Fix sooner/later buttons when crossing days

webapp.py

@@ -29,9 +29,15 @@ def results_page():
     except ValueError:
         hour = dt.datetime.now().hour
 
-    delta = int(request.forms.timedelta or 0)
-    hour = hour + delta
-    time = '{:0>2}:00'.format(hour)
+    hdelta = int(request.forms.timedelta or 0)
+    delta = dt.timedelta(hours=hdelta)
+
+    query_dt = dt.datetime.combine(day, dt.time(hour=hour))
+    query_dt = query_dt + delta
+
+    day = query_dt.date()
+    start_time = '{:0>2}:00'.format(query_dt.hour)
+    end_time = '{:0>2}:00'.format(query_dt.hour + 1)
     results = [
         { 'date': x.date,
           'song': x.song,
@@ -42,9 +48,9 @@ def results_page():
     ]
     return dict(results=results,
                 date=day,
-                time=time,
-                start_time=time,
-                end_time = '{:0>2}:00'.format(hour+1))
+                time=start_time,
+                start_time=start_time,
+                end_time=end_time)
 
 @route('/static/<filename>')
 def serve_static_file(filename):