using System.Collections.Generic;
using System.Linq;
using System.Net.NetworkInformation;
using System.Net.Sockets;

namespace LanDiscovery.Services
{
    public class NetworkInterfaceInfo
    {
        public string? Id { get; set; } // GUID
        public string? Name { get; set; } // Friendly Name
        public string? Description { get; set; }
        public string? IpAddress { get; set; }
        public string? SubnetMask { get; set; }
        public string? Gateway { get; set; }
        public NetworkInterface? NativeInterface { get; set; }

        public override string ToString()
        {
            return $"{Name} ({IpAddress})";
        }
    }

    public class NetworkInterfaceService
    {
        public List<NetworkInterfaceInfo> GetAllIpv4Interfaces()
        {
            var results = new List<NetworkInterfaceInfo>();

            foreach (var nic in NetworkInterface.GetAllNetworkInterfaces())
            {
                // Filter out non-ethernet/wifi/loopback to reduce noise, unless necessary.
                // For now, accept generic types but ensure they are Up and not Loopback
                if (nic.NetworkInterfaceType == NetworkInterfaceType.Loopback ||
                    nic.OperationalStatus != OperationalStatus.Up)
                {
                    continue;
                }

                var ipProps = nic.GetIPProperties();
                var ipv4 = ipProps.UnicastAddresses
                    .FirstOrDefault(addr => addr.Address.AddressFamily == AddressFamily.InterNetwork);

                if (ipv4 != null)
                {
                    var gateway = ipProps.GatewayAddresses
                        .FirstOrDefault(g => g.Address.AddressFamily == AddressFamily.InterNetwork)?.Address.ToString() ?? "";

                    results.Add(new NetworkInterfaceInfo
                    {
                        Id = nic.Id,
                        Name = nic.Name,
                        Description = nic.Description,
                        IpAddress = ipv4.Address.ToString(),
                        SubnetMask = ipv4.IPv4Mask.ToString(),
                        Gateway = gateway,
                        NativeInterface = nic
                    });
                }
            }

            // Sort: Interfaces with Gateway first
            // Then Ethernet, Then Wifi
            return results.OrderByDescending(r => !string.IsNullOrEmpty(r.Gateway))
                          .ThenBy(r => r.NativeInterface?.NetworkInterfaceType == NetworkInterfaceType.Ethernet ? 0 : 1)
                          .ThenBy(r => r.NativeInterface?.NetworkInterfaceType == NetworkInterfaceType.Wireless80211 ? 0 : 1)
                          .ToList();
        }
    }
}