using System;
using System.Collections;
using System.Collections.Generic;
using System.Threading.Tasks;
using Unity.Networking.Transport;
using Unity.Networking.Transport.Relay;
using Unity.Services.Relay.Models;
using UnityEngine;

namespace LobbyRelaySample.relay
{
	/// <summary>
	/// Responsible for setting up a connection with Relay using Unity Transport (UTP). A Relay Allocation is created by the host, and then all players
	/// bind UTP to that Allocation in order to send data to each other.
	/// Must be a MonoBehaviour since the binding process doesn't have asynchronous callback options.
	/// </summary>
	public abstract class RelayUtpSetup : MonoBehaviour
	{
		protected bool m_isRelayConnected = false;
		protected NetworkDriver m_networkDriver;
		protected List<NetworkConnection> m_connections;
		protected NetworkEndPoint m_endpointForServer;
		protected LocalLobby m_localLobby;
		protected LocalPlayer m_localUser;
		protected Action<bool, RelayUtpClient> m_onJoinComplete;

		public static string AddressFromEndpoint(NetworkEndPoint endpoint)
		{
			return endpoint.Address.Split(':')[0];
		}

		public void BeginRelayJoin(
			LocalLobby localLobby,
			LocalPlayer localUser,
			Action<bool, RelayUtpClient> onJoinComplete)
		{
			m_localLobby = localLobby;
			m_localUser = localUser;
			m_onJoinComplete = onJoinComplete;
			JoinRelay();
		}

		protected abstract void JoinRelay();


		/// <summary>
		/// Determine the server endpoint for connecting to the Relay server, for either an Allocation or a JoinAllocation.
		/// If DTLS encryption is available, and there's a secure server endpoint available, use that as a secure connection. Otherwise, just connect to the Relay IP unsecured.
		/// </summary>
		public static NetworkEndPoint GetEndpointForAllocation(
			List<RelayServerEndpoint> endpoints,
			string ip,
			int port,
			out bool isSecure)
		{
#if ENABLE_MANAGED_UNITYTLS
			foreach (RelayServerEndpoint endpoint in endpoints)
			{
				if (endpoint.Secure && endpoint.Network == RelayServerEndpoint.NetworkOptions.Udp)
				{
					isSecure = true;
					return NetworkEndPoint.Parse(endpoint.Host, (ushort) endpoint.Port);
				}
			}
#endif
			isSecure = false;
			return NetworkEndPoint.Parse(ip, (ushort) port);
		}

		/// <summary>
		/// Shared behavior for binding to the Relay allocation, which is required for use.
		/// Note that a host will send bytes from the Allocation it creates, whereas a client will send bytes from the JoinAllocation it receives using a relay code.
		/// </summary>
		protected void BindToAllocation(
			NetworkEndPoint serverEndpoint,
			byte[] allocationIdBytes,
			byte[] connectionDataBytes,
			byte[] hostConnectionDataBytes,
			byte[] hmacKeyBytes,
			int connectionCapacity,
			bool isSecure)
		{
			RelayAllocationId allocationId = ConvertAllocationIdBytes(allocationIdBytes);
			RelayConnectionData connectionData = ConvertConnectionDataBytes(connectionDataBytes);
			RelayConnectionData hostConnectionData = ConvertConnectionDataBytes(hostConnectionDataBytes);
			RelayHMACKey key = ConvertHMACKeyBytes(hmacKeyBytes);

			var relayServerData = new RelayServerData(ref serverEndpoint, 0, ref allocationId, ref connectionData,
				ref hostConnectionData, ref key, isSecure);
			relayServerData
				.ComputeNewNonce(); // For security, the nonce value sent when authenticating the allocation must be increased.
			var networkSettings = new NetworkSettings();

			m_networkDriver = NetworkDriver.Create(networkSettings.WithRelayParameters(ref relayServerData));
			m_connections = new List<NetworkConnection>(connectionCapacity);

			if (m_networkDriver.Bind(NetworkEndPoint.AnyIpv4) != 0)
				Debug.LogError("Failed to bind to Relay allocation.");
			else
				StartCoroutine(WaitForBindComplete());
		}

		private IEnumerator WaitForBindComplete()
		{
			while (!m_networkDriver.Bound)
			{
				m_networkDriver.ScheduleUpdate().Complete();
				yield return null;
			}

			OnBindingComplete();
		}

		protected abstract void OnBindingComplete();

		#region UTP uses pointers instead of managed arrays for performance reasons, so we use these helper functions to convert them.

		unsafe private static RelayAllocationId ConvertAllocationIdBytes(byte[] allocationIdBytes)
		{
			fixed (byte* ptr = allocationIdBytes)
			{
				return RelayAllocationId.FromBytePointer(ptr, allocationIdBytes.Length);
			}
		}

		unsafe private static RelayConnectionData ConvertConnectionDataBytes(byte[] connectionData)
		{
			fixed (byte* ptr = connectionData)
			{
				return RelayConnectionData.FromBytePointer(ptr, RelayConnectionData.k_Length);
			}
		}

		unsafe private static RelayHMACKey ConvertHMACKeyBytes(byte[] hmac)
		{
			fixed (byte* ptr = hmac)
			{
				return RelayHMACKey.FromBytePointer(ptr, RelayHMACKey.k_Length);
			}
		}

		#endregion

		private void OnDestroy()
		{
			if (!m_isRelayConnected && m_networkDriver.IsCreated)
				m_networkDriver.Dispose();
		}
	}

	/// <summary>
	/// Host logic: Request a new Allocation, and then both bind to it and request a join code. Once those are both complete, supply data back to the lobby.
	/// </summary>
	public class RelayUtpSetupHost : RelayUtpSetup
	{
		[Flags]
		private enum JoinState
		{
			None = 0,
			Bound = 1,
			Joined = 2
		}

		private JoinState m_joinState = JoinState.None;
		private Allocation m_allocation;

		protected override void JoinRelay()
		{
			RelayAPIInterface.AllocateAsync(m_localLobby.MaxPlayerCount.Value, OnAllocation);
		}

		private void OnAllocation(Allocation allocation)
		{
			m_allocation = allocation;
			RelayAPIInterface.GetJoinCodeAsync(allocation.AllocationId, OnRelayCode);
			bool isSecure = false;
			m_endpointForServer = GetEndpointForAllocation(allocation.ServerEndpoints, allocation.RelayServer.IpV4,
				allocation.RelayServer.Port, out isSecure);
			BindToAllocation(m_endpointForServer, allocation.AllocationIdBytes, allocation.ConnectionData,
				allocation.ConnectionData, allocation.Key, 16, isSecure);
		}

		private void OnRelayCode(string relayCode)
		{
			m_localLobby.RelayCode.Value = relayCode;
			m_localLobby.RelayServer.Value =
				new ServerAddress(AddressFromEndpoint(m_endpointForServer), m_endpointForServer.Port);
			m_joinState |= JoinState.Joined;
#pragma warning disable 4014
			CheckForComplete();
#pragma warning restore 4014
		}

		protected override void OnBindingComplete()
		{
			if (m_networkDriver.Listen() != 0)
			{
				Debug.LogError("RelayUtpSetupHost failed to bind to the Relay Allocation.");
				m_onJoinComplete(false, null);
			}
			else
			{
				Debug.Log("Relay host is bound.");
				m_joinState |= JoinState.Bound;
#pragma warning disable 4014
				CheckForComplete();
#pragma warning restore 4014
			}
		}

		private void CheckForComplete()
		{
			if (m_joinState == (JoinState.Joined | JoinState.Bound) && this != null
			) // this will equal null (i.e. this component has been destroyed) if the host left the lobby during the Relay connection sequence.
			{
				m_isRelayConnected = true;
				RelayUtpHost host = gameObject.AddComponent<RelayUtpHost>();
				host.Initialize(m_networkDriver, m_connections, m_localUser, m_localLobby);
				m_onJoinComplete(true, host);
				var connectionInfo = $"{m_allocation.RelayServer.IpV4}:{m_allocation.RelayServer.Port}";
				// await LobbyManager.Instance.UpdatePlayerRelayInfoAsync(m_allocation.AllocationId.ToString(), m_localLobby.RelayCode, connectionInfo);
			}
		}
	}

	/// <summary>
	/// Client logic: Wait until the Relay join code is retrieved from the lobby's shared data. Then, use that code to get the Allocation to bind to, and
	/// then create a connection to the host.
	/// </summary>
	public class RelayUtpSetupClient : RelayUtpSetup
	{
		private JoinAllocation m_allocation;

		protected override void JoinRelay()
		{
			m_localLobby.onChanged += OnLobbyChange;
		}

		private void OnLobbyChange(LocalLobby lobby)
		{
			if (m_localLobby.RelayCode != null)
			{
				RelayAPIInterface.JoinAsync(m_localLobby.RelayCode.Value, OnJoin);
				m_localLobby.onChanged -= OnLobbyChange;
			}
		}

		private void OnJoin(JoinAllocation joinAllocation)
		{
			if (joinAllocation == null || this == null
			) // The returned JoinAllocation is null if allocation failed. this would be destroyed already if you quit the lobby while Relay is connecting.
				return;
			m_allocation = joinAllocation;
			bool isSecure = false;
			m_endpointForServer = GetEndpointForAllocation(joinAllocation.ServerEndpoints,
				joinAllocation.RelayServer.IpV4, joinAllocation.RelayServer.Port, out isSecure);
			BindToAllocation(m_endpointForServer, joinAllocation.AllocationIdBytes, joinAllocation.ConnectionData,
				joinAllocation.HostConnectionData, joinAllocation.Key, 1, isSecure);
			m_localLobby.RelayServer.Value =
				new ServerAddress(AddressFromEndpoint(m_endpointForServer), m_endpointForServer.Port);
		}

		protected override void OnBindingComplete()
		{
#pragma warning disable 4014
			ConnectToServer();
#pragma warning restore 4014
		}

		private async Task ConnectToServer()
		{
			// Once the client is bound to the Relay server, send a connection request.
			m_connections.Add(m_networkDriver.Connect(m_endpointForServer));
			while (m_networkDriver.GetConnectionState(m_connections[0]) == NetworkConnection.State.Connecting)
			{
				m_networkDriver.ScheduleUpdate().Complete();
				await Task.Delay(100);
			}

			if (m_networkDriver.GetConnectionState(m_connections[0]) != NetworkConnection.State.Connected)
			{
				Debug.LogError("RelayUtpSetupClient could not connect to the host.");
				m_onJoinComplete(false, null);
			}
			else if (this != null)
			{
				m_isRelayConnected = true;
				RelayUtpClient client = gameObject.AddComponent<RelayUtpClient>();
				client.Initialize(m_networkDriver, m_connections, m_localUser, m_localLobby);
				m_onJoinComplete(true, client);
				var connectionInfo = $"{m_allocation.RelayServer.IpV4}:{m_allocation.RelayServer.Port}";

				//  await LobbyManager.Instance.UpdatePlayerRelayInfoAsync(m_allocation.AllocationId.ToString(), m_localLobby.RelayCode,connectionInfo);
			}
		}
	}
}