namespace Unosquare.Swan
{
    using System;
    using System.Linq;
    using System.Net;
    using System.Net.Sockets;

    /// <summary>
    /// Provides various extension methods for networking-related tasks.
    /// </summary>
    public static class NetworkExtensions
    {
        /// <summary>
        /// Determines whether the IP address is private.
        /// </summary>
        /// <param name="address">The IP address.</param>
        /// <returns>
        /// True if the IP Address is private; otherwise, false.
        /// </returns>
        /// <exception cref="ArgumentNullException">address.</exception>
        public static bool IsPrivateAddress(this IPAddress address)
        {
            if (address == null)
                throw new ArgumentNullException(nameof(address));

            var octets = address.ToString().Split(new[] { "." }, StringSplitOptions.RemoveEmptyEntries).Select(byte.Parse).ToArray();
            var is24Bit = octets[0] == 10;
            var is20Bit = octets[0] == 172 && (octets[1] >= 16 && octets[1] <= 31);
            var is16Bit = octets[0] == 192 && octets[1] == 168;

            return is24Bit || is20Bit || is16Bit;
        }

        /// <summary>
        /// Converts an IPv4 Address to its Unsigned, 32-bit integer representation.
        /// </summary>
        /// <param name="address">The address.</param>
        /// <returns>
        /// A 32-bit unsigned integer converted from four bytes at a specified position in a byte array.
        /// </returns>
        /// <exception cref="ArgumentNullException">address.</exception>
        /// <exception cref="ArgumentException">InterNetwork - address.</exception>
        public static uint ToUInt32(this IPAddress address)
        {
            if (address == null)
                throw new ArgumentNullException(nameof(address));

            if (address.AddressFamily != AddressFamily.InterNetwork)
                throw new ArgumentException($"Address has to be of family '{nameof(AddressFamily.InterNetwork)}'", nameof(address));

            var addressBytes = address.GetAddressBytes();
            if (BitConverter.IsLittleEndian)
                Array.Reverse(addressBytes);

            return BitConverter.ToUInt32(addressBytes, 0);
        }
    }
}