using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Linq;
using Robust.Shared.GameStates;
using Robust.Shared.Physics;
using Robust.Shared.Players;
using Robust.Shared.Utility;
using System.Runtime.CompilerServices;
using Robust.Shared.Log;
using System.Diagnostics;
#if EXCEPTION_TOLERANCE
using Robust.Shared.Exceptions;
#endif

namespace Robust.Shared.GameObjects
{
    /// <inheritdoc />
    public partial class EntityManager
    {
        [IoC.Dependency] private readonly IComponentFactory _componentFactory = default!;

#if EXCEPTION_TOLERANCE
        [IoC.Dependency] private readonly IRuntimeLog _runtimeLog = default!;
#endif

        public IComponentFactory ComponentFactory => _componentFactory;

        private const int TypeCapacity = 32;
        private const int ComponentCollectionCapacity = 1024;
        private const int EntityCapacity = 1024;
        private const int NetComponentCapacity = 8;

        private readonly Dictionary<EntityUid, Dictionary<ushort, Component>> _netComponents
            = new(EntityCapacity);

        private readonly Dictionary<Type, Dictionary<EntityUid, Component>> _entTraitDict
            = new();

        private Dictionary<EntityUid, Component>[] _entTraitArray
            = Array.Empty<Dictionary<EntityUid, Component>>();

        private readonly HashSet<Component> _deleteSet = new(TypeCapacity);

        private UniqueIndexHkm<EntityUid, Component> _entCompIndex =
            new(ComponentCollectionCapacity);

        /// <inheritdoc />
        public event Action<AddedComponentEventArgs>? ComponentAdded;

        /// <inheritdoc />
        public event Action<RemovedComponentEventArgs>? ComponentRemoved;

        /// <inheritdoc />
        public event Action<DeletedComponentEventArgs>? ComponentDeleted;

        public void InitializeComponents()
        {
            if (Initialized)
                throw new InvalidOperationException("Already initialized.");

            FillComponentDict();
            _componentFactory.ComponentAdded += OnComponentAdded;
            _componentFactory.ComponentReferenceAdded += OnComponentReferenceAdded;
        }

        /// <summary>
        ///     Instantly clears all components from the manager. This will NOT shut them down gracefully.
        ///     Any entities relying on existing components will be broken.
        /// </summary>
        public void ClearComponents()
        {
            _componentFactory.ComponentAdded -= OnComponentAdded;
            _componentFactory.ComponentReferenceAdded -= OnComponentReferenceAdded;
            _netComponents.Clear();
            _entCompIndex.Clear();
            _deleteSet.Clear();
            FillComponentDict();
        }

        private void AddComponentRefType(CompIdx type)
        {
            var dict = new Dictionary<EntityUid, Component>();
            _entTraitDict.Add(_componentFactory.IdxToType(type), dict);
            CompIdx.AssignArray(ref _entTraitArray, type, dict);
        }

        private void OnComponentAdded(ComponentRegistration obj)
        {
            AddComponentRefType(obj.Idx);
        }

        private void OnComponentReferenceAdded(ComponentRegistration reg, CompIdx type)
        {
            AddComponentRefType(type);
        }

        #region Component Management

        public void InitializeComponents(EntityUid uid, MetaDataComponent? metadata = null)
        {
            metadata ??= GetComponent<MetaDataComponent>(uid);
            DebugTools.Assert(metadata.EntityLifeStage == EntityLifeStage.PreInit);
            metadata.EntityLifeStage = EntityLifeStage.Initializing;

            // Initialize() can modify the collection of components. Copy them.
            FixedArray32<Component?> compsFixed = default;

            var comps = compsFixed.AsSpan;
            CopyComponentsInto(ref comps, uid);

            // TODO: please for the love of god remove these initialization order hacks.

            // Init transform first, we always have it.
            var transform = GetComponent<TransformComponent>(uid);
            if (transform.LifeStage < ComponentLifeStage.Initialized)
                transform.LifeInitialize(this);

            // Init physics second if it exists.
            if (TryGetComponent<PhysicsComponent>(uid, out var phys)
                && phys.LifeStage < ComponentLifeStage.Initialized)
            {
                phys.LifeInitialize(this);
            }

            // Do rest of components.
            foreach (var comp in comps)
            {
                if (comp is { LifeStage: < ComponentLifeStage.Initialized })
                    comp.LifeInitialize(this);
            }

#if DEBUG
            // Second integrity check in case of.
            foreach (var t in _entCompIndex[uid])
            {
                if (!t.Deleted && !t.Initialized)
                {
                    DebugTools.Assert(
                        $"Component {t.GetType()} was not initialized at the end of {nameof(InitializeComponents)}.");
                }
            }

#endif
            DebugTools.Assert(metadata.EntityLifeStage == EntityLifeStage.Initializing);
            metadata.EntityLifeStage = EntityLifeStage.Initialized;
            EventBus.RaiseEvent(EventSource.Local, new EntityInitializedMessage(uid));
        }

        public void StartComponents(EntityUid uid)
        {
            // Startup() can modify _components
            // This code can only handle additions to the list. Is there a better way? Probably not.
            FixedArray32<Component?> compsFixed = default;

            var comps = compsFixed.AsSpan;
            CopyComponentsInto(ref comps, uid);

            // TODO: please for the love of god remove these initialization order hacks.

            // Init transform first, we always have it.
            var transform = GetComponent<TransformComponent>(uid);
            if (transform.LifeStage == ComponentLifeStage.Initialized)
                transform.LifeStartup(this);

            // Init physics second if it exists.
            if (TryGetComponent<PhysicsComponent>(uid, out var phys)
                && phys.LifeStage == ComponentLifeStage.Initialized)
            {
                phys.LifeStartup(this);
            }

            // Do rest of components.
            foreach (var comp in comps)
            {
                if (comp is { LifeStage: ComponentLifeStage.Initialized })
                    comp.LifeStartup(this);
            }
        }

        public T AddComponent<T>(EntityUid uid) where T : Component, new()
        {
            var newComponent = _componentFactory.GetComponent<T>();
            newComponent.Owner = uid;
            AddComponent(uid, newComponent);
            return newComponent;
        }

        public readonly struct CompInitializeHandle<T> : IDisposable
            where T : Component
        {
            private readonly IEntityManager _entMan;
            public readonly T Comp;

            public CompInitializeHandle(IEntityManager entityManager, T comp)
            {
                _entMan = entityManager;
                Comp = comp;
            }

            public void Dispose()
            {
                var metadata = _entMan.GetComponent<MetaDataComponent>(Comp.Owner);

                if (!metadata.EntityInitialized && !metadata.EntityInitializing)
                    return;

                if (!Comp.Initialized)
                    Comp.LifeInitialize(_entMan);

                if (metadata.EntityInitialized && !Comp.Running)
                    Comp.LifeStartup(_entMan);
            }

            public static implicit operator T(CompInitializeHandle<T> handle)
            {
                return handle.Comp;
            }
        }

        /// <inheritdoc />
        public CompInitializeHandle<T> AddComponentUninitialized<T>(EntityUid uid) where T : Component, new()
        {
            var newComponent = _componentFactory.GetComponent<T>();
            newComponent.Owner = uid;

            if (!uid.IsValid() || !EntityExists(uid))
                throw new ArgumentException("Entity is not valid.", nameof(uid));

            if (newComponent == null) throw new ArgumentNullException(nameof(newComponent));

            if (newComponent.Owner != uid) throw new InvalidOperationException("Component is not owned by entity.");

            AddComponentInternal(uid, newComponent, false, true);

            return new CompInitializeHandle<T>(this, newComponent);
        }

        /// <inheritdoc />
        public void AddComponent<T>(EntityUid uid, T component, bool overwrite = false) where T : Component
        {
            if (!uid.IsValid() || !EntityExists(uid))
                throw new ArgumentException("Entity is not valid.", nameof(uid));

            if (component == null) throw new ArgumentNullException(nameof(component));

            if (component.Owner != uid) throw new InvalidOperationException("Component is not owned by entity.");

            AddComponentInternal(uid, component, overwrite, false);
        }

        private void AddComponentInternal<T>(EntityUid uid, T component, bool overwrite, bool skipInit) where T : Component
        {
            // get interface aliases for mapping
            var reg = _componentFactory.GetRegistration(component);

            // Check that there are no overlapping references.
            foreach (var type in reg.References)
            {
                var dict = _entTraitArray[type.Value];
                if (!dict.TryGetValue(uid, out var duplicate))
                    continue;

                if (!overwrite && !duplicate.Deleted)
                    throw new InvalidOperationException(
                        $"Component reference type {type} already occupied by {duplicate}");

                RemoveComponentImmediate(duplicate, uid, false);
            }

            // add the component to the grid
            foreach (var type in reg.References)
            {
                _entTraitArray[type.Value].Add(uid, component);
                _entCompIndex.Add(uid, component);
            }

            // add the component to the netId grid
            if (reg.NetID != null)
            {
                // the main comp grid keeps this in sync
                var netId = reg.NetID.Value;

                if (!_netComponents.TryGetValue(uid, out var netSet))
                {
                    netSet = new Dictionary<ushort, Component>(NetComponentCapacity);
                    _netComponents.Add(uid, netSet);
                }

                netSet.Add(netId, component);

                // mark the component as dirty for networking
                Dirty(component);
            }

            ComponentAdded?.Invoke(new AddedComponentEventArgs(new ComponentEventArgs(component, uid)));

            component.LifeAddToEntity(this);

            if (skipInit)
                return;

            var metadata = GetComponent<MetaDataComponent>(uid);

            if (!metadata.EntityInitialized && !metadata.EntityInitializing)
                return;

            component.LifeInitialize(this);

            if (metadata.EntityInitialized)
                component.LifeStartup(this);
        }

        /// <inheritdoc />
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public bool RemoveComponent<T>(EntityUid uid)
        {
            return RemoveComponent(uid, typeof(T));
        }

        /// <inheritdoc />
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public bool RemoveComponent(EntityUid uid, Type type)
        {
            if (!TryGetComponent(uid, type, out var comp))
                return false;

            RemoveComponentImmediate((Component)comp, uid, false);
            return true;
        }

        /// <inheritdoc />
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public bool RemoveComponent(EntityUid uid, ushort netId)
        {
            if (!TryGetComponent(uid, netId, out var comp))
                return false;

            RemoveComponentImmediate((Component)comp, uid, false);
            return true;
        }

        /// <inheritdoc />
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public void RemoveComponent(EntityUid uid, IComponent component)
        {
            RemoveComponent(uid, (Component)component);
        }

        /// <inheritdoc />
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public void RemoveComponent(EntityUid uid, Component component)
        {
            if (component == null) throw new ArgumentNullException(nameof(component));

            if (component.Owner != uid)
                throw new InvalidOperationException("Component is not owned by entity.");

            RemoveComponentImmediate(component, uid, false);
        }

        private static IEnumerable<Component> InSafeOrder(IEnumerable<Component> comps, bool forCreation = false)
        {
            static int Sequence(IComponent x)
                => x switch
                {
                    MetaDataComponent _ => 0,
                    TransformComponent _ => 1,
                    IPhysBody _ => 2,
                    _ => int.MaxValue
                };

            return forCreation
                ? comps.OrderBy(Sequence)
                : comps.OrderByDescending(Sequence);
        }

        /// <inheritdoc />
        public void RemoveComponents(EntityUid uid)
        {
            foreach (var comp in InSafeOrder(_entCompIndex[uid]))
            {
                RemoveComponentImmediate(comp, uid, false);
            }
        }

        /// <inheritdoc />
        public void DisposeComponents(EntityUid uid)
        {
            foreach (var comp in InSafeOrder(_entCompIndex[uid]))
            {
                RemoveComponentImmediate(comp, uid, true);
            }

            // DisposeComponents means the entity is getting deleted.
            // Safe to wipe the entity out of the index.
            _entCompIndex.Remove(uid);
        }

        private void RemoveComponentDeferred(Component component, EntityUid uid, bool removeProtected)
        {
            if (component == null) throw new ArgumentNullException(nameof(component));

            if (component.Deleted) return;

#if EXCEPTION_TOLERANCE
            try
            {
#endif
            // these two components are required on all entities and cannot be removed normally.
            if (!removeProtected && component is TransformComponent or MetaDataComponent)
            {
                DebugTools.Assert("Tried to remove a protected component.");
                return;
            }

            if (!_deleteSet.Add(component))
            {
                // already deferred deletion
                return;
            }

            if (component.Running)
                component.LifeShutdown(this);

            if (component.LifeStage != ComponentLifeStage.PreAdd)
                component.LifeRemoveFromEntity(this);
            ComponentRemoved?.Invoke(new RemovedComponentEventArgs(new ComponentEventArgs(component, uid)));
#if EXCEPTION_TOLERANCE
            }
            catch (Exception e)
            {
                _runtimeLog.LogException(e,
                    $"RemoveComponentDeferred, owner={component.Owner}, type={component.GetType()}");
            }
#endif
        }

        private void RemoveComponentImmediate(Component component, EntityUid uid, bool removeProtected)
        {
            if (component == null) throw new ArgumentNullException(nameof(component));

#if EXCEPTION_TOLERANCE
            try
            {
#endif
            if (!component.Deleted)
            {
                // these two components are required on all entities and cannot be removed.
                if (!removeProtected && component is TransformComponent or MetaDataComponent)
                {
                    DebugTools.Assert("Tried to remove a protected component.");
                    return;
                }

                if (component.Running)
                    component.LifeShutdown(this);

                if (component.LifeStage != ComponentLifeStage.PreAdd)
                    component.LifeRemoveFromEntity(this); // Sets delete

                ComponentRemoved?.Invoke(new RemovedComponentEventArgs(new ComponentEventArgs(component, uid)));
            }
#if EXCEPTION_TOLERANCE
            }
            catch (Exception e)
            {
                _runtimeLog.LogException(e,
                    $"RemoveComponentImmediate, owner={component.Owner}, type={component.GetType()}");
            }
#endif

            DeleteComponent(component);
        }

        /// <inheritdoc />
        public void CullRemovedComponents()
        {
            foreach (var component in InSafeOrder(_deleteSet))
            {
                DeleteComponent(component);
            }

            _deleteSet.Clear();
        }

        private void DeleteComponent(Component component)
        {
            var reg = _componentFactory.GetRegistration(component.GetType());

            var entityUid = component.Owner;

            // ReSharper disable once InvertIf
            if (reg.NetID != null)
            {
                var netSet = _netComponents[entityUid];
                if (netSet.Count == 1)
                    _netComponents.Remove(entityUid);
                else
                    netSet.Remove(reg.NetID.Value);

                Dirty(entityUid);
            }

            foreach (var refType in reg.References)
            {
                _entTraitArray[refType.Value].Remove(entityUid);
            }

            _entCompIndex.Remove(entityUid, component);
            ComponentDeleted?.Invoke(new DeletedComponentEventArgs(new ComponentEventArgs(component, entityUid)));
        }

        /// <inheritdoc />
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public bool HasComponent<T>(EntityUid uid)
        {
            return _entTraitArray[CompIdx.ArrayIndex<T>()].TryGetValue(uid, out var comp) && !comp.Deleted;
        }

        /// <inheritdoc />
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public bool HasComponent<T>(EntityUid? uid)
        {
            return uid.HasValue && HasComponent<T>(uid.Value);
        }

        /// <inheritdoc />
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public bool HasComponent(EntityUid uid, Type type)
        {
            var dict = _entTraitDict[type];
            return dict.TryGetValue(uid, out var comp) && !comp.Deleted;
        }

        /// <inheritdoc />
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public bool HasComponent(EntityUid? uid, Type type)
        {
            if (!uid.HasValue)
            {
                return false;
            }

            var dict = _entTraitDict[type];
            return dict.TryGetValue(uid.Value, out var comp) && !comp.Deleted;
        }

        /// <inheritdoc />
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public bool HasComponent(EntityUid uid, ushort netId)
        {
            return _netComponents.TryGetValue(uid, out var netSet)
                   && netSet.ContainsKey(netId);
        }

        /// <inheritdoc />
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public bool HasComponent(EntityUid? uid, ushort netId)
        {
            if (!uid.HasValue)
            {
                return false;
            }

            return _netComponents.TryGetValue(uid.Value, out var netSet)
                   && netSet.ContainsKey(netId);
        }

        /// <inheritdoc />
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public T EnsureComponent<T>(EntityUid uid) where T : Component, new()
        {
            if (TryGetComponent<T>(uid, out var component))
                return component;

            return AddComponent<T>(uid);
        }

        /// <inheritdoc />
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public bool EnsureComponent<T>(EntityUid entity, out T component) where T : Component, new()
        {
            if (TryGetComponent<T>(entity, out var comp))
            {
                component = comp;
                return true;
            }

            component = AddComponent<T>(entity);
            return false;
        }

        /// <inheritdoc />
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public T GetComponent<T>(EntityUid uid)
        {
            var dict = _entTraitArray[CompIdx.ArrayIndex<T>()];
            if (dict.TryGetValue(uid, out var comp))
            {
                if (!comp.Deleted)
                {
                    return (T)(IComponent)comp;
                }
            }

            throw new KeyNotFoundException($"Entity {uid} does not have a component of type {typeof(T)}");
        }

        public IComponent GetComponent(EntityUid uid, CompIdx type)
        {
            var dict = _entTraitArray[type.Value];
            if (dict.TryGetValue(uid, out var comp))
            {
                if (!comp.Deleted)
                    return comp;
            }

            throw new KeyNotFoundException($"Entity {uid} does not have a component of type {_componentFactory.IdxToType(type)}");
        }

        /// <inheritdoc />
        public IComponent GetComponent(EntityUid uid, Type type)
        {
            // ReSharper disable once InvertIf
            var dict = _entTraitDict[type];
            if (dict.TryGetValue(uid, out var comp))
            {
                if (!comp.Deleted)
                {
                    return comp;
                }
            }

            throw new KeyNotFoundException($"Entity {uid} does not have a component of type {type}");
        }

        /// <inheritdoc />
        public IComponent GetComponent(EntityUid uid, ushort netId)
        {
            return _netComponents[uid][netId];
        }

        /// <inheritdoc />
        public bool TryGetComponent<T>(EntityUid uid, [NotNullWhen(true)] out T component)
        {
            var dict = _entTraitArray[CompIdx.ArrayIndex<T>()];
            if (dict.TryGetValue(uid, out var comp))
            {
                if (!comp.Deleted)
                {
                    component = (T)(IComponent)comp;
                    return true;
                }
            }

            component = default!;
            return false;
        }

        /// <inheritdoc />
        public bool TryGetComponent<T>([NotNullWhen(true)] EntityUid? uid, [NotNullWhen(true)] out T component)
        {
            if (!uid.HasValue)
            {
                component = default!;
                return false;
            }

            if (TryGetComponent(uid.Value, typeof(T), out var comp))
            {
                if (!comp.Deleted)
                {
                    component = (T)comp;
                    return true;
                }
            }

            component = default!;
            return false;
        }

        /// <inheritdoc />
        public bool TryGetComponent(EntityUid uid, Type type, [NotNullWhen(true)] out IComponent? component)
        {
            var dict = _entTraitDict[type];
            if (dict.TryGetValue(uid, out var comp))
            {
                if (!comp.Deleted)
                {
                    component = comp;
                    return true;
                }
            }

            component = null;
            return false;
        }

        /// <inheritdoc />
        public bool TryGetComponent([NotNullWhen(true)] EntityUid? uid, Type type,
            [NotNullWhen(true)] out IComponent? component)
        {
            if (!uid.HasValue)
            {
                component = null;
                return false;
            }

            var dict = _entTraitDict[type];
            if (dict.TryGetValue(uid.Value, out var comp))
            {
                if (!comp.Deleted)
                {
                    component = comp;
                    return true;
                }
            }

            component = null;
            return false;
        }

        /// <inheritdoc />
        public bool TryGetComponent(EntityUid uid, ushort netId, [MaybeNullWhen(false)] out IComponent component)
        {
            if (_netComponents.TryGetValue(uid, out var netSet)
                && netSet.TryGetValue(netId, out var comp))
            {
                component = comp;
                return true;
            }

            component = default;
            return false;
        }

        /// <inheritdoc />
        public bool TryGetComponent([NotNullWhen(true)] EntityUid? uid, ushort netId,
            [MaybeNullWhen(false)] out IComponent component)
        {
            if (!uid.HasValue)
            {
                component = default;
                return false;
            }

            if (_netComponents.TryGetValue(uid.Value, out var netSet)
                && netSet.TryGetValue(netId, out var comp))
            {
                component = comp;
                return true;
            }

            component = default;
            return false;
        }

        public EntityQuery<TComp1> GetEntityQuery<TComp1>() where TComp1 : Component
        {
            return new EntityQuery<TComp1>(_entTraitArray[CompIdx.ArrayIndex<TComp1>()]);
        }

        /// <inheritdoc />
        public IEnumerable<IComponent> GetComponents(EntityUid uid)
        {
            // ReSharper disable once LoopCanBeConvertedToQuery
            foreach (Component comp in _entCompIndex[uid].ToArray())
            {
                if (comp.Deleted) continue;

                yield return comp;
            }
        }

        /// <summary>
        /// Copy the components for an entity into the given span,
        /// or re-allocate the span as an array if there's not enough space.
        /// </summary>
        private void CopyComponentsInto(ref Span<Component?> comps, EntityUid uid)
        {
            var set = _entCompIndex[uid];
            if (set.Count > comps.Length)
            {
                comps = new Component[set.Count];
            }

            var i = 0;
            foreach (var c in set)
            {
                comps[i++] = c;
            }
        }

        /// <inheritdoc />
        public IEnumerable<T> GetComponents<T>(EntityUid uid)
        {
            var comps = _entCompIndex[uid].ToArray();
            foreach (var comp in comps)
            {
                if (comp.Deleted || comp is not T tComp) continue;

                yield return tComp;
            }
        }

        /// <inheritdoc />
        public NetComponentEnumerable GetNetComponents(EntityUid uid)
        {
            return new NetComponentEnumerable(_netComponents[uid]);
        }

        #region Join Functions

        /// <inheritdoc />
        public IEnumerable<T> EntityQuery<T>(bool includePaused = false) where T : IComponent
        {
            var comps = _entTraitArray[CompIdx.ArrayIndex<T>()];

            if (includePaused)
            {
                foreach (var t1Comp in comps.Values)
                {
                    if (t1Comp.Deleted) continue;

                    yield return (T)(object)t1Comp;
                }
            }
            else
            {
                var metaComps = _entTraitArray[CompIdx.ArrayIndex<MetaDataComponent>()];

                foreach (var t1Comp in comps.Values)
                {
                    if (t1Comp.Deleted || !metaComps.TryGetValue(t1Comp.Owner, out var metaComp)) continue;

                    var meta = (MetaDataComponent)metaComp;

                    if (meta.EntityPaused) continue;

                    yield return (T)(object)t1Comp;
                }
            }
        }

        /// <inheritdoc />
        public IEnumerable<(TComp1, TComp2)> EntityQuery<TComp1, TComp2>(bool includePaused = false)
            where TComp1 : IComponent
            where TComp2 : IComponent
        {
            // this would prob be faster if trait1 was a list (or an array of structs hue).
            var trait1 = _entTraitArray[CompIdx.ArrayIndex<TComp1>()];
            var trait2 = _entTraitArray[CompIdx.ArrayIndex<TComp2>()];

            // you really want trait1 to be the smaller set of components
            if (includePaused)
            {
                foreach (var (uid, t1Comp) in trait1)
                {
                    if (!trait2.TryGetValue(uid, out var t2Comp) || t2Comp.Deleted)
                        continue;

                    yield return (
                        (TComp1)(object)t1Comp,
                        (TComp2)(object)t2Comp);
                }
            }
            else
            {
                var metaComps = _entTraitArray[CompIdx.ArrayIndex<MetaDataComponent>()];

                foreach (var (uid, t1Comp) in trait1)
                {
                    // Check paused last because 90% of the time the component's likely not gonna be paused.
                    if (!trait2.TryGetValue(uid, out var t2Comp) || t2Comp.Deleted)
                        continue;

                    if (t1Comp.Deleted || !metaComps.TryGetValue(t1Comp.Owner, out var metaComp)) continue;

                    var meta = (MetaDataComponent)metaComp;

                    if (meta.EntityPaused) continue;

                    yield return (
                        (TComp1)(object)t1Comp,
                        (TComp2)(object)t2Comp);
                }
            }
        }

        /// <inheritdoc />
        public IEnumerable<(TComp1, TComp2, TComp3)> EntityQuery<TComp1, TComp2, TComp3>(bool includePaused = false)
            where TComp1 : IComponent
            where TComp2 : IComponent
            where TComp3 : IComponent
        {
            var trait1 = _entTraitArray[CompIdx.ArrayIndex<TComp1>()];
            var trait2 = _entTraitArray[CompIdx.ArrayIndex<TComp2>()];
            var trait3 = _entTraitArray[CompIdx.ArrayIndex<TComp3>()];

            if (includePaused)
            {
                foreach (var (uid, t1Comp) in trait1)
                {
                    if (!trait2.TryGetValue(uid, out var t2Comp) || t2Comp.Deleted)
                        continue;

                    if (!trait3.TryGetValue(uid, out var t3Comp) || t3Comp.Deleted)
                        continue;

                    yield return (
                        (TComp1)(object)t1Comp,
                        (TComp2)(object)t2Comp,
                        (TComp3)(object)t3Comp);
                }
            }
            else
            {
                var metaComps = _entTraitArray[CompIdx.ArrayIndex<MetaDataComponent>()];

                foreach (var (uid, t1Comp) in trait1)
                {
                    // Check paused last because 90% of the time the component's likely not gonna be paused.
                    if (!trait2.TryGetValue(uid, out var t2Comp) || t2Comp.Deleted)
                        continue;

                    if (!trait3.TryGetValue(uid, out var t3Comp) || t3Comp.Deleted)
                        continue;

                    if (t1Comp.Deleted || !metaComps.TryGetValue(t1Comp.Owner, out var metaComp)) continue;

                    var meta = (MetaDataComponent)metaComp;

                    if (meta.EntityPaused) continue;

                    yield return (
                        (TComp1)(object)t1Comp,
                        (TComp2)(object)t2Comp,
                        (TComp3)(object)t3Comp);
                }
            }
        }

        /// <inheritdoc />
        public IEnumerable<(TComp1, TComp2, TComp3, TComp4)> EntityQuery<TComp1, TComp2, TComp3, TComp4>(
            bool includePaused = false)
            where TComp1 : IComponent
            where TComp2 : IComponent
            where TComp3 : IComponent
            where TComp4 : IComponent
        {
            var trait1 = _entTraitArray[CompIdx.ArrayIndex<TComp1>()];
            var trait2 = _entTraitArray[CompIdx.ArrayIndex<TComp2>()];
            var trait3 = _entTraitArray[CompIdx.ArrayIndex<TComp3>()];
            var trait4 = _entTraitArray[CompIdx.ArrayIndex<TComp4>()];

            if (includePaused)
            {
                foreach (var (uid, t1Comp) in trait1)
                {
                    if (!trait2.TryGetValue(uid, out var t2Comp) || t2Comp.Deleted)
                        continue;

                    if (!trait3.TryGetValue(uid, out var t3Comp) || t3Comp.Deleted)
                        continue;

                    if (!trait4.TryGetValue(uid, out var t4Comp) || t4Comp.Deleted)
                        continue;

                    yield return (
                        (TComp1)(object)t1Comp,
                        (TComp2)(object)t2Comp,
                        (TComp3)(object)t3Comp,
                        (TComp4)(object)t4Comp);
                }
            }
            else
            {
                var metaComps = _entTraitArray[CompIdx.ArrayIndex<MetaDataComponent>()];

                foreach (var (uid, t1Comp) in trait1)
                {
                    // Check paused last because 90% of the time the component's likely not gonna be paused.
                    if (!trait2.TryGetValue(uid, out var t2Comp) || t2Comp.Deleted)
                        continue;

                    if (!trait3.TryGetValue(uid, out var t3Comp) || t3Comp.Deleted)
                        continue;

                    if (!trait4.TryGetValue(uid, out var t4Comp) || t4Comp.Deleted)
                        continue;

                    if (t1Comp.Deleted || !metaComps.TryGetValue(t1Comp.Owner, out var metaComp)) continue;

                    var meta = (MetaDataComponent)metaComp;

                    if (meta.EntityPaused) continue;

                    yield return (
                        (TComp1)(object)t1Comp,
                        (TComp2)(object)t2Comp,
                        (TComp3)(object)t3Comp,
                        (TComp4)(object)t4Comp);
                }
            }
        }

        #endregion

        /// <inheritdoc />
        public IEnumerable<IComponent> GetAllComponents(Type type, bool includePaused = false)
        {
            var comps = _entTraitDict[type];

            if (includePaused)
            {
                foreach (var comp in comps.Values)
                {
                    if (comp.Deleted) continue;

                    yield return comp;
                }
            }
            else
            {
                var metaQuery = GetEntityQuery<MetaDataComponent>();

                foreach (var comp in comps.Values)
                {
                    if (comp.Deleted || !metaQuery.TryGetComponent(comp.Owner, out var meta) || meta.EntityPaused) continue;

                    yield return comp;
                }
            }
        }

        /// <inheritdoc />
        public ComponentState GetComponentState(IEventBus eventBus, IComponent component)
        {
            var getState = new ComponentGetState();
            eventBus.RaiseComponentEvent(component, ref getState);

            return getState.State ?? component.GetComponentState();
        }

        public bool CanGetComponentState(IEventBus eventBus, IComponent component, ICommonSession player)
        {
            var attempt = new ComponentGetStateAttemptEvent(player);
            eventBus.RaiseComponentEvent(component, ref attempt);
            return !attempt.Cancelled;
        }

        #endregion

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        private void FillComponentDict()
        {
            _entTraitDict.Clear();
            Array.Fill(_entTraitArray, null);

            foreach (var refType in _componentFactory.GetAllRefTypes())
            {
                AddComponentRefType(refType);
            }
        }
    }

    public readonly struct NetComponentEnumerable
    {
        private readonly Dictionary<ushort, Component> _dictionary;

        public NetComponentEnumerable(Dictionary<ushort, Component> dictionary) => _dictionary = dictionary;
        public NetComponentEnumerator GetEnumerator() => new(_dictionary);
    }

    public struct NetComponentEnumerator
    {
        // DO NOT MAKE THIS READONLY
        private Dictionary<ushort, Component>.Enumerator _dictEnum;

        public NetComponentEnumerator(Dictionary<ushort, Component> dictionary) =>
            _dictEnum = dictionary.GetEnumerator();

        public bool MoveNext() => _dictEnum.MoveNext();

        public (ushort netId, Component component) Current
        {
            get
            {
                var val = _dictEnum.Current;
                return (val.Key, val.Value);
            }
        }
    }

    public readonly struct EntityQuery<TComp1> where TComp1 : Component
    {
        private readonly Dictionary<EntityUid, Component> _traitDict;

        public EntityQuery(Dictionary<EntityUid, Component> traitDict)
        {
            _traitDict = traitDict;
        }

        public TComp1 GetComponent(EntityUid uid)
        {
            if (_traitDict.TryGetValue(uid, out var comp) && !comp.Deleted)
                return (TComp1) comp;

            throw new KeyNotFoundException($"Entity {uid} does not have a component of type {typeof(TComp1)}");
        }

        public bool TryGetComponent(EntityUid uid, [NotNullWhen(true)] out TComp1? component)
        {
            if (_traitDict.TryGetValue(uid, out var comp) && !comp.Deleted)
            {
                component = (TComp1) comp;
                return true;
            }

            component = default;
            return false;
        }

        public bool HasComponent(EntityUid uid)
        {
            return _traitDict.TryGetValue(uid, out var comp) && !comp.Deleted;
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public bool Resolve(EntityUid uid, [NotNullWhen(true)] ref TComp1? component, bool logMissing = true)
        {
            if (component != null)
            {
                DebugTools.Assert(uid == component.Owner, "Specified Entity is not the component's Owner!");
                return true;
            }

            if (_traitDict.TryGetValue(uid, out var comp) && !comp.Deleted)
            {
                component = (TComp1)comp;
                return true;
            }

            if (logMissing)
                Logger.ErrorS("resolve", $"Can't resolve \"{typeof(TComp1)}\" on entity {uid}!\n{new StackTrace(1, true)}");

            return false;
        }
    }
}