using System;
using UnityEngine;
using UnityEngine.EventSystems;

namespace HotUpdate.Gameplay
{
    /// <summary>Input behaviour on authored formation buttons; creates no UI objects.</summary>
    public sealed class FormationDragHandle : MonoBehaviour, IBeginDragHandler, IDragHandler, IEndDragHandler
    {
        public Func<bool> CanBegin;
        public Action<PointerEventData> Begin, Move, End;
        bool _dragging;
        public void OnBeginDrag(PointerEventData data)
        {
            if (data.button != PointerEventData.InputButton.Left || CanBegin?.Invoke() != true) return;
            _dragging = true; data.eligibleForClick = false; Begin?.Invoke(data);
        }
        public void OnDrag(PointerEventData data) { if (_dragging) Move?.Invoke(data); }
        public void OnEndDrag(PointerEventData data) { if (!_dragging) return; _dragging = false; End?.Invoke(data); }
        void OnDisable() { _dragging = false; }
    }
}