diff --git a/app/Http/Controllers/User/UserClassesController.php b/app/Http/Controllers/User/UserClassesController.php
index 6e83abc..f20e4f4 100644
--- a/app/Http/Controllers/User/UserClassesController.php
+++ b/app/Http/Controllers/User/UserClassesController.php
@@ -123,43 +123,63 @@ class UserClassesController extends Controller
         $student_name = $request->input('student_name');
         $student_surname = $request->input('student_surname');
         $classes = Classes::find($request->get('classes_id'));
+        $subject = Subject::find($classes->subject_id);
+        $room_capacity = Room::find($subject->room_id)->capacity;
+        $attendances = Attendance::where('classes_id', $classes->id)->get();
+        $student_ids = $attendances->pluck('student_id_number')->toArray();
+        $seat_numbers = $attendances->pluck('seat_number')->toArray();
 
-        if($classes->mode == 'quick') {
-            Attendance::create([
-                'classes_id' => $classes->id,
-                'student_id_number' => $student_id_number,
-                'student_name' => $student_name,
-                'student_surname' => $student_surname,
-                'seat_number' => null
-            ]);
-            return view('map.summary_map', ['student_name' => $student_name, 'student_surname' => $student_surname, 'seat_number' => null, 'student_id_number' => $student_id_number, 'classes_id' => $classes->id, 'mode' => $classes->mode]);
-
+        if(in_array($student_id_number, $student_ids)) { // if student attendance record already exists
+            $student_seat_number = Attendance::where('student_id_number', $student_id_number)->first()->seat_number;
+            $warning = 'Ten numer indeksu został już wcześniej zapisany na te zajęcia.';
+            return view('map.summary_map', ['student_name' => $student_name, 'student_surname' => $student_surname, 'seat_number' => $student_seat_number, 'student_id_number' => $student_id_number, 'classes_id' => $classes->id, 'mode' => $classes->mode, 'warning' => $warning]);
         } else {
-            $attendances = Attendance::where('classes_id', $classes->id)->get();
-            $seat_numbers = $attendances->pluck('seat_number')->toArray();
-            $subject = Subject::find($classes->subject_id);
-            $room_arrangement = Room::find($subject->room_id)->arrangement;
-            if(!$room_arrangement) {
-                $room_arrangement = Room::where('name', 'Inna sala')->first()->arrangement;
-            }
-            $room_rows = count(explode("++", $room_arrangement));
-            if($room_rows > 4) {  //max 4 rows on one page
-                $multi_parts = true;
-                $parts_number = ceil($room_rows/4);
+            if (count($seat_numbers) >= $room_capacity) { // if there are no more free seats in room, add student without assigning seat number (regardless of the classes mode)
+                Attendance::create([
+                    'classes_id' => $classes->id,
+                    'student_id_number' => $student_id_number,
+                    'student_name' => $student_name,
+                    'student_surname' => $student_surname,
+                    'seat_number' => null
+                ]);
+                $warning = "Zostałeś zapisany na listę obecności, ale bez przyznanego miejsca.";
+                return view('map.summary_map', ['student_name' => $student_name, 'student_surname' => $student_surname, 'seat_number' => null, 'student_id_number' => $student_id_number, 'classes_id' => $classes->id, 'mode' => $classes->mode, 'warning' => $warning]);
             } else {
-                $multi_parts = false;
-                $parts_number = 1;
-            }
+                if ($classes->mode == 'quick') {
+                    Attendance::create([
+                        'classes_id' => $classes->id,
+                        'student_id_number' => $student_id_number,
+                        'student_name' => $student_name,
+                        'student_surname' => $student_surname,
+                        'seat_number' => null
+                    ]);
+                    return view('map.summary_map', ['student_name' => $student_name, 'student_surname' => $student_surname, 'seat_number' => null, 'student_id_number' => $student_id_number, 'classes_id' => $classes->id, 'mode' => $classes->mode, 'warning' => null]);
+                } else {
+                    // prepare seat map
+                    $room_arrangement = Room::find($subject->room_id)->arrangement;
+                    if (!$room_arrangement) {
+                        $room_arrangement = Room::where('name', 'Inna sala')->first()->arrangement;
+                    }
+                    $room_rows = count(explode("++", $room_arrangement));
+                    if ($room_rows > 4) {  //max 4 rows on one page
+                        $multi_parts = true;
+                        $parts_number = ceil($room_rows / 4);
+                    } else {
+                        $multi_parts = false;
+                        $parts_number = 1;
+                    }
 
-            if($classes->mode == 'test') {
-                $room_capacity = Room::find($subject->room_id)->capacity;
-                $random_seat = rand(1, $room_capacity);
-                while(in_array($random_seat, $seat_numbers))  {
-                    $random_seat = rand(1, $room_capacity);
+                    if ($classes->mode == 'test') {
+                        $random_seat = rand(1, $room_capacity);
+                        while (in_array($random_seat, $seat_numbers)) {
+                            $random_seat = rand(1, $room_capacity);
+                        }
+                        return view('map.seat_map', ['student_name' => $student_name, 'student_surname' => $student_surname, 'seat_number' => $random_seat, 'student_id_number' => $student_id_number, 'classes_id' => $classes->id, 'seat_numbers' => $seat_numbers, 'room_arrangement' => $room_arrangement, 'multi_parts' => $multi_parts, 'parts_number' => $parts_number, 'mode' => 'test', 'random_seat' => $random_seat]);
+                    } else {
+                        return view('map.seat_map', ['student_name' => $student_name, 'student_surname' => $student_surname, 'student_id_number' => $student_id_number, 'classes_id' => $classes->id, 'seat_numbers' => $seat_numbers, 'room_arrangement' => $room_arrangement, 'multi_parts' => $multi_parts, 'parts_number' => $parts_number, 'mode' => null]);
+                    }
                 }
-                return view('map.seat_map', ['student_name' => $student_name, 'student_surname' => $student_surname, 'seat_number' => $random_seat, 'student_id_number' => $student_id_number, 'classes_id' => $classes->id, 'seat_numbers' => $seat_numbers, 'room_arrangement' => $room_arrangement, 'multi_parts' => $multi_parts, 'parts_number' =>$parts_number, 'mode' => 'test', 'random_seat' => $random_seat]);
             }
-            return view('map.seat_map', ['student_name' => $student_name, 'student_surname' => $student_surname, 'student_id_number' => $student_id_number, 'classes_id' => $classes->id, 'seat_numbers' => $seat_numbers, 'room_arrangement' => $room_arrangement, 'multi_parts' => $multi_parts, 'parts_number' =>$parts_number, 'mode' => null]);
         }
     }
 
@@ -177,7 +197,7 @@ class UserClassesController extends Controller
             'student_surname' => $student_surname,
             'seat_number' => $seat_number
         ]);
-        return view('map.summary_map', ['student_name' => $student_name, 'student_surname' => $student_surname, 'seat_number' => $seat_number, 'student_id_number' => $student_id_number, 'classes_id' => $classes_id, 'mode' => null]);
+        return view('map.summary_map', ['student_name' => $student_name, 'student_surname' => $student_surname, 'seat_number' => $seat_number, 'student_id_number' => $student_id_number, 'classes_id' => $classes_id, 'mode' => null, 'warning' => null]);
     }
 
     public function preview_classes($classes_id, $orderBy='student_surname', $orderDirection='ASC')
diff --git a/public/js/map/seatchart-preview.js b/public/js/map/seatchart-preview.js
index 1ab22cb..2274265 100644
--- a/public/js/map/seatchart-preview.js
+++ b/public/js/map/seatchart-preview.js
@@ -5,34 +5,37 @@ function assignPlaces() {
         const seat_number = $(this).attr('id').split('++')[0];
         const name = $(this).attr('id').split('++')[1];
         const surname = $(this).attr('id').split('++')[2];
-        let map_seat = '';
-        if(!multi_parts) {
-            map_seat = $('#seat-map').find(`#${seat_number}`);
-        } else {
-            const parts_number = $('#multi_parts_number').val();
-            let index = 0;
-            map_seat = $('#seat-map-0').find(`#${seat_number}`);
-            while (!map_seat.length && index < parts_number) {
-                index++;
-                map_seat = $(`#seat-map-${index}`).find(`#${seat_number}`);
+        if(seat_number) {
+            let map_seat = '';
+            if(!multi_parts) {
+                map_seat = $('#seat-map').find(`#${seat_number}`);
+            } else {
+                const parts_number = $('#multi_parts_number').val();
+                let index = 0;
+                map_seat = $('#seat-map-0').find(`#${seat_number}`);
+                while (!map_seat.length && index < parts_number) {
+                    index++;
+                    map_seat = $(`#seat-map-${index}`).find(`#${seat_number}`);
+                }
+            }
+            if(map_seat.length) {
+                map_seat.html(`<b>${seat_number}</b> <br><span class="preview-name">${name} ${surname}</span>`);
+                map_seat.on('mouseover', () => {
+                    map_seat.css('backgroundColor', 'lightgrey');
+                    $(this).css('backgroundColor', 'lightgrey');
+                }).on('mouseleave', () => {
+                    map_seat.css('backgroundColor', '#649a24');
+                    $(this).css('backgroundColor', 'unset');
+                });
+                $(this).on('mouseover', () => {
+                    map_seat.css('backgroundColor', 'lightgrey');
+                    $(this).css('backgroundColor', 'lightgrey');
+                }).on('mouseleave', () => {
+                    map_seat.css('backgroundColor', '#649a24');
+                    $(this).css('backgroundColor', 'unset');
+                })
             }
         }
-        console.log(map_seat);
-        map_seat.html(`<b>${seat_number}</b> <br><span class="preview-name">${name} ${surname}</span>`);
-        map_seat.on('mouseover', () => {
-            map_seat.css('backgroundColor', 'lightgrey');
-            $(this).css('backgroundColor', 'lightgrey');
-        }).on('mouseleave', () => {
-            map_seat.css('backgroundColor', '#649a24');
-            $(this).css('backgroundColor', 'unset');
-        });
-        $(this).on('mouseover', () => {
-            map_seat.css('backgroundColor', 'lightgrey');
-            $(this).css('backgroundColor', 'lightgrey');
-        }).on('mouseleave', () => {
-            map_seat.css('backgroundColor', '#649a24');
-            $(this).css('backgroundColor', 'unset');
-        })
     })
 }
 
diff --git a/resources/views/map/start_map.blade.php b/resources/views/map/start_map.blade.php
index 3041638..4a9f8e2 100644
--- a/resources/views/map/start_map.blade.php
+++ b/resources/views/map/start_map.blade.php
@@ -34,6 +34,27 @@
                 <button type="submit" id="submit" class="checkout-button"> Dodaj studenta </button>
             </form>
         </div>
+
+        <div class="modal fade" id="already-exist-modal" tabindex="-1" role="dialog" aria-labelledby="already-exist-modal" aria-hidden="true">
+            <div class="modal-dialog modal-dialog-centered" role="document">
+                <div class="modal-content">
+                    <div class="modal-header">
+                        <h5>Taki student już istnieje</h5>
+                        <button type="button" class="close" data-dismiss="modal" aria-label="Close">
+                            <span aria-hidden="true">&times;</span>
+                        </button>
+                    </div>
+                    <div class="modal-body">
+                        <p> Student <span class="student"></span> już istnieje </p>
+                    </div>
+                    <div class="modal-footer">
+                        <button type="button" class="btn btn-primary" data-dismiss="modal" title="OK"> OK </button>
+                    </div>
+
+                </div>
+            </div>
+        </div>
+
         <script>
             var classes_code_input = $('#classes_code_input').html();
             const client = new WebSocket('ws://127.0.0.1:8888', classes_code_input);
diff --git a/resources/views/map/summary_map.blade.php b/resources/views/map/summary_map.blade.php
index f13a7e0..9ce0e51 100644
--- a/resources/views/map/summary_map.blade.php
+++ b/resources/views/map/summary_map.blade.php
@@ -10,9 +10,17 @@
         <div class="map-buttons">
             <a href="{{ route('user_classes') }}" class="checkout-button end-button"> Zakończ zapisy </a>
         </div>
-        <h1> Zostałeś poprawnie zapisany.</h1>
+        @if($warning)
+            <h1> {{ $warning }} </h1>
+        @else
+            <h1> Zostałeś poprawnie zapisany.</h1>
+        @endif
+        <br><br>
         <h2> {{ $student_name }} {{ $student_surname }} </h2>
+        <br><br>
+
         <h3> {{ $student_id_number }} </h3>
+        <br><br>
         @if(!$mode == "quick")
             <h3> miejsce: </h3>
             <ul id="sel-seat"> {{ $seat_number }} </ul>