using System;
using System.Collections;
using System.Collections.Generic;
using Unity.Netcode;
using UnityEngine;

namespace LobbyRelaySample.ngo
{
    /// <summary>
    /// Once the NetworkManager has been spawned, we need something to manage the game state and setup other in-game objects
    /// that is itself a networked object, to track things like network connect events.
    /// </summary>
    public class InGameRunner : NetworkBehaviour, IInGameInputHandler
    {
        private Action m_onConnectionVerified, m_onGameEnd;
        private int m_expectedPlayerCount; // Used by the host, but we can't call the RPC until the network connection completes.
        private bool? m_canSpawnInGameObjects;
        private Queue<Vector2> m_pendingSymbolPositions = new Queue<Vector2>();
        private float m_symbolSpawnTimer = 0.5f; // Initial time buffer to ensure connectivity before loading objects.
        private int m_remainingSymbolCount = 0; // Only used by the host.

        [SerializeField] private NetworkObject    m_playerCursorPrefab = default;
        [SerializeField] private NetworkObject    m_symbolContainerPrefab = default;
        [SerializeField] private NetworkObject    m_symbolObjectPrefab = default;
        [SerializeField] private SequenceSelector m_sequenceSelector = default;
        [SerializeField] private Scorer           m_scorer = default;
        [SerializeField] private SymbolKillVolume m_killVolume = default;
        private Transform m_symbolContainerInstance;

        private ulong m_localId; // This is not necessarily the same as the OwnerClientId, since all clients will see all spawned objects regardless of ownership.

        private float m_timeout = 10;

        public void Initialize(Action onConnectionVerified, int expectedPlayerCount, Action onGameEnd)
        {
            m_onConnectionVerified = onConnectionVerified;
            m_expectedPlayerCount = expectedPlayerCount;
            m_onGameEnd = onGameEnd;
            m_canSpawnInGameObjects = null;
            Locator.Get.Provide(this); // Simplifies access since some networked objects can't easily communicate locally (e.g. the host might call a ClientRpc without that client knowing where the call originated).
        }

        public override void OnNetworkSpawn()
        {
            if (IsHost)
                FinishInitialize();
            m_localId = NetworkManager.Singleton.LocalClientId;
            VerifyConnection_ServerRpc(m_localId);
        }

        public override void OnNetworkDespawn()
        {
            m_onGameEnd(); // As a backup to ensure in-game objects get cleaned up, if this is disconnected unexpectedly.
        }

        private void FinishInitialize()
        {
            m_symbolContainerInstance = NetworkObject.Instantiate(m_symbolContainerPrefab).transform;
            ResetPendingSymbolPositions();
            m_killVolume.Initialize(OnSymbolDeactivated);
        }

        private void ResetPendingSymbolPositions()
        {
            m_pendingSymbolPositions.Clear();
            for (int n = 0; n < SequenceSelector.k_symbolCount; n++)
            {
                // TEMP we need to do a BSP or some such to mix up the positions.
                m_pendingSymbolPositions.Enqueue(new Vector2(-9 + (n % 10) * 2, n / 10 * 3));
            }
        }

        /// <summary>
        /// To verify the connection, invoke a server RPC call that then invokes a client RPC call.
        /// </summary>
        [ServerRpc(RequireOwnership = false)]
        private void VerifyConnection_ServerRpc(ulong clientId)
        {
            VerifyConnection_ClientRpc(clientId);
            // While we could start pooling symbol objects now, incoming clients would be flooded with the Spawn calls.
            // This could lead to dropped packets such that the InGameRunner's Spawn call fails to occur, so we'll wait until all players join.
        }
        [ClientRpc]
        private void VerifyConnection_ClientRpc(ulong clientId)
        {
            if (clientId == m_localId)
                VerifyConnectionConfirm_ServerRpc(m_localId);
        }
        /// <summary>
        /// Once the connection is confirmed, check if all players have connected.
        /// </summary>
        [ServerRpc(RequireOwnership = false)]
        private void VerifyConnectionConfirm_ServerRpc(ulong clientId)
        {
            NetworkObject playerCursor = NetworkObject.Instantiate(m_playerCursorPrefab);
            playerCursor.SpawnWithOwnership(clientId);
            playerCursor.name += clientId;

            bool areAllPlayersConnected = NetworkManager.ConnectedClients.Count >= m_expectedPlayerCount; // The game will begin at this point, or else there's a timeout for booting any unconnected players.
            VerifyConnectionConfirm_ClientRpc(clientId, areAllPlayersConnected);
        }
        [ClientRpc]
        private void VerifyConnectionConfirm_ClientRpc(ulong clientId, bool shouldStartImmediately)
        {
            if (clientId == m_localId)
                m_onConnectionVerified?.Invoke();
            if (shouldStartImmediately)
            {
                m_timeout = -1;
                BeginGame();
            }
        }

        private void BeginGame()
        {
            m_canSpawnInGameObjects = true;
            Locator.Get.Messenger.OnReceiveMessage(MessageType.GameBeginning, null); // TODO: Might need to delay this a frame to ensure the client finished initializing (since I sometimes hit the "failed to join" message even when joining).
        }

        public void Update()
        {
            CheckIfCanSpawnNewSymbol();
            if (m_timeout >= 0)
            {
                m_timeout -= Time.deltaTime;
                if (m_timeout < 0)
                    BeginGame();
            }

            // TODO: BSP for choosing symbol spawn positions?
            // TODO: Remove the timer to test for packet loss.
            void CheckIfCanSpawnNewSymbol()
            {
                if (!m_canSpawnInGameObjects.GetValueOrDefault() || m_remainingSymbolCount >= SequenceSelector.k_symbolCount || !IsHost)
                    return;
                if (m_pendingSymbolPositions.Count > 0)
                {
                    m_symbolSpawnTimer -= Time.deltaTime;
                    if (m_symbolSpawnTimer < 0)
                    {
                        m_symbolSpawnTimer = 0.02f; // Space out the object spawning a little to prevent a lag spike.
                        SpawnNewSymbol();
                        if (m_remainingSymbolCount >= SequenceSelector.k_symbolCount)
                            m_canSpawnInGameObjects = false;
                    }
                }
            }
            void SpawnNewSymbol()
            {
                int index = SequenceSelector.k_symbolCount - m_pendingSymbolPositions.Count;
                Vector3 pendingPos = m_pendingSymbolPositions.Dequeue();
                NetworkObject symbolObj = NetworkObject.Instantiate(m_symbolObjectPrefab);
                symbolObj.Spawn();
                symbolObj.name = "Symbol" + index;
                symbolObj.TrySetParent(m_symbolContainerInstance, false);
                symbolObj.transform.localPosition = pendingPos;
                symbolObj.GetComponent<SymbolObject>().symbolIndex.Value = m_sequenceSelector.GetNextSymbol(index);
                m_remainingSymbolCount++;
            }
        }

        /// <summary>
        /// Called while on the host to determine if incoming input has scored or not.
        /// </summary>
        public void OnPlayerInput(ulong id, SymbolObject selectedSymbol)
        {
            if (m_sequenceSelector.ConfirmSymbolCorrect(id, selectedSymbol.symbolIndex.Value))
            {
                selectedSymbol.OnSelectConfirmed_ClientRpc();
                selectedSymbol.Destroy_ServerRpc();
                m_scorer.ScoreSuccess(id);
                OnSymbolDeactivated();
            }
            else
                m_scorer.ScoreFailure(id);
        }

        public void OnSymbolDeactivated()
        {
            if (--m_remainingSymbolCount <= 0)
                EndGame_ServerRpc();
        }

        /// <summary>
        /// The server determines when the game should end. Once it does, it needs to inform the clients to clean up their networked objects first,
        /// since disconnecting before that happens will prevent them from doing so (since they can't receive despawn events from the disconnected server).
        /// </summary>
        [ServerRpc]
        private void EndGame_ServerRpc()
        {
            // TODO: Display results
            this.StartCoroutine(EndGame());
        }

        private IEnumerator EndGame()
        {
            EndGame_ClientRpc();
            yield return null;
            m_onGameEnd();
        }

        [ClientRpc]
        private void EndGame_ClientRpc()
        {
            if (IsHost)
                return;
            m_onGameEnd();
        }

        public void OnReProvided(IInGameInputHandler previousProvider) { /*No-op*/ }
    }
}