Add MediaStreamProtocol enum (#10153)

* Add MediaStreamProtocol enum

* Add default handling for enum during deserialization

---------

Co-authored-by: Cody Robibero <cody@robibe.ro>

src/Jellyfin.Extensions/Json/Converters/JsonDefaultStringEnumConverter.cs

@@ -0,0 +1,49 @@
+using System;
+using System.ComponentModel;
+using System.Reflection;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace Jellyfin.Extensions.Json.Converters;
+
+/// <summary>
+/// Json unknown enum converter.
+/// </summary>
+/// <typeparam name="T">The type of enum.</typeparam>
+public class JsonDefaultStringEnumConverter<T> : JsonConverter<T>
+    where T : struct, Enum
+{
+    private readonly JsonConverter<T> _baseConverter;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="JsonDefaultStringEnumConverter{T}"/> class.
+    /// </summary>
+    /// <param name="baseConverter">The base json converter.</param>
+    public JsonDefaultStringEnumConverter(JsonConverter<T> baseConverter)
+    {
+        _baseConverter = baseConverter;
+    }
+
+    /// <inheritdoc />
+    public override T Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
+    {
+        if (reader.IsNull() || reader.IsEmptyString())
+        {
+            var customValueAttribute = typeToConvert.GetCustomAttribute<DefaultValueAttribute>();
+            if (customValueAttribute?.Value is null)
+            {
+                throw new InvalidOperationException($"Default value not set for '{typeToConvert.Name}'");
+            }
+
+            return (T)customValueAttribute.Value;
+        }
+
+        return _baseConverter.Read(ref reader, typeToConvert, options);
+    }
+
+    /// <inheritdoc />
+    public override void Write(Utf8JsonWriter writer, T value, JsonSerializerOptions options)
+    {
+        _baseConverter.Write(writer, value, options);
+    }
+}

src/Jellyfin.Extensions/Json/Converters/JsonDefaultStringEnumConverterFactory.cs

@@ -0,0 +1,31 @@
+using System;
+using System.ComponentModel;
+using System.Reflection;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace Jellyfin.Extensions.Json.Converters;
+
+/// <summary>
+/// Utilizes the JsonStringEnumConverter and sets a default value if not provided.
+/// </summary>
+public class JsonDefaultStringEnumConverterFactory : JsonConverterFactory
+{
+    private static readonly JsonStringEnumConverter _baseConverterFactory = new();
+
+    /// <inheritdoc />
+    public override bool CanConvert(Type typeToConvert)
+    {
+        return _baseConverterFactory.CanConvert(typeToConvert)
+               && typeToConvert.IsDefined(typeof(DefaultValueAttribute));
+    }
+
+    /// <inheritdoc />
+    public override JsonConverter? CreateConverter(Type typeToConvert, JsonSerializerOptions options)
+    {
+        var baseConverter = _baseConverterFactory.CreateConverter(typeToConvert, options);
+        var converterType = typeof(JsonDefaultStringEnumConverter<>).MakeGenericType(typeToConvert);
+
+        return (JsonConverter?)Activator.CreateInstance(converterType, baseConverter);
+    }
+}

src/Jellyfin.Extensions/Json/Converters/JsonGuidConverter.cs

@@ -12,7 +12,7 @@ namespace Jellyfin.Extensions.Json.Converters
     {
         /// <inheritdoc />
         public override Guid Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
-            => reader.TokenType == JsonTokenType.Null
+            => reader.IsNull()
                 ? Guid.Empty
                 : ReadInternal(ref reader);
 

src/Jellyfin.Extensions/Json/Converters/JsonNullableStructConverter.cs

@@ -15,10 +15,7 @@ namespace Jellyfin.Extensions.Json.Converters
         /// <inheritdoc />
         public override TStruct? Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
         {
-            // Token is empty string.
-            if (reader.TokenType == JsonTokenType.String
-                && ((reader.HasValueSequence && reader.ValueSequence.IsEmpty)
-                    || (!reader.HasValueSequence && reader.ValueSpan.IsEmpty)))
+            if (reader.IsEmptyString())
             {
                 return null;
             }

src/Jellyfin.Extensions/Json/JsonDefaults.cs

@@ -38,6 +38,7 @@ namespace Jellyfin.Extensions.Json
                 new JsonNullableGuidConverter(),
                 new JsonVersionConverter(),
                 new JsonFlagEnumConverterFactory(),
+                new JsonDefaultStringEnumConverterFactory(),
                 new JsonStringEnumConverter(),
                 new JsonNullableStructConverterFactory(),
                 new JsonDateTimeConverter(),

src/Jellyfin.Extensions/Json/Utf8JsonExtensions.cs

@@ -0,0 +1,27 @@
+using System.Text.Json;
+
+namespace Jellyfin.Extensions.Json;
+
+/// <summary>
+/// Extensions for Utf8JsonReader and Utf8JsonWriter.
+/// </summary>
+public static class Utf8JsonExtensions
+{
+    /// <summary>
+    /// Determines if the reader contains an empty string.
+    /// </summary>
+    /// <param name="reader">The reader.</param>
+    /// <returns>Whether the reader contains an empty string.</returns>
+    public static bool IsEmptyString(this Utf8JsonReader reader)
+        => reader.TokenType == JsonTokenType.String
+           && ((reader.HasValueSequence && reader.ValueSequence.IsEmpty)
+               || (!reader.HasValueSequence && reader.ValueSpan.IsEmpty));
+
+    /// <summary>
+    /// Determines if the reader contains a null value.
+    /// </summary>
+    /// <param name="reader">The reader.</param>
+    /// <returns>Whether the reader contains null.</returns>
+    public static bool IsNull(this Utf8JsonReader reader)
+        => reader.TokenType == JsonTokenType.Null;
+}