From 1d3af4743ac1120bc80f5d4675e7865743e03b26 Mon Sep 17 00:00:00 2001
From: Dan Heron <dan@heron.li>
Date: Fri, 19 Jan 2024 08:56:17 +0100
Subject: [PATCH] Check that end date of calendar item is valid

---
 .../Calendar/CalendarInvalidEndDateTest.razor    | 16 ++++++++++++++++
 Heron.MudCalendar/Base/DayWeekViewBase.razor.cs  |  6 ++++++
 2 files changed, 22 insertions(+)
 create mode 100644 Heron.MudCalendar.UnitTests.Viewer/TestComponents/Calendar/CalendarInvalidEndDateTest.razor

diff --git a/Heron.MudCalendar.UnitTests.Viewer/TestComponents/Calendar/CalendarInvalidEndDateTest.razor b/Heron.MudCalendar.UnitTests.Viewer/TestComponents/Calendar/CalendarInvalidEndDateTest.razor
new file mode 100644
index 0000000..416ef8f
--- /dev/null
+++ b/Heron.MudCalendar.UnitTests.Viewer/TestComponents/Calendar/CalendarInvalidEndDateTest.razor
@@ -0,0 +1,16 @@
+<MudCalendar Items="_events" Height="500"/>
+
+@code {
+    public static string __description__ = "Calendar Invalid End Date Tests";
+
+    private List<CalendarItem> _events = new()
+    {
+        new CalendarItem
+        {
+            Start = DateTime.Today.AddHours(10),
+            End = DateTime.Today.AddHours(10),
+            Text = "Event 1"
+        }
+    };
+
+}
diff --git a/Heron.MudCalendar/Base/DayWeekViewBase.razor.cs b/Heron.MudCalendar/Base/DayWeekViewBase.razor.cs
index e0e0238..1a8b2ac 100644
--- a/Heron.MudCalendar/Base/DayWeekViewBase.razor.cs
+++ b/Heron.MudCalendar/Base/DayWeekViewBase.razor.cs
@@ -233,6 +233,12 @@ private static IEnumerable<ItemPosition> CalcPositions(IEnumerable<CalendarItem>
         var overlaps = new List<ItemPosition>();
         foreach (var item in items)
         {
+            // Check that the end date is valid
+            if (item.End.HasValue && item.End <= item.Start)
+            {
+                throw new ApplicationException("End date of calendar item must be after start date");
+            }
+            
             overlaps.RemoveAll(o => (o.Item.End ?? o.Item.Start.AddHours(1)) <= item.Start);
 
             // Create new position object