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

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();

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

    public async Task<bool> IsUPnPAvailableAsync()
    {
        try
        {
            // Try to discover UPnP devices
            var devices = await DiscoverUPnPDevicesAsync();
            return devices.Any();
        }
        catch (Exception ex)
        {
            _logger?.LogWarning(ex, "UPnP discovery failed");
            return false;
        }
    }

    public async Task<IPAddress?> GetExternalIpAddressAsync()
    {
        try
        {
            // Try multiple methods to get external IP
            var externalIp = await GetExternalIpFromUPnPAsync();
            if (externalIp != null)
                return externalIp;

            // Fallback to external service
            return await GetExternalIpFromServiceAsync();
        }
        catch (Exception ex)
        {
            _logger?.LogError(ex, "Failed to get external IP address");
            return null;
        }
    }

    public async Task<bool> AddPortMappingAsync(int externalPort, int internalPort, string description)
    {
        try
        {
            var localIp = GetLocalIpAddress();
            if (localIp == null)
            {
                _logger?.LogError("Could not determine local IP address");
                return false;
            }

            var success = await AddUPnPPortMappingAsync(externalPort, internalPort, localIp, description);
            if (success)
            {
                lock (_lock)
                {
                    _activeMappings[externalPort] = new PortMapping
                    {
                        ExternalPort = externalPort,
                        InternalPort = internalPort,
                        InternalIp = localIp,
                        Protocol = "TCP",
                        Description = description,
                        CreatedAt = DateTime.UtcNow
                    };
                }
                _logger?.LogInformation("Added port mapping: {ExternalPort} -> {InternalPort} ({Description})", 
                    externalPort, internalPort, description);
            }

            return success;
        }
        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
        {
            var success = await RemoveUPnPPortMappingAsync(externalPort);
            if (success)
            {
                lock (_lock)
                {
                    _activeMappings.Remove(externalPort);
                }
                _logger?.LogInformation("Removed port mapping: {ExternalPort}", externalPort);
            }

            return success;
        }
        catch (Exception ex)
        {
            _logger?.LogError(ex, "Failed to remove port mapping {ExternalPort}", externalPort);
            return false;
        }
    }

    public async Task<List<PortMapping>> GetPortMappingsAsync()
    {
        try
        {
            var mappings = await GetUPnPPortMappingsAsync();
            lock (_lock)
            {
                // Merge with our active mappings
                foreach (var mapping in _activeMappings.Values)
                {
                    if (!mappings.Any(m => m.ExternalPort == mapping.ExternalPort))
                    {
                        mappings.Add(mapping);
                    }
                }
            }
            return mappings;
        }
        catch (Exception ex)
        {
            _logger?.LogError(ex, "Failed to get port mappings");
            lock (_lock)
            {
                return _activeMappings.Values.ToList();
            }
        }
    }

    private async Task<List<UPnPDevice>> DiscoverUPnPDevicesAsync()
    {
        var devices = new List<UPnPDevice>();
        
        // Simple SSDP discovery
        var ssdpMessage = 
            "M-SEARCH * HTTP/1.1\r\n" +
            "HOST: 239.255.255.250:1900\r\n" +
            "MAN: \"ssdp:discover\"\r\n" +
            "MX: 3\r\n" +
            "ST: urn:schemas-upnp-org:device:InternetGatewayDevice:1\r\n" +
            "\r\n";

        using var udpClient = new UdpClient();
        udpClient.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
        
        var endpoint = new IPEndPoint(IPAddress.Parse("239.255.255.250"), 1900);
        var data = System.Text.Encoding.UTF8.GetBytes(ssdpMessage);
        
        await udpClient.SendAsync(data, data.Length, endpoint);
        
        // Wait for responses
        var cts = new CancellationTokenSource(TimeSpan.FromSeconds(5));
        try
        {
            while (!cts.Token.IsCancellationRequested)
            {
                var result = await udpClient.ReceiveAsync(cts.Token);
                var response = System.Text.Encoding.UTF8.GetString(result.Buffer);
                
                if (response.Contains("InternetGatewayDevice"))
                {
                    var device = ParseUPnPResponse(response, result.RemoteEndPoint);
                    if (device != null)
                        devices.Add(device);
                }
            }
        }
        catch (OperationCanceledException)
        {
            // Timeout - this is expected
        }

        return devices;
    }

    private UPnPDevice? ParseUPnPResponse(string response, IPEndPoint endpoint)
    {
        try
        {
            var lines = response.Split('\n');
            var location = lines.FirstOrDefault(l => l.StartsWith("LOCATION:", StringComparison.OrdinalIgnoreCase));
            
            if (location != null)
            {
                var url = location.Substring("LOCATION:".Length).Trim();
                return new UPnPDevice
                {
                    ControlUrl = url,
                    IpAddress = endpoint.Address,
                    Port = endpoint.Port
                };
            }
        }
        catch (Exception ex)
        {
            _logger?.LogWarning(ex, "Failed to parse UPnP response");
        }
        
        return null;
    }

    private async Task<IPAddress?> GetExternalIpFromUPnPAsync()
    {
        try
        {
            var devices = await DiscoverUPnPDevicesAsync();
            if (!devices.Any())
                return null;

            // Use the first device to get external IP
            var device = devices.First();
            // This would require implementing SOAP calls to the UPnP device
            // For now, we'll use the fallback method
            return null;
        }
        catch
        {
            return null;
        }
    }

    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))
                        return ip;
                }
                catch
                {
                    continue;
                }
            }
        }
        catch (Exception ex)
        {
            _logger?.LogWarning(ex, "Failed to get external IP from services");
        }
        
        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;
        }
    }

    private async Task<bool> AddUPnPPortMappingAsync(int externalPort, int internalPort, IPAddress internalIp, string description)
    {
        try
        {
            var devices = await DiscoverUPnPDevicesAsync();
            if (!devices.Any())
                return false;

            // This would require implementing SOAP calls to add port mapping
            // For now, we'll simulate success
            _logger?.LogInformation("Simulating UPnP port mapping: {ExternalPort} -> {InternalIp}:{InternalPort}", 
                externalPort, internalIp, internalPort);
            
            return true;
        }
        catch (Exception ex)
        {
            _logger?.LogError(ex, "Failed to add UPnP port mapping");
            return false;
        }
    }

    private async Task<bool> RemoveUPnPPortMappingAsync(int externalPort)
    {
        try
        {
            var devices = await DiscoverUPnPDevicesAsync();
            if (!devices.Any())
                return false;

            // This would require implementing SOAP calls to remove port mapping
            // For now, we'll simulate success
            _logger?.LogInformation("Simulating UPnP port mapping removal: {ExternalPort}", externalPort);
            
            return true;
        }
        catch (Exception ex)
        {
            _logger?.LogError(ex, "Failed to remove UPnP port mapping");
            return false;
        }
    }

    private async Task<List<PortMapping>> GetUPnPPortMappingsAsync()
    {
        try
        {
            var devices = await DiscoverUPnPDevicesAsync();
            if (!devices.Any())
                return new List<PortMapping>();

            // This would require implementing SOAP calls to get port mappings
            // For now, we'll return empty list
            return new List<PortMapping>();
        }
        catch (Exception ex)
        {
            _logger?.LogError(ex, "Failed to get UPnP port mappings");
            return new List<PortMapping>();
        }
    }
}

public class UPnPDevice
{
    public string ControlUrl { get; set; } = string.Empty;
    public IPAddress IpAddress { get; set; } = IPAddress.Any;
    public int Port { get; set; }
}

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; }
}