using UnityEngine;
using UnityEngine.InputSystem;
using UnityEngine.UIElements;

namespace DanieleMarotta.RiversongCodeShowcase
{
    [Service(typeof(IPointerService))]
    [GameSystemGroup(typeof(EarlyGameSystemGroup))]
    public class PointerSystem : GameSystem, IUpdatable, IPointerService
    {
        [InjectService]
        private IScene _scene;

        [InjectService]
        private GameConfig _config;

        [InjectService]
        private ITileSpace _tileSpace;

        [InjectService]
        private World _world;

        [InjectService]
        private UIService _uiService;

        private int _leftButtonClickCount;

        private Vector3? _positionOnTerrain;

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

        public bool IsPointerOverUI { get; private set; }

        public void Update()
        {
            _leftButtonClickCount = 0;

            UpdateIsPointerOverUIFlag();

            UpdatePositionOnTerrain();
        }

        private void UpdateIsPointerOverUIFlag()
        {
            var panel = _uiService.UIRoot.RootVisualElement.panel;

            var position = Mouse.current.position.ReadValue();
            position.y = Screen.height - position.y;
            position = RuntimePanelUtils.ScreenToPanel(panel, position);

            IsPointerOverUI = panel.Pick(position) != null;
        }

        private void UpdatePositionOnTerrain()
        {
            _positionOnTerrain = null;

            var ray = _scene.MainCamera.ScreenPointToRay(Mouse.current.position.ReadValue());
            if (Physics.Raycast(ray, out var hit, float.PositiveInfinity))
            {
                if (!Mathf.Approximately(Vector3.Dot(hit.normal, Vector3.up), 1)) return;

                if (_tileSpace.GetElevation(hit.point.y) != _config.GeneralSettings.BaseElevation) return;

                _positionOnTerrain = hit.point;
            }
        }

        public bool TryGetPositionOnTerrain(out Vector3 position)
        {
            position = _positionOnTerrain ?? Vector3.zero;
            return _positionOnTerrain != null;
        }

        public bool TryConsumeLeftClick(int maxClickCount = 0)
        {
            return !IsPointerOverUI && Mouse.current.leftButton.wasPressedThisFrame && _leftButtonClickCount++ <= maxClickCount;
        }
    }
}