using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.Sockets;
using System.Text;
using System.Threading;
using UnityEngine;
using System.Net;
using UnityEngine.SceneManagement;
using System.IO;

namespace VelNet
{
	[AddComponentMenu("VelNet/VelNet Manager")]
	public class VelNetManager : MonoBehaviour
	{
		public enum MessageSendType
		{
			MESSAGE_OTHERS_ORDERED = 7,
			MESSAGE_ALL_ORDERED = 8,
			MESSAGE_LOGIN = 0,
			MESSAGE_GETROOMS = 1,
			MESSAGE_JOINROOM = 2,
			MESSAGE_OTHERS = 3,
			MESSAGE_ALL = 4,
			MESSAGE_GROUP = 5,
			MESSAGE_SETGROUP = 6
		};

		public string host;
		public int port;

		public static VelNetManager instance;

		private TcpClient socketConnection;
		private Socket udpSocket;
		public bool udpConnected;
		private IPEndPoint RemoteEndPoint;
		private Thread clientReceiveThread;
		private Thread clientReceiveThreadUDP;
		public int userid = -1;

		public readonly Dictionary<int, VelNetPlayer> players = new Dictionary<int, VelNetPlayer>();

		#region Callbacks

		/// <summary>
		/// We just joined a room
		/// string - the room name
		/// </summary>
		public static Action<string> OnJoinedRoom;

		/// <summary>
		/// We just left a room
		/// string - the room name we left
		/// </summary>
		public static Action<string> OnLeftRoom;

		/// <summary>
		/// Somebody else just joined our room
		/// </summary>
		public static Action<VelNetPlayer> OnPlayerJoined;

		/// <summary>
		/// Somebody else just left our room
		/// </summary>
		public static Action<VelNetPlayer> OnPlayerLeft;

		public static Action OnConnectedToServer;
		public static Action OnLoggedIn;
		public static Action<RoomsMessage> RoomsReceived;

		public static Action<Message> MessageReceived;

		#endregion

		public bool connected;

		public List<NetworkObject> prefabs = new List<NetworkObject>();
		public NetworkObject[] sceneObjects;
		public List<string> deletedSceneObjects = new List<string>();

		/// <summary>
		/// Maintains a list of all known objects on the server (ones that have ids)
		/// </summary>
		public readonly Dictionary<string, NetworkObject> objects = new Dictionary<string, NetworkObject>();

		/// <summary>
		/// Maintains a list of all known groups on the server
		/// </summary>
		public readonly Dictionary<string, List<int>> groups = new Dictionary<string, List<int>>();

		private VelNetPlayer masterPlayer;
		public static VelNetPlayer LocalPlayer => instance != null ? instance.players.Where(p => p.Value.isLocal).Select(p => p.Value).FirstOrDefault() : null;
		public static bool InRoom => LocalPlayer != null && LocalPlayer.room != "-1" && LocalPlayer.room != "";
		public static string Room => LocalPlayer?.room;

		/// <summary>
		/// The player count in this room.
		/// -1 if not in a room.
		/// </summary>
		public static int PlayerCount => instance.players.Count;

		/// <summary>
		/// The player count in all rooms.
		/// Will include players connected to the server but not in a room?
		/// </summary>
		public static int PlayerCountInAllRooms => PlayerCount; // TODO hook up to actual player count

		public static bool IsConnected => instance != null && instance.connected && instance.udpConnected;

		//this is for sending udp packets
		private static readonly byte[] toSend = new byte[1024];

		// Use this for initialization
		public abstract class Message
		{
		}

		public class ListedRoom
		{
			public string name;
			public int numUsers;

			public override string ToString()
			{
				return "Room Name: " + name + "\tUsers: " + numUsers;
			}
		}

		public class LoginMessage : Message
		{
			public int userId;
		}

		public class RoomsMessage : Message
		{
			public List<ListedRoom> rooms;

			public override string ToString()
			{
				return string.Join("\n", rooms);
			}
		}

		public class JoinMessage : Message
		{
			public int userId;
			public string room;
		}

		public class DataMessage : Message
		{
			public int senderId;
			public byte[] data;
		}

		public class ChangeMasterMessage : Message
		{
			public int masterId;
		}

		public class ConnectedMessage : Message
		{
		}

		public readonly List<Message> receivedMessages = new List<Message>();

		private void Awake()
		{
			if (instance != null)
			{
				Debug.LogError("Multiple NetworkManagers detected! Bad!", this);
			}

			instance = this;

			SceneManager.sceneLoaded += (scene, mode) =>
			{
				// add all local network objects
				sceneObjects = FindObjectsOfType<NetworkObject>().Where(o => o.isSceneObject).ToArray();
			};
		}

		private void Start()
		{
			ConnectToTcpServer();
		}


		private void AddMessage(Message m)
		{
			lock (receivedMessages)
			{
				//Debug.Log(messagesReceived++);
				receivedMessages.Add(m);
			}

			try
			{
				MessageReceived?.Invoke(m);
			}
			catch (Exception e)
			{
				Debug.LogError(e);
			}
		}

		private void Update()
		{
			lock (receivedMessages)
			{
				//the main thread, which can do Unity stuff
				foreach (Message m in receivedMessages)
				{
					switch (m)
					{
						case ConnectedMessage msg:
						{
							try
							{
								OnConnectedToServer?.Invoke();
							}
							// prevent errors in subscribers from breaking our code
							catch (Exception e)
							{
								Debug.LogError(e);
							}

							break;
						}
						case LoginMessage lm:
						{
							userid = lm.userId;
							Debug.Log("Joined server " + userid);

							try
							{
								OnLoggedIn?.Invoke();
							}
							// prevent errors in subscribers from breaking our code
							catch (Exception e)
							{
								Debug.LogError(e);
							}

							//start the udp thread 
							clientReceiveThreadUDP = new Thread(ListenForDataUDP);
							clientReceiveThreadUDP.Start();

							break;
						}
						case RoomsMessage rm:
						{
							Debug.Log("Got Rooms Message:\n" + rm);

							try
							{
								RoomsReceived?.Invoke(rm);
							}
							// prevent errors in subscribers from breaking our code
							catch (Exception e)
							{
								Debug.LogError(e);
							}

							break;
						}
						case JoinMessage jm:
						{
							if (userid == jm.userId) //this is us
							{
								string oldRoom = LocalPlayer?.room;

								// we clear the list, but will recreate as we get messages from people in our room
								players.Clear();
								masterPlayer = null;

								if (jm.room != "")
								{
									VelNetPlayer player = new VelNetPlayer
									{
										isLocal = true,
										userid = jm.userId,
										room = jm.room
									};

									players.Add(userid, player);

									try
									{
										OnJoinedRoom?.Invoke(jm.room);
									}
									// prevent errors in subscribers from breaking our code
									catch (Exception e)
									{
										Debug.LogError(e);
									}
								}
								// we just left a room
								else
								{
									// delete all networkobjects that aren't sceneobjects or are null now
									objects
										.Where(kvp => kvp.Value == null || !kvp.Value.isSceneObject)
										.Select(o => o.Key)
										.ToList().ForEach(NetworkDestroy);

									// then remove references to the ones that are left
									objects.Clear();

									// empty all the groups
									foreach (string group in instance.groups.Keys)
									{
										SetupMessageGroup(group, new List<int>());
									}

									instance.groups.Clear();

									try
									{
										OnLeftRoom?.Invoke(oldRoom);
									}
									// prevent errors in subscribers from breaking our code
									catch (Exception e)
									{
										Debug.LogError(e);
									}
								}
							}
							else
							{
								VelNetPlayer me = players[userid];

								if (me.room != jm.room)
								{
									// we got a left message, kill it
									// change ownership of all objects to master
									List<string> deleteObjects = new List<string>();
									foreach (KeyValuePair<string, NetworkObject> kvp in objects)
									{
										if (kvp.Value.owner == players[jm.userId]) // the owner is the player that left
										{
											// if this object has locked ownership, delete it
											if (kvp.Value.ownershipLocked)
											{
												deleteObjects.Add(kvp.Value.networkId);
											}
											// I'm the local master player, so can take ownership immediately
											else if (me.isLocal && me == masterPlayer)
											{
												TakeOwnership(kvp.Key);
											}
											// the master player left, so everyone should set the owner null (we should get a new master shortly)
											else if (players[jm.userId] == masterPlayer)
											{
												kvp.Value.owner = null;
											}
										}
									}

									// TODO this may check for ownership in the future. We don't need ownership here
									deleteObjects.ForEach(NetworkDestroy);

									VelNetPlayer leftPlayer = players[jm.userId];
									players.Remove(jm.userId);

									try
									{
										OnPlayerLeft?.Invoke(leftPlayer);
									}
									// prevent errors in subscribers from breaking our code
									catch (Exception e)
									{
										Debug.LogError(e);
									}
								}
								else
								{
									// we got a join message, create it
									VelNetPlayer player = new VelNetPlayer
									{
										isLocal = false,
										room = jm.room,
										userid = jm.userId
									};
									players.Add(jm.userId, player);
									try
									{
										OnPlayerJoined?.Invoke(player);
									}
									// prevent errors in subscribers from breaking our code
									catch (Exception e)
									{
										Debug.LogError(e);
									}
								}
							}

							break;
						}
						case DataMessage dm:
						{
							if (players.ContainsKey(dm.senderId))
							{
								players[dm.senderId]?.HandleMessage(dm); //todo
							}
							else
							{
								Debug.LogError("Received message from player that doesn't exist ");
							}

							break;
						}
						case ChangeMasterMessage cm:
						{
							if (masterPlayer == null)
							{
								masterPlayer = players[cm.masterId];

								// no master player yet, add the scene objects

								for (int i = 0; i < sceneObjects.Length; i++)
								{
									sceneObjects[i].networkId = -1 + "-" + i;
									sceneObjects[i].owner = masterPlayer;
									sceneObjects[i].isSceneObject = true; // needed for special handling when deleted
									objects.Add(sceneObjects[i].networkId, sceneObjects[i]);
								}
							}
							else
							{
								masterPlayer = players[cm.masterId];
							}

							masterPlayer.SetAsMasterPlayer();

							// master player should take over any objects that do not have an owner
							foreach (KeyValuePair<string, NetworkObject> kvp in objects)
							{
								kvp.Value.owner ??= masterPlayer;
							}

							break;
						}
					}

					//MessageReceived?.Invoke(m);
				}

				receivedMessages.Clear();
			}
		}

		private void OnApplicationQuit()
		{
			socketConnection?.Close();
		}

		/// <summary> 	
		/// Setup socket connection. 	
		/// </summary> 	
		private void ConnectToTcpServer()
		{
			try
			{
				clientReceiveThread = new Thread(ListenForData);
				clientReceiveThread.Start();
			}
			catch (Exception e)
			{
				Debug.Log("On client connect exception " + e);
			}
		}


		/// <summary> 	
		/// Runs in background clientReceiveThread; Listens for incoming data. 	
		/// </summary>
		private static byte[] ReadExact(Stream stream, int N)
		{
			byte[] toReturn = new byte[N];

			int numRead = 0;
			int numLeft = N;
			while (numLeft > 0)
			{
				numRead += stream.Read(toReturn, numRead, numLeft);
				numLeft = N - numRead;
			}

			return toReturn;
		}

		private static int GetIntFromBytes(byte[] bytes)
		{
			return BitConverter.ToInt32(BitConverter.IsLittleEndian ? bytes.Reverse().ToArray() : bytes, 0);
		}

		private void ListenForData()
		{
			connected = true;
			try
			{
				socketConnection = new TcpClient(host, port);
				socketConnection.NoDelay = true;
				NetworkStream stream = socketConnection.GetStream();
				//now we are connected, so add a message to the queue
				AddMessage(new ConnectedMessage());
				//Join("MyRoom");
				//SendTo(MessageSendType.MESSAGE_OTHERS, Encoding.UTF8.GetBytes("Hello"));
				//FormGroup("close", new List<uint> { 1 });
				//SendToGroup("close", Encoding.UTF8.GetBytes("HelloGroup"));
				while (true)
				{
					// Get a stream object for reading 				


					//read a byte
					byte type = (byte)stream.ReadByte();

					if (type == 0) //login
					{
						LoginMessage m = new LoginMessage();
						m.userId = GetIntFromBytes(ReadExact(stream, 4)); //not really the sender...
						AddMessage(m);
					}
					else if (type == 1) //rooms
					{
						RoomsMessage m = new RoomsMessage();
						m.rooms = new List<ListedRoom>();
						int N = GetIntFromBytes(ReadExact(stream, 4)); //the size of the payload
						byte[] utf8data = ReadExact(stream, N);
						string roomMessage = Encoding.UTF8.GetString(utf8data);


						string[] sections = roomMessage.Split(',');
						foreach (string s in sections)
						{
							string[] pieces = s.Split(':');
							if (pieces.Length == 2)
							{
								ListedRoom lr = new ListedRoom();
								lr.name = pieces[0];
								lr.numUsers = int.Parse(pieces[1]);
								m.rooms.Add(lr);
							}
						}

						AddMessage(m);
					}
					else if (type == 2) //joined
					{
						JoinMessage m = new JoinMessage();
						m.userId = GetIntFromBytes(ReadExact(stream, 4));
						int N = stream.ReadByte();
						byte[] utf8data = ReadExact(stream, N); //the room name, encoded as utf-8
						m.room = Encoding.UTF8.GetString(utf8data);
						AddMessage(m);
					}
					else if (type == 3) //data
					{
						DataMessage m = new DataMessage();
						m.senderId = GetIntFromBytes(ReadExact(stream, 4));
						int N = GetIntFromBytes(ReadExact(stream, 4)); //the size of the payload
						m.data = ReadExact(stream, N); //the message
						AddMessage(m);
					}
					else if (type == 4) //new master
					{
						ChangeMasterMessage m = new ChangeMasterMessage();
						m.masterId = GetIntFromBytes(ReadExact(stream, 4)); //sender is the new master
						AddMessage(m);
					}
				}
			}


			catch (Exception socketException)
			{
				Debug.Log("Socket exception: " + socketException);
			}

			connected = false;
		}

		private void ListenForDataUDP()
		{
			//I don't yet have a UDP connection
			try
			{
				IPAddress[] addresses = Dns.GetHostAddresses(host);
				Debug.Assert(addresses.Length > 0);
				RemoteEndPoint = new IPEndPoint(addresses[0], port);


				udpSocket = new Socket(AddressFamily.InterNetwork,
					SocketType.Dgram, ProtocolType.Udp);


				udpConnected = false;
				byte[] buffer = new byte[1024];
				while (true)
				{
					buffer[0] = 0;
					Array.Copy(get_be_bytes(userid), 0, buffer, 1, 4);
					udpSocket.SendTo(buffer, 5, SocketFlags.None, RemoteEndPoint);

					if (udpSocket.Available == 0)
					{
						Thread.Sleep(100);
						Debug.Log("Waiting for UDP response");
					}
					else
					{
						break;
					}
				}

				udpConnected = true;
				while (true)
				{
					int numReceived = udpSocket.Receive(buffer);
					switch (buffer[0])
					{
						case 0:
							Debug.Log("UDP connected");
							break;
						case 3:
						{
							DataMessage m = new DataMessage();
							//we should get the sender address
							byte[] senderBytes = new byte[4];
							Array.Copy(buffer, 1, senderBytes, 0, 4);
							m.senderId = GetIntFromBytes(senderBytes);
							byte[] messageBytes = new byte[numReceived - 5];
							Array.Copy(buffer, 5, messageBytes, 0, messageBytes.Length);
							m.data = messageBytes;
							AddMessage(m);
							break;
						}
					}
				}
			}
			catch (Exception socketException)
			{
				Debug.Log("Socket exception: " + socketException);
			}
		}

		private static void SendUdpMessage(byte[] message, int N)
		{
			if (instance.udpSocket == null || !instance.udpConnected)
			{
				return;
			}

			instance.udpSocket.SendTo(message, N, SocketFlags.None, instance.RemoteEndPoint);
		}

		/// <summary> 	
		/// Send message to server using socket connection. 	
		/// </summary> 	
		private static void SendTcpMessage(byte[] message) //we can assume that this message is already formatted, so we just send it
		{
			// Debug.Log("Sent: " + clientMessage);
			if (instance.socketConnection == null)
			{
				return;
			}

			try
			{
				// Get a stream object for writing. 			
				NetworkStream stream = instance.socketConnection.GetStream();
				if (stream.CanWrite)
				{
					stream.Write(message, 0, message.Length);
				}
			}
			catch (SocketException socketException)
			{
				Debug.Log("Socket exception: " + socketException);
			}
		}

		/// <summary>
		/// Connects to the server with a username
		/// </summary>
		/// 
		public static byte[] get_be_bytes(int n)
		{
			return BitConverter.GetBytes(n).Reverse().ToArray();
		}

		public static void Login(string username, string password)
		{
			MemoryStream stream = new MemoryStream();
			BinaryWriter writer = new BinaryWriter(stream);

			byte[] uB = Encoding.UTF8.GetBytes(username);
			byte[] pB = Encoding.UTF8.GetBytes(password);
			writer.Write((byte)0);
			writer.Write((byte)uB.Length);
			writer.Write(uB);
			writer.Write((byte)pB.Length);
			writer.Write(pB);

			SendTcpMessage(stream.ToArray());
		}

		public static void GetRooms()
		{
			SendTcpMessage(new byte[] { 1 }); //very simple message
		}

		/// <summary>
		/// Joins a room by name
		/// </summary>
		/// <param name="roomname">The name of the room to join</param>
		public static void Join(string roomname)
		{
			MemoryStream stream = new MemoryStream();
			BinaryWriter writer = new BinaryWriter(stream);

			byte[] R = Encoding.UTF8.GetBytes(roomname);
			writer.Write((byte)2);
			writer.Write((byte)R.Length);
			writer.Write(R);
			SendTcpMessage(stream.ToArray());
		}


		/// <summary>
		/// Leaves a room if we're in one
		/// </summary>
		public static void Leave()
		{
			if (InRoom)
			{
				Join(""); //super secret way to leave
			}
		}

		public static void SendToRoom(byte[] message, bool include_self = false, bool reliable = true, bool ordered = false)
		{
			byte sendType = (byte)MessageSendType.MESSAGE_OTHERS;
			if (include_self && ordered) sendType = (byte)MessageSendType.MESSAGE_ALL_ORDERED;
			if (include_self && !ordered) sendType = (byte)MessageSendType.MESSAGE_ALL;
			if (!include_self && ordered) sendType = (byte)MessageSendType.MESSAGE_OTHERS_ORDERED;


			if (reliable)
			{
				MemoryStream stream = new MemoryStream();
				BinaryWriter writer = new BinaryWriter(stream);
				writer.Write(sendType);
				writer.Write(get_be_bytes(message.Length));
				writer.Write(message);
				SendTcpMessage(stream.ToArray());
			}
			else
			{
				//udp message needs the type
				toSend[0] = sendType; //we don't 
				Array.Copy(get_be_bytes(instance.userid), 0, toSend, 1, 4);
				Array.Copy(message, 0, toSend, 5, message.Length);
				SendUdpMessage(toSend, message.Length + 5); //shouldn't be over 1024...
			}
		}


		public static void SendToGroup(string group, byte[] message, bool reliable = true)
		{
			byte[] utf8bytes = Encoding.UTF8.GetBytes(group);
			if (reliable)
			{
				MemoryStream stream = new MemoryStream();
				BinaryWriter writer = new BinaryWriter(stream);
				writer.Write((byte)MessageSendType.MESSAGE_GROUP);
				writer.Write(get_be_bytes(message.Length));
				writer.Write(message);
				writer.Write((byte)utf8bytes.Length);
				writer.Write(utf8bytes);
				SendTcpMessage(stream.ToArray());
			}
			else
			{
				toSend[0] = (byte)MessageSendType.MESSAGE_GROUP;
				Array.Copy(get_be_bytes(instance.userid), 0, toSend, 1, 4);
				//also need to send the group
				toSend[5] = (byte)utf8bytes.Length;
				Array.Copy(utf8bytes, 0, toSend, 6, utf8bytes.Length);
				Array.Copy(message, 0, toSend, 6 + utf8bytes.Length, message.Length);
				SendUdpMessage(toSend, 6 + utf8bytes.Length + message.Length);
			}
		}

		/// <summary>
		/// changes the designated group that sendto(4) will go to
		/// </summary>
		public static void SetupMessageGroup(string groupname, List<int> client_ids)
		{
			if (client_ids.Count > 0)
			{
				instance.groups[groupname] = client_ids.ToList();
			}

			MemoryStream stream = new MemoryStream();
			BinaryWriter writer = new BinaryWriter(stream);
			byte[] R = Encoding.UTF8.GetBytes(groupname);
			writer.Write((byte)6);
			writer.Write((byte)R.Length);
			writer.Write(R);
			writer.Write(get_be_bytes(client_ids.Count * 4));
			for (int i = 0; i < client_ids.Count; i++)
			{
				writer.Write(get_be_bytes(client_ids[i]));
			}

			SendTcpMessage(stream.ToArray());
		}


		public static NetworkObject InstantiateNetworkObject(string prefabName)
		{
			VelNetPlayer localPlayer = LocalPlayer;
			NetworkObject prefab = instance.prefabs.Find(p => p.name == prefabName);
			if (prefab == null)
			{
				Debug.LogError("Couldn't find a prefab with that name: " + prefabName);
				return null;
			}

			string networkId = localPlayer.userid + "-" + localPlayer.lastObjectId++;
			if (instance.objects.ContainsKey(networkId))
			{
				Debug.LogError("Can't instantiate object. Obj with that network ID was already instantiated.", instance.objects[networkId]);
				return null;
			}

			NetworkObject newObject = Instantiate(prefab);
			newObject.networkId = networkId;
			newObject.prefabName = prefabName;
			newObject.owner = localPlayer;
			instance.objects.Add(newObject.networkId, newObject);

			// only sent to others, as I already instantiated this.  Nice that it happens immediately.
			SendToRoom(Encoding.UTF8.GetBytes("7," + newObject.networkId + "," + prefabName), false, true);

			return newObject;
		}

		public static void SomebodyInstantiatedNetworkObject(string networkId, string prefabName, VelNetPlayer owner)
		{
			NetworkObject prefab = instance.prefabs.Find(p => p.name == prefabName);
			if (prefab == null) return;
			NetworkObject newObject = Instantiate(prefab);
			newObject.networkId = networkId;
			newObject.prefabName = prefabName;
			newObject.owner = owner;
			instance.objects.Add(newObject.networkId, newObject);
		}

		public static void NetworkDestroy(NetworkObject obj)
		{
			NetworkDestroy(obj.networkId);
		}

		public static void NetworkDestroy(string networkId)
		{
			if (!instance.objects.ContainsKey(networkId)) return;
			NetworkObject obj = instance.objects[networkId];
			if (obj == null)
			{
				instance.objects.Remove(networkId);
				return;
			}

			if (obj.isSceneObject)
			{
				instance.deletedSceneObjects.Add(networkId);
			}

			Destroy(obj.gameObject);
			instance.objects.Remove(networkId);
		}

		/// <summary>
		/// Takes local ownership of an object by id.
		/// </summary>
		/// <param name="networkId">Network ID of the object to transfer</param>
		/// <returns>True if successfully transferred, False if transfer message not sent</returns>
		public static bool TakeOwnership(string networkId)
		{
			// local player must exist
			if (LocalPlayer == null)
			{
				Debug.LogError("Can't take ownership. No local player.");
				return false;
			}

			// obj must exist
			if (!instance.objects.ContainsKey(networkId))
			{
				Debug.LogError("Can't take ownership. Object with that network id doesn't exist.");
				return false;
			}

			// if the ownership is locked, fail
			if (instance.objects[networkId].ownershipLocked)
			{
				Debug.LogError("Can't take ownership. Ownership for this object is locked.");
				return false;
			}

			// immediately successful
			instance.objects[networkId].owner = LocalPlayer;

			// must be ordered, so that ownership transfers are not confused.  Also sent to all players, so that multiple simultaneous requests will result in the same outcome.
			SendToRoom(Encoding.UTF8.GetBytes("6," + networkId));

			return true;
		}
	}
}