using System;
using System.Net.NetworkInformation;
using System.Runtime.InteropServices;
using System.Net;
using System.Net.Sockets;

namespace SBRL.Utilities
{
	public static class NetTools
	{
		/// <summary>
		/// case-insensitively gets the IPv4 index of the network interface with the given name.
		/// </summary>
		/// <param name="interfaceName">The interface name to search for.</param>
		/// <returns>The IPv4 index of the network interface with the given name.</returns>
		public static int GetNetworkIndexByName4(string targetInterfaceName)
		{
			NetworkInterface[] nics = NetworkInterface.GetAllNetworkInterfaces();
			foreach (NetworkInterface nic in nics)
			{
				Console.WriteLine("Id: {0}, Description: {1}", nic.Id, nic.Description);
				if (nic.Id == targetInterfaceName)
					return nic.GetIPv4Index();
			}
			throw new Exception($"Error: Can't find network interface with the name {targetInterfaceName}.");
		}

		/// <summary>
		/// Gets the NetworkInterface with the given IP address.
		/// </summary>
		/// <param name="targetIP">The target IP to search for.</param>
		/// <returns>The network index with the given IP address.</returns>
		public static int GetNetworkIndexByIP(IPAddress targetIP)
		{
			NetworkInterface[] nics = NetworkInterface.GetAllNetworkInterfaces();
			foreach(NetworkInterface nic in nics)
			{
				IPInterfaceProperties ipProps = nic.GetIPProperties();
				foreach(UnicastIPAddressInformation ip in ipProps.UnicastAddresses)
				{
					// Only bother with external addresses
					if (ip.Address.AddressFamily != AddressFamily.InterNetwork)
						continue;
					if (ip.Address == targetIP)
					{
						IPv4InterfaceProperties ip4Props = ipProps.GetIPv4Properties();
						return ip4Props.Index;
					}
				}
			}
		}

		public static int GetIPv4Index(this NetworkInterface nic)
		{
			IPInterfaceProperties ipProps = nic.GetIPProperties();
			IPv4InterfaceProperties ip4Props = ipProps.GetIPv4Properties();
			return ip4Props.Index;
		}
	}
}