using System.Collections.Concurrent;
using System.Reflection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;

namespace Server;

public class PacketDistributorService : IHostedService
{
    private readonly ConcurrentQueue<Packet> _concurrentQueue;
    private readonly ILogger<PacketDistributorService> _logger;
    private readonly CancellationTokenSource _cancellationTokenSource = new();
    private readonly Dictionary<OperationCode, IPacketHandler> _actions;

    public PacketDistributorService(ILogger<PacketDistributorService> logger)
    {
        _concurrentQueue = new ConcurrentQueue<Packet>();
        _logger = logger;
        _actions = new Dictionary<OperationCode, IPacketHandler>();
        var packetHandlers = Assembly.GetExecutingAssembly().GetTypes().Where(t =>
            t.GetCustomAttributes().Any(attribute => attribute.GetType() == typeof(PacketHandler)) &&
            t.GetInterfaces().Contains(typeof(IPacketHandler)));
        foreach (var type in packetHandlers)
        {
            PacketHandler packetHandler = type.GetCustomAttribute<PacketHandler>()!;
            _actions.Add(packetHandler.Code,
                type.GetConstructor( Type.EmptyTypes)
                    .Invoke(null) as IPacketHandler);
            _logger.LogInformation(
                "Handler for ID \"{PacketHandlerCode}\" has been added with name \"{PacketHandlerName}\"",
                packetHandler.Code, type.Name);
        }
    }

    public Task StartAsync(CancellationToken cancellationToken)
    {
        return Task.CompletedTask;
    }

    public Task AddPacket(Packet packet)
    {
        _logger.LogInformation("Packet with ID: {MessageOperationCode} has been received",
            packet.OperationCode);
        _concurrentQueue.Enqueue(packet);
        return Task.Run(DequeueAndProcessAsync);
    }

    private async Task DequeueAndProcessAsync()
    {
        while (!_cancellationTokenSource.IsCancellationRequested)
        {
            if (_concurrentQueue.TryDequeue(out var item))
            {
                Parallel.Invoke(() =>
                {
                    var tempId = Guid.NewGuid();
                    _logger.LogInformation("[{TempId}] Packet with ID: {MessageOperationCode} is being dequeued",tempId, item.OperationCode);
                    var packetHandler = _actions[item.OperationCode];
                    packetHandler.Process(item);
                    _logger.LogInformation("[{TempId}] Packet with ID: {MessageOperationCode} has finished",tempId, item.OperationCode);
                });
            }
            else
            {
                await Task.Delay(100); // Delay to prevent busy-waiting, can be adjusted based on needs
            }
        }
    }

    public Task StopAsync(CancellationToken cancellationToken)
    {
        return Task.CompletedTask;
    }
}