Fix intermittent missing meetings

We were using a DASL query with "OR" and it would sometimes miss random meetings, regardless of what properties we set. This change splits the query into two, and then combines the results so that it's transparent to callers of GetAppointmentsInRange.

ChimeHelper/ChimeOutlookHelper/OutlookHelper.cs

@@ -38,7 +38,7 @@ public static Outlook.Folder GetCalendar()
       throw new InvalidOperationException("Couldn't find a Calendar in the current Outlook installation");
     }
 
-    public static Outlook.Items GetAppointmentsAroundNow(Outlook.Folder calendar, int hours = DEFAULT_SEARCH_HOURS)
+    public static List<Outlook.AppointmentItem> GetAppointmentsAroundNow(Outlook.Folder calendar, int hours = DEFAULT_SEARCH_HOURS)
     {
       var now = DateTime.Now;
 
@@ -52,15 +52,44 @@ public static Outlook.Items GetAppointmentsAroundNow(Outlook.Folder calendar, in
       return GetAppointmentsInRange(calendar, start, end);
     }
 
-    public static Outlook.Items GetAppointmentsInRange(Outlook.Folder folder, DateTime start, DateTime end, bool includeRecurrences = true)
+    public static List<Outlook.AppointmentItem> GetAppointmentsInRange(Outlook.Folder folder, DateTime start, DateTime end, bool includeRecurrences = true)
     {
-      var filter = $"([Start] >= '{start.ToString("g")}' AND [Start] <= '{end.ToString("g")}') OR ([Start] < '{start.ToString("g")}' AND [End] >= '{start.ToString("g")}')";
+      // we originally combined the filters with an "OR" but it would seemingly miss some random meetings for no apparent reason
+      // explored whether or not there was API caching but couldn't find any. Splitting it out into two queries seems to solve the 
+      // issue, even if the code is a little more weird.
+
+      // find all meetings that start within the period (regardless of when they end specifically)
+      var filter = $"[Start] >= '{start.ToString("g")}' AND [Start] <= '{end.ToString("g")}'";
+
+      var rv = RestrictItems(folder, filter, includeRecurrences);
+
+      // find meetings that are in-progress during the period (for example, all day events that start before the period but end
+      // during or after it
+      filter = $"[Start] < '{start.ToString("g")}' AND [End] >= '{start.ToString("g")}'";
+
+      rv.AddRange(RestrictItems(folder, filter, includeRecurrences));
+
+      return rv;
+    }
+
+    public static List<Outlook.AppointmentItem> RestrictItems(Outlook.Folder folder, string filter, bool includeRecurrences)
+    {
+      var rv = new List<Outlook.AppointmentItem>();
 
       var items = folder.Items;
       items.IncludeRecurrences = includeRecurrences;
       items.Sort("[Start]", Type.Missing);
 
-      return items.Restrict(filter);
+      var restricted = items.Restrict(filter);
+
+      foreach (Outlook.AppointmentItem item in restricted)
+      {
+        rv.Add(item);
+
+        Debug.WriteLine("++: " + item.Start + " -> " + item.End + ": " + item.Subject);
+      }
+
+      return rv;
     }
 
   }