next scan dsiplay DRY

server/__main__.py

@@ -124,16 +124,10 @@ def main():
             # last time any scan or maintenance/upkeep was run
             conf.last_scan_run = loop_start_time
 
-            # Compute the next scheduled run time across enabled device_scanner plugins
+            # Header (also broadcasts last_scan_run to frontend via SSE / app_state.json)
-            scanner_prefixes = {p["unique_prefix"] for p in all_plugins if p.get("plugin_type") == "device_scanner"}
-            scanner_next = [s.last_next_schedule for s in conf.mySchedules if s.service in scanner_prefixes]
-            next_scan_dt = min(scanner_next, default=None)
-            next_scan_time_iso = next_scan_dt.replace(microsecond=0).isoformat() if next_scan_dt else ""
-
-            # Header (also broadcasts last_scan_run + next_scan_time to frontend via SSE / app_state.json)
             updateState("Process: Start",
                         last_scan_run=loop_start_time.replace(microsecond=0).isoformat(),
-                        next_scan_time=next_scan_time_iso)
+                        next_scan_time="")
 
             # Timestamp
             startTime = loop_start_time
@@ -142,6 +136,17 @@ def main():
             # Check if any plugins need to run on schedule
             pm.run_plugin_scripts("schedule")
 
+            # Compute the next scheduled run time AFTER schedule check (which updates last_next_schedule)
+            # Only device_scanner plugins have meaningful next_scan times for user display
+            scanner_prefixes = {p["unique_prefix"] for p in all_plugins if p.get("plugin_type") == "device_scanner"}
+            scanner_next = [s.last_next_schedule for s in conf.mySchedules if s.service in scanner_prefixes]
+            
+            # Get the earliest next scan time across all device scanners and broadcast.
+            # updateState validates the value is in the future before storing/broadcasting.
+            if scanner_next:
+                next_scan_dt = min(scanner_next)
+                updateState(next_scan_time=next_scan_dt.replace(microsecond=0).isoformat())
+
             # determine run/scan type based on passed time
             # --------------------------------------------
 

server/app_state.py

@@ -4,7 +4,7 @@ import json
 from const import applicationPath, apiPath
 from logger import mylog
 from helper import checkNewVersion
-from utils.datetime_utils import timeNowUTC
+from utils.datetime_utils import timeNowUTC, is_datetime_future, normalizeTimeStamp
 from api_server.sse_broadcast import broadcast_state_update
 
 # Register NetAlertX directories using runtime configuration
@@ -142,7 +142,12 @@ class app_state_class:
         if last_scan_run is not None:
             self.last_scan_run = last_scan_run
         if next_scan_time is not None:
-            self.next_scan_time = next_scan_time
+            # Guard against stale/past timestamps — only store if genuinely in the future.
+            # This enforces correctness regardless of which caller sets next_scan_time.
+            if next_scan_time == "" or is_datetime_future(normalizeTimeStamp(next_scan_time)):
+                self.next_scan_time = next_scan_time
+            else:
+                self.next_scan_time = ""
         # check for new version every hour and if currently not running new version
         if self.isNewVersion is False and self.isNewVersionChecked + 3600 < int(
             timeNowUTC(as_string=False).timestamp()

server/initialise.py

@@ -13,7 +13,7 @@ import conf
 from const import fullConfPath, fullConfFolder, default_tz, applicationPath
 from db.db_upgrade import ensure_views
 from helper import getBuildTimeStampAndVersion, collect_lang_strings, updateSubnets, generate_random_string
-from utils.datetime_utils import timeNowUTC
+from utils.datetime_utils import timeNowUTC, ensure_future_datetime
 from app_state import updateState
 from logger import mylog
 from api import update_api
@@ -682,9 +682,12 @@ def importConfigs(pm, db, all_plugins):
             newSchedule = Cron(run_sch).schedule(
                 start_date=timeNowUTC(as_string=False)
             )
+            # Get initial next schedule time, ensuring it's in the future
+            next_schedule_time = ensure_future_datetime(newSchedule, timeNowUTC(as_string=False))
+
             conf.mySchedules.append(
                 schedule_class(
-                    plugin["unique_prefix"], newSchedule, newSchedule.next(), False
+                    plugin["unique_prefix"], newSchedule, next_schedule_time, False
                 )
             )
 

server/scheduler.py

@@ -3,7 +3,7 @@
 import datetime
 
 from logger import mylog
-from utils.datetime_utils import timeNowTZ
+from utils.datetime_utils import timeNowTZ, ensure_future_datetime
 
 
 # -------------------------------------------------------------------------------
@@ -48,6 +48,7 @@ class schedule_class:
 
         if self.was_last_schedule_used:
             self.was_last_schedule_used = False
-            self.last_next_schedule = self.scheduleObject.next()
+            # Get the next scheduled time, ensuring it's in the future
+            self.last_next_schedule = ensure_future_datetime(self.scheduleObject, timeNowTZ(as_string=False))
 
         return result

server/utils/datetime_utils.py

@@ -88,6 +88,74 @@ def get_timezone_offset():
 #  Date and time methods
 # -------------------------------------------------------------------------------
 
+def is_datetime_future(dt, current_threshold=None):
+    """
+    Check if a datetime is strictly in the future.
+    
+    Utility for validating that a datetime hasn't already passed.
+    Used after retrieving pre-computed schedule times to ensure they're still valid.
+    
+    Args:
+        dt: datetime.datetime object to validate
+        current_threshold: datetime to compare against. If None, uses timeNowUTC(as_string=False)
+    
+    Returns:
+        bool: True if dt is in the future, False otherwise
+    
+    Examples:
+        if is_datetime_future(next_scan_dt):
+            broadcast_to_frontend(next_scan_dt)
+    """
+    if dt is None:
+        return False
+    
+    if current_threshold is None:
+        current_threshold = timeNowUTC(as_string=False)
+    
+    return dt > current_threshold
+
+
+def ensure_future_datetime(schedule_obj, current_threshold=None, max_retries=5):
+    """
+    Ensure a schedule's next() call returns a datetime strictly in the future.
+    
+    This is a defensive utility for cron/schedule libraries that should always return
+    future times but may have edge cases. Validates and retries if needed.
+    
+    Args:
+        schedule_obj: A schedule object with a .next() method (e.g., from croniter/APScheduler)
+        current_threshold: datetime to compare against. If None, uses timeNowTZ(as_string=False)
+        max_retries: Maximum times to call .next() if result is not in future (default: 5)
+    
+    Returns:
+        datetime.datetime: A guaranteed future datetime from schedule_obj.next()
+    
+    Raises:
+        RuntimeError: If max_retries exceeded without getting a future time
+    
+    Examples:
+        newSchedule = Cron(run_sch).schedule(start_date=timeNowUTC(as_string=False))
+        next_time = ensure_future_datetime(newSchedule)
+    """
+    if current_threshold is None:
+        current_threshold = timeNowTZ(as_string=False)
+    
+    next_time = schedule_obj.next()
+    retries = 0
+    
+    while next_time <= current_threshold and retries < max_retries:
+        next_time = schedule_obj.next()
+        retries += 1
+    
+    if next_time <= current_threshold:
+        raise RuntimeError(
+            f"[ensure_future_datetime] Failed to get future time after {max_retries} retries. "
+            f"Last attempt: {next_time}, Current time: {current_threshold}"
+        )
+    
+    return next_time
+
+
 def normalizeTimeStamp(inputTimeStamp):
     """
     Normalize various timestamp formats into a datetime.datetime object.