From 843fd903840501d0082300b7f7755f55e38ae450 Mon Sep 17 00:00:00 2001
From: Craig Hawker <craig.hawker@m-files.com>
Date: Wed, 23 Oct 2024 11:42:34 +0100
Subject: [PATCH] Resolved issue with .FirstOrDefault which was returning
 DateTime.MinValue if no schedule was found. Resolved issue where a schedule
 was not correctly calculated if the daylight saving offset occurred on the
 next iteration of the schedule.

---
 .../ScheduledExecution/WeeklyTriggerTests.cs   | 18 ++++++++++++++++++
 .../ScheduledExecution/DailyTrigger.cs         |  8 +++++++-
 .../ScheduledExecution/Schedule.cs             |  8 ++++----
 .../ScheduledExecution/WeeklyTrigger.cs        |  5 ++---
 4 files changed, 31 insertions(+), 8 deletions(-)

diff --git a/MFiles.VAF.Extensions.Tests/Configuration/ScheduledExecution/WeeklyTriggerTests.cs b/MFiles.VAF.Extensions.Tests/Configuration/ScheduledExecution/WeeklyTriggerTests.cs
index 362eb9dd..9f9b04ce 100644
--- a/MFiles.VAF.Extensions.Tests/Configuration/ScheduledExecution/WeeklyTriggerTests.cs
+++ b/MFiles.VAF.Extensions.Tests/Configuration/ScheduledExecution/WeeklyTriggerTests.cs
@@ -193,5 +193,23 @@ public static IEnumerable<object[]> GetNextDayOfWeekData()
 				new DateTime ?[] { new DateTime(2021, 03, 20, 0, 0, 0, 0) }
 			};
 		}
+
+		[TestMethod]
+		public void WeeklyValueNotReturnedWhenDaylightsavingChanges()
+		{
+			var now = new DateTimeOffset(new DateTime(2024, 10, 23, 10, 27, 0), new TimeSpan(0, 0, 0));
+			var expected = new DateTimeOffset(new DateTime(2024, 10, 30, 9, 0, 0), new TimeSpan(2, 0, 0));
+
+			var trigger = new WeeklyTrigger()
+			{
+				TriggerTimes = new List<TimeSpan>()
+				{
+					new TimeSpan(9, 0, 0)
+				},
+				TriggerDays = new List<DayOfWeek>() { DayOfWeek.Wednesday }
+			};
+			var execution = trigger.GetNextExecution(now, TimeZoneInfo.FindSystemTimeZoneById("FLE Standard Time"));
+			Assert.AreEqual(expected.ToUniversalTime(), execution?.ToUniversalTime());
+		}
 	}
 }
diff --git a/MFiles.VAF.Extensions/Configuration/ScheduledExecution/DailyTrigger.cs b/MFiles.VAF.Extensions/Configuration/ScheduledExecution/DailyTrigger.cs
index c4abc532..3110a93e 100644
--- a/MFiles.VAF.Extensions/Configuration/ScheduledExecution/DailyTrigger.cs
+++ b/MFiles.VAF.Extensions/Configuration/ScheduledExecution/DailyTrigger.cs
@@ -59,6 +59,7 @@ public DailyTrigger()
 			timeZoneInfo = timeZoneInfo ?? TimeZoneInfo.Local;
 
 			// When should we start looking?
+			var before = after.Value;
 			after = (after ?? DateTime.UtcNow).ToUniversalTime();
 
 			// Convert the time into the timezone we're after.
@@ -73,7 +74,12 @@ public DailyTrigger()
 						// What is the potential time that this will run?
 						DateTimeOffset potential;
 						{
-							var dateTime = after.Value.Date.Add(t);
+							// If the timezone conversion changed the date then go back to the start of the date.
+							var date = after.Value.Date;
+							if (after.Value.Date != before.Date)
+								date = new DateTime(before.Date.Ticks);
+
+							var dateTime = date.Add(t);
 							potential = new DateTimeOffset(dateTime, timeZoneInfo.GetUtcOffset(dateTime));
 						}
 
diff --git a/MFiles.VAF.Extensions/Configuration/ScheduledExecution/Schedule.cs b/MFiles.VAF.Extensions/Configuration/ScheduledExecution/Schedule.cs
index 1c2e6e41..906312f7 100644
--- a/MFiles.VAF.Extensions/Configuration/ScheduledExecution/Schedule.cs
+++ b/MFiles.VAF.Extensions/Configuration/ScheduledExecution/Schedule.cs
@@ -106,11 +106,11 @@ public class Schedule
 			}
 
 			// Get the next execution date from the triggers.
-			return this.Triggers?
+			var next = this.Triggers?
 				.Select(t => t.GetNextExecution(after, timeZoneInfo))
-				.Where(d => d.HasValue)
-				.OrderBy(d => d)
-				.FirstOrDefault();
+				.Where(d => d.HasValue && d.Value.DateTime != DateTime.MinValue)
+				.OrderBy(d => d);
+			return next.Any() ? next.First() : null;
 		}
 
 
diff --git a/MFiles.VAF.Extensions/Configuration/ScheduledExecution/WeeklyTrigger.cs b/MFiles.VAF.Extensions/Configuration/ScheduledExecution/WeeklyTrigger.cs
index e35ce7f0..17ed8f3e 100644
--- a/MFiles.VAF.Extensions/Configuration/ScheduledExecution/WeeklyTrigger.cs
+++ b/MFiles.VAF.Extensions/Configuration/ScheduledExecution/WeeklyTrigger.cs
@@ -74,13 +74,12 @@ public WeeklyTrigger()
 				.Select(d => d.Value)
 				.Where(d => d > after.Value)
 				.OrderBy(d => d)
+				.Select(d => d.ToUniversalTime())
 				.ToList();
 
 			this.Logger?.Trace($"These are the potential matches: {string.Join(", ", potentialMatches)}");
 
-			return potentialMatches
-				.Select(d => d.ToUniversalTime())
-				.FirstOrDefault();
+			return potentialMatches.Any() ? (DateTimeOffset?)potentialMatches.First() : null;
 		}
 
 		/// <summary>