using UnityEngine;

namespace AibisDream.Framework
{
    public class MoveableSystem : IMonoKit
    {
        private bool _isDragging;
        private IMoveable _dragObj;
        private Vector3 _offset;
        private readonly Camera _camera = Camera.main;

        public void OnUpdate()
        {
            // 鼠标按下
            if (Input.GetMouseButtonDown(0))
            {
                OnMouseClickDown();
            }

            // 鼠标按住
            if (Input.GetMouseButton(0) && _isDragging)
            {
                OnMouseHolding();
            }

            // 鼠标松开
            if (Input.GetMouseButtonUp(0))
            {
                OnMouseClickUp();
            }
        }

        private void OnMouseClickDown()
        {
            // 按下时发出检查射线
            Ray ray = _camera.ScreenPointToRay(Input.mousePosition);
            RaycastHit2D hit = Physics2D.Raycast(ray.origin, ray.direction);

            // 检测命中的物体
            if (hit.collider && hit.collider.CompareTag("Moveable"))
            {
                _dragObj = hit.collider.gameObject.GetComponent<IMoveable>();
                if (_dragObj == null) return;
                
                _dragObj.StartMove();
                _offset = hit.collider.transform.position - GetMouseAsWorldPoint();
                
                _isDragging = true;
            }
        }
        
        private void OnMouseHolding()
        {
            _dragObj.Move(GetMouseAsWorldPoint() + _offset);
        }
        
        private void OnMouseClickUp()
        {
            if (!_isDragging) return;
            
            _dragObj?.StopMove();
            _dragObj = null;
            _isDragging = false;
        }
        
        private Vector3 GetMouseAsWorldPoint()
        {
            Vector3 mousePoint = Input.mousePosition;
            mousePoint.z = _camera.nearClipPlane;
            return _camera.ScreenToWorldPoint(mousePoint);
        }
    }
}