Add overlap check after schedule button is hit

When schedule button was hit, calculated observations were scheduled
without any check if between calculation and scheduling has been any
change on the already scheduled station observations.

This resulted to scheduling of the same observation more than one
time, if you opened and calculated the same observation in two
different tabs and then hit schedule button.

With this commit, this issue if fixed as a check is done when the
schedule button is hit. If there is an overlap it returns an error
message which inform the user that there are one or more overlaps.

network/base/helpers.py

@@ -47,14 +47,14 @@ def resolve_overlaps(station, gs_data, start, end):
                     return ()
                 if start < datum.start and end > datum.end:
                     start1 = start
-                    end1 = datum.start
-                    start2 = datum.end
+                    end1 = datum.start - timedelta(seconds=10)
+                    start2 = datum.end + timedelta(seconds=10)
                     end2 = end
                     return start1, end1, start2, end2
                 if datum.start <= start:
-                    start = datum.end
+                    start = datum.end + timedelta(seconds=10)
                 if datum.end >= end:
-                    end = datum.start
+                    end = datum.start - timedelta(seconds=10)
     if overlapped:
         return start, end, overlapped
     else:

network/base/views.py

@@ -235,6 +235,33 @@ def observation_new(request):
             messages.error(request, 'Please schedule an observation that begins in the future')
             return redirect(reverse('base:observation_new'))
 
+        total = int(request.POST.get('total'))
+        changed = 0
+        for item in range(total):
+            start = make_aware(datetime.strptime(
+                request.POST.get('{0}-starting_time'.format(item)), '%Y-%m-%d %H:%M:%S.%f'
+            ))
+            end = make_aware(datetime.strptime(
+                request.POST.get('{}-ending_time'.format(item)), '%Y-%m-%d %H:%M:%S.%f'
+            ))
+            station_id = request.POST.get('{}-station'.format(item))
+            station = Station.objects.get(id=station_id)
+            gs_data = Observation.objects.filter(ground_station=station)
+            window = resolve_overlaps(station, gs_data, start, end)
+            if (len(window) > 2 or len(window) == 0):
+                changed += 1
+
+        if changed > 0:
+            error_message = (
+                str(changed) + " observations are already scheduled or overlap with others."
+                " Please recalculate and try schedule them again."
+            )
+            if(changed == 1):
+                error_message = (
+                    "The observation is already scheduled or overlaps with others."
+                    " Please recalculate and try schedule it again.")
+            messages.error(request, error_message)
+            return redirect(reverse('base:observation_new'))
         start = make_aware(start_time, utc)
         end = make_aware(end_time, utc)
         sat = Satellite.objects.get(norad_cat_id=sat_id)
@@ -247,8 +274,6 @@ def observation_new(request):
         observer = ephem.Observer()
         observer.date = str(start)
 
-        total = int(request.POST.get('total'))
-
         scheduled = []
 
         for item in range(total):