROUP BY tbl_classes.id";
    
    $result = mysqli_query($conn, $query);

    $classes = array();

    while ($row = mysqli_fetch_assoc($result)) {
        $classes[] = $row;
    }

    return $classes;
}


function getClassesGroupedByLevel($status)
{
    global $conn;

    if (!$status) {
        $querystatus = "";
    } elseif ($status) {
        $querystatus = "WHERE status='$status'";
    }

    $query = "SELECT id, sek, CONCAT(sek, ' ', type, ' - ', name) AS display_name FROM tbl_classes $querystatus ORDER BY sek ASC, display_name ASC";
    $result = mysqli_query($conn, $query);

    $groupedClasses = array();

    if ($result) {
        while ($row = mysqli_fetch_assoc($result)) {
            $level = $row['sek'];

            // Erstelle ein neues Array für die Stufe, wenn es noch nicht existiert
            if (!isset($groupedClasses[$level])) {
                $groupedClasses[$level] = array();
            }

            // Füge die Klasse zur entsprechenden Stufe hinzu
            $groupedClasses[$level][] = array(
                'id' => $row['id'],
                'display_name' => $row['display_name']
            );
        }
    }

    return $groupedClasses;
}

function getAssignedItems($tableName, $primaryId, $secondaryColumn, $primaryColumn)
{
    global $conn;

    $primaryId = validate($primaryId);

    $query = "SELECT $secondaryColumn FROM $tableName WHERE $primaryColumn = '$primaryId'";
    $result = mysqli_query($conn, $query);

    $assignedItems = array();
    while ($row = mysqli_fetch_assoc($result)) {
        $assignedItems[] = $row[$secondaryColumn];
    }

    return $assignedItems;
}

function getStudentInformation($id)
{
    global $conn;

    $id = validate($id);

    $query = "SELECT
    tbl_students.id, 
    tbl_students.firstname,
    tbl_students.lastname,
    tbl_students.userid,
    tbl_students.status,
    tbl_students.dateofbirth,
    tbl_students.gender,
    tbl_students.class,
    tbl_students.emailstudent,
    tbl_students.emailparent1,
    tbl_students.emailparent2,
    CONCAT(tbl_classes.sek, ' ', tbl_classes.type, ' - ', tbl_classes.name) AS classDisplayName 
    FROM tbl_students 
    JOIN tbl_classes ON tbl_students.class = tbl_classes.id 
    WHERE tbl_students.id = '$id'"; 
    $result = mysqli_query($conn, $query);
    if($result)
    {
        if(mysqli_num_rows($result) == 1)
        {
            $row = mysqli_fetch_array($result, MYSQLI_ASSOC);
            $response = [
                'data' => $row
            ];
            return $response;
        }
    }

}

function getCategories($id)
{
    global $conn;

    $id = validate($id);

    $query = "SELECT 
    tbl_students.id,
    tbl_categories.id AS category_id,
    tbl_categories.name
    FROM 
    tbl_students
    JOIN 
    tbl_classes ON tbl_students.class = tbl_classes.id
    JOIN 
    tbl_assign_categories_classes ON tbl_classes.id = tbl_assign_categories_classes.class_id
    JOIN 
    tbl_categories ON tbl_assign_categories_classes.category_id = tbl_categories.id
    WHERE 
    tbl_students.id = '$id'";
    
    $result = mysqli_query($conn, $query);
    if($result) {
        $categories = array();

        while ($row = mysqli_fetch_assoc($result)) {
            $categories[] = $row;
        }
    
        return $categories;
    }
}

function getForms($student_id)
{
    global $conn;

    $student_id = validate($student_id);

    $query = "SELECT 
        tbl_forms.id AS form_id,
        tbl_forms.name AS form_name,
        tbl_forms.deadline AS deadline
    FROM 
        tbl_forms
    JOIN 
        tbl_assign_forms_classes ON tbl_forms.id = tbl_assign_forms_classes.form_id
    JOIN 
        tbl_students ON tbl_assign_forms_classes.class_id = tbl_students.class
    WHERE 
        tbl_students.id = '$student_id'";
    
    $result = mysqli_query($conn, $query);
    if($result) {
        $forms = array();

        while ($row = mysqli_fetch_assoc($result)) {
            $forms[] = $row;
        }
    
        return $forms;
    }
}

function getClassesPerCategory($category_id){
global $conn;
$category_id = validate($category_id);

$query = "
    SELECT tbl_classes.id,
    tbl_classes.sek,
    CONCAT(tbl_classes.sek, ' ', tbl_classes.type, ' - ', tbl_classes.name) AS classDisplayName
    FROM tbl_classes
    LEFT JOIN tbl_assign_categories_classes ON tbl_classes.id = tbl_assign_categories_classes.class_id
    WHERE tbl_classes.status = 'active'
        AND (tbl_assign_categories_classes.category_id = '$category_id' OR tbl_assign_categories_classes.category_id IS NULL)
        ORDER BY sek ASC, classDisplayName ASC
";

$result = mysqli_query($conn, $query); // Annahme: $conn ist Ihre MySQL-Verbindung

// Hier können Sie die verfügbaren Klassen für die Anzeige verwenden
if ($result) {
    $classes = array();
    while ($row = mysqli_fetch_assoc($result)) {
        $classes[] = $row; // Hier können Sie die Klasse anzeigen oder in Ihrer Anwendung verwenden
    }
    return $classes;
} 
}

function getClassesPerForm($form_id){
    global $conn;
    $form_id = validate($form_id);
    
    $query = "
        SELECT tbl_classes.id,
        tbl_classes.sek,
        CONCAT(tbl_classes.sek, ' ', tbl_classes.type, ' - ', tbl_classes.name) AS classDisplayName
        FROM tbl_classes
        INNER JOIN tbl_assign_forms_classes ON tbl_classes.id = tbl_assign_forms_classes.class_id
        WHERE tbl_classes.status = 'active'
            AND (tbl_assign_forms_classes.form_id = '$form_id')
            ORDER BY sek ASC, classDisplayName ASC
    ";
    
    $result = mysqli_query($conn, $query); // Annahme: $conn ist Ihre MySQL-Verbindung
    
    // Hier können Sie die verfügbaren Klassen für die Anzeige verwenden
    if ($result) {
        $classes = array();
        while ($row = mysqli_fetch_assoc($result)) {
            $classes[] = $row; // Hier können Sie die Klasse anzeigen oder in Ihrer Anwendung verwenden
        }
        return $classes;
    } 
}
    

function getClassesPerFormContent($formcontent_id){
    global $conn;
    $formcontent_id = validate($formcontent_id);
    
    $query = "
        SELECT tbl_classes.id,
        tbl_classes.sek,
        CONCAT(tbl_classes.sek, ' ', tbl_classes.type, ' - ', tbl_classes.name) AS classDisplayName
        FROM tbl_classes
        INNER JOIN tbl_assign_formcontents_classes ON tbl_classes.id = tbl_assign_formcontents_classes.class_id
        WHERE tbl_classes.status = 'active'
            AND (tbl_assign_formcontents_classes.formcontent_id = '$formcontent_id')
            ORDER BY sek ASC, classDisplayName ASC
    ";
    
    $result = mysqli_query($conn, $query);
    
    if ($result) {
        $classes = array();
        while ($row = mysqli_fetch_assoc($result)) {
            $classes[] = $row;
        }
        return $classes;
    } 
}

function getTeachers()
{
    global $conn;
    
    // Führe die Abfrage aus
    $query = "SELECT CONCAT(firstname, ' ', lastname) AS name, id FROM tbl_teachers ORDER BY name ASC";
    $result = mysqli_query($conn, $query);
    
    // Überprüfe, ob die Abfrage erfolgreich war
    if (!$result) {
        die("Fehler beim Ausführen der Abfrage: " . mysqli_error($conn));
    }
    
    // Fetch die Ergebnisse und speichere nur die benötigten Informationen
    $data = array();
    while ($row = mysqli_fetch_assoc($result)) {
        $data[] = $row;
    }
    
    return $data;
}

function getCourseTeacher($id)
{
    global $conn;
    
    // Führe die Abfrage aus
    $query = "SELECT CONCAT(firstname, ' ', lastname) AS name FROM tbl_teachers WHERE id='$id'";
    $result = mysqli_query($conn, $query);
    
    if ($result) {
        // Holen Sie den Datensatz aus dem Ergebnis
        $row = mysqli_fetch_assoc($result);
        // Rückgabe des Namens des Kursleiters
        return $row['name'];
    } else {
        // Rückgabe eines leeren Strings im Fehlerfall
        return '';
    }
}

function getCourseDatesByCourseID($courseID)
{
    global $conn;

    $courseID = validate($courseID);

    $query = "SELECT * FROM tbl_coursedates WHERE course_id='$courseID'";
    $result = mysqli_query($conn, $query);

    $courseDates = array();

    if ($result) {
        while ($row = mysqli_fetch_assoc($result)) {
            $courseDates[] = $row;
        }
    }

    return $courseDates;
}

function getCoursesByClassAndCategory($classID, $categoryID)
{
    global $conn;

    $classID = validate($classID);
    $categoryID = validate($categoryID);

    $query = "SELECT 
                tbl_courses.id,
                tbl_courses.name,
                tbl_courses.slogan
            FROM 
                tbl_courses
            INNER JOIN 
                tbl_assign_courses_classes ON tbl_courses.id = tbl_assign_courses_classes.course_id
            INNER JOIN 
                tbl_categories ON tbl_courses.category_id = tbl_categories.id
            INNER JOIN 
                tbl_classes ON tbl_assign_courses_classes.class_id = tbl_classes.id
            WHERE 
                tbl_classes.id = '$classID' AND tbl_categories.id = '$categoryID'";

    $result = mysqli_query($conn, $query);

    if($result) {
        $courses = array();

        while ($row = mysqli_fetch_assoc($result)) {
            $courses[] = $row;
        }
        return $courses;
    } 
}

function getDeadline($categoryID, $classID)
{
    global $conn;

    $categoryID = validate($categoryID);
    $classID = validate($classID);

    // Zuerst prüfen, ob die Deadline für die Kategorie festgelegt ist
    $query = "SELECT registration, showuntil, showuntil_set, deadline_set, deadline FROM tbl_categories WHERE id='$categoryID'";
    $result = mysqli_query($conn, $query);
    if ($result) {
        $row = mysqli_fetch_assoc($result);
        if (($row['registration'] == 'yes') && ($row['deadline_set'] == 'yes')) {
            return $row['deadline'];
        }
        if (($row['registration'] == 'yes') && ($row['deadline_set'] == 'custom')) {
            // Abfrage, um die neueste Deadline aller Kurse der Kategorie und Klasse zu finden
            $courseQuery = "SELECT MAX(tbl_courses.deadline) AS max_deadline 
            FROM tbl_courses
            INNER JOIN tbl_assign_courses_classes ON tbl_courses.id = tbl_assign_courses_classes.course_id
            WHERE tbl_courses.category_id='$categoryID' AND tbl_assign_courses_classes.class_id='$classID'";
            $courseResult = mysqli_query($conn, $courseQuery);
            $courseRow = mysqli_fetch_assoc($courseResult);
            return $courseRow['max_deadline'];
        }
        if (($row['registration'] == 'no') && ($row['showuntil_set'] == 'yes')) {
            return $row['showuntil'];
        }
        if (($row['registration'] == 'no') && ($row['showuntil_set'] == 'custom')) {
            // Abfrage, um die neueste Deadline aller Kurse der Kategorie und Klasse zu finden
            $courseQuery = "SELECT MAX(tbl_courses.show_until) AS max_showuntil 
            FROM tbl_courses
            INNER JOIN tbl_assign_courses_classes ON tbl_courses.id = tbl_assign_courses_classes.course_id
            WHERE tbl_courses.category_id='$categoryID' AND tbl_assign_courses_classes.class_id='$classID'";
            $courseResult = mysqli_query($conn, $courseQuery);
            $courseRow = mysqli_fetch_assoc($courseResult);
            return $courseRow['max_showuntil'];
        }
        if (($row['registration'] == 'custom')) {
            // Abfrage, um die neueste Deadline oder show_until aller Kurse der Kategorie und Klasse zu finden
            $courseQuery = "SELECT MAX(CASE 
                                    WHEN tbl_courses.registration = 'yes' THEN tbl_courses.deadline 
                                    WHEN tbl_courses.registration = 'no' THEN tbl_courses.show_until 
                                    ELSE NULL 
                                END) AS max_deadline_or_showuntil
                            FROM tbl_courses
                            INNER JOIN tbl_assign_courses_classes ON tbl_courses.id = tbl_assign_courses_classes.course_id
                            WHERE tbl_courses.category_id='$categoryID' AND tbl_assign_courses_classes.class_id='$classID'";
            $courseResult = mysqli_query($conn, $courseQuery);
            $courseRow = mysqli_fetch_assoc($courseResult);
            return $courseRow['max_deadline_or_showuntil'];
        }
    }
    return null; // Rückgabe von null, wenn keine Deadline gefunden wurde
}

function getCourseDeadline($courseID)
{
    global $conn;

    $courseID = validate($courseID);


    // Abfrage, um die Kategorie-ID des Kurses zu finden
    $query = "SELECT category_id FROM tbl_courses WHERE id='$courseID'";
    $result = mysqli_query($conn, $query);

    if ($result && mysqli_num_rows($result) > 0) {
        $row = mysqli_fetch_assoc($result);
        $categoryID = $row['category_id'];

        // Abfrage, um den Namen der Kategorie anhand der Kategorie-ID zu finden
        $query = "SELECT registration, showuntil, showuntil_set, deadline_set, deadline FROM tbl_categories WHERE id='$categoryID'";
        $result = mysqli_query($conn, $query);

        if ($result && mysqli_num_rows($result) > 0) {
            $row = mysqli_fetch_assoc($result);
            if (($row['registration'] == 'yes') && ($row['deadline_set'] == 'yes')) {
                return $row['deadline'];
            }
            if (($row['registration'] == 'yes') && ($row['deadline_set'] == 'custom')) {
                // Abfrage, um die neueste Deadline aller Kurse der Kategorie und Klasse zu finden
                $courseQuery = "SELECT deadline FROM tbl_courses WHERE id='$courseID'";
                $courseResult = mysqli_query($conn, $courseQuery);
                $courseRow = mysqli_fetch_assoc($courseResult);
                return $courseRow['deadline'];
            }
            if (($row['registration'] == 'no') && ($row['showuntil_set'] == 'yes')) {
                return $row['showuntil'];
            }
            if (($row['registration'] == 'no') && ($row['showuntil_set'] == 'custom')) {
                // Abfrage, um die neueste Deadline aller Kurse der Kategorie und Klasse zu finden
                $courseQuery = "SELECT show_until FROM tbl_courses WHERE id='$courseID'";
                $courseResult = mysqli_query($conn, $courseQuery);
                $courseRow = mysqli_fetch_assoc($courseResult);
                return $courseRow['show_until'];
            }
            if (($row['registration'] == 'custom')) {
                // Abfrage, um die neueste Deadline oder show_until aller Kurse der Kategorie und Klasse zu finden
                $courseQuery = "SELECT (CASE 
                                        WHEN registration = 'yes' THEN deadline 
                                        WHEN registration = 'no' THEN show_until 
                                        ELSE NULL 
                                    END) AS deadline_or_showuntil
                                FROM tbl_courses
                                WHERE id='$courseID'";
                $courseResult = mysqli_query($conn, $courseQuery);
                $courseRow = mysqli_fetch_assoc($courseResult);
                return $courseRow['deadline_or_showuntil'];
            }
        }
    }
    return null;

    // Zuerst prüfen, ob die Deadline für die Kategorie festgelegt ist
    $query = "SELECT registration, showuntil, showuntil_set, deadline_set, deadline FROM tbl_categories WHERE id='$categoryID'";
    $result = mysqli_query($conn, $query);
    if ($result) {
        $row = mysqli_fetch_assoc($result);
        if (($row['registration'] == 'yes') && ($row['deadline_set'] == 'yes')) {
            return $row['deadline'];
        }
        if (($row['registration'] == 'yes') && ($row['deadline_set'] == 'custom')) {
            // Abfrage, um die neueste Deadline aller Kurse der Kategorie und Klasse zu finden
            $courseQuery = "SELECT MAX(tbl_courses.deadline) AS max_deadline 
            FROM tbl_courses
            INNER JOIN tbl_assign_courses_classes ON tbl_courses.id = tbl_assign_courses_classes.course_id
            WHERE tbl_courses.category_id='$categoryID' AND tbl_assign_courses_classes.class_id='$classID'";
            $courseResult = mysqli_query($conn, $courseQuery);
            $courseRow = mysqli_fetch_assoc($courseResult);
            return $courseRow['max_deadline'];
        }
        if (($row['registration'] == 'no') && ($row['showuntil_set'] == 'yes')) {
            return $row['showuntil'];
        }
        if (($row['registration'] == 'no') && ($row['showuntil_set'] == 'custom')) {
            // Abfrage, um die neueste Deadline aller Kurse der Kategorie und Klasse zu finden
            $courseQuery = "SELECT MAX(tbl_courses.show_until) AS max_showuntil 
            FROM tbl_courses
            INNER JOIN tbl_assign_courses_classes ON tbl_courses.id = tbl_assign_courses_classes.course_id
            WHERE tbl_courses.category_id='$categoryID' AND tbl_assign_courses_classes.class_id='$classID'";
            $courseResult = mysqli_query($conn, $courseQuery);
            $courseRow = mysqli_fetch_assoc($courseResult);
            return $courseRow['max_showuntil'];
        }
        if (($row['registration'] == 'custom')) {
            // Abfrage, um die neueste Deadline oder show_until aller Kurse der Kategorie und Klasse zu finden
            $courseQuery = "SELECT MAX(CASE 
                                    WHEN tbl_courses.registration = 'yes' THEN tbl_courses.deadline 
                                    WHEN tbl_courses.registration = 'no' THEN tbl_courses.show_until 
                                    ELSE NULL 
                                END) AS max_deadline_or_showuntil
                            FROM tbl_courses
                            INNER JOIN tbl_assign_courses_classes ON tbl_courses.id = tbl_assign_courses_classes.course_id
                            WHERE tbl_courses.category_id='$categoryID' AND tbl_assign_courses_classes.class_id='$classID'";
            $courseResult = mysqli_query($conn, $courseQuery);
            $courseRow = mysqli_fetch_assoc($courseResult);
            return $courseRow['max_deadline_or_showuntil'];
        }
    }
    return null; // Rückgabe von null, wenn keine Deadline gefunden wurde
}

function getActiveStudentsByCategory($categoryID) {
    global $conn;
    
    $categoryID = validate($categoryID);

    // Abfrage, um alle aktiven Schüler abzurufen, die einer bestimmten Kategorie zugewiesen sind
    $query = "SELECT DISTINCT tbl_students.id, tbl_students.class, tbl_students.firstname, tbl_students.lastname, CONCAT(tbl_students.firstname, ' ', tbl_students.lastname) AS name
              FROM tbl_students
              INNER JOIN tbl_assign_categories_classes ON tbl_students.class = tbl_assign_categories_classes.class_id
              WHERE tbl_assign_categories_classes.category_id = '$categoryID'
              AND tbl_students.status != 'archived'";
    
    $result = mysqli_query($conn, $query);
    $students = [];
    
    if ($result && mysqli_num_rows($result) > 0) {
        while ($row = mysqli_fetch_assoc($result)) {
            $students[] = $row;
        }
    }
    
    return $students;
}

function getStudentCourseData($studentID, $courseID) {
    global $conn;

    $studentID = validate($studentID);
    $courseID = validate($courseID);

    // Abfrage, um die Daten des Schülers für den angegebenen Kurs abzurufen
    $query = "SELECT * FROM tbl_assign_students_courses 
              WHERE student_id='$studentID' AND course_id='$courseID'";
    $result = mysqli_query($conn, $query);

    if ($result && mysqli_num_rows($result) > 0) {
        $row = mysqli_fetch_assoc($result);
        return $row;
    }
}


function getCoursesByCategory($categoryID) {
    global $conn;

    $categoryID = validate($categoryID);

    // Abfrage, um alle Kurse abzurufen, die einer bestimmten Kategorie zugeordnet sind
    $query = "SELECT * FROM tbl_courses WHERE category_id = '$categoryID'";

    $result = mysqli_query($conn, $query);
    $courses = [];

    if ($result && mysqli_num_rows($result) > 0) {
        while ($row = mysqli_fetch_assoc($result)) {
            $courses[] = $row;
        }
    }

    return $courses;
}

function getStudentAssignments($studentID)
{
    global $conn;
    $studentID = validate($studentID);
    $query = "SELECT * FROM tbl_assign_students_courses WHERE student_id = $studentID";

    $result = mysqli_query($conn, $query);

    if ($result) {
        $assignments = array();

        while ($row = mysqli_fetch_assoc($result)) {
            $assignments[] = $row;
        }

        return $assignments;
    } else {
        return false;
    }
}

function updatePassword($userId, $newPassword) {
    global $conn;
    $userId = validate($userId);
    $newPassword = validate($newPassword);

    $query = "UPDATE users SET password='$newPassword' WHERE id='$userId'";
    $result = mysqli_query($conn, $query);

    return $result;
}

function deleteResetToken($userId) {
    global $conn;
    $userId = validate($userId);

    $query = "UPDATE users SET reset_token=NULL, reset_token_expiry=NULL WHERE id='$userId'";
    $result = mysqli_query($conn, $query);

    return $result;
}

function isStudentRegisteredForCourse($studentId, $courseId) {
    // Hier eine Abfrage zur Datenbank machen, um zu prüfen, ob ein Eintrag in tbl_assign_students_courses existiert
    global $conn; // Annahme, dass $conn die Datenbankverbindung ist
    $query = "SELECT COUNT(*) FROM tbl_assign_students_courses WHERE student_id = ? AND course_id = ?";
    $stmt = $conn->prepare($query);
    $stmt->bind_param('ii', $studentId, $courseId);
    $stmt->execute();
    $stmt->bind_result($count);
    $stmt->fetch();
    $stmt->close();
    
    return $count > 0;
}


// Function to get all courses assigned to a student
function getAllAssignedCourses($studentID) {
    global $conn;
    $assignedCourses = array();

    $query = "SELECT course_id FROM tbl_assign_students_courses WHERE student_id = '$studentID'";
    $result = mysqli_query($conn, $query);

    if ($result) {
        while ($row = mysqli_fetch_assoc($result)) {
            $assignedCourses[] = $row['course_id'];
        }
    }

    return $assignedCourses;
}

function getAllAssignedCoursesByCategory($studentID, $categoryID) {
    global $conn;
    $assignedCourses = array();

    $query = "SELECT tac.course_id FROM tbl_assign_students_courses tac 
              JOIN tbl_courses tc ON tac.course_id = tc.id 
              WHERE tac.student_id = '$studentID' AND tc.category_id = '$categoryID'";
    $result = mysqli_query($conn, $query);

    if ($result) {
        while ($row = mysqli_fetch_assoc($result)) {
            $assignedCourses[] = $row['course_id'];
        }
    }

    return $assignedCourses;
}

?>