using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
#if NET8_0_OR_GREATER
using IPNetwork = System.Net.IPNetwork;
#else
using Microsoft.AspNetCore.HttpOverrides;
using IPNetwork = Microsoft.AspNetCore.HttpOverrides.IPNetwork;
#endif

namespace Newtonsoft.Json
{
	/// <summary>
	/// Converts an <see cref="IPNetwork"/> from and to JSON.
	/// </summary>
	[System.Diagnostics.CodeAnalysis.ExcludeFromCodeCoverage]
	public class IpNetworkConverter : JsonConverter
	{
		/// <summary>
		/// List of known types to use this converver.
		/// </summary>
		public static readonly Type[] KnownTypes =
		[
			typeof(IPNetwork),
			typeof(IPNetwork[]),
			typeof(List<IPNetwork>),
			typeof(IEnumerable<IPNetwork>)
		];

		/// <inheritdoc/>
		public override bool CanConvert(Type objectType)
			=> KnownTypes.Contains(objectType);

		/// <inheritdoc/>
		public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
		{
			if (reader.Value == null)
				return null;

			string str = (string)reader.Value;

			if (typeof(IPNetwork) == objectType)
				return Parse(str);

			var networks = str.Split(';').Select(Parse);

			if (typeof(IPNetwork[]) == objectType)
				return networks.ToArray();

			if (typeof(List<IPNetwork>) == objectType)
				return networks.ToList();

			return networks;
		}

		/// <inheritdoc/>
		public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
		{
			string str = null;
			if (value == null)
			{
				writer.WriteValue(str);
				return;
			}

			if (value is IPNetwork net)
				str = ToString(net);

			if (value is IPNetwork[] netArray)
				str = string.Join(";", netArray.Select(ToString));

			if (value is List<IPNetwork> netList)
				str = string.Join(";", netList.Select(ToString));

			if (value is IEnumerable<IPNetwork> netEnum)
				str = string.Join(";", netEnum.Select(ToString));

			writer.WriteValue(str);
		}

		private static string ToString(IPNetwork net)
		{
#if NET8_0_OR_GREATER
			return $"{net.BaseAddress}/{net.PrefixLength}";
#else
			return $"{net.Prefix}/{net.PrefixLength}";
#endif
		}

		private static IPNetwork Parse(string str)
		{
			string[] parts = str.Split('/');
			var prefix = IPAddress.Parse(parts.First());
			int prefixLength = int.Parse(parts.Last());

			return new IPNetwork(prefix, prefixLength);
		}
	}
}