using FluentValidation;
using Shogi.Contracts.Socket;
using Shogi.Contracts.Types;
using Shogi.Api.Extensions;
using Shogi.Api.Managers;
using System.Net;
using System.Net.WebSockets;
using System.Text.Json;

namespace Shogi.Api.Services
{
  public interface ISocketService
  {
    Task HandleSocketRequest(HttpContext context);
  }

  /// <summary>
  /// Services a single websocket connection. Authenticates the socket connection, accepts messages, and sends messages.
  /// </summary>
  public class SocketService : ISocketService
  {
    private readonly ILogger<SocketService> logger;
    private readonly ISocketConnectionManager communicationManager;
    private readonly ISocketTokenCache tokenManager;

    public SocketService(
      ILogger<SocketService> logger,
      ISocketConnectionManager communicationManager,
      ISocketTokenCache tokenManager) : base()
    {
      this.logger = logger;
      this.communicationManager = communicationManager;
      this.tokenManager = tokenManager;
    }

    public async Task HandleSocketRequest(HttpContext context)
    {
      if (!context.Request.Query.Keys.Contains("token"))
      {
        context.Response.StatusCode = (int)HttpStatusCode.Unauthorized;
        return;
      }
      var token = Guid.Parse(context.Request.Query["token"][0]);
      var userName = tokenManager.GetUsername(token);

      if (string.IsNullOrEmpty(userName))
      {
        context.Response.StatusCode = (int)HttpStatusCode.Unauthorized;
        return;
      }
      var socket = await context.WebSockets.AcceptWebSocketAsync();

      communicationManager.Subscribe(socket, userName);
      while (socket.State == WebSocketState.Open)
      {
        try
        {
          var message = await socket.ReceiveTextAsync();
          if (string.IsNullOrWhiteSpace(message)) continue;
          logger.LogInformation("Request \n{0}\n", message);
          var request = JsonSerializer.Deserialize<ISocketRequest>(message);
          if (request == null || !Enum.IsDefined(typeof(SocketAction), request.Action))
          {
            await socket.SendTextAsync("Error: Action not recognized.");
            continue;
          }
          switch (request.Action)
          {
            default:
              await socket.SendTextAsync($"Received your message with action {request.Action}, but did no work.");
              break;
          }
        }
        catch (OperationCanceledException ex)
        {
          logger.LogError(ex.Message);
        }
        catch (WebSocketException ex)
        {
          logger.LogInformation($"{nameof(WebSocketException)} in {nameof(SocketConnectionManager)}.");
          logger.LogInformation("Probably tried writing to a closed socket.");
          logger.LogError(ex.Message);
        }
        communicationManager.Unsubscribe(userName);
      }
    }

    public async Task<bool> ValidateRequestAndReplyIfInvalid<TRequest>(WebSocket socket, IValidator<TRequest> validator, TRequest request)
    {
      var results = validator.Validate(request);
      if (!results.IsValid)
      {
        var errors = string.Join('\n', results.Errors.Select(_ => _.ErrorMessage));
        await socket.SendTextAsync(errors);
      }
      return results.IsValid;
    }
  }
}