OptionalConverter.cs

// <copyright file="OptionalConverter.cs" company="Selenium Committers">
// Licensed to the Software Freedom Conservancy (SFC) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The SFC licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.
// </copyright>

using System;
using System.Text.Json;
using System.Text.Json.Serialization;

namespace OpenQA.Selenium.BiDi.Json.Converters;

public sealed class OptionalConverter<T> : JsonConverter<Optional<T>>
{
    public override Optional<T> Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
    {
        if (reader.TokenType == JsonTokenType.Null)
        {
            reader.Read(); // consume null
            return new Optional<T>(default!);
        }

        T value = JsonSerializer.Deserialize(ref reader, options.GetTypeInfo<T>())!;
        return new Optional<T>(value);
    }

    public override void Write(Utf8JsonWriter writer, Optional<T> value, JsonSerializerOptions options)
    {
        if (value.TryGetValue(out var optionalValue))
        {
            JsonSerializer.Serialize(writer, optionalValue, options.GetTypeInfo<T>());
        }
        else
        {
            writer.WriteNullValue();
        }
    }
}