Enable NRT for Collections and Proxies namespace

Ical.Net.Tests/RecurrenceTests.cs

@@ -108,7 +108,7 @@ public void EventOccurrenceTest(
             """;
 
         var cal = Calendar.Load(calendarIcalStr);
-        var tzid = cal.Events.Single().Start?.TzId;
+        var tzid = cal.Events.Single().Start!.TzId;
 
         var periodSerializer = new PeriodSerializer();
         var periods = expectedPeriods
@@ -2337,7 +2337,7 @@ public void Yearly1()
     public void Bug2912657()
     {
         var iCal = Calendar.Load(IcsFiles.Bug2912657);
-        var localTzid = iCal.Events.First().Start?.TzId;
+        var localTzid = iCal.Events.First().Start!.TzId;
 
         // Daily recurrence
         EventOccurrenceTest(
@@ -2602,7 +2602,7 @@ public void DurationOfRecurrencesOverDst(string dtStart, string dtEnd, string? d
         for (var index = 0; index < expectedPeriods.Length; index++)
         {
             var p = expectedPeriods[index];
-            var newStart = p.StartTime.ToTimeZone(start?.TzId);
+            var newStart = p.StartTime.ToTimeZone(start!.TzId);
             expectedPeriods[index] = Period.Create(newStart, end: newStart.Add(p.Duration!.Value));
         }
 

Ical.Net/CalendarComponents/Alarm.cs

@@ -17,13 +17,13 @@
 /// </summary>
 public class Alarm : CalendarComponent
 {
-    public virtual string Action
+    public virtual string? Action
     {
         get => Properties.Get<string>(AlarmAction.Key);
         set => Properties.Set(AlarmAction.Key, value);
     }
 
-    public virtual Attachment Attachment
+    public virtual Attachment? Attachment
     {
         get => Properties.Get<Attachment>("ATTACH");
         set => Properties.Set("ATTACH", value);
@@ -35,13 +35,13 @@
         set => Properties.Set("ATTENDEE", value);
     }
 
-    public virtual string Description
+    public virtual string? Description
     {
         get => Properties.Get<string>("DESCRIPTION");
         set => Properties.Set("DESCRIPTION", value);
     }
 
-    public virtual Duration Duration
+    public virtual Duration? Duration
     {
         get => Properties.Get<Duration>("DURATION");
         set => Properties.Set("DURATION", value);
@@ -53,7 +53,7 @@
         set => Properties.Set("REPEAT", value);
     }
 
-    public virtual string Summary
+    public virtual string? Summary
     {
         get => Properties.Get<string>("SUMMARY");
         set => Properties.Set("SUMMARY", value);
@@ -182,7 +182,9 @@
 
             for (var j = 0; j < Repeat; j++)
             {
-                alarmTime = alarmTime?.Add(Duration);
+                if (Duration != null)
+                    alarmTime = alarmTime?.Add(Duration.Value);
+
                 if (alarmTime != null)
                 {
                     occurrences.Add(new AlarmOccurrence(this, alarmTime.Copy(), ao.Component));

Ical.Net/CalendarComponents/CalendarEvent.cs

@@ -56,7 +56,7 @@ private void SetProperty<T>(string group, T value)
     /// </summary>
     public virtual CalDateTime? DtEnd
     {
-        get => Properties.Get<CalDateTime?>("DTEND");
+        get => Properties.Get<CalDateTime>("DTEND");
         set
         {
             if (Duration is not null) throw new InvalidOperationException("DTEND property cannot be set when DURATION property is not null.");
@@ -82,6 +82,7 @@ public virtual CalDateTime? DtEnd
     /// </remarks>
     public virtual Duration? Duration
     {
+        // Duration is a struct, so we need to use Nullable<Duration> to allow null values
         get => Properties.Get<Duration?>("DURATION");
         set
         {
@@ -181,7 +182,7 @@ public virtual CalDateTime? End
     /// </summary>
     public virtual GeographicLocation? GeographicLocation
     {
-        get => Properties.Get<GeographicLocation?>("GEO");
+        get => Properties.Get<GeographicLocation>("GEO");
         set => SetProperty("GEO", value);
     }
 
@@ -190,7 +191,7 @@ public virtual GeographicLocation? GeographicLocation
     /// </summary>
     public virtual string? Location
     {
-        get => Properties.Get<string?>("LOCATION");
+        get => Properties.Get<string>("LOCATION");
         set => SetProperty("LOCATION", value);
     }
 
@@ -212,7 +213,7 @@ public virtual IList<string> Resources
     /// </summary>
     public virtual string? Status
     {
-        get => Properties.Get<string?>("STATUS");
+        get => Properties.Get<string>("STATUS");
         set => SetProperty("STATUS", value);
     }
 
@@ -225,7 +226,7 @@ public virtual string? Status
     /// </summary>
     public virtual string? Transparency
     {
-        get => Properties.Get<string?>(TransparencyType.Key);
+        get => Properties.Get<string>(TransparencyType.Key);
         set => SetProperty(TransparencyType.Key, value);
     }
 
@@ -340,20 +341,5 @@ public override int GetHashCode()
     }
 
     /// <inheritdoc/>
-    public int CompareTo(CalendarEvent? other)
-    {
-        if (other is null)
-        {
-            return 1;
-        }
-        if (DtStart is null)
-        {
-            return other.DtStart is null ? 0 : -1;
-        }
-        if (other.DtStart is null)
-        {
-            return 1;
-        }
-        return DtStart.CompareTo(other.DtStart);
-    }
+    public int CompareTo(CalendarEvent? other) => DtStart?.CompareTo(other?.DtStart) ?? -1;
 }

Ical.Net/CalendarComponents/FreeBusy.cs

@@ -130,25 +130,25 @@ public virtual IList<FreeBusyEntry> Entries
         set => Properties.Set("FREEBUSY", value);
     }
 
-    public virtual CalDateTime DtStart
+    public virtual CalDateTime? DtStart
     {
         get => Properties.Get<CalDateTime>("DTSTART");
         set => Properties.Set("DTSTART", value);
     }
 
-    public virtual CalDateTime DtEnd
+    public virtual CalDateTime? DtEnd
     {
         get => Properties.Get<CalDateTime>("DTEND");
         set => Properties.Set("DTEND", value);
     }
 
-    public virtual CalDateTime Start
+    public virtual CalDateTime? Start
     {
         get => Properties.Get<CalDateTime>("DTSTART");
         set => Properties.Set("DTSTART", value);
     }
 
-    public virtual CalDateTime End
+    public virtual CalDateTime? End
     {
         get => Properties.Get<CalDateTime>("DTEND");
         set => Properties.Set("DTEND", value);

Ical.Net/CalendarComponents/Journal.cs

@@ -14,7 +14,7 @@ namespace Ical.Net.CalendarComponents;
 /// </summary>
 public class Journal : RecurringComponent
 {
-    public string Status
+    public string? Status
     {
         get => Properties.Get<string>(JournalStatus.Key);
         set => Properties.Set(JournalStatus.Key, value);

Ical.Net/CalendarComponents/Todo.cs

@@ -91,7 +91,7 @@ public virtual IList<string> Resources
     /// <summary>
     /// The status of the item.
     /// </summary>
-    public virtual string Status
+    public virtual string? Status
     {
         get => Properties.Get<string>(TodoStatus.Key);
         set
@@ -171,7 +171,7 @@ public virtual bool IsActive(CalDateTime currDt)
 
     protected override void OnDeserializing(StreamingContext context)
     {
-        //ToDo: a necessary evil, for now
+        //A necessary evil, for now
         base.OnDeserializing(context);
     }
 }

Ical.Net/CalendarComponents/VTimeZone.cs

@@ -287,7 +287,6 @@
         Name = Components.Timezone;
     }
 
-
     public VTimeZone(string tzId) : this()
     {
         if (string.IsNullOrWhiteSpace(tzId))
@@ -301,7 +300,7 @@
 
     private DateTimeZone _nodaZone = DateTimeZone.Utc; // must initialize
     private string? _tzId;
-    public virtual string TzId
+    public virtual string? TzId
     {
         get
         {
@@ -322,9 +321,10 @@
             {
                 _tzId = null;
                 Properties.Remove("TZID");
+                return;
             }
 
             _nodaZone = DateUtil.GetZone(value);
             var id = _nodaZone.Id;
             if (string.IsNullOrWhiteSpace(id))
             {
@@ -384,7 +384,7 @@
         unchecked
         {
             var hashCode = Name?.GetHashCode() ?? 0;
-            hashCode = (hashCode * 397) ^ (TzId.GetHashCode());
+            hashCode = (hashCode * 397) ^ (TzId?.GetHashCode() ?? 0);
             hashCode = (hashCode * 397) ^ (Url?.GetHashCode() ?? 0);
             return hashCode;
         }

Ical.Net/CalendarParameter.cs

@@ -3,6 +3,7 @@
 // Licensed under the MIT license.
 //
 
+#nullable enable
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
@@ -15,7 +16,7 @@
 [DebuggerDisplay("{Name}={string.Join(\",\", Values)}")]
 public class CalendarParameter : CalendarObject, IValueObject<string>
 {
-    private HashSet<string> _values;
+    private HashSet<string> _values = new();
 
     public CalendarParameter()
     {
@@ -27,7 +28,7 @@
         Initialize();
     }
 
-    public CalendarParameter(string name, string value) : base(name)
+    public CalendarParameter(string name, string? value) : base(name)
     {
         Initialize();
         AddValue(value);
@@ -72,7 +73,7 @@
 
     public virtual bool ContainsValue(string value) => _values.Contains(value);
 
-    public virtual int ValueCount => _values?.Count ?? 0;
+    public virtual int ValueCount => _values.Count;
 
     public virtual void SetValue(string value)
     {
@@ -87,25 +88,29 @@
         _values.UnionWith(values.Where(IsValidValue));
     }
 
-    private bool IsValidValue(string value) => !string.IsNullOrWhiteSpace(value);
+    private static bool IsValidValue(string? value) => !string.IsNullOrWhiteSpace(value);
 
-    public virtual void AddValue(string value)
+    public virtual void AddValue(string? value)
     {
         if (!IsValidValue(value))
         {
             return;
         }
-        _values.Add(value);
+        _values.Add(value!);
     }
 
-    public virtual void RemoveValue(string value)
-    {
-        _values.Remove(value);
-    }
+    public virtual void RemoveValue(string value) => _values.Remove(value);
 
-    public virtual string Value
+    public virtual string? Value
     {
-        get => Values?.FirstOrDefault();
-        set => SetValue(value);
+        get => Values.FirstOrDefault();
+        set
+        {
+            if (value == null)
+            {
+                throw new ArgumentNullException(nameof(value), "Value cannot be null.");
+            }
+            SetValue(value);
+        }
     }
-}
+}

Ical.Net/CalendarProperty.cs

@@ -62,9 +62,7 @@ public virtual void AddParameter(string name, string value)
     /// Adds a parameter to the iCalendar object.
     /// </summary>
     public virtual void AddParameter(CalendarParameter p)
-    {
-        Parameters.Add(p);
-    }
+        => Parameters.Add(p);
 
     /// <inheritdoc/>
     public override void CopyFrom(ICopyable obj)
@@ -153,4 +151,4 @@ public virtual void RemoveValue(object value)
         }
         _values.Remove(value);
     }
-}
+}