using Steamworks;
using System;
using System.IO;
using UnityEngine;

namespace Mirror.FizzySteam
{
	[HelpURL("https://github.com/Chykary/FizzyFacepunch")]
	public class FizzyFacepunch : Transport
	{
		private const string STEAM_SCHEME = "steam";

		private static IClient client;
		private static IServer server;

		[SerializeField]
		public P2PSend[] Channels = new P2PSend[2] { P2PSend.Reliable, P2PSend.UnreliableNoDelay };

		[Tooltip("Timeout for connecting in seconds.")]
		public int Timeout = 25;
		[Tooltip("The Steam ID for your application.")]
		public string SteamAppID = "480";
		[Tooltip("Allow or disallow P2P connections to fall back to being relayed through the Steam servers if a direct connection or NAT-traversal cannot be established.")]
		public bool AllowSteamRelay = true;

		[Tooltip("Use SteamSockets instead of the (deprecated) SteamNetworking. This will always use Relay.")]
		public bool UseNextGenSteamNetworking = true;

		[Tooltip("Check this if you want the transport to initialise Facepunch.")]
		public bool InitFacepunch = true;

		[Header("Info")]
		[Tooltip("This will display your Steam User ID when you start or connect to a server.")]
		public ulong SteamUserID;

		public Action<string> SetTransportError;

		private void Awake()
		{
			const string fileName = "steam_appid.txt";
			if (File.Exists(fileName))
			{
				var content = File.ReadAllText(fileName);
				if (content != SteamAppID)
				{
					File.WriteAllText(fileName, SteamAppID.ToString());
					Debug.Log($"Updating {fileName}. Previous: {content}, new SteamAppID {SteamAppID}");
				}
			}
			else
			{
				File.WriteAllText(fileName, SteamAppID.ToString());
				Debug.Log($"New {fileName} written with SteamAppID {SteamAppID}");
			}

			Debug.Assert(Channels != null && Channels.Length > 0, "No channel configured for FizzySteamworks.");

			if (InitFacepunch)
			{
				SteamClient.Init(uint.Parse(SteamAppID), true);
			}

			Invoke(nameof(FetchSteamID), 1f);
		}

		public override void ClientEarlyUpdate()
		{
			if (enabled && client != null && !client.Error)
			{
				client?.ReceiveData();
			}
		}

		public override void ServerEarlyUpdate()
		{
			if (enabled)
			{
				server?.ReceiveData();
			}
		}

		public override void ClientLateUpdate()
		{
			if (enabled && client != null && !client.Error)
			{
				client?.FlushData();
			}
		}

		public override void ServerLateUpdate()
		{
			if (enabled)
			{
				server?.FlushData();
			}
		}

		public override bool ClientConnected() => ClientActive() && client.Connected;
		public override void ClientConnect(string address)
		{
			if (!SteamClient.IsValid)
			{
				Debug.LogError("SteamWorks not initialized. Client could not be started.");
				OnClientDisconnected.Invoke();
				return;
			}

			FetchSteamID();

			if (ServerActive())
			{
				Debug.LogError("Transport already running as server!");
				return;
			}

			if (!ClientActive() || client.Error)
			{
				if (UseNextGenSteamNetworking)
				{
					Debug.Log($"Starting client [SteamSockets], target address {address}.");
					client = NextClient.CreateClient(this, address);
				}
				else
				{
					Debug.Log($"Starting client [DEPRECATED SteamNetworking], target address {address}. Relay enabled: {AllowSteamRelay}");
					SteamNetworking.AllowP2PPacketRelay(AllowSteamRelay);
					client = LegacyClient.CreateClient(this, address);
				}
			}
			else
			{
				Debug.LogError("Client already running!");
			}
		}

		public override void ClientConnect(Uri uri)
		{
			if (uri.Scheme != STEAM_SCHEME)
			{
				throw new ArgumentException($"Invalid url {uri}, use {STEAM_SCHEME}://SteamID instead", nameof(uri));
			}

			ClientConnect(uri.Host);
		}

		public override void ClientSend(ArraySegment<byte> segment, int channelId)
		{
			var data = new byte[segment.Count];
			Array.Copy(segment.Array, segment.Offset, data, 0, segment.Count);
			client.Send(data, channelId);
		}

		public override void ClientDisconnect()
		{
			if (ClientActive())
			{
				Shutdown();
			}
		}
		public bool ClientActive() => client != null;


		public override bool ServerActive() => server != null;
		public override void ServerStart()
		{
			if (!SteamClient.IsValid)
			{
				Debug.LogError("SteamWorks not initialized. Server could not be started.");
				return;
			}

			FetchSteamID();

			if (ClientActive())
			{
				Debug.LogError("Transport already running as client!");
				return;
			}

			if (!ServerActive())
			{
				if (UseNextGenSteamNetworking)
				{
					Debug.Log($"Starting server [SteamSockets].");
					server = NextServer.CreateServer(this, NetworkManager.singleton.maxConnections);
				}
				else
				{
					Debug.Log($"Starting server [DEPRECATED SteamNetworking]. Relay enabled: {AllowSteamRelay}");
					SteamNetworking.AllowP2PPacketRelay(AllowSteamRelay);
					server = LegacyServer.CreateServer(this, NetworkManager.singleton.maxConnections);
				}
			}
			else
			{
				Debug.LogError("Server already started!");
			}
		}

		public override Uri ServerUri()
		{
			var steamBuilder = new UriBuilder
			{
				Scheme = STEAM_SCHEME,
				Host = SteamClient.SteamId.Value.ToString()
			};

			return steamBuilder.Uri;
		}

		public override void ServerSend(int connectionId, ArraySegment<byte> segment, int channelId)
		{
			if (ServerActive())
			{
				var data = new byte[segment.Count];
				Array.Copy(segment.Array, segment.Offset, data, 0, segment.Count);
				server.Send(connectionId, data, channelId);
			}
		}
		public override void ServerDisconnect(int connectionId)
		{
			if (ServerActive())
			{
				server.Disconnect(connectionId);
			}
		}
		public override string ServerGetClientAddress(int connectionId) => ServerActive() ? server.ServerGetClientAddress(connectionId) : string.Empty;
		public override void ServerStop()
		{
			if (ServerActive())
			{
				Shutdown();
			}
		}

		public override void Shutdown()
		{
			if (server != null)
			{
				server.Shutdown();
				server = null;
				Debug.Log("Transport shut down - was server.");
			}

			if (client != null)
			{
				client.Disconnect();
				client = null;
				Debug.Log("Transport shut down - was client.");
			}
		}

		public override int GetMaxPacketSize(int channelId)
		{
			if (channelId >= Channels.Length)
			{
				Debug.LogError("Channel Id exceeded configured channels! Please configure more channels.");
				return 1200;
			}

			switch (Channels[channelId])
			{
				case P2PSend.Unreliable:
				case P2PSend.UnreliableNoDelay:
					return 1200;
				case P2PSend.Reliable:
				case P2PSend.ReliableWithBuffering:
					return 1048576;
				default:
					throw new NotSupportedException();
			}
		}

		public override bool Available()
		{
			try
			{
				return SteamClient.IsValid;
			}
			catch
			{
				return false;
			}
		}

		private void FetchSteamID()
		{
			if (SteamClient.IsValid)
			{
				if (UseNextGenSteamNetworking)
				{
					SteamNetworkingUtils.InitRelayNetworkAccess();
				}

				SteamUserID = SteamClient.SteamId;
			}
		}

		private void OnDestroy() => Shutdown();
	}
}