using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using Godot;

public partial class GameManager : Node3D
{
	[Export] public Control GameMenu { get; private set; }
	[Export] public QueueManager QueueManager { get; private set; }
	[Export] public Node3D SpaceRoot { get; private set; }

	[Export] public double closeDistance = 50;
	[Export] public double closeTickInterval = 1;
	[Export] public double farTickInterval = 10;
	[Export] public int maxFarThreads = 16;

	public static bool Loading { get; private set; } = true;
	public static GameManager Instance { get; private set; }
	public static IGenerator Generator { get; private set; }
	public static Universe GameUniverse { get; private set; }
	public Player MainPlayer { get; private set; }
	public Dictionary<long, Player> Players { get; private set; } = [];
	public Dictionary<long, HashSet<GameObject>> PlayerSpawnedObjects { get; private set; } = [];

	private double closeTickTimer = 0;
	private double farTickTimer = 0;

	public bool simulatingClose = false;
	public bool simulatingFar = false;
	public bool playerReady = false;

	private readonly Dictionary<GameObject, Node3D> localSpawnedObjects = [];
	private readonly ConcurrentQueue<GameObject> spawnQueue = [];

	public override void _EnterTree()
	{
		Instance = this;
	}

	public override void _Ready()
	{
		Generator = new TestGenerator();

		if (Global.IsGameHost)
		{
			GameUniverse = Generator.GenerateUniverse();
			Loading = false;
		}
	}

	private void OnPlayerReady()
	{
		playerReady = true;
	}

	public override void _ExitTree()
	{
		Loading = true;
		Instance = null;
	}

	public override void _Process(double delta)
	{
		if (!playerReady || !Global.IsGameHost)
		{
			return;
		}

		closeTickTimer += delta;
		if (closeTickTimer >= closeTickInterval && !simulatingClose)
		{
			SimulateClose(closeTickTimer);
			SyncClose();
			closeTickTimer = 0;
		}

		farTickTimer += delta;
		if (farTickTimer >= farTickInterval && !simulatingFar && QueueManager.SectorReassignQueue.IsEmpty)
		{
			double taskFarTickTimer = farTickTimer;
			Task.Run(() =>
			{
				SimulateFar(taskFarTickTimer);
			});

			farTickTimer = 0;
		}
	}

	public Sector GetCurrentSector()
	{
		return MainPlayer.PlayerData.CurrentSector;
	}

	public Player GetPlayer(long id)
	{
		Players.TryGetValue(id, out Player player);
		return player;
	}

	private void SimulateClose(double delta)
	{
		simulatingClose = true;

		HashSet<GameObject> objectsToSimulate = [];

		foreach (KeyValuePair<long, Player> player in Players)
		{
			Character character = player.Value.PlayerData;

			List<Sector> playerSectors = character.CurrentSector.GetNeighbouringSectors();
			playerSectors.ForEach(sector =>
			{
				sector.GameObjects.ForEach(gameObject =>
				{
					double distance = character.GetDistanceToObject(gameObject);
					if (distance <= closeDistance)
					{
						objectsToSimulate.Add(gameObject);
					}
				});
			});
		}

		foreach (GameObject gameObject in objectsToSimulate)
		{
			gameObject.Simulate(delta);
		}

		simulatingClose = false;
	}

	private void SyncClose()
	{
		foreach (KeyValuePair<long, Player> player in Players)
		{
			bool isHostPlayer = player.Key == 1;
			long playerKey = player.Key;
			Character character = player.Value.PlayerData;

			PlayerSpawnedObjects.TryGetValue(playerKey, out HashSet<GameObject> playerSpawnedObjects);
			playerSpawnedObjects ??= [];
			HashSet<GameObject> playerNewSpawnedObjects = [];

			List<Sector> playerSectors = character.CurrentSector.GetNeighbouringSectors();

			// Spawn/Send object
			playerSectors.ForEach(sector =>
			{
				sector.GameObjects.ForEach(gameObject =>
				{
					double distance = character.GetDistanceToObject(gameObject);
					if (distance <= closeDistance)
					{
						if (isHostPlayer)
							Spawn(gameObject);
						else
							gameObject.NetworkWrite(playerKey, !playerSpawnedObjects.Contains(gameObject));

						playerNewSpawnedObjects.Add(gameObject);
					}
				});
			});

			// Despawn object
			foreach (GameObject gameObject in playerSpawnedObjects)
			{
				if (!playerNewSpawnedObjects.Contains(gameObject))
				{
					if (isHostPlayer)
						Despawn(gameObject);
					else
						RPCNode.Instance.RpcId(playerKey, nameof(RPCNode.RpcDespawnGameObject), gameObject.UUID.ToString());
				}
			}

			PlayerSpawnedObjects[playerKey] = playerNewSpawnedObjects;
		}
	}

	private void SimulateFar(double delta)
	{
		simulatingFar = true;

		Sector[,,] sectors = GameUniverse.Sectors;

		HashSet<GameObject> allSpawnedObjects = [];
		foreach (HashSet<GameObject> item in PlayerSpawnedObjects.Values)
		{
			foreach (GameObject gameObject in item)
			{
				allSpawnedObjects.Add(gameObject);
			}
		}

		int sizeX = sectors.GetLength(0);

		double taskDelta = delta;
		Parallel.For(0, sizeX, x =>
		{
			SimulateFarClustered(allSpawnedObjects, taskDelta, x);
		});

		simulatingFar = false;
	}

	private static void SimulateFarClustered(HashSet<GameObject> ignoreObjects, double delta, int x)
	{
		Sector[,,] sectors = GameUniverse.Sectors;

		int sizeY = sectors.GetLength(1);
		int sizeZ = sectors.GetLength(2);

		for (int y = 0; y < sizeY; y++)
		{
			for (int z = 0; z < sizeZ; z++)
			{
				try
				{
					sectors[x, y, z].Simulate(delta, ignoreObjects);
				}
				catch (Exception e)
				{
					QueueManager.LogQueue.Enqueue("EXCEPTION: " + e.Message);
				}
			}
		}
	}

	public Player SpawnPlayer(Character character, long networkId, bool isMainPlayer = false)
	{
		Player player = character.InstantiatePlayer();
		player.GameMenu = GameMenu;

		if (isMainPlayer)
		{
			MainPlayer = player;
			OnPlayerReady();
		}

		Players.Add(networkId, player);

		character.UpdateSector();

		SpaceRoot.CallDeferred("add_child", player);
		return player;
	}

	public void DespawnPlayer(Player player, long id)
	{
		Players.Remove(id);

		SpaceRoot.CallDeferred("remove_child", player);
		player.CallDeferred("queue_free");
	}

	public void Spawn(GameObject gameObject)
	{
		spawnQueue.Enqueue(gameObject);
		CallDeferred(nameof(ProcessSpawnQueue));
	}

	private void ProcessSpawnQueue()
	{
		spawnQueue.TryDequeue(out GameObject gameObject);
		if (gameObject == null)
		{
			return;
		}
		if (localSpawnedObjects.ContainsKey(gameObject))
		{
			return;
		}

		Node3D instance = gameObject.Instantiate(GetCurrentSector());
		localSpawnedObjects.Add(gameObject, instance);

		SpaceRoot.CallDeferred("add_child", instance);
	}

	public void Despawn(GameObject gameObject)
	{
		if (!localSpawnedObjects.ContainsKey(gameObject))
		{
			return;
		}

		Node3D nodeToDespawn = localSpawnedObjects.GetValueOrDefault(gameObject);
		localSpawnedObjects.Remove(gameObject);

		SpaceRoot.CallDeferred("remove_child", nodeToDespawn);
		nodeToDespawn.CallDeferred("queue_free");
	}

	public void Despawn(Guid uuid)
	{
		foreach (GameObject gameObject in localSpawnedObjects.Keys)
		{
			if (gameObject.UUID == uuid)
			{
				Despawn(gameObject);
				break;
			}
		}
	}

	public void ApplyOrigin()
	{
		Sector current = GetCurrentSector();

		foreach (KeyValuePair<long, Player> player in Players)
		{
			player.Value.PlayerData.UpdateSectorOffset(current);
			player.Value.PlayerData.UpdateNodePosition();
		}

		foreach (KeyValuePair<GameObject, Node3D> spawned in localSpawnedObjects)
		{
			GameObject gameObject = spawned.Key;
			Node3D node = spawned.Value;

			gameObject.UpdateSectorOffset(current);
			node._Process(0);
		}
	}

	public void SendUniverseToClient(long id)
	{
		RpcId(id, nameof(RpcDownloadUniverse), Generator.GetUniverseSize(), Generator.GetSectorSize());
	}

	[Rpc(MultiplayerApi.RpcMode.Authority)]
	public void RpcDownloadUniverse(Vector3I universeSize, Vector3 sectorSize)
	{
		GameUniverse = Generator.InitializeEmptyUniverse(universeSize, sectorSize);

		Loading = false;
	}
}