using Shogi.Contracts.Socket;
using Shogi.Api.Extensions;
using System.Collections.Concurrent;
using System.Net.WebSockets;
using System.Text.Json;

namespace Shogi.Api.Managers;

public interface ISocketConnectionManager
{
  Task BroadcastToAll(ISocketMessage response);
  void Subscribe(WebSocket socket, string playerName);
  void Unsubscribe(string playerName);
  Task BroadcastToPlayers(ISocketMessage response, params string?[] playerNames);
}

/// <summary>
/// Retains all active socket connections and provides convenient methods for sending messages to clients.
/// </summary>
public class SocketConnectionManager : ISocketConnectionManager
{
  /// <summary>Dictionary key is player name.</summary>
  private readonly ConcurrentDictionary<string, WebSocket> connections;
  private readonly JsonSerializerOptions serializeOptions;

  /// <summary>Dictionary key is game name.</summary>
  private readonly ILogger<SocketConnectionManager> logger;

  public SocketConnectionManager(ILogger<SocketConnectionManager> logger)
  {
    this.logger = logger;
    this.connections = new ConcurrentDictionary<string, WebSocket>();
    this.serializeOptions = new JsonSerializerOptions(JsonSerializerDefaults.General);

  }

  public void Subscribe(WebSocket socket, string playerName)
  {
    connections.TryRemove(playerName, out var _);
    connections.TryAdd(playerName, socket);
  }

  public void Unsubscribe(string playerName)
  {
    connections.TryRemove(playerName, out _);
  }

  public async Task BroadcastToPlayers(ISocketMessage response, params string?[] playerNames)
  {
    var tasks = new List<Task>(playerNames.Length);
    foreach (var name in playerNames)
    {
      if (!string.IsNullOrEmpty(name) && connections.TryGetValue(name, out var socket))
      {
        var serialized = Serialize(response);
        logger.LogInformation("Response to {0} \n{1}\n", name, serialized);
        tasks.Add(socket.SendTextAsync(serialized));
      }
    }
    await Task.WhenAll(tasks);
  }
  public Task BroadcastToAll(ISocketMessage response)
  {
    var message = Serialize(response);
    logger.LogInformation("Broadcasting:\n{0}\nDone Broadcasting.", message);
    var tasks = new List<Task>(connections.Count);
    foreach (var kvp in connections)
    {
      var socket = kvp.Value;
      try
      {
        tasks.Add(socket.SendTextAsync(message));
      }
      catch (WebSocketException)
      {
        logger.LogInformation("Tried sending a message to socket connection for user [{user}], but found the connection has closed.", kvp.Key);
        Unsubscribe(kvp.Key);
      }
      catch
      {
        logger.LogInformation("Tried sending a message to socket connection for user [{user}], but found the connection has closed.", kvp.Key);
        Unsubscribe(kvp.Key);
      }
    }
    return Task.WhenAll(tasks);
  }

  private string Serialize(object o) => JsonSerializer.Serialize(o, this.serializeOptions);
}