JsonProtoBufBridge.cs

using System;
using System.Linq;

using System.Collections.Generic;

using Newtonsoft.Json;
using Newtonsoft.Json.Linq;

using Google.Protobuf;
using Google.Protobuf.Collections;
using Google.Cloud.Firestore.V1Beta1;

public static partial class Ext
{
	public static JObject ToJSon<T>(this T fields) where T : IEnumerable<KeyValuePair<string,Value>>
	{
		return JObject.FromObject(fields.ToDictionary((pair) => pair.Key,(pair) => pair.Value.ToJSon()));
	}

	public static JToken ToJSon(this Value input)
	{
		switch(input?.ValueTypeCase)
		{
			case null:
				return null;
			case Value.ValueTypeOneofCase.NullValue:
				return JValue.CreateNull();

			case Value.ValueTypeOneofCase.BooleanValue:
				return input.BooleanValue;
			case Value.ValueTypeOneofCase.StringValue:
				return input.StringValue;
			case Value.ValueTypeOneofCase.DoubleValue:
				return input.DoubleValue;
			case Value.ValueTypeOneofCase.IntegerValue:
				return input.IntegerValue;

			case Value.ValueTypeOneofCase.ArrayValue:
				return new JArray(input.ArrayValue?.Values.Select((item) => item.ToJSon()));
			case Value.ValueTypeOneofCase.MapValue:
				return JObject.FromObject(input.MapValue.Fields.ToDictionary((pair) => pair.Key,(pair) => pair.Value.ToJSon()));

			case Value.ValueTypeOneofCase.BytesValue:
				return input.BytesValue.ToByteArray();
			case Value.ValueTypeOneofCase.TimestampValue:
				return input.TimestampValue.ToDateTimeOffset();
			case Value.ValueTypeOneofCase.ReferenceValue:
				return new JObject(){ ["referenceValue"] = input.ReferenceValue };
			case Value.ValueTypeOneofCase.GeoPointValue:
				return new JObject(){ ["geoPointValue"] = JObject.FromObject(input.GeoPointValue) };

			default:
				throw new NotSupportedException(input.ValueTypeCase.ToString());
		}
	}

	public static MapField<string,Value> ToFields<T>(this JObject fields)
	{
		var map	= new MapField<string,Value>();
		map.Add(fields.Properties().ToDictionary((pair) => pair.Name,(pair) => pair.Value.ToValue()));
		return map;
	}

	static readonly string[] FireStoreValueNames	= new[]{ "nullValue","booleanValue","integerValue","doubleValue","timestampValue","stringValue","bytesValue","referenceValue","geoPointValue","arrayValue","mapValue"};
	public static Value ToValue(this JToken input)
	{
		if(input is null)
			return null;

		if(input is JObject jobj)
		{
			if(jobj.Properties().FirstOrDefault() is JProperty prop && FireStoreValueNames.Contains(prop.Name))
				return Value.Parser.ParseJson(prop.Value.ToString());

			var map	= new MapValue();
			map.Fields.Add(jobj.Properties().ToDictionary((pair) => pair.Name,(pair) => pair.Value.ToValue()));
			return new Value() { MapValue = map };
		}

		if(input is JArray jarr)
		{
			var arr	= new ArrayValue();
			arr.Values.Add(jarr.Select((item) => item.ToValue()));
			return new Value() { ArrayValue = arr };
		}

		switch(input.Type)
		{
			case JTokenType.None:
			case JTokenType.Null:
				return new Value() { NullValue = Google.Protobuf.WellKnownTypes.NullValue.NullValue };

			case JTokenType.Boolean:
				return new Value() { BooleanValue = (bool)input };
			case JTokenType.Integer:
				return new Value() { IntegerValue = (long)input };
			case JTokenType.Float:
				return new Value() { DoubleValue = (double)input };
			case JTokenType.String:
				return new Value() { StringValue = (string)input };
			case JTokenType.Date:
				return new Value() { TimestampValue = Google.Protobuf.WellKnownTypes.Timestamp.FromDateTimeOffset((DateTimeOffset)input) };
			case JTokenType.Bytes:
				return new Value() { BytesValue = ByteString.CopyFrom((byte[])input) };

			default:
				throw new NotSupportedException(input.ToString(Formatting.None));
		}
	}
}