using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Net;
using System.Net.Security;
using System.Security.Principal;
using System.ServiceModel;
namespace TGServiceInterface
{
	public class Server
	{
		/// <summary>
		/// List of types that can be used with GetComponen
		/// </summary>
		public static readonly IList<Type> ValidInterfaces = new List<Type> { typeof(ITGByond), typeof(ITGChat), typeof(ITGCompiler), typeof(ITGConfig), typeof(ITGDreamDaemon), typeof(ITGRepository), typeof(ITGSService), typeof(ITGConnectivity), typeof(ITGAdministration), typeof(ITGInterop) };

		/// <summary>
		/// The maximum message size to and from a local server 
		/// </summary>
		public static readonly long TransferLimitLocal = Int32.MaxValue;   //2GB can't go higher

		/// <summary>
		/// The maximum message size to and from a remote server
		/// </summary>
		public static readonly long TransferLimitRemote = 10485760;	//10 MB

		/// <summary>
		/// Base name of the communication pipe
		/// they are formatted as MasterPipeName/ComponentName
		/// </summary>
		public static string MasterInterfaceName = "TGStationServerService";

		/// <summary>
		/// If this is set, we will try and connect to an HTTPS server running at this address
		/// </summary>
		static string HTTPSURL;

		/// <summary>
		/// The port used by the service
		/// </summary>
		static ushort HTTPSPort = 38607;

		/// <summary>
		/// Username for remote operations
		/// </summary>
		static string HTTPSUsername;

		/// <summary>
		/// Password for remote operations
		/// </summary>
		static string HTTPSPassword;

		static Dictionary<Type, ChannelFactory> ChannelFactoryCache = new Dictionary<Type, ChannelFactory>();
		public static void SetBadCertificateHandler(Func<string, bool> handler)
		{
			ServicePointManager.ServerCertificateValidationCallback = (sender, cert, chain, error) =>
			{
				string ErrorMessage;
				switch (error)
				{
					case SslPolicyErrors.None:
						return true;
					case SslPolicyErrors.RemoteCertificateChainErrors:
						ErrorMessage = "There are certificate chain errors.";
						break;
					case SslPolicyErrors.RemoteCertificateNameMismatch:
						ErrorMessage = "The certificate name does not match.";
						break;
					case SslPolicyErrors.RemoteCertificateNotAvailable:
						ErrorMessage = "The certificate doesn't exist in the trust store.";
						break;
					default:
						ErrorMessage = "An unknown error occurred.";
						break;
				}
				ErrorMessage = String.Format("The certificate failed to verify for {0}:{1}. {2} {3}", HTTPSURL, HTTPSPort, ErrorMessage, cert.ToString());
				return handler(ErrorMessage);
			};
		}

		/// <summary>
		/// Set the interface to look for services on the current computer
		/// </summary>
		public static void MakeLocalConnection()
		{
			HTTPSURL = null;
			HTTPSPassword = null;
			ClearCachedChannels();
		}

		static void ClearCachedChannels()
		{
			foreach (var I in ChannelFactoryCache)
				CloseChannel(I.Value);
			ChannelFactoryCache.Clear();
		}

		public static bool VersionMismatch(out string errorMessage)
		{
			var splits = Server.GetComponent<ITGSService>().Version().Split(' ');
			var theirs = new Version(splits[splits.Length - 1].Substring(1));
			var ours = new Version(FileVersionInfo.GetVersionInfo(System.Reflection.Assembly.GetExecutingAssembly().Location).FileVersion);
			if(theirs != ours)
			{
				errorMessage = String.Format("Version mismatch between interface version ({0}) and service version ({1}). Some functionality may crash this program.", ours, theirs);
				return true;
			}
			errorMessage = null;
			return false;
		}

		/// <summary>
		/// Set the interface to look for services on a remote computer
		/// </summary>
		/// <param name="address"></param>
		/// <param name="port"></param>
		public static void SetRemoteLoginInformation(string address, ushort port, string username, string password)
		{
			HTTPSURL = address;
			HTTPSPort = port;
			HTTPSUsername = username;
			HTTPSPassword = password;
			ClearCachedChannels();
		}

		public static void CloseChannel(ChannelFactory cf)
		{
			try
			{
				cf.Close();
			}
			catch
			{
				cf.Abort();
			}
		}

		/// <summary>
		/// Returns the requested server component interface. This does not guarantee a successful connection
		/// </summary>
		/// <typeparam name="T">The type of the component to retrieve</typeparam>
		/// <returns>The correct component</returns>
		public static T GetComponent<T>()
		{
			var tot = typeof(T);
			ChannelFactory<T> cf;

			lock (ChannelFactoryCache)
			{
				if (ChannelFactoryCache.ContainsKey(tot))
					try
					{
						cf = ((ChannelFactory<T>)ChannelFactoryCache[tot]);
						if (cf.State != CommunicationState.Opened)
							throw new Exception();
						return cf.CreateChannel();
					}
					catch
					{
						ChannelFactoryCache[tot].Abort();
						ChannelFactoryCache.Remove(tot);
					}
				cf = CreateChannel<T>();
				ChannelFactoryCache[tot] = cf;
			}
			return cf.CreateChannel();
		}

		public static ChannelFactory<T> CreateChannel<T>()
		{
			var ToT = typeof(T);
			if (!ValidInterfaces.Contains(ToT))
				throw new Exception("Invalid type!");
			var InterfaceName = typeof(T).Name;
			if (HTTPSURL == null)
			{
				var res2 = new ChannelFactory<T>(
				new NetNamedPipeBinding { SendTimeout = new TimeSpan(0, 0, 30), MaxReceivedMessageSize = TransferLimitLocal }, new EndpointAddress(String.Format("net.pipe://localhost/{0}/{1}", MasterInterfaceName, InterfaceName)));														//10 megs
				res2.Credentials.Windows.AllowedImpersonationLevel = TokenImpersonationLevel.Impersonation;
				return res2;
			}

			//okay we're going over
			var binding = new WSHttpBinding()
			{
				SendTimeout = new TimeSpan(0, 0, 40),
				MaxReceivedMessageSize = TransferLimitRemote
			};
			var requireAuth = InterfaceName != typeof(ITGConnectivity).Name;
			binding.Security.Transport.ClientCredentialType = HttpClientCredentialType.None;
			binding.Security.Mode = requireAuth ? SecurityMode.TransportWithMessageCredential : SecurityMode.Transport;    //do not require auth for a connectivity check
			binding.Security.Message.ClientCredentialType = requireAuth ? MessageCredentialType.UserName : MessageCredentialType.None;
			var address = new EndpointAddress(String.Format("https://{0}:{1}/{2}/{3}", HTTPSURL, HTTPSPort, MasterInterfaceName, InterfaceName));
			var res = new ChannelFactory<T>(binding, address);
			if (requireAuth)
			{
				res.Credentials.UserName.UserName = HTTPSUsername;
				res.Credentials.UserName.Password = HTTPSPassword;
			}
			return res;
		}

		/// <summary>
		/// Used to test if the service is avaiable on the machine
		/// Note that state can technically change at any time
		/// and any call to the service may throw an exception because it failed
		/// </summary>
		/// <returns>null on successful connection, error message on failure</returns>
		public static string VerifyConnection()
		{
			try
			{
				GetComponent<ITGConnectivity>().VerifyConnection();
				return null;
			}
			catch (Exception e)
			{
				return e.ToString();
			}
		}

		/// <summary>
		/// As opposed to VerifyConnection(), this check user credentials
		/// Requires a prior call to <see cref="VerifyConnection"/>
		/// </summary>
		/// <returns>true if credentials are valid, false otherwise</returns>
		public static bool Authenticate()
		{
			try
			{
				GetComponent<ITGSService>().Version();
				return true;
			}
			catch
			{
				return false;
			}
		}

		/// <summary>
		/// As opposed to Authentication() this returns true if the current login can use the <see cref="ITGAdministration"/> interface.
		/// Requires a prior call to <see cref="Authenticate"/>
		/// </summary>
		/// <returns>true if the connection may use the <see cref="ITGAdministration"/> interface, false otherwise</returns>
		public static bool AuthenticateAdmin()
		{
			try
			{
				GetComponent<ITGAdministration>().GetCurrentAuthorizedGroup();
				return true;
			}
			catch
			{
				return false;
			}
		}
	}
}