diff --git a/DBManager.py b/DBManager.py
new file mode 100644
index 0000000..2c8ffef
--- /dev/null
+++ b/DBManager.py
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+import json
+import os.path
+
+# PRZYKLADOWY SCHEMAT DB
+# informacje o dacie dnia dzisiejszego oraz nazwie tego dnia (pon, wt) będzie trzeba podawać przy inicjalizacji klasy
+# może być od użytkownika z konsoli lub od systemu
+# {
+#     "06.06.2021": [
+#         {
+#             "date": "06.06.2021",
+#             "time": "12:00-13:30",
+#             "place": "Restauracja Alfa",
+#             "participants": ["Jan Kowalski", "Adam Nowak"],
+#             "description": None
+#         },
+#         {
+#             "date": "06.06.2021",
+#             "time": "18:00-18:45",
+#             "place": "Stadion Miejski",
+#             "participants": ["Jan Kowalski"],
+#             "description": None
+#         }
+#     ],
+#     "07.06.2021": [
+#         {
+#             "date": "07.06.2021",
+#             "time": "9:00-10:30",
+#             "place": "MS Teams",
+#             "participants": ["Adam Nowak"],
+#             "description": "Wykład z matematyki"
+#         }
+#     ]
+# }
+
+
+
+class calender_db:
+    def __init__(self, date="07.06.2021", name="poniedziałek", start_day_time="8:00", end_day_time="20:00", file_path="data-base/calender.json"):
+        self.DB = {}
+        self.start_day_time = start_day_time
+        self.end_day_time = end_day_time
+        self.today_date = date
+        self.today_day_name = name
+        self.today_day, self.today_month, self.today_year = self.get_day_month_year(self.today_date)
+        if os.path.isfile(file_path):
+            with open(file_path, 'r+') as input:
+                self.DB = json.load(input)
+
+    def save_db(self):
+        with open(file_path, 'w+') as output:
+            self.DB = json.dumps(input)
+
+    # CRUD methods
+
+    def create_meeting(self, meeting_dict):
+        date = meeting_dict['date'].lower()
+        if date == "dziś":
+            date = self.today_date
+        elif is_date_day_name(date):
+            offset = get_days_difference(date)
+            date = calculate_date_with_offset(offset)
+        #TODO chceck date format
+        if date in self.DB.keys():
+            self.DB[date].append(meeting_dict)
+            self.save_db()
+        else:
+            self.DB[date] = [meeting_dict]
+            self.save_db()
+
+    def is_collision(self, date, time):
+        # TODO zaimplementować oferowanie innego czasu w razie kolizji
+        if date in self.DB.keys():
+            meetings = DB[date]
+            for m in meetings:
+                meeting_time = m['time'].split("-")
+                start = meeting_time[0]
+                # meeting has start and end time
+                if len(meeting_time > 1):
+                    end = meeting_time[1]
+                    seeking_hour, seeking_min = self.get_hour_minutes(time)
+                    seeking_hour_s, seeking_min_s = self.get_hour_minutes(start)
+                    seeking_hour_e, seeking_min_e = self.get_hour_minutes(end)
+                    if seeking_hour < seeking_hour_s:
+                        return False
+                    if seeking_hour == seeking_hour_s and seeking_min < seeking_min_s:
+                        return False
+                    if seeking_hour == seeking_hour_e and seeking_min >= seeking_min_e:
+                        return False
+                    if seeking_hour > seeking_hour_e:
+                        return False
+                    return True
+                # meeting has only start time
+                else:
+                    seeking_hour, seeking_min = self.get_hour_minutes(time)
+                    seeking_hour_s, seeking_min_s = self.get_hour_minutes(start)
+                    if seeking_hour == seeking_hour_s and seeking_min == seeking_min_s:
+                        return True
+                    else:
+                        return False
+        else:
+            return False
+
+    def is_collision(self, date, time_start, time_end):
+        # TODO zaimplementować oferowanie innego czasu w razie kolizji
+        if date in self.DB.keys():
+            meetings = DB[date]
+            for m in meetings:
+                meeting_time = m['time'].split("-")
+                start = meeting_time[0]
+                # meeting has start and end time
+                if len(meeting_time > 1):
+                    end = meeting_time[1]
+                    hour_s, min_s = self.get_hour_minutes(time_start)
+                    hour_e, min_e = self.get_hour_minutes(time_end)
+                    seeking_hour_s, seeking_min_s = self.get_hour_minutes(start)
+                    seeking_hour_e, seeking_min_e = self.get_hour_minutes(end)
+                    if hour_s < seeking_hour_s and hour_e < seeking_hour_s:
+                        return False
+                    if hour_s < seeking_hour_s and hour_e == seeking_hour_s and min_e <= seeking_min_s:
+                        return False
+                    if hour_s == seeking_hour_s and min_s < seeking_min_s and hour_e == seeking_hour_s and min_e <= seeking_min_s:
+                        return False
+                    if hour_s == seeking_hour_e and min_s >= seeking_min_e:
+                        return False
+                    if hour_s > seeking_hour_e:
+                        return False
+                    return True
+                # meeting has only start time
+                else:
+                    seeking_hour, seeking_min = self.get_hour_minutes(time)
+                    seeking_hour_s, seeking_min_s = self.get_hour_minutes(start)
+                    if seeking_hour == seeking_hour_s and seeking_min == seeking_min_s:
+                        return True
+                    else:
+                        return False
+        else:
+            return False
+
+    def find_meeting(self, date, time):
+        if date in self.DB.keys():
+            meetings = DB[date]
+            for m in meetings:
+                if time == m['time']:
+                    return m
+            return None
+        else:
+            return None
+
+    def get_meetings(self, date_list):
+        meetings = []
+        for date in date_list:
+            if date in self.DB.keys():
+                date_meetings = self.DB[date]
+                for m in date_meetings:
+                    meetings.append(m)
+        return meetings
+
+    def get_freetime(self, date_list):
+        freetime_dict = {}
+        for date in date_list:
+            time_str = self.start_day_time + "-" + self.end_day_time
+            freetime_dict[date] = [time_str]
+            # Change free time if there are meetings at this day
+            if date in self.DB.keys():
+                for meeting in self.DB[date]:
+                    meeting_time = meeting['time'].split("-")
+                    start = meeting_time[0]
+                    # meeting has start and end time
+                    if len(meeting_time > 1):
+                        end = meeting_time[1]
+                        meet_start_h, meet_start_m = self.get_hour_minutes(start)
+                        meet_end_h, meet_end_m = self.get_hour_minutes(end)
+                        for slot in freetime_dict[date]:
+                            slot_time = slot.split("-")
+                            slot_start_h, slot_start_m = self.get_hour_minutes(slot_time[0])
+                            slot_end_h, slot_end_m = self.get_hour_minutes(slot_time[1])
+                            # if meeting time have collision with slot time - change / split slot
+
+                            # meeting starts inside slot
+                            if meet_start_h == slot_start_h and meet_start_m > slot_start_m and meet_start_h < slot_end_h:
+                                pass
+                            elif meet_start_h == slot_start_h and meet_start_m > slot_start_m and meet_start_h == slot_end_h and meet_start_m < slot_end_m:
+                                pass
+                            elif meet_start_h > slot_start_h and meet_start_h < slot_end_h:
+                                pass
+                            elif meet_start_h > slot_start_h and meet_start_h == slot_end_h and meet_start_m < slot_end_m:
+                                pass
+
+                            # starts before slot, ends inside slot
+                            elif (meet_end_h > slot_start_h) or (meet_end_h == slot_start_h and meet_end_m > slot_start_h):
+                                # meeting in whole slot - delete this slot
+                                if meet_end_h == slot_end_h and meet_end_m == slot_end_m:
+                                    pass
+                                # cut slot from left side
+                                else:
+                                    pass
+                            # if meeting starts and ends before slot start time - do nothing
+                    # meeting has only start time
+                    else:
+                        m_start_h, m_start_m = self.get_hour_minutes(start)
+
+    def update_meeting(self, date, time, new_meeting_dict):
+        # TODO nie testowane
+        if date in self.DB.keys():
+            meetings = DB[date]
+            to_update = next(m for m in meetings if m['time'] == time)
+            if type(to_update) is dict:
+                to_update = new_meeting_dict
+                self.save_db()
+
+    def delete_meeting(self, date, time):
+        # TODO nie testowane
+        if date in self.DB.keys():
+            meetings = DB[date]
+            to_delete = next(m for m in meetings if m['time'] == time)
+            if type(to_delete) is dict:
+                del to_delete
+                self.save_db()
+
+    # other methods
+
+    def get_hour_minutes(self, time):
+        temp = time.split(":")
+        return int(temp[0]), int(temp[1])
+
+    def get_day_month_year(self, date):
+        temp = date.split(".")
+        return int(temp[0]), int(temp[1]), int(temp[2])
+
+    def calculate_date_with_offset(self, offset):
+        last_month_day = self.month_last_day(self.today_month, self.today_year)
+        new_day = self.today_day + offset
+        if new_day > last_month_day:
+            while True:
+                difference = new_day - last_month_day
+                if self.today_month == 12:
+                    new_month = 1
+                    new_year = self.today_year+1
+                else:
+                    new_month = self.today_month+1
+                    new_year = self.today_year
+                last_month_day = self.month_last_day(new_month, new_year)
+                new_day = difference
+                if new_day <= last_month_day:
+                    date_str = ""
+                    if new_day < 10:
+                        date_str += "0"
+                    date_str += str(new_day)
+                    date_str += "."
+                    if new_month < 10:
+                        date_str += "0"
+                    date_str += str(new_month)
+                    date_str += "."
+                    date_str += str(new_year)
+                    return date_str
+        else:
+            date_str = ""
+            if new_day < 10:
+                date_str += "0"
+            date_str += str(new_day)
+            date_str += "."
+            if self.today_month < 10:
+                date_str += "0"
+            date_str += str(self.today_month)
+            date_str += "."
+            date_str += str(self.today_year)
+            return date_str
+
+    def month_last_day(self, month, year):
+        last_month_day = 30
+        if month == 1 or month == 3 or month == 5 or month == 7 or month == 8 or month == 10 or month == 12:
+            last_month_day = 31
+        elif month == 2:
+            if year % 4 == 0:
+                last_month_day = 29
+            else:
+                last_month_day = 28
+        return last_month_day
+
+    def is_date_day_name(self, date):
+        if date == "poniedziałek":
+            return True
+        if date == "wtorek":
+            return True
+        if date == "środa":
+            return True
+        if date == "czwartek":
+            return True
+        if date == "piątek":
+            return True
+        if date == "sobota":
+            return True
+        if date == "niedziela":
+            return True
+        return False
+
+    def get_days_difference(self, date):
+        if date == "poniedziałek":
+            if date == "poniedziałek":
+                return 7
+            if date == "wtorek":
+                return 1
+            if date == "środa":
+                return 2
+            if date == "czwartek":
+                return 3
+            if date == "piątek":
+                return 4
+            if date == "sobota":
+                return 5
+            if date == "niedziela":
+                return 6
+        if date == "wtorek":
+            if date == "poniedziałek":
+                return 6
+            if date == "wtorek":
+                return 7
+            if date == "środa":
+                return 1
+            if date == "czwartek":
+                return 2
+            if date == "piątek":
+                return 3
+            if date == "sobota":
+                return 4
+            if date == "niedziela":
+                return 5
+        if date == "środa":
+            if date == "poniedziałek":
+                return 5
+            if date == "wtorek":
+                return 6
+            if date == "środa":
+                return 7
+            if date == "czwartek":
+                return 1
+            if date == "piątek":
+                return 2
+            if date == "sobota":
+                return 3
+            if date == "niedziela":
+                return 4
+        if date == "czwartek":
+            if date == "poniedziałek":
+                return 4
+            if date == "wtorek":
+                return 5
+            if date == "środa":
+                return 6
+            if date == "czwartek":
+                return 7
+            if date == "piątek":
+                return 1
+            if date == "sobota":
+                return 2
+            if date == "niedziela":
+                return 3
+        if date == "piątek":
+            if date == "poniedziałek":
+                return 3
+            if date == "wtorek":
+                return 4
+            if date == "środa":
+                return 5
+            if date == "czwartek":
+                return 6
+            if date == "piątek":
+                return 7
+            if date == "sobota":
+                return 1
+            if date == "niedziela":
+                return 2
+        if date == "sobota":
+            if date == "poniedziałek":
+                return 2
+            if date == "wtorek":
+                return 3
+            if date == "środa":
+                return 4
+            if date == "czwartek":
+                return 5
+            if date == "piątek":
+                return 6
+            if date == "sobota":
+                return 7
+            if date == "niedziela":
+                return 1
+        if date == "niedziela":
+            if date == "poniedziałek":
+                return 1
+            if date == "wtorek":
+                return 2
+            if date == "środa":
+                return 3
+            if date == "czwartek":
+                return 4
+            if date == "piątek":
+                return 5
+            if date == "sobota":
+                return 6
+            if date == "niedziela":
+                return 7