Framework for granular hourly record updates

1 files changed, 28 insertions, 8 deletions

diff --git a/BartService.cs b/BartService.cs
index 9966a7e..b7dffda 100644
--- a/BartService.cs
+++ b/BartService.cs
@@ -146,12 +146,23 @@ namespace PagerParser.Bart {
                 return;
             }
 
+            // Fetch the most recent status for each member returned by BART
+            // across the requested time span. We'll use this to check if a
+            // member's status has changed since the last fetch, and if an
+            // entry reflecting the modified availability status needs to be
+            // recorded in the DB.
+            //
+            // The reason we do this, is to achieve a more granular availability
+            // history reflecting updates to each hour. BART's availability
+            // endpoint will only tell us when a member last updated the status
+            // for an entire day, so by comparing each hour to the last fetch,
+            // we can build a history of exactly which hourly slots have changed
+            // and when.
             var existingRecords = db.BartAvailabilityRecords
                 .Include(r => r.Member)
-                .IntersectBy(users.Select(u => u.BartMemberId), r => r.Member.BartMemberId)
-                .OrderByDescending(r => r.Timestamp)
-                .GroupBy(r => r.Timestamp)
-                .Select(g => g.First())
+                .Where(r => users.Select(u => u.BartMemberId).Contains(r.Member.BartMemberId))
+                .GroupBy(r => new { r.Member.BartMemberId, r.Timestamp })
+                .Select(g => g.OrderBy(r => r.Timestamp).Last())
                 .ToArray();
 
             LinkedList<BartAvailabilityRecord> availabilityRecords = new();
@@ -178,6 +189,18 @@ namespace PagerParser.Bart {
                             CreatedBy  = users.FirstOrDefault(u => u.MemberName == entry.CreatedBy)
                         };
 
+                        // If the availability for this hour is present in the
+                        // database and hasn't changed since the last fetch,
+                        // skip it
+                        var exists = existingRecords
+                            .Where(r => r.Member.BartMemberId == record.Member.BartMemberId)
+                            .Where(r => r.Timestamp == record.Timestamp)
+                            .Where(r => r.Status == record.Status)
+                            .Any();
+
+                        if(exists)
+                            continue;
+
                         // Optionally set the create/modify time if
                         // one is present in the fetched record
                         if(entry.ModifiedOn is not null)
@@ -195,11 +218,8 @@ namespace PagerParser.Bart {
                 }
             }
 
-            var toAdd = availabilityRecords
-                .ExceptBy(db.BartAvailabilityRecords.Select(e => e.Hashcode), e => e.Hashcode);
-
             try {
-                await db.BartAvailabilityRecords.AddRangeAsync(toAdd);
+                await db.BartAvailabilityRecords.AddRangeAsync(availabilityRecords);
                 await db.SaveChangesAsync();
             } catch(Exception e) {
                 logger.LogError(e, "Error committing availability entries to the DB");