implementation of the export for users

Web/app.py

@@ -8628,6 +8628,72 @@ def register_csv():
         mimetype='application/pdf'
     )
 
+@app.route('/export_users_csv', methods=['POST'])
+def export_users_csv():
+    """
+    Exports a filtered list of users to a CSV file.
+    Receives a JSON array of usernames from the frontend.
+    """
+    if 'username' not in session:
+        flash('Ihnen ist es nicht gestattet, diese Aktion auszuführen.', 'error')
+        return redirect(url_for('login'))
+
+    usernames_json = request.form.get('usernames')
+    if not usernames_json:
+        flash('Keine Benutzer zum Exportieren ausgewählt.', 'error')
+        return redirect(url_for('user_del'))
+
+    try:
+        target_usernames = json.loads(usernames_json)
+    except json.JSONDecodeError:
+        flash('Ungültige Daten beim Export übermittelt.', 'error')
+        return redirect(url_for('user_del'))
+
+    # Fetch all users
+    all_users = us.get_all_users()
+
+    # Create CSV in memory
+    si = io.StringIO()
+    # Delimiter set to semicolon (standard for Excel in German locales)
+    cw = csv.writer(si, delimiter=';')
+
+    # Write headers
+    cw.writerow(['Benutzername', 'Vorname', 'Nachname', 'Administrator', 'Rechte-Preset'])
+
+    for user in all_users:
+        encrypted_username = user.get('Username')
+        if not encrypted_username:
+            continue
+
+        uname = decrypt_text(encrypted_username)
+
+        # Only process users that were present in the frontend's filtered view
+        if uname in target_usernames:
+            try:
+                permissions_payload = us.get_effective_permissions(uname)
+                preset = permissions_payload.get('preset', 'standard_user')
+            except Exception:
+                preset = 'standard_user'
+
+            try:
+                name = us.get_name(uname) or ""
+                last_name = us.get_last_name(uname) or ""
+            except Exception:
+                name = ""
+                last_name = ""
+
+            admin_status = "Ja" if user.get('Admin', False) else "Nein"
+
+            cw.writerow([uname, name, last_name, admin_status, preset])
+
+    # Prefix with BOM (Byte Order Mark) to ensure Excel reads UTF-8 (Umlauts) correctly
+    output = '\ufeff' + si.getvalue()
+
+    return Response(
+        output,
+        mimetype="text/csv",
+        headers={"Content-disposition": "attachment; filename=benutzer_export.csv"}
+    )
 
 @app.route('/user_del', methods=['GET'])
 def user_del():