dotnet/src/webdriver/Internal/ResponseValueJsonConverter.cs

// <copyright file="ResponseValueJsonConverter.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.Collections.Generic;
using System.Text.Json;
using System.Text.Json.Serialization;

namespace OpenQA.Selenium.Internal;

/// <summary>
/// Converts the response to JSON
/// </summary>
internal class ResponseValueJsonConverter : JsonConverter<object>
{
    public override object? Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
    {
        return ProcessReadToken(ref reader, options);
    }

    public override void Write(Utf8JsonWriter writer, object value, JsonSerializerOptions options)
    {
        switch (value)
        {
            case null:
                writer.WriteNullValue();
                break;
            case Enum:
                writer.WriteNumberValue(Convert.ToInt64(value));
                break;
            case IEnumerable<object> list:
                writer.WriteStartArray();
                foreach (var item in list)
                {
                    Write(writer, item, options);
                }
                writer.WriteEndArray();
                break;
            case IDictionary<string, object> dictionary:
                writer.WriteStartObject();
                foreach (var pair in dictionary)
                {
                    writer.WritePropertyName(pair.Key);
                    Write(writer, pair.Value, options);
                }
                writer.WriteEndObject();
                break;
            case object obj:
                JsonSerializer.Serialize(writer, obj, options.GetTypeInfo(obj.GetType()));
                break;
        }
    }

    private static object? ProcessReadToken(ref Utf8JsonReader reader, JsonSerializerOptions options)
    {
        // Recursively processes a token. This is required for elements that next other elements.
        object? processedObject;

        switch (reader.TokenType)
        {
            case JsonTokenType.StartObject:
                {
                    Dictionary<string, object?> dictionaryValue = [];
                    while (reader.Read() && reader.TokenType != JsonTokenType.EndObject)
                    {
                        string elementKey = reader.GetString()!;
                        reader.Read();
                        dictionaryValue.Add(elementKey, ProcessReadToken(ref reader, options));
                    }

                    processedObject = dictionaryValue;
                    break;
                }

            case JsonTokenType.StartArray:
                {
                    List<object?> arrayValue = [];
                    while (reader.Read() && reader.TokenType != JsonTokenType.EndArray)
                    {
                        arrayValue.Add(ProcessReadToken(ref reader, options));
                    }

                    processedObject = arrayValue.ToArray();
                    break;
                }

            case JsonTokenType.Null:
                processedObject = null;
                break;
            case JsonTokenType.False:
                processedObject = false;
                break;
            case JsonTokenType.True:
                processedObject = true;
                break;
            case JsonTokenType.String:
                processedObject = reader.GetString();
                break;
            case JsonTokenType.Number:
                {
                    if (reader.TryGetInt64(out long longValue))
                    {
                        processedObject = longValue;
                    }
                    else if (reader.TryGetDouble(out double doubleValue))
                    {
                        processedObject = doubleValue;
                    }
                    else
                    {
                        throw new JsonException($"Unrecognized '{JsonElement.ParseValue(ref reader)}' token as a number value.");
                    }

                    break;
                }

            default:
                throw new JsonException($"Unrecognized '{reader.TokenType}' token type while parsing command response.");
        }

        return processedObject;
    }
}