[UpdateInGroup(typeof(SyncPointCauserSystemGroup))]
public partial class BuildingSystem : SystemBase
{
    private bool _onBuildPreview;
    private Camera _mainCamera;
    private Entity _staticResourcesContainer;
    private Entity _candidateEntity;
    private BuildingAuthoring _candidateBuilding;
    private BatchMaterialID _buildPreviewOkMaterial;
    private BatchMaterialID _buildPreviewErrorMaterial;
    private BatchMaterialID _buildRequestMaterial;
    private EndSimulationEntityCommandBufferSystem _ecbSystem;
    protected override void OnCreate()
    {
        _ecbSystem = World.GetOrCreateSystemManaged<EndSimulationEntityCommandBufferSystem>();
        RequireForUpdate<PrefabsContainerData>();
    }
    protected override void OnStartRunning()
    {
        EventCenter.Register<BuildingAuthoring>(EventType.OnBuildPreview, OnBuildPreview);
        EventCenter.Register<BuildingAuthoring, HexUnitAspect>(EventType.OnRequestBuild, OnBuildRequest);
        var inputAsset = InputManager.Instance.InputAsset;
        inputAsset.InGame.CancelAction.performed += OnPerformCancel;
        _mainCamera = Camera.main;
        _staticResourcesContainer = SystemAPI.GetSingletonEntity<StaticResourcesContainerAspect>();
        var container = SystemAPI.GetAspect<StaticResourcesContainerAspect>(_staticResourcesContainer);
        _buildPreviewOkMaterial = container.GetMaterialIndex(StaticResourcesContainer.Instance.buildPreviewOk.GetInstanceID());
        _buildPreviewErrorMaterial = container.GetMaterialIndex(StaticResourcesContainer.Instance.buildPreviewError.GetInstanceID());
        _buildRequestMaterial = container.GetMaterialIndex(StaticResourcesContainer.Instance.buildRequest.GetInstanceID());
    }
    protected override void OnUpdate()
    {
        if (_onBuildPreview)
            PreviewBuilding();
    }
    private void OnBuildPreview(BuildingAuthoring building)
    {
        if (_onBuildPreview && building.buildingName == _candidateBuilding.buildingName)
            return;
        _candidateBuilding = building;
        SystemAPI.GetAspect<StaticResourcesContainerAspect>(_staticResourcesContainer)
            .TryGetBuildingPrefab(building.buildingName, out var candidate);
        _candidateEntity = EntityManager.Instantiate(candidate);
        _onBuildPreview = true;
    }
    private void OnBuildRequest(BuildingAuthoring building, HexUnitAspect unit)
    {
        EntityCommandBuffer ecb = _ecbSystem.CreateCommandBuffer();
        ecb.RemoveComponent<PreviewBuildingTag>(_candidateEntity);
        ecb.AddComponent<WaitingForTaskRegTag>(_candidateEntity);
        ecb.AddComponent<BuildTaskData>(_candidateEntity);
        ecb.SetComponent(_candidateEntity, new BuildTaskData
        {
            priority = 1
        });
        ecb.SetComponent(_candidateEntity, new BuildingMaterialData
        {
            missing = new NativeParallelHashMap<int, int>(4, Allocator.Persistent),
            transmitted = new NativeParallelHashMap<int, int>(4, Allocator.Persistent),
            required = new NativeParallelHashMap<int, int>(4, Allocator.Persistent)
        });
    }
    private void PreviewBuilding()
    {
        if (!Raycast(out var targetUnit))
            return;
        PreviewBuildingAspect building = SystemAPI.GetAspect<PreviewBuildingAspect>(_candidateEntity);
        building.Position = targetUnit.SurfaceCenterNoZFighting;
        bool isBuildable = targetUnit.Data.occupant == Entity.Null && !targetUnit.Data.isUnderwater;
        if (Pointer.current.press.wasPressedThisFrame && isBuildable)
        {
            SystemAPI.GetComponentRW<MaterialMeshInfo>(_candidateEntity).ValueRW.MaterialID = _buildRequestMaterial;
            targetUnit.Occupy(_candidateEntity);
            _onBuildPreview = false;
            EventCenter.BroadCast(EventType.OnRequestBuild, _candidateBuilding, targetUnit);
        }
        else
        {
            SystemAPI.GetComponentRW<MaterialMeshInfo>(_candidateEntity).ValueRW.MaterialID =
                isBuildable ? _buildPreviewOkMaterial : _buildPreviewErrorMaterial;
        }
    }
    private bool Raycast(out HexUnitAspect result)
    {
        SystemAPI.GetSingleton<PhysicsWorldSingleton>().CollisionWorld
            .CastRay(RaycastInputFactory.CreateRaycastInput
            (
                _mainCamera.ScreenPointToRay(Pointer.current.position.value),
                CollisionLayer.PlayerRaycast
            ), out var hit);
        if (!SystemAPI.HasComponent<HexUnitData>(hit.Entity))
        {
            result = default;
            return false;
        }
        result = SystemAPI.GetAspect<HexUnitAspect>(hit.Entity);
        return true;
    }
    private void OnPerformCancel(InputAction.CallbackContext ctx)
    {
        if (!_onBuildPreview)
            return;
        EntityManager.DestroyEntity(_candidateEntity);
        _candidateEntity = Entity.Null;
        _onBuildPreview = false;
    }
}