riversong-code-showcase/Source/Riversong/Game/World/Buildings/BuildingSelectionSystem.cs

using Cysharp.Threading.Tasks;

namespace DanieleMarotta.RiversongCodeShowcase
{
    [UpdateAfter(typeof(EditingStateGameSystem))]
    public class BuildingSelectionSystem : GameSystem, IInitializable, IUpdatable
    {
        [InjectService]
        private GameConfig _gameConfig;

        [InjectService]
        private IPointerService _pointerService;

        [InjectService]
        private UIState _uiState;

        [InjectService]
        private ITileSpace _tileSpace;

        [InjectService]
        private IEntityCollection _entityCollection;

        [InjectService]
        private ICancelAction _cancelAction;

        [InjectService]
        private EditingState _editingState;

        [InjectService]
        private ISignalBus _signalBus;

        [InjectService]
        private IBuildingVisualizationCollection _buildingVisualizationCollection;

        [InjectService]
        private World _world;

        [InjectService]
        private MaterialReplacementCache _materialReplacementCache;

        public BuildingSelectionSystem(IServiceLocator serviceLocator) : base(serviceLocator)
        {
        }

        public UniTask InitializeAsync()
        {
            _cancelAction.AddHandler(
                (int)CancelActions.CancelSelection,
                _ =>
                {
                    if (_uiState.SelectedBuilding == null) return false;
                    SetSelectedBuilding(null);
                    return true;
                });

            return UniTask.CompletedTask;
        }

        public void Update()
        {
            if (_uiState.SelectedBuilding != null && !_entityCollection.Exists(_uiState.SelectedBuilding.Id))
            {
                SetSelectedBuilding(null);
                return;
            }

            if (_editingState.ActiveTool != null)
            {
                SetSelectedBuilding(null);
                return;
            }

            var buildingUnderPointer = GetBuildingUnderPointer();
            if (_pointerService.TryConsumeLeftClick()) SetSelectedBuilding(buildingUnderPointer);

            HighlightBuilding(buildingUnderPointer);
            HighlightBuilding(_uiState.SelectedBuilding);
        }

        private Building GetBuildingUnderPointer()
        {
            if (_pointerService.IsPointerOverUI) return null;
            if (!_pointerService.TryGetPositionOnTerrain(out var position)) return null;

            var tile = _tileSpace.WorldToTile(position);
            ref var entityIdMapValue = ref _world.EntityIdMap.GetValueRW(tile);
            if (entityIdMapValue.BuildingId == Entity.InvalidId) return null;

            return _entityCollection.TryGet<Building>(entityIdMapValue.BuildingId, out var building) ? building : null;
        }

        private void HighlightBuilding(Building building)
        {
            if (building == null) return;
            if (!_buildingVisualizationCollection.TryGetVisualization(building.Id, out var visualization)) return;

            _materialReplacementCache.ReplaceMaterials(visualization.gameObject, _gameConfig.UI.HighlightedGameObjectsMaterial);
        }

        private void SetSelectedBuilding(Building selectedBuilding)
        {
            if (_uiState.SelectedBuilding == selectedBuilding) return;

            var oldSelection = _uiState.SelectedBuilding;
            _uiState.SelectedBuilding = selectedBuilding;

            _signalBus.Raise(new SelectedBuildingChangedSignal(oldSelection, _uiState.SelectedBuilding));
        }
    }
}