using System;
using System.Net.Sockets;
using System.Threading.Tasks;
using System.Net;
using SBRL.Utilities;
using System.IO;
using System.Collections.Generic;

namespace PixelHub.Server
{
	/// <summary>
	/// Provides the server component of the Hull Pixelbot server that can be used to control any number of pixel bots at once.
	/// </summary>
	public class PixelHub
	{
		TextWriter logger;
		IPAddress bindAddress = IPAddress.Any;
		int port;

		TcpListener server;

		/// <summary>
		/// A list of PixelBots that are currently connected to the PixelHub.
		/// </summary>
		public List<PixelBot> ConnectedBots = new List<PixelBot>();

		/// <summary>
		/// Whether the Hull Pixelbot server is currently active and listening.
		/// </summary>
		public bool Active { get; private set; } = false;
		/// <summary>
		/// The IPAddress that the PixelHub is (or should be) bound to.
		/// </summary>
		/// <remarks>
		/// You can only set this Property with generating an exception if the server
		/// hasn't already been started with Listen().
		/// </remarks>
		public IPAddress BindAddress
		{
			get {
				return bindAddress;
			}
			set {
				if (Active == true)
					throw new InvalidOperationException("Error: The bind address can't be changed once the server has started listening!");
				bindAddress = value;
			}
		}
		/// <summary>
		/// The port number that the PixelHb is (or should be) listening on.
		/// </summary>
		/// <remarks>
		/// You can only set this Property with generating an exception if the server
		/// hasn't already been started with Listen().
		/// </remarks>
		public int Port
		{
			get {
				return port;
			}
			set {
				if (Active == true)
					throw new InvalidOperationException("Error: The port can't be changed once the server has started listening!");
				port = value;
			}
		}
		/// <summary>
		/// Squashes the BindAddress and the port number together to form the endpoint that the server
		/// is (or should be) listening on.
		/// </summary>
		public IPEndPoint Endpoint
		{
			get {
				return new IPEndPoint(BindAddress, Port);
			}
		}

		/// <summary>
		/// Creates a new Pixelhub instance.
		/// </summary>
		/// <param name="inPort">The port to listen on.</param>
		/// <param name="inLogger">The TextWriter to send log messages to.</param>
		public PixelHub(int inPort, TextWriter inLogger)
		{
			Port = inPort;
			logger = inLogger;
		}
		/// <summary>
		/// Creates a new Pixelhub instance.
		/// </summary>
		/// <param name="inPort">The port to listen on.</param>
		public PixelHub(int inPort) : this(inPort, Console.Out)
		{
		}

		/// <summary>
		/// Starts the PixelHub server and begins listening for connections.
		/// </summary>
		public async Task Listen()
		{
			server = new TcpListener(Endpoint);
			server.Start();
			logger.WriteLine("TCP Listener set up on {0}.", Endpoint);
			Active = true;
			while(true)
			{
				TcpClient nextClient = await server.AcceptTcpClientAsync();
				AsyncTools.ForgetTask(Handle(nextClient));
			}
			// TODO: Add an shutdown CancellationToken thingy here
			//Active = false;
		}

		/// <summary>
		/// Handles a single connection.
		/// </summary>
		/// <param name="client">The TcpClient connection to handle.</param>
		private async Task Handle(TcpClient client)
		{
			logger.WriteLine("Accepted connection from {0}.", client.Client.RemoteEndPoint);

			PixelBot pixelBot = new PixelBot(client);
			ConnectedBots.Add(pixelBot);

			await pixelBot.Handle();

			ConnectedBots.Remove(pixelBot);

			logger.WriteLine("Lost connection from {0}.", client.Client.RemoteEndPoint);
		}
	}
}