Connected.Framework/Connected.Interop/Serializer.cs

using Connected.Interop.Merging;
using System.Collections;
using System.Reflection;
using System.Text;
using System.Text.Json;
using System.Text.Json.Nodes;

namespace Connected.Interop;

public static class Serializer
{
	private static readonly JsonSerializerOptions _options;

	static Serializer()
	{
		_options = new JsonSerializerOptions
		{
			AllowTrailingCommas = true,
			IncludeFields = false,
			IgnoreReadOnlyFields = false,
			IgnoreReadOnlyProperties = true,
			PropertyNameCaseInsensitive = true,
			PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
			WriteIndented = true
		};
	}

	internal static JsonSerializerOptions SerializerOptions => _options;

	public static async Task<T?> Deserialize<T>(string value)
	{
		using var ms = new MemoryStream(Encoding.UTF8.GetBytes(value));

		ms.Seek(0, SeekOrigin.Begin);

		return await JsonSerializer.DeserializeAsync<T>(ms, _options);
	}

	public static async Task<string?> Serialize(object value)
	{
		using var ms = new MemoryStream();
		using var writer = new Utf8JsonWriter(ms, new JsonWriterOptions { Indented = true, SkipValidation = false });

		if (value.GetType().IsEnumerable())
			SerializeArray(writer, null, value);
		else if (value.GetType().IsTypePrimitive())
			SerializePrimitive(writer, value);
		else
			SerializeObject(writer, null, value);

		await writer.FlushAsync();

		ms.Seek(0, SeekOrigin.Begin);

		return Encoding.UTF8.GetString(ms.ToArray());
	}

	private static void SerializeObject(Utf8JsonWriter writer, PropertyInfo property, object value)
	{
		if (value is null)
			return;

		var properties = value.GetType().GetProperties(BindingFlags.Public | BindingFlags.Instance);

		if (property is not null)
			writer.WriteStartObject(property.Name.ToCamelCase());
		else
			writer.WriteStartObject();

		foreach (var p in properties)
			SerializeProperty(writer, p, value);

		writer.WriteEndObject();
	}

	private static void SerializeArray(Utf8JsonWriter writer, PropertyInfo property, object value)
	{
		if (value is null)
			return;

		if (property is not null)
			writer.WriteStartArray(property.Name.ToCamelCase());
		else
			writer.WriteStartArray();

		if (value is IEnumerable enumerable)
		{
			var enumerator = enumerable.GetEnumerator();

			while (enumerator.MoveNext())
				SerializeObject(writer, null, enumerator.Current);
		}

		writer.WriteEndArray();
	}

	private static void SerializeProperty(Utf8JsonWriter writer, PropertyInfo property, object value)
	{
		if (property.PropertyType.IsEnumerable())
			SerializeArray(writer, property, value);
		else if (!property.PropertyType.IsTypePrimitive())
			SerializeObject(writer, property, value);

		writer.WritePropertyName(property.Name.ToCamelCase());

		SerializePrimitive(writer, property.GetValue(value));
	}

	private static void SerializePrimitive(Utf8JsonWriter writer, object? value)
	{
		if (value is null)
		{
			writer.WriteNullValue();
			return;
		}

		if (value.GetType().IsNumber())
			SerializeNumber(writer, value);
		else if (value is string)
			writer.WriteStringValue(value.ToString());
		else if (value is DateTime date)
			writer.WriteStringValue(date);
		else if (value is DateTimeOffset offset)
			writer.WriteStringValue(offset);
		else if (value is Guid guid)
			writer.WriteStringValue(guid);
		else if (value is bool @bool)
			writer.WriteBooleanValue(@bool);
		else if (value is Enum en)
		{
			var type = Enum.GetUnderlyingType(en.GetType());

			if (TypeConversion.TryConvert(value, out object? enumNumber, type))
				SerializeNumber(writer, enumNumber);
		}
	}

	private static void SerializeNumber(Utf8JsonWriter writer, object? value)
	{
		if (value is decimal @decimal)
			writer.WriteNumberValue(@decimal);
		else if (value is double @double)
			writer.WriteNumberValue(@double);
		else if (value is float @float)
			writer.WriteNumberValue(@float);
		else if (value is int @int)
			writer.WriteNumberValue(@int);
		else if (value is long @long)
			writer.WriteNumberValue(@long);
		else if (value is uint @uint)
			writer.WriteNumberValue(@uint);
		else if (value is ulong @ulong)
			writer.WriteNumberValue(@ulong);
		else if (value is byte @byte)
			writer.WriteNumberValue(@byte);
		else if (value is sbyte @sbyte)
			writer.WriteNumberValue(@sbyte);
		else if (value is short @short)
			writer.WriteNumberValue(@short);
		else if (value is ushort @ushort)
			writer.WriteNumberValue(@ushort);
	}

	public static T Merge<T>(T destination, params object[] sources)
	{
		if (destination is null)
			return default;

		if (sources is null || !sources.Any())
			return destination;

		var hasJson = false;

		foreach (var source in sources)
		{
			if (source is JsonNode)
			{
				hasJson = true;
				break;
			}
		}

		if (!hasJson)
			new ObjectMerger().Merge(destination, sources);
		else
		{
			foreach (var source in sources)
			{
				if (source is JsonNode node)
					new JsonMerger().Merge(destination, node);
				else
					new ObjectMerger().Merge(destination, source);
			}
		}

		return destination;
	}

	public static T Merge<T>(T destination, string value)
	{
		var node = Deserialize<JsonNode>(value);

		return Merge(destination, node);
	}
}