using System;
using System.Collections.Generic;
using System.Net.Sockets;
using System.Threading;
using System.Threading.Tasks;
using Moq;

namespace AMWD.Common.Test
{
	/// <summary>
	/// Wrapps the <see cref="Mock{TcpClient}"/> including the setup.
	/// </summary>
	public class TcpClientMoq
	{
		private readonly Mock<NetworkStream> _streamMock;

		/// <summary>
		/// Initializes a new instance of the <see cref="TcpClientMoq"/> class.
		/// </summary>
		public TcpClientMoq()
		{
			Callbacks = new();
			Response = new byte[0];

			_streamMock = new();
			_streamMock
				.Setup(s => s.WriteAsync(It.IsAny<byte[]>(), It.IsAny<int>(), It.IsAny<int>(), It.IsAny<CancellationToken>()))
				.Callback<byte[], int, int, CancellationToken>((buffer, offset, count, _) =>
				{
					var callback = new TcpClientCallback
					{
						Buffer = new byte[count],
						Offset = offset,
						Count = count,
						Type = TcpClientCallback.WriteType.Asynchronous
					};
					Array.Copy(buffer, offset, callback.Buffer, 0, count);

					Callbacks.Add(callback);
				})
				.Returns(Task.CompletedTask);
			_streamMock
				.Setup(s => s.Write(It.IsAny<byte[]>(), It.IsAny<int>(), It.IsAny<int>()))
				.Callback<byte[], int, int>((buffer, offset, count) =>
				{
					var callback = new TcpClientCallback
					{
						Buffer = new byte[count],
						Offset = offset,
						Count = count,
						Type = TcpClientCallback.WriteType.Synchronous
					};
					Array.Copy(buffer, offset, callback.Buffer, 0, count);

					Callbacks.Add(callback);
				});

			_streamMock
				.Setup(s => s.ReadAsync(It.IsAny<byte[]>(), It.IsAny<int>(), It.IsAny<int>(), It.IsAny<CancellationToken>()))
				.Callback<byte[], int, int, CancellationToken>((buffer, offset, count, _) =>
				{
					byte[] bytes = Response ?? new byte[0];
					Array.Copy(bytes, 0, buffer, offset, Math.Min(bytes.Length, count));
				})
				.ReturnsAsync(Response?.Length ?? 0);
			_streamMock
				.Setup(s => s.Read(It.IsAny<byte[]>(), It.IsAny<int>(), It.IsAny<int>()))
				.Callback<byte[], int, int>((buffer, offset, count) =>
				{
					byte[] bytes = Response ?? new byte[0];
					Array.Copy(bytes, 0, buffer, offset, Math.Min(bytes.Length, count));
				})
				.Returns(Response?.Length ?? 0);

			Mock = new();
			Mock
				.Setup(c => c.GetStream())
				.Returns(_streamMock.Object);
		}

		/// <summary>
		/// Gets the mocked <see cref="TcpClient"/>.
		/// </summary>
		public Mock<TcpClient> Mock { get; }

		/// <summary>
		/// Gets the placed request.
		/// </summary>
		public List<TcpClientCallback> Callbacks { get; }

		/// <summary>
		/// Gets the byte response, that should be "sent".
		/// </summary>
		public byte[] Response { get; set; }

		/// <summary>
		/// Resets the <see cref="Response"/> and <see cref="Callbacks"/>.
		/// </summary>
		public void Reset()
		{
			Response = new byte[0];
			Callbacks.Clear();
		}

		/// <summary>
		/// Verifies the number of calls writing asynchronous to the stream.
		/// </summary>
		/// <param name="times">Number of calls.</param>
		public void VerifyWriteAsync(Times times)
			=> _streamMock.Verify(s => s.WriteAsync(It.IsAny<byte[]>(), It.IsAny<int>(), It.IsAny<int>(), It.IsAny<CancellationToken>()), times);

		/// <summary>
		/// Verifies the number of calls writing synchronous to the stream.
		/// </summary>
		/// <param name="times">Number of calls.</param>
		public void VerifyWriteSync(Times times)
			=> _streamMock.Verify(s => s.Write(It.IsAny<byte[]>(), It.IsAny<int>(), It.IsAny<int>()), times);

		/// <summary>
		/// Verifies the number of calls reading asynchronous from the stream.
		/// </summary>
		/// <param name="times">Number of calls.</param>
		public void VerifyReadAsync(Times times)
			=> _streamMock.Verify(s => s.ReadAsync(It.IsAny<byte[]>(), It.IsAny<int>(), It.IsAny<int>(), It.IsAny<CancellationToken>()), times);

		/// <summary>
		/// Verifies the number of calls reading synchronous from the stream.
		/// </summary>
		/// <param name="times">Number of calls.</param>
		public void VerifyReadSync(Times times)
			=> _streamMock.Verify(s => s.Read(It.IsAny<byte[]>(), It.IsAny<int>(), It.IsAny<int>()), times);

		/// <summary>
		/// Represents the placed TCP request.
		/// </summary>
		public class TcpClientCallback
		{
			/// <summary>
			/// Gets or sets the type (a/synchronous call).
			/// </summary>
			public WriteType Type { get; set; }

			/// <summary>
			/// Gets or sets the buffer content.
			/// </summary>
			public byte[] Buffer { get; set; }

			/// <summary>
			/// Gets or sets the offset.
			/// </summary>
			public int Offset { get; set; }

			/// <summary>
			/// Gets or sets the byte count.
			/// </summary>
			public int Count { get; set; }

			/// <summary>
			/// Lists the possible request types.
			/// </summary>
			public enum WriteType
			{
				/// <summary>
				/// The request was synchronous.
				/// </summary>
				Synchronous = 1,

				/// <summary>
				/// The request was asynchronous.
				/// </summary>
				Asynchronous = 2
			}
		}
	}
}