using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace Shogi.Api.Managers
{
  public interface ISocketTokenCache
  {
    Guid GenerateToken(string s);
    string? GetUsername(Guid g);
  }

  public class SocketTokenCache : ISocketTokenCache
  {
    /// <summary>
    /// Key is userName or webSessionId
    /// </summary>
    private readonly ConcurrentDictionary<string, Guid> Tokens;

    public SocketTokenCache()
    {
      Tokens = new ConcurrentDictionary<string, Guid>();
    }

    public Guid GenerateToken(string userName)
    {
      Tokens.Remove(userName, out _);

      var guid = Guid.NewGuid();
      Tokens.TryAdd(userName, guid);

      _ = Task.Run(async () =>
      {
        await Task.Delay(TimeSpan.FromMinutes(1));
        Tokens.Remove(userName, out _);
      }).ConfigureAwait(false);

      return guid;
    }

    /// <returns>User name associated to the guid or null.</returns>
    public string? GetUsername(Guid guid)
    {
      var userName = Tokens.FirstOrDefault(kvp => kvp.Value == guid).Key;
      if (userName != null)
      {
        Tokens.Remove(userName, out _);
      }
      return userName;
    }
  }
}