using System.Net;
using System.Net.Sockets;
using Microsoft.Extensions.Logging;
using QemuVmManager.Models;
using Open.Nat;

namespace QemuVmManager.Core;

public interface IUPnPManager
{
    Task<bool> IsUPnPAvailableAsync();
    Task<IPAddress?> GetExternalIpAddressAsync();
    Task<bool> AddPortMappingAsync(int externalPort, int internalPort, string description);
    Task<bool> RemovePortMappingAsync(int externalPort);
    Task<List<PortMapping>> GetPortMappingsAsync();
}

public class UPnPManager : IUPnPManager
{
    private readonly ILogger<UPnPManager>? _logger;
    private readonly Dictionary<int, PortMapping> _activeMappings = new();
    private readonly object _lock = new();
    private NatDevice? _natDevice;
    private bool _isInitialized = false;

    public UPnPManager(ILogger<UPnPManager>? logger = null)
    {
        _logger = logger;
    }

    private async Task InitializeAsync()
    {
        if (_isInitialized) return;

        try
        {
            _logger?.LogInformation("Initializing UPnP/NAT discovery...");
            
            // Create a new NAT discoverer
            var discoverer = new NatDiscoverer();
            
            // Discover UPnP devices with a 10-second timeout
            _natDevice = await discoverer.DiscoverDeviceAsync(PortMapper.Upnp, new CancellationTokenSource(TimeSpan.FromSeconds(10)));
            
            if (_natDevice != null)
            {
                _logger?.LogInformation("UPnP device discovered successfully");
                _isInitialized = true;
            }
            else
            {
                _logger?.LogWarning("No UPnP devices found");
            }
        }
        catch (Exception ex)
        {
            _logger?.LogWarning(ex, "UPnP initialization failed");
            _natDevice = null;
            _isInitialized = false;
        }
    }

    public async Task<bool> IsUPnPAvailableAsync()
    {
        try
        {
            await InitializeAsync();
            return _natDevice != null;
        }
        catch (Exception ex)
        {
            _logger?.LogWarning(ex, "UPnP availability check failed");
            return false;
        }
    }

    public async Task<IPAddress?> GetExternalIpAddressAsync()
    {
        try
        {
            await InitializeAsync();
            
            if (_natDevice == null)
            {
                _logger?.LogWarning("No UPnP device available for external IP lookup");
                return await GetExternalIpFromServiceAsync();
            }

            var externalIp = await _natDevice.GetExternalIPAsync();
            _logger?.LogInformation("External IP from UPnP: {ExternalIP}", externalIp);
            return externalIp;
        }
        catch (Exception ex)
        {
            _logger?.LogWarning(ex, "Failed to get external IP from UPnP, falling back to external service");
            return await GetExternalIpFromServiceAsync();
        }
    }

    public async Task<bool> AddPortMappingAsync(int externalPort, int internalPort, string description)
    {
        try
        {
            await InitializeAsync();
            
            if (_natDevice == null)
            {
                _logger?.LogError("No UPnP device available for port mapping");
                return false;
            }

            var localIp = GetLocalIpAddress();
            if (localIp == null)
            {
                _logger?.LogError("Could not determine local IP address");
                return false;
            }

            // Create the port mapping
            var mapping = new Mapping(Protocol.Tcp, internalPort, externalPort, description);
            
            // Add the mapping
            await _natDevice.CreatePortMapAsync(mapping);
            
            lock (_lock)
            {
                _activeMappings[externalPort] = new PortMapping
                {
                    ExternalPort = externalPort,
                    InternalPort = internalPort,
                    InternalIp = localIp,
                    Protocol = "TCP",
                    Description = description,
                    CreatedAt = DateTime.UtcNow
                };
            }
            
            _logger?.LogInformation("Successfully added port mapping: {ExternalPort} -> {InternalIp}:{InternalPort} ({Description})", 
                externalPort, localIp, internalPort, description);
            
            return true;
        }
        catch (Exception ex)
        {
            _logger?.LogError(ex, "Failed to add port mapping {ExternalPort} -> {InternalPort}", 
                externalPort, internalPort);
            return false;
        }
    }

    public async Task<bool> RemovePortMappingAsync(int externalPort)
    {
        try
        {
            await InitializeAsync();
            
            if (_natDevice == null)
            {
                _logger?.LogError("No UPnP device available for port mapping removal");
                return false;
            }

            var localIp = GetLocalIpAddress();
            if (localIp == null)
            {
                _logger?.LogError("Could not determine local IP address for mapping removal");
                return false;
            }

            // Create the mapping object for removal
            var mapping = new Mapping(Protocol.Tcp, 0, externalPort, "");
            
            // Remove the mapping
            await _natDevice.DeletePortMapAsync(mapping);
            
            lock (_lock)
            {
                _activeMappings.Remove(externalPort);
            }
            
            _logger?.LogInformation("Successfully removed port mapping: {ExternalPort}", externalPort);
            return true;
        }
        catch (Exception ex)
        {
            _logger?.LogError(ex, "Failed to remove port mapping {ExternalPort}", externalPort);
            return false;
        }
    }

    public async Task<List<PortMapping>> GetPortMappingsAsync()
    {
        try
        {
            await InitializeAsync();
            
            if (_natDevice == null)
            {
                _logger?.LogWarning("No UPnP device available for port mapping retrieval");
                lock (_lock)
                {
                    return _activeMappings.Values.ToList();
                }
            }

            var mappings = new List<PortMapping>();
            
            // For now, just return our active mappings since the Open.NAT API is complex
            // In a full implementation, we would query the device for all mappings
            lock (_lock)
            {
                mappings.AddRange(_activeMappings.Values);
            }
            
            return mappings;
        }
        catch (Exception ex)
        {
            _logger?.LogError(ex, "Failed to get port mappings from UPnP device");
            lock (_lock)
            {
                return _activeMappings.Values.ToList();
            }
        }
    }

    private async Task<IPAddress?> GetExternalIpFromServiceAsync()
    {
        try
        {
            using var client = new HttpClient();
            client.Timeout = TimeSpan.FromSeconds(10);
            
            // Try multiple external IP services
            var services = new[]
            {
                "https://api.ipify.org",
                "https://icanhazip.com",
                "https://ifconfig.me/ip"
            };

            foreach (var service in services)
            {
                try
                {
                    var response = await client.GetStringAsync(service);
                    var ipString = response.Trim();
                    if (IPAddress.TryParse(ipString, out var ip))
                    {
                        _logger?.LogInformation("External IP from service {Service}: {IP}", service, ip);
                        return ip;
                    }
                }
                catch (Exception ex)
                {
                    _logger?.LogDebug(ex, "Failed to get external IP from {Service}", service);
                    continue;
                }
            }
        }
        catch (Exception ex)
        {
            _logger?.LogWarning(ex, "Failed to get external IP from any service");
        }
        
        return null;
    }

    private IPAddress? GetLocalIpAddress()
    {
        try
        {
            var host = Dns.GetHostEntry(Dns.GetHostName());
            return host.AddressList.FirstOrDefault(ip => 
                ip.AddressFamily == AddressFamily.InterNetwork && 
                !IPAddress.IsLoopback(ip));
        }
        catch (Exception ex)
        {
            _logger?.LogWarning(ex, "Failed to get local IP address");
            return null;
        }
    }
}

public class PortMapping
{
    public int ExternalPort { get; set; }
    public int InternalPort { get; set; }
    public IPAddress InternalIp { get; set; } = IPAddress.Any;
    public string Protocol { get; set; } = "TCP";
    public string Description { get; set; } = string.Empty;
    public DateTime CreatedAt { get; set; }
}