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

namespace MessagePack.Formatters
{
	/// <summary>
	/// Serialization of an <see cref="IPAddress"/> array to and from <see cref="MessagePack"/>.
	/// </summary>
	[System.Diagnostics.CodeAnalysis.ExcludeFromCodeCoverage]
	public class IPAddressArrayFormatter : IMessagePackFormatter<IPAddress[]>
	{
		/// <inheritdoc/>
		public IPAddress[] Deserialize(ref MessagePackReader reader, MessagePackSerializerOptions options)
		{
			if (reader.IsNil)
				return null;

			int bytePos = 0;
			byte[] bytes = options.Resolver.GetFormatterWithVerify<byte[]>().Deserialize(ref reader, options);
			byte[] buffer = bytes.Skip(bytePos).Take(sizeof(int)).ToArray();
			bytePos += sizeof(int);

			Swap(buffer);
			int length = BitConverter.ToInt32(buffer, 0);

			int arrayPos = 0;
			var array = new IPAddress[length];
			while (bytePos < bytes.Length)
			{
				byte len = bytes.Skip(bytePos).First();
				bytePos++;

				buffer = bytes.Skip(bytePos).Take(len).ToArray();
				bytePos += len;

				array[arrayPos] = new IPAddress(buffer);
				arrayPos++;
			}

			return array;
		}

		/// <inheritdoc/>
		public void Serialize(ref MessagePackWriter writer, IPAddress[] value, MessagePackSerializerOptions options)
		{
			if (value == null)
			{
				writer.WriteNil();
				return;
			}

			var bytes = new List<byte>();

			int length = value.Length;
			byte[] buffer = BitConverter.GetBytes(length);
			Swap(buffer);
			bytes.AddRange(buffer);

			foreach (var ip in value)
			{
				buffer = ip.GetAddressBytes();
				bytes.Add((byte)buffer.Length);
				bytes.AddRange(buffer);
			}

			options.Resolver.GetFormatterWithVerify<byte[]>().Serialize(ref writer, bytes.ToArray(), options);
		}

		private void Swap(byte[] bytes)
		{
			if (BitConverter.IsLittleEndian)
				Array.Reverse(bytes);
		}
	}
}