using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.UI;

namespace BrewMonster.Scripts.Managers
{
    /// <summary>
    /// Forwards pointer drag events from the GameObject to the nearest parent ScrollRect.
    /// Attach to UI elements (Buttons) that should allow ScrollRect dragging while still receiving clicks.
    /// </summary>
    public sealed class ForwardDragToScrollRect : MonoBehaviour, IBeginDragHandler, IDragHandler, IEndDragHandler
    {
        private ScrollRect _target;

        public ScrollRect Target
        {
            get
            {
                if (_target == null)
                    _target = GetComponentInParent<ScrollRect>();
                return _target;
            }
            set => _target = value;
        }

        public void OnBeginDrag(PointerEventData eventData)
        {
            var t = Target;
            if (t != null)
                ExecuteEvents.Execute(t.gameObject, eventData, ExecuteEvents.beginDragHandler);
        }

        public void OnDrag(PointerEventData eventData)
        {
            var t = Target;
            if (t != null)
                ExecuteEvents.Execute(t.gameObject, eventData, ExecuteEvents.dragHandler);
        }

        public void OnEndDrag(PointerEventData eventData)
        {
            var t = Target;
            if (t != null)
                ExecuteEvents.Execute(t.gameObject, eventData, ExecuteEvents.endDragHandler);
        }
    }
}