using Network;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;
using Newtonsoft.Json.Serialization;
using Oxide.Core;
using Oxide.Core.Libraries.Covalence;
using Oxide.Core.Plugins;
using Rust.Modular;
using System.Collections.Generic;
using System.Linq;
using UnityEngine;

namespace Oxide.Plugins
{
    [Info("Modular Car Turrets", "WhiteThunder", "1.1.0")]
    [Description("Allows players to deploy auto turrets onto modular cars.")]
    internal class CarTurrets : CovalencePlugin
    {
        #region Fields

        [PluginReference]
        Plugin VehicleDeployedLocks;

        private const string Permission_DeployCommand = "carturrets.deploy.command";
        private const string Permission_DeployInventory = "carturrets.deploy.inventory";
        private const string Permission_Free = "carturrets.free";

        private const string Permission_Limit_2 = "carturrets.limit.2";
        private const string Permission_Limit_3 = "carturrets.limit.3";
        private const string Permission_Limit_4 = "carturrets.limit.4";

        private const string Permission_SpawnWithCar = "carturrets.spawnwithcar";

        private const string Permission_AllModules = "carturrets.allmodules";
        private const string Permission_ModuleFormat = "carturrets.{0}";

        private const string Prefab_Entity_AutoTurret = "assets/prefabs/npc/autoturret/autoturret_deployed.prefab";
        private const string Prefab_Entity_ElectricSwitch = "assets/prefabs/deployable/playerioents/simpleswitch/switch.prefab";
        private const string Prefab_Effect_DeployAutoTurret = "assets/prefabs/npc/autoturret/effects/autoturret-deploy.prefab";

        private const int ItemId_AutoTurret = -2139580305;

        private static readonly Vector3 TurretSwitchPosition = new Vector3(0, -0.64f, -0.32f);
        private static readonly Quaternion TurretBackwardRotation = Quaternion.Euler(0, 180, 0);
        private static readonly Quaternion TurretSwitchRotation = Quaternion.Euler(0, 180, 0);

        private Configuration _pluginConfig;

        #endregion

        #region Hooks

        private void Init()
        {
            permission.RegisterPermission(Permission_DeployCommand, this);
            permission.RegisterPermission(Permission_DeployInventory, this);
            permission.RegisterPermission(Permission_Free, this);

            permission.RegisterPermission(Permission_Limit_2, this);
            permission.RegisterPermission(Permission_Limit_3, this);
            permission.RegisterPermission(Permission_Limit_4, this);

            permission.RegisterPermission(Permission_SpawnWithCar, this);

            permission.RegisterPermission(Permission_AllModules, this);
            foreach (var moduleItemShortName in _pluginConfig.ModulePositions.Keys)
                permission.RegisterPermission(GetAutoTurretPermission(moduleItemShortName), this);

            if (_pluginConfig.EnableTurretPickup)
            {
                Unsubscribe(nameof(CanPickupEntity));
                Unsubscribe(nameof(canRemove));
            }

            if (!_pluginConfig.SpawnWithCarConfig.Enabled)
                Unsubscribe(nameof(OnEntitySpawned));
        }

        private void OnServerInitialized(bool initialBoot)
        {
            if (initialBoot)
                InitializeAutoTurrets();
        }

        private void OnEntitySpawned(ModularCar car)
        {
            if (Rust.Application.isLoadingSave || !ShouldSpawnTurretsWithCar(car))
                return;

            // Intentionally using both NextTick and Invoke.
            // Using NextTick to delay until the items have been added to the module inventory.
            // Using Invoke since that's what the game uses to delay spawning module entities.
            NextTick(() =>
            {
                if (car == null)
                    return;

                car.Invoke(() =>
                {
                    var ownerIdString = car.OwnerID != 0 ? car.OwnerID.ToString() : string.Empty;
                    var ownerPlayer = FindEntityOwner(car);

                    var allowedTurretsRemaining = GetCarAutoTurretLimit(car);
                    for (var i = 0; i < car.AttachedModuleEntities.Count && allowedTurretsRemaining > 0; i++)
                    {
                        var vehicleModule = car.AttachedModuleEntities[i];

                        Vector3 position;
                        if (!TryGetAutoTurretPositionForModule(vehicleModule, out position) ||
                            GetModuleAutoTurret(vehicleModule) != null ||
                            ownerIdString != string.Empty && !HasPermissionToVehicleModule(ownerIdString, vehicleModule) ||
                            UnityEngine.Random.Range(0, 100) >= GetAutoTurretChanceForModule(vehicleModule) ||
                            DeployWasBlocked(vehicleModule, ownerPlayer, automatedDeployment: true))
                            continue;

                        if (ownerPlayer == null)
                            DeployAutoTurret(car, vehicleModule, position);
                        else
                            DeployAutoTurretForPlayer(car, vehicleModule, position, ownerPlayer);

                        allowedTurretsRemaining--;
                    }
                }, 0);
            });
        }

        private object CanMoveItem(Item item, PlayerInventory playerInventory, uint targetContainerId, int targetSlot, int amount)
        {
            if (item == null || playerInventory == null)
                return null;

            var basePlayer = playerInventory.GetComponent<BasePlayer>();
            if (basePlayer == null)
                return null;

            var targetContainer = playerInventory.FindContainer(targetContainerId);
            if (item.parent == null || item.parent == targetContainer)
                return null;

            var fromCar = item.parent.entityOwner as ModularCar;
            if (fromCar != null)
                return HandleRemoveTurret(basePlayer, item, fromCar, targetContainer);

            if (targetContainer == null)
                return null;

            var toCar = targetContainer.entityOwner as ModularCar;
            if (toCar != null)
                return HandleAddTurret(basePlayer, item, toCar, targetContainer, targetSlot);

            return null;
        }

        private object HandleAddTurret(BasePlayer basePlayer, Item item, ModularCar car, ItemContainer targetContainer, int targetSlot)
        {
            var player = basePlayer.IPlayer;

            var itemid = item.info.itemid;
            if (itemid != ItemId_AutoTurret)
                return null;

            // In case a future update or a plugin adds another storage container to the car.
            if (car.Inventory.ModuleContainer != targetContainer)
                return null;

            if (!player.HasPermission(Permission_DeployInventory))
            {
                ChatMessage(basePlayer, "Generic.Error.NoPermission");
                return null;
            }

            if (!VerifyCarHasAutoTurretCapacity(player, car, replyInChat: true))
                return null;

            if (targetSlot == -1)
                targetSlot = FindFirstSuitableSocketIndex(car, basePlayer);

            if (targetSlot == -1)
            {
                ChatMessage(basePlayer, "Deploy.Error.NoSuitableModule");
                return null;
            }

            var moduleItem = targetContainer.GetSlot(targetSlot);
            if (moduleItem == null)
                return null;

            var vehicleModule = car.GetModuleForItem(moduleItem);
            if (vehicleModule == null)
                return null;

            if (!HasPermissionToVehicleModule(player.Id, vehicleModule))
            {
                ChatMessage(basePlayer, "Deploy.Error.NoPermissionToModule");
                return null;
            }

            if (GetModuleAutoTurret(vehicleModule) != null)
            {
                ChatMessage(basePlayer, "Deploy.Error.ModuleAlreadyHasTurret");
                return null;
            }

            Vector3 position;
            if (!TryGetAutoTurretPositionForModule(vehicleModule, out position) ||
                DeployWasBlocked(vehicleModule, basePlayer))
                return null;

            if (DeployAutoTurretForPlayer(car, vehicleModule, position, basePlayer, GetItemConditionFraction(item)) == null)
                return null;

            if (!player.HasPermission(Permission_Free))
                UseItem(basePlayer, item);

            return false;
        }

        private object HandleRemoveTurret(BasePlayer basePlayer, Item moduleItem, ModularCar car, ItemContainer targetContainer)
        {
            if (car.Inventory.ModuleContainer != moduleItem.parent)
                return null;

            var vehicleModule = car.GetModuleForItem(moduleItem);
            if (vehicleModule == null)
                return null;

            var autoTurret = GetModuleAutoTurret(vehicleModule);
            if (autoTurret == null)
                return null;

            var turretItem = ItemManager.CreateByItemID(ItemId_AutoTurret);
            if (turretItem == null)
                return null;

            if (_pluginConfig.EnableTurretPickup)
            {
                if (turretItem.info.condition.enabled)
                turretItem.condition = autoTurret.healthFraction * 100;

                if (targetContainer == null)
                {
                    if (!basePlayer.inventory.GiveItem(turretItem))
                    {
                        turretItem.Remove();
                        return false;
                    }
                }
                else if (!turretItem.MoveToContainer(targetContainer))
                {
                    turretItem.Remove();
                    return false;
                }

                basePlayer.Command("note.inv", ItemId_AutoTurret, 1);
            }

            autoTurret.Kill();
            return null;
        }

        private void OnItemDropped(Item item, BaseEntity itemEntity)
        {
            if (item == null || item.parent == null)
                return;

            var car = item.parent.entityOwner as ModularCar;
            if (car == null)
                return;

            if (item.info.GetComponent<ItemModVehicleModule>() == null)
                return;

            var vehicleModule = car.GetModuleForItem(item);
            if (vehicleModule == null)
                return;

            var autoTurret = GetModuleAutoTurret(vehicleModule);
            if (autoTurret == null)
                return;

            var turretItem = CreateItemFromAutoTurret(autoTurret);
            if (turretItem == null)
                return;

            var rigidBody = itemEntity.GetComponent<Rigidbody>();
            turretItem.Drop(itemEntity.transform.position, rigidBody?.velocity ?? Vector3.zero, itemEntity.transform.rotation);
        }

        // Automatically move a deployed turret when a module moves.
        // This is not done in the CanMoveItem hook since we don't know if it's being moved yet.
        private void OnEntityKill(BaseVehicleModule vehicleModule)
        {
            var moduleItem = vehicleModule.AssociatedItemInstance;
            if (moduleItem == null)
                return;

            var car = vehicleModule.Vehicle as ModularCar;
            if (car == null)
                return;

            var autoTurret = GetModuleAutoTurret(vehicleModule);
            if (autoTurret == null)
                return;

            autoTurret.SetParent(null);

            NextTick(() =>
            {
                if (car == null)
                {
                    autoTurret.Kill();
                }
                else
                {
                    var newModule = car.GetModuleForItem(moduleItem);
                    if (newModule == null)
                        autoTurret.Kill();
                    else
                        autoTurret.SetParent(newModule);
                }
            });
        }

        private object OnSwitchToggled(ElectricSwitch electricSwitch)
        {
            var autoTurret = GetParentTurret(electricSwitch);
            if (autoTurret == null)
                return null;

            var vehicleModule = GetParentVehicleModule(autoTurret);
            if (vehicleModule == null)
                return null;

            if (electricSwitch.IsOn())
                autoTurret.InitiateStartup();
            else
                autoTurret.InitiateShutdown();

            return null;
        }

        private object OnTurretTarget(AutoTurret turret, BasePlayer basePlayer)
        {
            if (turret == null || basePlayer == null || GetParentVehicleModule(turret) == null)
                return null;

            // Don't target human or NPC players in safe zones, unless they are hostile.
            if (basePlayer.InSafeZone() && (basePlayer.IsNpc || !basePlayer.IsHostile()))
                return false;

            return null;
        }

        // Prevent damage to turret switches on cars.
        private object OnEntityTakeDamage(ElectricSwitch electricSwitch)
        {
            var autoTurret = GetParentTurret(electricSwitch);
            if (autoTurret == null)
                return null;

            var vehicleModule = GetParentVehicleModule(autoTurret);
            if (vehicleModule == null)
                return null;

            return true;
        }

        // This is only subscribed while config option EnableTurretPickup is false.
        private object CanPickupEntity(BasePlayer player, AutoTurret turret)
        {
            if (GetParentVehicleModule(turret) != null)
                return false;

            return null;
        }

        // This hook is exposed by plugin: Remover Tool (RemoverTool).
        // Only subscribed while config option EnableTurretPickup is false.
        private object canRemove(BasePlayer player, AutoTurret turret)
        {
            if (GetParentVehicleModule(turret) != null)
                return false;

            return null;
        }

        #endregion

        #region API

        private AutoTurret API_DeployAutoTurret(BaseVehicleModule vehicleModule, BasePlayer basePlayer)
        {
            var car = vehicleModule.Vehicle as ModularCar;
            if (car == null)
                return null;

            Vector3 position;
            if (!TryGetAutoTurretPositionForModule(vehicleModule, out position) ||
                GetModuleAutoTurret(vehicleModule) != null ||
                DeployWasBlocked(vehicleModule, basePlayer))
                return null;

            if (basePlayer == null)
                return DeployAutoTurret(car, vehicleModule, position);
            else
                return DeployAutoTurretForPlayer(car, vehicleModule, position, basePlayer);
        }

        #endregion

        #region Commands

        [Command("carturret")]
        private void CommandDeploy(IPlayer player, string cmd, string[] args)
        {
            if (player.IsServer || !VerifyPermissionAny(player, Permission_DeployCommand))
                return;

            var basePlayer = player.Object as BasePlayer;
            ModularCar car;
            BaseVehicleModule vehicleModule;

            if (!VerifyCanBuild(player) ||
                !VerifyVehicleModuleFound(player, out car, out vehicleModule) ||
                !CanAccessVehicle(car, basePlayer) ||
                !VerifyCarHasAutoTurretCapacity(player, car) ||
                !VerifyPermissionToModule(player, vehicleModule))
                return;

            if (GetModuleAutoTurret(vehicleModule) != null)
            {
                ReplyToPlayer(player, "Deploy.Error.ModuleAlreadyHasTurret");
                return;
            }

            Vector3 position;
            if (!TryGetAutoTurretPositionForModule(vehicleModule, out position))
            {
                ReplyToPlayer(player, "Deploy.Error.UnsupportedModule");
                return;
            }

            Item autoTurretItem = null;
            var conditionFraction = 1.0f;

            var isFree = player.HasPermission(Permission_Free);
            if (!isFree)
            {
                autoTurretItem = FindPlayerAutoTurretItem(basePlayer);
                if (autoTurretItem == null)
                {
                    ReplyToPlayer(player, "Deploy.Error.NoTurret");
                    return;
                }
                conditionFraction = GetItemConditionFraction(autoTurretItem);
            }

            if (DeployWasBlocked(vehicleModule, basePlayer))
                return;

            if (DeployAutoTurretForPlayer(car, vehicleModule, position, basePlayer, conditionFraction) != null && !isFree && autoTurretItem != null)
                UseItem(basePlayer, autoTurretItem);
        }

        #endregion

        #region Helper Methods

        private static bool DeployWasBlocked(BaseVehicleModule vehicleModule, BasePlayer basePlayer, bool automatedDeployment = false)
        {
            object hookResult = Interface.CallHook("OnCarAutoTurretDeploy", vehicleModule, basePlayer, automatedDeployment);
            return hookResult is bool && (bool)hookResult == false;
        }

        private static void InitializeAutoTurrets()
        {
            foreach (var autoTurret in BaseNetworkable.serverEntities.OfType<AutoTurret>())
            {
                var vehicleModule = GetParentVehicleModule(autoTurret);
                if (vehicleModule == null) continue;

                RemoveProblemComponents(autoTurret);

                var turretSwitch = autoTurret.GetComponentInChildren<ElectricSwitch>();
                if (turretSwitch != null)
                    SetupTurretSwitch(turretSwitch);
            }
        }

        private static BaseVehicleModule FindClosestModuleToAim(ModularCar car, BasePlayer basePlayer)
        {
            var headRay = basePlayer.eyes.HeadRay();

            BaseVehicleModule closestModule = null;
            float closestDistance = 0;

            for (var socketIndex = 0; socketIndex < car.TotalSockets; socketIndex++)
            {
                BaseVehicleModule currentModule;
                if (car.TryGetModuleAt(socketIndex, out currentModule) && currentModule.FirstSocketIndex == socketIndex)
                {
                    var currentDistance = Vector3.Cross(headRay.direction, currentModule.CenterPoint() - headRay.origin).magnitude;
                    if (ReferenceEquals(closestModule, null))
                    {
                        closestModule = currentModule;
                        closestDistance = currentDistance;
                    }
                    else if (currentDistance < closestDistance)
                    {
                        closestModule = currentModule;
                        closestDistance = currentDistance;
                    }
                }
            }

            return closestModule;
        }

        private static void UseItem(BasePlayer basePlayer, Item item, int amountToConsume = 1)
        {
            item.amount -= amountToConsume;
            if (item.amount <= 0)
            {
                item.RemoveFromContainer();
                item.Remove();
            }
            else
                item.MarkDirty();

            basePlayer.Command("note.inv", item.info.itemid, -amountToConsume);
        }

        private static float GetItemConditionFraction(Item item) =>
            item.hasCondition ? item.condition / item.info.condition.max : 1.0f;

        private static Item FindPlayerAutoTurretItem(BasePlayer basePlayer) =>
            basePlayer.inventory.FindItemID(ItemId_AutoTurret);

        private static Item CreateItemFromAutoTurret(AutoTurret autoTurret)
        {
            var turretItem = ItemManager.CreateByItemID(ItemId_AutoTurret);
            if (turretItem == null)
                return null;

            if (turretItem.info.condition.enabled)
                turretItem.condition = autoTurret.healthFraction * 100;

            return turretItem;
        }

        private static string GetAutoTurretPermissionForModule(BaseVehicleModule vehicleModule) =>
            GetAutoTurretPermission(vehicleModule.AssociatedItemDef.shortname);

        private static string GetAutoTurretPermission(string moduleItemShrotName) =>
            string.Format(Permission_ModuleFormat, moduleItemShrotName);

        private static int GetCarTurretCount(ModularCar car)
        {
            var numTurrets = 0;
            foreach (var module in car.AttachedModuleEntities)
            {
                var turret = GetModuleAutoTurret(module);
                if (turret != null)
                    numTurrets++;
            }
            return numTurrets;
        }

        private static AutoTurret GetModuleAutoTurret(BaseVehicleModule vehicleModule)
        {
            foreach (var child in vehicleModule.children)
            {
                var turret = child as AutoTurret;
                if (turret != null)
                    return turret;
            }
            return null;
        }

        private static bool IsNaturalCarSpawn(ModularCar car)
        {
            var spawnable = car.GetComponent<Spawnable>();
            return spawnable != null && spawnable.Population != null;
        }

        private static BaseVehicleModule GetParentVehicleModule(BaseEntity entity) =>
            entity.GetParentEntity() as BaseVehicleModule;

        private static AutoTurret GetParentTurret(BaseEntity entity) =>
            entity.GetParentEntity() as AutoTurret;

        private static void RunOnEntityBuilt(Item turretItem, AutoTurret autoTurret) =>
            Interface.CallHook("OnEntityBuilt", turretItem.GetHeldEntity(), autoTurret.gameObject);

        private static AutoTurret DeployAutoTurret(ModularCar car, BaseVehicleModule vehicleModule, Vector3 position, float conditionFraction = 1, ulong ownerId = 0)
        {
            var autoTurret = GameManager.server.CreateEntity(Prefab_Entity_AutoTurret, position, GetIdealTurretRotation(car, vehicleModule)) as AutoTurret;
            if (autoTurret == null)
                return null;

            autoTurret.SetFlag(IOEntity.Flag_HasPower, true);
            autoTurret.SetParent(vehicleModule);
            autoTurret.OwnerID = ownerId;
            RemoveProblemComponents(autoTurret);
            autoTurret.Spawn();
            autoTurret.SetHealth(autoTurret.MaxHealth() * conditionFraction);
            AttachTurretSwitch(autoTurret);

            Effect.server.Run(Prefab_Effect_DeployAutoTurret, autoTurret.transform.position);

            return autoTurret;
        }

        private static ElectricSwitch AttachTurretSwitch(AutoTurret autoTurret)
        {
            var turretSwitch = GameManager.server.CreateEntity(Prefab_Entity_ElectricSwitch, autoTurret.transform.TransformPoint(TurretSwitchPosition), autoTurret.transform.rotation * TurretSwitchRotation) as ElectricSwitch;
            if (turretSwitch == null)
                return null;

            SetupTurretSwitch(turretSwitch);
            turretSwitch.Spawn();
            turretSwitch.SetParent(autoTurret, true);

            return turretSwitch;
        }

        private static void SetupTurretSwitch(ElectricSwitch electricSwitch)
        {
            electricSwitch.pickup.enabled = false;
            electricSwitch.SetFlag(IOEntity.Flag_HasPower, true);
            RemoveProblemComponents(electricSwitch);
            HideInputsAndOutputs(electricSwitch);
        }

        private static void HideInputsAndOutputs(IOEntity ioEntity)
        {
            // Hide the inputs and outputs on the client.
            foreach (var input in ioEntity.inputs)
                input.type = IOEntity.IOType.Generic;

            foreach (var output in ioEntity.outputs)
                output.type = IOEntity.IOType.Generic;
        }

        private static Quaternion GetIdealTurretRotation(ModularCar car, BaseVehicleModule vehicleModule) =>
            vehicleModule.FirstSocketIndex + 1 > (car.TotalSockets + 1) / 2 ? TurretBackwardRotation : Quaternion.identity;

        private static void RemoveProblemComponents(BaseEntity ent)
        {
            foreach (var meshCollider in ent.GetComponentsInChildren<MeshCollider>())
                UnityEngine.Object.DestroyImmediate(meshCollider);

            UnityEngine.Object.DestroyImmediate(ent.GetComponent<DestroyOnGroundMissing>());
            UnityEngine.Object.DestroyImmediate(ent.GetComponent<GroundWatch>());
        }

        private static BaseEntity GetLookEntity(BasePlayer basePlayer, float maxDistance = 3)
        {
            RaycastHit hit;
            return Physics.Raycast(basePlayer.eyes.HeadRay(), out hit, maxDistance, Physics.DefaultRaycastLayers, QueryTriggerInteraction.Ignore)
                ? hit.GetEntity()
                : null;
        }

        private static BasePlayer FindEntityOwner(BaseEntity entity) =>
            entity.OwnerID != 0 ? BasePlayer.FindByID(entity.OwnerID) : null;

        private bool CanAccessVehicle(BaseVehicle vehicle, BasePlayer basePlayer, bool provideFeedback = true)
        {
            if (VehicleDeployedLocks == null)
                return true;

            var canAccess = VehicleDeployedLocks.Call("API_CanAccessVehicle", basePlayer, vehicle, provideFeedback);
            return !(canAccess is bool) || (bool)canAccess;
        }

        private bool VerifyPermissionAny(IPlayer player, params string[] permissionNames)
        {
            foreach (var perm in permissionNames)
                if (player.HasPermission(perm))
                    return true;

            ReplyToPlayer(player, "Generic.Error.NoPermission");
            return false;
        }

        private bool VerifyCanBuild(IPlayer player)
        {
            if ((player.Object as BasePlayer).CanBuild())
                return true;

            ReplyToPlayer(player, "Generic.Error.BuildingBlocked");
            return false;
        }

        private bool VerifyVehicleModuleFound(IPlayer player, out ModularCar car, out BaseVehicleModule vehicleModule)
        {
            var basePlayer = player.Object as BasePlayer;
            var entity = GetLookEntity(basePlayer);

            vehicleModule = entity as BaseVehicleModule;
            if (vehicleModule != null)
            {
                car = vehicleModule.Vehicle as ModularCar;
                if (car != null)
                    return true;

                ReplyToPlayer(player, "Deploy.Error.NoCarFound");
                return false;
            }

            car = entity as ModularCar;
            if (car == null)
            {
                var lift = entity as ModularCarGarage;
                car = lift?.carOccupant;
                if (car == null)
                {
                    ReplyToPlayer(player, "Deploy.Error.NoCarFound");
                    return false;
                }
            }

            BaseVehicleModule closestModule = FindClosestModuleToAim(car, basePlayer);

            if (closestModule != null)
            {
                vehicleModule = closestModule;
                return true;
            }

            ReplyToPlayer(player, "Deploy.Error.NoModules");
            return false;
        }

        private bool VerifyCarHasAutoTurretCapacity(IPlayer player, ModularCar car, bool replyInChat = false)
        {
            var limit = GetCarAutoTurretLimit(car);
            if (GetCarTurretCount(car) < limit)
                return true;

            if (replyInChat)
                ChatMessage(player.Object as BasePlayer, "Deploy.Error.TurretLimit", limit);
            else
                ReplyToPlayer(player, "Deploy.Error.TurretLimit", limit);

            return false;
        }

        private bool VerifyPermissionToModule(IPlayer player, BaseVehicleModule vehicleModule)
        {
            if (HasPermissionToVehicleModule(player.Id, vehicleModule))
                return true;

            ReplyToPlayer(player, "Deploy.Error.NoPermissionToModule");
            return false;
        }

        private int FindFirstSuitableSocketIndex(ModularCar car, BasePlayer basePlayer)
        {
            for (var socketIndex = 0; socketIndex < car.TotalSockets; socketIndex++)
            {
                BaseVehicleModule currentModule;
                if (car.TryGetModuleAt(socketIndex, out currentModule)
                    && currentModule.FirstSocketIndex == socketIndex
                    && HasPermissionToVehicleModule(basePlayer.UserIDString, currentModule)
                    && GetModuleAutoTurret(currentModule) == null)
                {
                    return socketIndex;
                }
            }

            return -1;
        }

        private int GetCarAutoTurretLimit(ModularCar car)
        {
            var defaultLimit = _pluginConfig.DefaultLimitPerCar;

            if (car.OwnerID == 0)
                return defaultLimit;

            var ownerIdString = car.OwnerID.ToString();

            if (defaultLimit < 4 && permission.UserHasPermission(ownerIdString, Permission_Limit_4))
                return 4;
            else if (defaultLimit < 3 && permission.UserHasPermission(ownerIdString, Permission_Limit_3))
                return 3;
            else if (defaultLimit < 2 && permission.UserHasPermission(ownerIdString, Permission_Limit_2))
                return 2;

            return defaultLimit;
        }

        private bool HasPermissionToVehicleModule(string userId, BaseVehicleModule vehicleModule) =>
            permission.UserHasPermission(userId, Permission_AllModules) ||
            permission.UserHasPermission(userId, GetAutoTurretPermissionForModule(vehicleModule));

        private bool ShouldSpawnTurretsWithCar(ModularCar car)
        {
            var spawnWithCarConfig = _pluginConfig.SpawnWithCarConfig;
            if (!spawnWithCarConfig.Enabled)
                return false;

            if (IsNaturalCarSpawn(car))
                return spawnWithCarConfig.NaturalCarSpawns.Enabled;

            if (!spawnWithCarConfig.OtherCarSpawns.Enabled)
                return false;

            if (!spawnWithCarConfig.OtherCarSpawns.RequirePermission)
                return true;

            return car.OwnerID != 0 && permission.UserHasPermission(car.OwnerID.ToString(), Permission_SpawnWithCar);
        }

        private bool TryGetAutoTurretPositionForModule(BaseVehicleModule vehicleModule, out Vector3 position) =>
            _pluginConfig.ModulePositions.TryGetValue(vehicleModule.AssociatedItemDef.shortname, out position);

        private int GetAutoTurretChanceForModule(BaseVehicleModule vehicleModule)
        {
            int chance;
            return _pluginConfig.SpawnWithCarConfig.SpawnChanceByModule.TryGetValue(vehicleModule.AssociatedItemDef.shortname, out chance)
                ? chance
                : 0;
        }

        private AutoTurret DeployAutoTurretForPlayer(ModularCar car, BaseVehicleModule vehicleModule, Vector3 position, BasePlayer basePlayer, float conditionFraction = 1)
        {
            var autoTurret = DeployAutoTurret(car, vehicleModule, position, conditionFraction, basePlayer.userID);
            if (autoTurret == null)
                return null;

            autoTurret.authorizedPlayers.Add(new ProtoBuf.PlayerNameID
            {
                userid = basePlayer.userID,
                username = basePlayer.displayName
            });
            autoTurret.SendNetworkUpdate();

            // Allow other plugins to detect the auto turret being deployed (e.g., to add a weapon automatically).
            var turretItem = FindPlayerAutoTurretItem(basePlayer);
            if (turretItem != null)
            {
                RunOnEntityBuilt(turretItem, autoTurret);
            }
            else
            {
                // Temporarily increase the player inventory capacity to ensure there is enough space.
                basePlayer.inventory.containerMain.capacity++;
                var temporaryTurretItem = ItemManager.CreateByItemID(ItemId_AutoTurret);
                if (basePlayer.inventory.GiveItem(temporaryTurretItem))
                {
                    RunOnEntityBuilt(temporaryTurretItem, autoTurret);
                    temporaryTurretItem.RemoveFromContainer();
                }
                temporaryTurretItem.Remove();
                basePlayer.inventory.containerMain.capacity--;
            }

            return autoTurret;
        }

        #endregion

        #region Configuration

        internal class Configuration : SerializableConfiguration
        {
            [JsonProperty("DefaultLimitPerCar")]
            public int DefaultLimitPerCar = 4;

            [JsonProperty("EnableTurretPickup")]
            public bool EnableTurretPickup = true;

            [JsonProperty("SpawnWithCar")]
            public SpawnWithCarConfig SpawnWithCarConfig = new SpawnWithCarConfig();

            [JsonProperty("AutoTurretPositionByModule")]
            public Dictionary<string, Vector3> ModulePositions = new Dictionary<string, Vector3>()
            {
                ["vehicle.1mod.cockpit"] = new Vector3(0, 1.39f, -0.3f),
                ["vehicle.1mod.cockpit.armored"] = new Vector3(0, 1.39f, -0.3f),
                ["vehicle.1mod.cockpit.with.engine"] = new Vector3(0, 1.39f, -0.85f),
                ["vehicle.1mod.engine"] = new Vector3(0, 0.4f, 0),
                ["vehicle.1mod.flatbed"] = new Vector3(0, 0.06f, 0),
                ["vehicle.1mod.passengers.armored"] = new Vector3(0, 1.38f, -0.31f),
                ["vehicle.1mod.rear.seats"] = new Vector3(0, 1.4f, -0.12f),
                ["vehicle.1mod.storage"] = new Vector3(0, 0.61f, 0),
                ["vehicle.1mod.taxi"] = new Vector3(0, 1.38f, -0.13f),
                ["vehicle.2mod.flatbed"] = new Vector3(0, 0.06f, -0.7f),
                ["vehicle.2mod.fuel.tank"] = new Vector3(0, 1.28f, -0.85f),
                ["vehicle.2mod.passengers"] = new Vector3(0, 1.4f, -0.9f)
            };
        }

        internal class SpawnWithCarConfig
        {
            [JsonProperty("NaturalCarSpawns")]
            public NaturalCarSpawnsConfig NaturalCarSpawns = new NaturalCarSpawnsConfig();

            [JsonProperty("OtherCarSpawns")]
            public OtherCarSpawnsConfig OtherCarSpawns = new OtherCarSpawnsConfig();

            [JsonProperty("SpawnChanceByModule")]
            public Dictionary<string, int> SpawnChanceByModule = new Dictionary<string, int>()
            {
                ["vehicle.1mod.cockpit"] = 0,
                ["vehicle.1mod.cockpit.armored"] = 0,
                ["vehicle.1mod.cockpit.with.engine"] = 0,
                ["vehicle.1mod.engine"] = 0,
                ["vehicle.1mod.flatbed"] = 0,
                ["vehicle.1mod.passengers.armored"] = 0,
                ["vehicle.1mod.rear.seats"] = 0,
                ["vehicle.1mod.storage"] = 0,
                ["vehicle.1mod.taxi"] = 0,
                ["vehicle.2mod.flatbed"] = 0,
                ["vehicle.2mod.fuel.tank"] = 0,
                ["vehicle.2mod.passengers"] = 0
            };

            [JsonIgnore]
            public bool Enabled =>
                NaturalCarSpawns.Enabled || OtherCarSpawns.Enabled;
        }

        internal class NaturalCarSpawnsConfig
        {
            [JsonProperty("Enabled")]
            public bool Enabled = false;
        }

        internal class OtherCarSpawnsConfig
        {
            [JsonProperty("Enabled")]
            public bool Enabled = false;

            [JsonProperty("RequirePermission")]
            public bool RequirePermission = false;
        }

        private Configuration GetDefaultConfig() => new Configuration();

        #endregion

        #region Configuration Boilerplate

        internal class SerializableConfiguration
        {
            public string ToJson() => JsonConvert.SerializeObject(this);

            public Dictionary<string, object> ToDictionary() => JsonHelper.Deserialize(ToJson()) as Dictionary<string, object>;
        }

        internal static class JsonHelper
        {
            public static object Deserialize(string json) => ToObject(JToken.Parse(json));

            private static object ToObject(JToken token)
            {
                switch (token.Type)
                {
                    case JTokenType.Object:
                        return token.Children<JProperty>()
                                    .ToDictionary(prop => prop.Name,
                                                  prop => ToObject(prop.Value));

                    case JTokenType.Array:
                        return token.Select(ToObject).ToList();

                    default:
                        return ((JValue)token).Value;
                }
            }
        }

        private bool MaybeUpdateConfig(SerializableConfiguration config)
        {
            var currentWithDefaults = config.ToDictionary();
            var currentRaw = Config.ToDictionary(x => x.Key, x => x.Value);
            return MaybeUpdateConfigDict(currentWithDefaults, currentRaw);
        }

        private bool MaybeUpdateConfigDict(Dictionary<string, object> currentWithDefaults, Dictionary<string, object> currentRaw)
        {
            bool changed = false;

            foreach (var key in currentWithDefaults.Keys)
            {
                object currentRawValue;
                if (currentRaw.TryGetValue(key, out currentRawValue))
                {
                    var defaultDictValue = currentWithDefaults[key] as Dictionary<string, object>;
                    var currentDictValue = currentRawValue as Dictionary<string, object>;

                    if (defaultDictValue != null)
                    {
                        if (currentDictValue == null)
                        {
                            currentRaw[key] = currentWithDefaults[key];
                            changed = true;
                        }
                        else if (MaybeUpdateConfigDict(defaultDictValue, currentDictValue))
                            changed = true;
                    }
                }
                else
                {
                    currentRaw[key] = currentWithDefaults[key];
                    changed = true;
                }
            }

            return changed;
        }

        protected override void LoadDefaultConfig() => _pluginConfig = GetDefaultConfig();

        protected override void LoadConfig()
        {
            base.LoadConfig();
            try
            {
                _pluginConfig = Config.ReadObject<Configuration>();
                if (_pluginConfig == null)
                {
                    throw new JsonException();
                }

                if (MaybeUpdateConfig(_pluginConfig))
                {
                    LogWarning("Configuration appears to be outdated; updating and saving");
                    SaveConfig();
                }
            }
            catch
            {
                LogWarning($"Configuration file {Name}.json is invalid; using defaults");
                LoadDefaultConfig();
            }
        }

        protected override void SaveConfig()
        {
            Log($"Configuration changes saved to {Name}.json");
            Config.WriteObject(_pluginConfig, true);
        }

        #endregion

        #region Localization

        private void ReplyToPlayer(IPlayer player, string messageName, params object[] args) =>
            player.Reply(string.Format(GetMessage(player, messageName), args));

        private void ChatMessage(BasePlayer basePlayer, string messageName, params object[] args) =>
            basePlayer.ChatMessage(string.Format(GetMessage(basePlayer.IPlayer, messageName), args));

        private string GetMessage(IPlayer player, string messageName, params object[] args)
        {
            var message = lang.GetMessage(messageName, this, player.Id);
            return args.Length > 0 ? string.Format(message, args) : message;
        }

        protected override void LoadDefaultMessages()
        {
            lang.RegisterMessages(new Dictionary<string, string>
            {
                ["Generic.Error.NoPermission"] = "You don't have permission to do that.",
                ["Generic.Error.BuildingBlocked"] = "Error: Cannot do that while building blocked.",
                ["Deploy.Error.NoCarFound"] = "Error: No car found.",
                ["Deploy.Error.NoModules"] = "Error: That car has no modules.",
                ["Deploy.Error.NoPermissionToModule"] = "You don't have permission to do that to that module type.",
                ["Deploy.Error.ModuleAlreadyHasTurret"] = "Error: That module already has a turret.",
                ["Deploy.Error.UnsupportedModule"] = "Error: That module is not supported.",
                ["Deploy.Error.TurretLimit"] = "Error: That car may only have {0} turret(s).",
                ["Deploy.Error.NoSuitableModule"] = "Error: No suitable module found.",
                ["Deploy.Error.NoTurret"] = "Error: You need an auto turret to do that.",
            }, this, "en");
        }

        #endregion
    }
}