using System;
using Unity.Netcode;
using UnityEngine;

public enum CannonState : byte
{
    Empty,
    Loaded,
    Countdown
}

public struct CannonShotState : INetworkSerializable, IEquatable<CannonShotState>
{
    public uint Sequence;
    public MissileType MissileType;

    public CannonShotState(uint sequence, MissileType missileType)
    {
        Sequence = sequence;
        MissileType = missileType;
    }

    public void NetworkSerialize<T>(BufferSerializer<T> serializer)
        where T : IReaderWriter
    {
        serializer.SerializeValue(ref Sequence);
        serializer.SerializeValue(ref MissileType);
    }

    public bool Equals(CannonShotState other) =>
        Sequence == other.Sequence && MissileType == other.MissileType;
}

[DisallowMultipleComponent]
[RequireComponent(typeof(NetworkObject))]
public sealed class NetworkCannonController : NetworkBehaviour
{
    private const ulong EmptyRocketId = ulong.MaxValue;

    [Header("Configuration")]
    [SerializeField] private CannonConfig config;

    [Header("Rocket Slot")]
    [SerializeField] private CannonRocketSlot rocketSlot;
    [SerializeField] private Transform rocketSnapPoint;
    [SerializeField, Min(0.5f)] private float maximumTakeDistance = 4f;
    [SerializeField, Min(0f)] private float minimumReinsertBlockDuration = 0.1f;

    [Header("Output")]
    [SerializeField] private MapController mapController;
    [SerializeField] private NetworkShockwaveEmitter shotShockwave;

    private readonly NetworkVariable<CannonState> state = new(
        CannonState.Empty,
        NetworkVariableReadPermission.Everyone,
        NetworkVariableWritePermission.Server);
    private readonly NetworkVariable<ulong> loadedRocketId = new(
        EmptyRocketId,
        NetworkVariableReadPermission.Everyone,
        NetworkVariableWritePermission.Server);
    private readonly NetworkVariable<float> selectedDelay = new(
        5f,
        NetworkVariableReadPermission.Everyone,
        NetworkVariableWritePermission.Server);
    private readonly NetworkVariable<double> fireAt = new(
        0d,
        NetworkVariableReadPermission.Everyone,
        NetworkVariableWritePermission.Server);
    private readonly NetworkVariable<CannonShotState> lastShot = new(
        default,
        NetworkVariableReadPermission.Everyone,
        NetworkVariableWritePermission.Server);

    private NetworkRocketItem loadedRocket;
    private IWorkstationItemControl loadedRocketControl;
    private ulong blockedRocketId = EmptyRocketId;
    private Collider[] blockedRocketColliders;
    private double unblockAfter;

    public CannonState State => state.Value;
    public CannonConfig Config => config;
    public NetworkRocketItem LoadedRocket => loadedRocket != null
        ? loadedRocket
        : ResolveLoadedRocket();
    public float SelectedDelay => selectedDelay.Value;
    public double FireAt => fireAt.Value;
    public float RemainingSeconds => State == CannonState.Countdown && NetworkManager != null
        ? Mathf.Max(0f, (float)(fireAt.Value - NetworkManager.ServerTime.Time))
        : 0f;
    public bool CanTakeRocket => IsSpawned && State == CannonState.Loaded &&
        loadedRocketId.Value != EmptyRocketId;
    public CannonShotState LastShot => lastShot.Value;

    public event Action Changed;
    public event Action<CannonShotState> ShotFired;

    private void Awake()
    {
        if (rocketSnapPoint == null && rocketSlot != null)
            rocketSnapPoint = rocketSlot.SnapPoint;
        rocketSlot?.Configure(this);
    }

    public override void OnNetworkSpawn()
    {
        state.OnValueChanged += HandleStateChanged;
        loadedRocketId.OnValueChanged += HandleRocketIdChanged;
        selectedDelay.OnValueChanged += HandleDelayChanged;
        fireAt.OnValueChanged += HandleFireAtChanged;
        lastShot.OnValueChanged += HandleShotChanged;

        rocketSlot?.Configure(this);
        if (IsServer)
        {
            state.Value = CannonState.Empty;
            loadedRocketId.Value = EmptyRocketId;
            selectedDelay.Value = config != null ? config.DefaultDelay : 5f;
            fireAt.Value = 0d;
        }
        Changed?.Invoke();
    }

    public override void OnNetworkDespawn()
    {
        state.OnValueChanged -= HandleStateChanged;
        loadedRocketId.OnValueChanged -= HandleRocketIdChanged;
        selectedDelay.OnValueChanged -= HandleDelayChanged;
        fireAt.OnValueChanged -= HandleFireAtChanged;
        lastShot.OnValueChanged -= HandleShotChanged;
    }

    private void Update()
    {
        if (!IsServer || !IsSpawned)
            return;

        UpdateReinsertBlock();
        if (State == CannonState.Countdown &&
            NetworkManager != null && NetworkManager.ServerTime.Time >= fireAt.Value)
        {
            FireOnServer();
        }
    }

    private void LateUpdate()
    {
        if (!IsServer || !IsSpawned || LoadedRocket == null ||
            rocketSnapPoint == null)
            return;

        loadedRocket.transform.SetPositionAndRotation(
            rocketSnapPoint.position,
            rocketSnapPoint.rotation);
    }

    public bool TryInsertRocket(NetworkRocketItem rocket)
    {
        if (!IsServer || !IsSpawned || State != CannonState.Empty ||
            rocket == null || !rocket.IsSpawned || rocket.Definition == null ||
            rocket.NetworkObjectId == blockedRocketId ||
            (config != null && !config.AcceptDefectiveRockets && rocket.IsDefective) ||
            (config != null && !config.AcceptCriticallyDamagedRockets &&
                rocket.IsCriticallyDamaged) ||
            !WorkstationItemControlUtility.TryGetControl(
                rocket.GetComponent<NetworkItem>(),
                out IWorkstationItemControl control) ||
            !control.TryAcquireExternalControl())
        {
            return false;
        }

        loadedRocket = rocket;
        loadedRocketControl = control;
        loadedRocketId.Value = rocket.NetworkObjectId;
        state.Value = CannonState.Loaded;
        SnapLoadedRocket();
        return true;
    }

    public void RequestTakeRocket()
    {
        if (CanTakeRocket)
            RequestTakeRocketRpc();
    }

    public void RequestSetShotDelay(float seconds)
    {
        if (!IsSpawned)
            return;
        if (IsServer)
            SetShotDelayOnServer(seconds);
        else
            RequestSetShotDelayRpc(seconds);
    }

    public void RequestAdjustShotDelay(float delta)
    {
        RequestSetShotDelay(SelectedDelay + delta);
    }

    public void RequestIncreaseShotDelay()
    {
        RequestAdjustShotDelay(config != null ? config.AdjustmentStep : 1f);
    }

    public void RequestDecreaseShotDelay()
    {
        RequestAdjustShotDelay(-(config != null ? config.AdjustmentStep : 1f));
    }

    public void RequestStartCountdown()
    {
        if (!IsSpawned)
            return;
        if (IsServer)
            TryStartCountdownOnServer();
        else
            RequestStartCountdownRpc();
    }

    public void SetFireRequested(bool isActivated)
    {
        if (isActivated && IsServer && IsSpawned)
            TryStartCountdownOnServer();
    }

    [ContextMenu("Debug/Start Countdown (Server Play Mode)")]
    private void StartCountdownFromContextMenu()
    {
        if (Application.isPlaying)
            TryStartCountdownOnServer();
    }

    [Rpc(SendTo.Server, InvokePermission = RpcInvokePermission.Everyone)]
    private void RequestSetShotDelayRpc(float seconds) => SetShotDelayOnServer(seconds);

    [Rpc(SendTo.Server, InvokePermission = RpcInvokePermission.Everyone)]
    private void RequestStartCountdownRpc() => TryStartCountdownOnServer();

    [Rpc(SendTo.Server, InvokePermission = RpcInvokePermission.Everyone)]
    private void RequestTakeRocketRpc(RpcParams rpcParams = default)
    {
        if (!CanTakeRocket || rocketSlot == null ||
            !TryGetPlayerObject(rpcParams.Receive.SenderClientId, out NetworkObject player))
            return;

        float maxDistanceSquared = maximumTakeDistance * maximumTakeDistance;
        if ((player.transform.position - rocketSlot.InteractionPosition).sqrMagnitude >
            maxDistanceSquared)
            return;

        NetworkRocketItem rocket = LoadedRocket;
        IWorkstationItemControl control = loadedRocketControl ?? ResolveLoadedControl();
        if (rocket == null || control == null ||
            !control.TryReleaseExternalControlToPlayer(rpcParams.Receive.SenderClientId))
            return;

        blockedRocketId = rocket.NetworkObjectId;
        blockedRocketColliders = rocket.GetComponentsInChildren<Collider>(true);
        unblockAfter = GetNetworkTime() + minimumReinsertBlockDuration;
        ClearRocketSlot();
    }

    private void SetShotDelayOnServer(float seconds)
    {
        if (!IsServer || State == CannonState.Countdown)
            return;
        selectedDelay.Value = config != null
            ? config.ClampDelay(seconds)
            : Mathf.Clamp(seconds, 0f, 60f);
    }

    private bool TryStartCountdownOnServer()
    {
        if (!IsServer || !IsSpawned || State != CannonState.Loaded ||
            LoadedRocket == null || NetworkManager == null)
            return false;

        fireAt.Value = NetworkManager.ServerTime.Time + selectedDelay.Value;
        state.Value = CannonState.Countdown;
        return true;
    }

    private void FireOnServer()
    {
        NetworkRocketItem rocket = LoadedRocket;
        if (rocket == null || rocket.Definition == null)
        {
            ClearRocketSlot();
            return;
        }

        MissileType missileType = rocket.Definition.MissileType;
        mapController?.RequestShot(missileType);
        shotShockwave?.EmitShockwave();
        lastShot.Value = new CannonShotState(lastShot.Value.Sequence + 1, missileType);

        NetworkObject rocketObject = rocket.NetworkObject;
        loadedRocket = null;
        loadedRocketControl = null;
        loadedRocketId.Value = EmptyRocketId;
        fireAt.Value = 0d;
        state.Value = CannonState.Empty;

        if (rocketObject != null && rocketObject.IsSpawned)
            rocketObject.Despawn(true);
    }

    private void ClearRocketSlot()
    {
        loadedRocket = null;
        loadedRocketControl = null;
        loadedRocketId.Value = EmptyRocketId;
        fireAt.Value = 0d;
        state.Value = CannonState.Empty;
    }

    private void SnapLoadedRocket()
    {
        if (loadedRocket != null && rocketSnapPoint != null)
        {
            loadedRocket.transform.SetPositionAndRotation(
                rocketSnapPoint.position,
                rocketSnapPoint.rotation);
        }
    }

    private NetworkRocketItem ResolveLoadedRocket()
    {
        if (loadedRocketId.Value == EmptyRocketId || NetworkManager == null ||
            NetworkManager.SpawnManager == null ||
            !NetworkManager.SpawnManager.SpawnedObjects.TryGetValue(
                loadedRocketId.Value, out NetworkObject networkObject))
            return null;

        loadedRocket = networkObject.GetComponent<NetworkRocketItem>();
        return loadedRocket;
    }

    private IWorkstationItemControl ResolveLoadedControl()
    {
        NetworkRocketItem rocket = LoadedRocket;
        WorkstationItemControlUtility.TryGetControl(
            rocket != null ? rocket.GetComponent<NetworkItem>() : null,
            out loadedRocketControl);
        return loadedRocketControl;
    }

    private bool TryGetPlayerObject(ulong clientId, out NetworkObject player)
    {
        player = null;
        return NetworkManager != null &&
            NetworkManager.ConnectedClients.TryGetValue(clientId, out NetworkClient client) &&
            (player = client.PlayerObject) != null;
    }

    private void UpdateReinsertBlock()
    {
        if (blockedRocketId == EmptyRocketId || rocketSlot == null ||
            GetNetworkTime() < unblockAfter ||
            rocketSlot.OverlapsAny(blockedRocketColliders, 0.05f))
            return;

        blockedRocketId = EmptyRocketId;
        blockedRocketColliders = null;
    }

    private double GetNetworkTime() => NetworkManager != null
        ? NetworkManager.ServerTime.Time
        : Time.timeAsDouble;

    private void HandleStateChanged(CannonState _, CannonState __) => Changed?.Invoke();
    private void HandleRocketIdChanged(ulong _, ulong __)
    {
        loadedRocket = null;
        loadedRocketControl = null;
        Changed?.Invoke();
    }
    private void HandleDelayChanged(float _, float __) => Changed?.Invoke();
    private void HandleFireAtChanged(double _, double __) => Changed?.Invoke();
    private void HandleShotChanged(CannonShotState previous, CannonShotState current)
    {
        if (current.Sequence == previous.Sequence)
            return;
        ShotFired?.Invoke(current);
        Changed?.Invoke();
    }
}