/* Copyright (c) 2010 Michael Lidgren

Permission is hereby granted, free of charge, to any person obtaining a copy of this software
and associated documentation files (the "Software"), to deal in the Software without
restriction, including without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom
the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or
substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
USE OR OTHER DEALINGS IN THE SOFTWARE.

*/
using System;
using System.Net;
using System.Net.NetworkInformation;
using System.Net.Sockets;
using System.Text;
using System.Text.RegularExpressions;

namespace Lidgren.Network
{
	/// <summary>
	/// Utility methods
	/// </summary>
	public static class NetUtility
	{
		/// <summary>
		/// Get IPv4 endpoint from notation (xxx.xxx.xxx.xxx) or hostname and port number
		/// </summary>
		public static IPEndPoint Resolve(string ipOrHost, int port)
		{
			IPAddress adr = Resolve(ipOrHost);
			return new IPEndPoint(adr, port);
		}

		/// <summary>
		/// Get IPv4 address from notation (xxx.xxx.xxx.xxx) or hostname
		/// </summary>
		public static IPAddress Resolve(string ipOrHost)
		{
			if (string.IsNullOrEmpty(ipOrHost))
				throw new ArgumentException("Supplied string must not be empty", "ipOrHost");

			ipOrHost = ipOrHost.Trim();

			IPAddress ipAddress = null;
			if (IPAddress.TryParse(ipOrHost, out ipAddress))
			{
				if (ipAddress.AddressFamily == AddressFamily.InterNetwork)
					return ipAddress;
				throw new ArgumentException("This method will not currently resolve other than ipv4 addresses");
			}

			// ok must be a host name
			IPHostEntry entry;
			try
			{
				entry = Dns.GetHostEntry(ipOrHost);
				if (entry == null)
					return null;

				// check each entry for a valid IP address
				foreach (IPAddress ipCurrent in entry.AddressList)
				{
					if (ipCurrent.AddressFamily == AddressFamily.InterNetwork)
						return ipCurrent;
				}

				return null;
			}
			catch (SocketException ex)
			{
				if (ex.SocketErrorCode == SocketError.HostNotFound)
				{
					//LogWrite(string.Format(CultureInfo.InvariantCulture, "Failed to resolve host '{0}'.", ipOrHost));
					return null;
				}
				else
				{
					throw;
				}
			}
		}

		private static NetworkInterface GetNetworkInterface()
		{
			IPGlobalProperties computerProperties = IPGlobalProperties.GetIPGlobalProperties();
			if (computerProperties == null)
				return null;

			NetworkInterface[] nics = NetworkInterface.GetAllNetworkInterfaces();
			if (nics == null || nics.Length < 1)
				return null;

			NetworkInterface best = null;
			foreach (NetworkInterface adapter in nics)
			{
				if (adapter.NetworkInterfaceType == NetworkInterfaceType.Loopback || adapter.NetworkInterfaceType == NetworkInterfaceType.Unknown)
					continue;
				if (!adapter.Supports(NetworkInterfaceComponent.IPv4))
					continue;
				if (best == null)
					best = adapter;
				if (adapter.OperationalStatus != OperationalStatus.Up)
					continue;

				// A computer could have several adapters (more than one network card)
				// here but just return the first one for now...
				return adapter;
			}
			return best;
		}

		public static PhysicalAddress GetMacAddress()
		{
			NetworkInterface ni = GetNetworkInterface();
			if (ni == null)
				return null;
			return ni.GetPhysicalAddress();
		}

		public static string ToHexString(long data)
		{
			return ToHexString(BitConverter.GetBytes(data));
		}

		public static string ToHexString(byte[] data)
		{
			char[] c = new char[data.Length * 2];
			byte b;
			for (int i = 0; i < data.Length; ++i)
			{
				b = ((byte)(data[i] >> 4));
				c[i * 2] = (char)(b > 9 ? b + 0x37 : b + 0x30);
				b = ((byte)(data[i] & 0xF));
				c[i * 2 + 1] = (char)(b > 9 ? b + 0x37 : b + 0x30);
			}
			return new string(c);
		}

		/// <summary>
		/// Gets my local IP address (not necessarily external) and subnet mask
		/// </summary>
		public static IPAddress GetMyAddress(out IPAddress mask)
		{
			NetworkInterface ni = GetNetworkInterface();
			if (ni == null)
			{
				mask = null;
				return null;
			}

			IPInterfaceProperties properties = ni.GetIPProperties();
			foreach (UnicastIPAddressInformation unicastAddress in properties.UnicastAddresses)
			{
				if (unicastAddress != null && unicastAddress.Address != null && unicastAddress.Address.AddressFamily == AddressFamily.InterNetwork)
				{
					mask = unicastAddress.IPv4Mask;
					return unicastAddress.Address;
				}
			}

			mask = null;
			return null;
		}

		/// <summary>
		/// Returns true if the IPEndPoint supplied is on the same subnet as this host
		/// </summary>
		public static bool IsLocal(IPEndPoint endpoint)
		{
			if (endpoint == null)
				return false;
			return IsLocal(endpoint.Address);
		}

		/// <summary>
		/// Returns true if the IPAddress supplied is on the same subnet as this host
		/// </summary>
		public static bool IsLocal(IPAddress remote)
		{
			IPAddress mask;
			IPAddress local = GetMyAddress(out mask);

			if (mask == null)
				return false;

			uint maskBits = BitConverter.ToUInt32(mask.GetAddressBytes(), 0);
			uint remoteBits = BitConverter.ToUInt32(remote.GetAddressBytes(), 0);
			uint localBits = BitConverter.ToUInt32(local.GetAddressBytes(), 0);

			// compare network portions
			return ((remoteBits & maskBits) == (localBits & maskBits));
		}

		/// <summary>
		/// Returns how many bits are necessary to hold a certain number
		/// </summary>
		[CLSCompliant(false)]
		public static int BitsToHoldUInt(uint value)
		{
			int bits = 1;
			while ((value >>= 1) != 0)
				bits++;
			return bits;
		}

		/// <summary>
		/// Returns how many bytes are required to hold a certain number of bits
		/// </summary>
		public static int BytesToHoldBits(int numBits)
		{
			return (numBits + 7) / 8;
		}

		[CLSCompliant(false)]
		public static UInt32 SwapByteOrder(UInt32 value)
		{
			return
				((value & 0xff000000) >> 24) |
				((value & 0x00ff0000) >> 8) |
				((value & 0x0000ff00) << 8) |
				((value & 0x000000ff) << 24);
		}

		[CLSCompliant(false)]
		public static UInt64 SwapByteOrder(UInt64 value)
		{
			return
				((value & 0xff00000000000000L) >> 56) |
				((value & 0x00ff000000000000L) >> 40) |
				((value & 0x0000ff0000000000L) >> 24) |
				((value & 0x000000ff00000000L) >> 8) |
				((value & 0x00000000ff000000L) << 8) |
				((value & 0x0000000000ff0000L) << 24) |
				((value & 0x000000000000ff00L) << 40) |
				((value & 0x00000000000000ffL) << 56);
		}

		public static bool CompareElements(byte[] one, byte[] two)
		{
			if (one.Length != two.Length)
				return false;
			for (int i = 0; i < one.Length; i++)
				if (one[i] != two[i])
					return false;
			return true;
		}

		public static byte[] ToByteArray(String hexString)
		{
			byte[] retval = new byte[hexString.Length / 2];
			for (int i = 0; i < hexString.Length; i += 2)
				retval[i / 2] = Convert.ToByte(hexString.Substring(i, 2), 16);
			return retval;
		}

		public static string ToHumanReadable(long bytes)
		{
			if (bytes < 4000) // 1-4 kb is printed in bytes
				return bytes + " bytes";
			if (bytes < 1000 * 1000) // 4-999 kb is printed in kb
				return Math.Round(((double)bytes / 1000.0), 2) + " kilobytes";
			return Math.Round(((double)bytes / (1000.0 * 1000.0)), 2) + " megabytes"; // else megabytes
		}

		internal static int RelativeSequenceNumber(int nr, int expected)
		{
			int retval = ((nr + NetConstants.NumSequenceNumbers) - expected) % NetConstants.NumSequenceNumbers;
			if (retval > (NetConstants.NumSequenceNumbers / 2))
				retval -= NetConstants.NumSequenceNumbers;
			return retval;
		}

		// shell sort
		internal static void SortMembersList(System.Reflection.MemberInfo[] list)
		{
			int h;
			int j;
			System.Reflection.MemberInfo tmp;

			h = 1;
			while (h * 3 + 1 <= list.Length)
				h = 3 * h + 1;

			while (h > 0)
			{
				for (int i = h - 1; i < list.Length; i++)
				{
					tmp = list[i];
					j = i;
					while (true)
					{
						if (j >= h)
						{
							if (string.Compare(list[j - h].Name, tmp.Name, StringComparison.InvariantCulture) > 0)
							{
								list[j] = list[j - h];
								j -= h;
							}
							else
								break;
						}
						else
							break;
					}

					list[j] = tmp;
				}
				h /= 3;
			}
		}
	}
}