XRLib/Assets/Scripts/UVC/UI/List/DraggableListItem.cs

#nullable enable
using System;
using TMPro;
using UnityEngine;
using UnityEngine.EventSystems;

namespace UVC.UI.List
{
    /// <summary>
    /// 개별 드래그 가능한 아이템의 UI 컴포넌트
    /// 드래그 동작과 시각적 피드백을 담당
    /// </summary>
    public class DraggableListItem : MonoBehaviour
    {
        [Header("UI 컴포넌트")]
        [SerializeField] protected CanvasGroup? canvasGroup;
        [SerializeField] protected RectTransform? rectTransform;
        [SerializeField] protected DraggableItem? dragAnchor;
        [SerializeField] protected TMP_InputField? inputField;

        [Header("드래그 설정")]
        [SerializeField] protected float dragAlpha = 0.6f;
        [SerializeField] protected bool blockRaycastsWhileDragging = false;

        // 프로퍼티
        public DraggableItemData? Data { get; private set; }
        public RectTransform? RectTransform => rectTransform;
        public bool IsDragging { get; private set; }

        public event Action<DraggableListItem>? OnBeginDragEvent;
        public event Action<DraggableListItem, Vector2>? OnDragEvent;
        public event Action<DraggableListItem>? OnEndDragEvent;

        private Vector2 originalPosition;
        private Transform? originalParent;
        private int originalSiblingIndex;

        /// <summary>
        /// 컴포넌트 초기화
        /// </summary>
        private void Awake()
        {
            // null 체크 및 자동 할당
            if (rectTransform == null)
                rectTransform = GetComponent<RectTransform>();

            if (canvasGroup == null)
                canvasGroup = GetComponent<CanvasGroup>();

            // CanvasGroup이 없으면 추가
            if (canvasGroup == null)
                canvasGroup = gameObject.AddComponent<CanvasGroup>();

            if (dragAnchor == null)
            {
                Debug.LogError("Drag Anchor is not assigned. Please assign it in the inspector.");
                return;
            }

            dragAnchor.OnBeginDragEvent += OnBeginDrag;
            dragAnchor.OnDragEvent += OnDrag;
            dragAnchor.OnEndDragEvent += OnEndDrag;
        }

        /// <summary>
        /// 아이템 데이터로 UI 업데이트
        /// </summary>
        /// <param name="data">표시할 데이터</param>
        public void SetData(DraggableItemData? data)
        {
            if (data == null) return;

            Data = data;
            UpdateUI();
        }

        /// <summary>
        /// UI 요소들을 데이터에 맞게 업데이트
        /// </summary>
        protected virtual void UpdateUI()
        {
            if (Data == null) return;
            if(inputField != null)
            {
                inputField.text = Data.Id;
            }
        }

        /// <summary>
        /// 드래그 시작 시 호출
        /// </summary>
        public void OnBeginDrag(PointerEventData eventData)
        {
            if (rectTransform == null) return;

            IsDragging = true;

            // 원래 위치와 부모 저장
            originalPosition = rectTransform.anchoredPosition;
            originalParent = transform.parent;
            originalSiblingIndex = transform.GetSiblingIndex();

            // 시각적 피드백 적용
            ApplyDragVisuals(true);

            // 이벤트 발생
            OnBeginDragEvent?.Invoke(this);
        }

        /// <summary>
        /// 드래그 중 호출
        /// </summary>
        public void OnDrag(PointerEventData eventData)
        {
            if (rectTransform == null) return;

            // 마우스 위치로 아이템 이동
            rectTransform.anchoredPosition += new Vector2(0, eventData.delta.y);//eventData.delta

            // 이벤트 발생
            OnDragEvent?.Invoke(this, rectTransform.anchoredPosition);
        }

        /// <summary>
        /// 드래그 종료 시 호출
        /// </summary>
        public void OnEndDrag(PointerEventData eventData)
        {
            IsDragging = false;

            // 시각적 피드백 복원
            ApplyDragVisuals(false);

            // 이벤트 발생
            OnEndDragEvent?.Invoke(this);
        }

        /// <summary>
        /// 드래그 시각적 효과 적용/해제
        /// </summary>
        /// <param name="isDragging">드래그 중인지 여부</param>
        private void ApplyDragVisuals(bool isDragging)
        {
            if (canvasGroup == null) return;

            if (isDragging)
            {
                canvasGroup.alpha = dragAlpha;
                canvasGroup.blocksRaycasts = blockRaycastsWhileDragging;
            }
            else
            {
                canvasGroup.alpha = 1f;
                canvasGroup.blocksRaycasts = true;
            }
        }

        /// <summary>
        /// 원래 위치로 되돌리기 (드래그 취소 시 사용)
        /// </summary>
        public void ResetToOriginalPosition()
        {
            if (rectTransform == null || originalParent == null) return;

            transform.SetParent(originalParent);
            transform.SetSiblingIndex(originalSiblingIndex);
            rectTransform.anchoredPosition = originalPosition;
        }

        public void OnDestroy()
        {
            // 이벤트 구독 해제
            if (dragAnchor != null)
            {
                dragAnchor.OnBeginDragEvent -= OnBeginDrag;
                dragAnchor.OnDragEvent -= OnDrag;
                dragAnchor.OnEndDragEvent -= OnEndDrag;
            }

            OnBeginDragEvent = null;
            OnDragEvent = null;
            OnEndDragEvent = null;

            // 리소스 정리
            canvasGroup = null;
            rectTransform = null;
            dragAnchor = null;
        }

    }
}