riversong-code-showcase/Source/Riversong/Game/EditTools/DragTool.cs

using Cysharp.Threading.Tasks;
using Unity.Mathematics;
using UnityEngine.InputSystem;

namespace DanieleMarotta.RiversongCodeShowcase
{
    public abstract class DragTool : EditTool
    {
        private IPointerService _pointerService;

        private ITileSpace _tileSpace;

        private bool _isDragging;

        private int2 _startTile;

        private int2 _endTile;

        private bool _isValid;

        protected DragTool(IServiceLocator serviceLocator) : base(serviceLocator)
        {
        }

        protected virtual DeletedGameObjectsFilter DeletedGameObjectsFilter => DeletedGameObjectsFilter.None;

        public override async UniTask InitializeAsync()
        {
            await base.InitializeAsync();

            _pointerService = ServiceLocator.GetService<IPointerService>();
            _tileSpace = ServiceLocator.GetService<ITileSpace>();
        }

        public override void OnDisabled()
        {
            base.OnDisabled();

            _isDragging = false;
        }

        public override void Update()
        {
            base.Update();

            AffectedTiles.Clear();

            var lmb = Mouse.current.leftButton;

            var isPointerOnTerrain = _pointerService.TryGetPositionOnTerrain(out var position);
            if (!isPointerOnTerrain)
            {
                _isDragging &= lmb.isPressed;
                _isValid = false;
                return;
            }

            if (!_isDragging)
            {
                _startTile = _tileSpace.WorldToTile(position);
                _endTile = _startTile;
            }
            _isDragging |= _pointerService.TryConsumeLeftClick();
            if (_isDragging && !_pointerService.IsPointerOverUI) _endTile = _tileSpace.WorldToTile(position);

            _isValid = Validate(ref _startTile, ref _endTile);
            UpdateAffectedTiles(_isValid, _startTile, _endTile);

            if (lmb.wasReleasedThisFrame)
            {
                if (_isValid && !_pointerService.IsPointerOverUI) DoTool(_startTile, _endTile);

                _isDragging = false;
            }
        }

        protected abstract bool Validate(ref int2 startTile, ref int2 endTile);

        protected abstract void UpdateAffectedTiles(bool isValid, int2 startTile, int2 endTile);

        protected abstract void DoTool(int2 startTile, int2 endTile);

        public override void GetDeleteGameObjectsPreviewInfo(out DeletedGameObjectsFilter filter, out TileRect rect)
        {
            if (!_isValid)
            {
                filter = DeletedGameObjectsFilter.None;
                rect = TileRect.Empty;
                return;
            }

            filter = DeletedGameObjectsFilter;
            rect = new TileRect(_startTile, _endTile);
        }
    }
}