using JsonRPC4.Common;
using JsonRPC4.Router.Abstractions;
using Microsoft.Extensions.Options;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text.Json;
using System.Threading;
using System.Threading.Tasks;

namespace JsonRPC4.Router.Defaults
{
	public class DefaultRpcResponseSerializer : IRpcResponseSerializer
	{
		private IOptions<RpcServerConfiguration> serverConfig
		{
			get;
		}

		public DefaultRpcResponseSerializer(IOptions<RpcServerConfiguration> serverConfig)
		{
			this.serverConfig = serverConfig;
		}

		public Task SerializeBulkAsync(IEnumerable<RpcResponse> responses, Stream stream)
		{
			return SerializeInternalAsync(responses, isBulkRequest: true, stream);
		}

		public Task SerializeAsync(RpcResponse response, Stream stream)
		{
			return SerializeInternalAsync(new RpcResponse[1]
			{
			response
			}, isBulkRequest: false, stream);
		}

		private async Task SerializeInternalAsync(IEnumerable<RpcResponse> responses, bool isBulkRequest, Stream stream)
		{
			Utf8JsonWriter jsonWriter = (Utf8JsonWriter)(object)new Utf8JsonWriter(stream, default(JsonWriterOptions));
			try
			{
				if (isBulkRequest)
				{
					jsonWriter.WriteStartArray();
					foreach (RpcResponse response in responses)
					{
						SerializeResponse(response, jsonWriter);
					}
					jsonWriter.WriteEndArray();
				}
				else
				{
					SerializeResponse(responses.Single(), jsonWriter);
				}
			}
			finally
			{
				await jsonWriter.FlushAsync(default(CancellationToken));
				await jsonWriter.DisposeAsync();
			}
		}

		private void SerializeResponse(RpcResponse response, Utf8JsonWriter jsonWriter)
		{
			jsonWriter.WriteStartObject();
			jsonWriter.WritePropertyName("id");
			switch (response.Id.Type)
			{
				case RpcIdType.Number:
					jsonWriter.WriteNumberValue(response.Id.NumberValue);
					break;
				case RpcIdType.String:
					jsonWriter.WriteStringValue(response.Id.StringValue);
					break;
				default:
					throw new NotImplementedException();
			}
			jsonWriter.WriteString("jsonrpc", "2.0");
			if (!response.HasError)
			{
				jsonWriter.WritePropertyName("result");
				SerializeValue(response.Result, jsonWriter);
			}
			else
			{
				jsonWriter.WritePropertyName("error");
				jsonWriter.WriteStartObject();
				jsonWriter.WriteNumber("code", response.Error.Code);
				jsonWriter.WriteString("message", response.Error.Message);
				jsonWriter.WritePropertyName("data");
				SerializeValue(response.Error.Data, jsonWriter);
				jsonWriter.WriteEndObject();
			}
			jsonWriter.WriteEndObject();
		}

		private void SerializeValue(object value, Utf8JsonWriter jsonWriter)
		{
			if (value != null)
			{
				JsonSerializerOptions jsonSerializerSettings = serverConfig.Value.JsonSerializerSettings;
				JsonDocument.Parse( JsonSerializer.SerializeToUtf8Bytes(value, value.GetType(), jsonSerializerSettings), default(JsonDocumentOptions)).WriteTo(jsonWriter);
			}
			else
			{
				jsonWriter.WriteNullValue();
			}
		}
	}

}