added the same dotenv config as the client and added a function to convert the loaded data into readable json for the frontend. Last sessions and the pie chart now work great!!

server/.env.example

@@ -0,0 +1,9 @@
+# full url. for example: https://calendar.com/user/study
+CALDAV_URL=
+
+# CalDAV credentials
+CALDAV_USER=
+CALDAV_PASS=
+
+# timezone. for example the default: Europe/Berlin
+TIMEZONE=

server/app.py

@@ -1,21 +1,9 @@
 from flask import Flask, jsonify, render_template
+from src.fetch_sessions import get_events
 
 app = Flask(__name__)
 
-sessions = [
-  { "subject": "Krypto",     "minutes": 50, "ts": "26.03.2026 08:16" },
-  { "subject": "Netzwerke",  "minutes": 40, "ts": "25.03.2026 19:02" },
-  { "subject": "Statistik",  "minutes": 65, "ts": "25.03.2026 14:30" },
-  { "subject": "Krypto",     "minutes": 30, "ts": "24.03.2026 09:12" },
-  { "subject": "Math",       "minutes": 90, "ts": "23.03.2026 20:45" },
-  { "subject": "Databases",  "minutes": 20, "ts": "23.03.2026 08:05" },
-  { "subject": "Krypto",     "minutes": 50, "ts": "26.03.2026 08:16" },
-  { "subject": "Netzwerke",  "minutes": 40, "ts": "25.03.2026 19:02" },
-  { "subject": "Statistik",  "minutes": 65, "ts": "25.03.2026 14:30" },
-  { "subject": "Krypto",     "minutes": 30, "ts": "24.03.2026 09:12" },
-  { "subject": "Math",       "minutes": 90, "ts": "23.03.2026 20:45" },
-  { "subject": "Databases",  "minutes": 20, "ts": "23.03.2026 08:05" },
-]
+sessions = get_events()
 
 def calculate_totals(sessions):
     totals = {}

server/src/fetch_sessions.py

@@ -0,0 +1,42 @@
+from dotenv import load_dotenv
+from zoneinfo import ZoneInfo
+import caldav, os
+
+# load settings from .env
+try:
+    load_dotenv()
+    CALDAV_URL = os.environ["CALDAV_URL"]
+    CALDAV_USER = os.environ["CALDAV_USER"]
+    CALDAV_PASS = os.environ["CALDAV_PASS"]
+    TIME_ZONE = ZoneInfo(os.environ.get("TIMEZONE", "Europe/Berlin"))
+except Exception:
+    print("Failed to read settings from .env!\nTake a look at .env.example for the required structure!")
+
+client = caldav.DAVClient(
+    url=CALDAV_URL,
+    username=CALDAV_USER,
+    password=CALDAV_PASS,
+)
+calendar = client.calendar(url=CALDAV_URL)
+
+
+def get_events():
+    events = calendar.events()
+    events.sort(key=lambda e: e.vobject_instance.vevent.dtstart.value)
+
+    event_list = []
+    for event in events:
+        event.load()  # fetch full data
+        e = event.vobject_instance.vevent
+        event_list.append({
+            "subject":e.summary.value,
+            "ts":e.dtstart.value.strftime("%d.%m.%Y %H:%M"),
+            "minutes":int((e.dtend.value - e.dtstart.value).total_seconds() / 60)
+#            "start":e.dtstart.value,
+#            "end":e.dtend.value,
+        })
+    return event_list
+
+
+def get_sessions():
+    events = get_events()