From 6fbd3968326116131519b66dc53d584dfb063b75 Mon Sep 17 00:00:00 2001
From: Cenk Ergen <57065323+Cenngo@users.noreply.github.com>
Date: Wed, 18 May 2022 10:45:18 +0300
Subject: [PATCH] Add Nullable ComponentTypeConverter and TypeReader (#2307)

* add nullable ComponentTypeConverter and TypeReader

* add converter and reader to interactionservice
---
 .../InteractionService.cs                     |  6 +++--
 .../NullableComponentConverter.cs             | 23 +++++++++++++++++++
 .../TypeReaders/NullableReader.cs             | 23 +++++++++++++++++++
 3 files changed, 50 insertions(+), 2 deletions(-)
 create mode 100644 src/Discord.Net.Interactions/TypeConverters/ComponentInteractions/NullableComponentConverter.cs
 create mode 100644 src/Discord.Net.Interactions/TypeReaders/NullableReader.cs

diff --git a/src/Discord.Net.Interactions/InteractionService.cs b/src/Discord.Net.Interactions/InteractionService.cs
index 6afa5c086..f57c75a31 100644
--- a/src/Discord.Net.Interactions/InteractionService.cs
+++ b/src/Discord.Net.Interactions/InteractionService.cs
@@ -223,7 +223,8 @@ namespace Discord.Interactions
                 new ConcurrentDictionary<Type, Type>
                 {
                     [typeof(Array)] = typeof(DefaultArrayComponentConverter<>),
-                    [typeof(IConvertible)] = typeof(DefaultValueComponentConverter<>)
+                    [typeof(IConvertible)] = typeof(DefaultValueComponentConverter<>),
+                    [typeof(Nullable<>)] = typeof(NullableComponentConverter<>)
                 });
 
             _typeReaderMap = new TypeMap<TypeReader, string>(this, new ConcurrentDictionary<Type, TypeReader>(),
@@ -234,7 +235,8 @@ namespace Discord.Interactions
                     [typeof(IUser)] = typeof(DefaultUserReader<>),
                     [typeof(IMessage)] = typeof(DefaultMessageReader<>),
                     [typeof(IConvertible)] = typeof(DefaultValueReader<>),
-                    [typeof(Enum)] = typeof(EnumReader<>)
+                    [typeof(Enum)] = typeof(EnumReader<>),
+                    [typeof(Nullable<>)] = typeof(NullableReader<>)
                 });
         }
 
diff --git a/src/Discord.Net.Interactions/TypeConverters/ComponentInteractions/NullableComponentConverter.cs b/src/Discord.Net.Interactions/TypeConverters/ComponentInteractions/NullableComponentConverter.cs
new file mode 100644
index 000000000..ba6568ad1
--- /dev/null
+++ b/src/Discord.Net.Interactions/TypeConverters/ComponentInteractions/NullableComponentConverter.cs
@@ -0,0 +1,23 @@
+using System;
+using System.Threading.Tasks;
+
+namespace Discord.Interactions
+{
+    internal class NullableComponentConverter<T> : ComponentTypeConverter<T>
+    {
+        private readonly ComponentTypeConverter _typeConverter;
+
+        public NullableComponentConverter(InteractionService interactionService, IServiceProvider services)
+        {
+            var type = Nullable.GetUnderlyingType(typeof(T));
+
+            if (type is null)
+                throw new ArgumentException($"No type {nameof(TypeConverter)} is defined for this {type.FullName}", "type");
+
+            _typeConverter = interactionService.GetComponentTypeConverter(type, services);
+        }
+
+        public override Task<TypeConverterResult> ReadAsync(IInteractionContext context, IComponentInteractionData option, IServiceProvider services)
+            => string.IsNullOrEmpty(option.Value) ? Task.FromResult(TypeConverterResult.FromSuccess(null)) : _typeConverter.ReadAsync(context, option, services);
+    }
+}
diff --git a/src/Discord.Net.Interactions/TypeReaders/NullableReader.cs b/src/Discord.Net.Interactions/TypeReaders/NullableReader.cs
new file mode 100644
index 000000000..ed88dc64a
--- /dev/null
+++ b/src/Discord.Net.Interactions/TypeReaders/NullableReader.cs
@@ -0,0 +1,23 @@
+using System;
+using System.Threading.Tasks;
+
+namespace Discord.Interactions
+{
+    internal class NullableReader<T> : TypeReader<T>
+    {
+        private readonly TypeReader _typeReader;
+
+        public NullableReader(InteractionService interactionService, IServiceProvider services)
+        {
+            var type = Nullable.GetUnderlyingType(typeof(T));
+
+            if (type is null)
+                throw new ArgumentException($"No type {nameof(TypeConverter)} is defined for this {type.FullName}", "type");
+
+            _typeReader = interactionService.GetTypeReader(type, services);
+        }
+
+        public override Task<TypeConverterResult> ReadAsync(IInteractionContext context, string option, IServiceProvider services)
+            => string.IsNullOrEmpty(option) ? Task.FromResult(TypeConverterResult.FromSuccess(null)) : _typeReader.ReadAsync(context, option, services);
+    }
+}