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

namespace Superlazy.UI
{
    public class SLUIScrollRect : SLUIComponent, IBeginDragHandler, IEndDragHandler, IDragHandler
    {
        public bool snap = false;
        public float itemSize;
        public string indexBind;
        public string stateBind;

        private ScrollRect scrollRect;
        private RectTransform container;
        private bool snapping;
        private Vector2 snapTargetPosition;
        private bool dragging = false;
        private int index = -1;

        // 나중에 휘리릭용으로 사용할 예정
        //private Vector2 positionOnDragStart = Vector3.zero;

        protected override void Validate()
        {
            scrollRect = gameObject.GetComponent<ScrollRect>();
        }

        protected override void Init()
        {
            container = scrollRect.content;
        }

        protected override void Enable()
        {
            if (snap)
            {
                snapping = false;
                dragging = false;
                index = -1;

                if (indexBind != string.Empty)
                {
                    SLGame.AddNotify(bindParent.BindPath.CombinePath(indexBind), OnChangeIndex);

                    OnChangeIndex();
                    container.anchoredPosition = snapTargetPosition;
                }
                else
                {
                    container.anchoredPosition = Vector2.zero;
                }

                if (stateBind != string.Empty)
                {
                    SLGame.SessionGet(bindParent.BindPath).Set(stateBind, "Idle");
                }
            }
        }

        protected override void Disable()
        {
            if (snap)
            {
                snapping = false;
                dragging = false;
                index = -1;

                if (indexBind != string.Empty)
                {
                    SLGame.RemoveNotify(bindParent.BindPath.CombinePath(indexBind), OnChangeIndex);
                }

                if (stateBind != string.Empty)
                {
                    SLGame.SessionGet(bindParent.BindPath).Set(stateBind, false);
                }
            }
        }

        private void OnChangeIndex()
        {
            if (snap == false) return;

            var newIndex = SLGame.SessionGet(bindParent.BindPath).Get(indexBind);

            if (newIndex == false && index == -1) return; // 삭제 관련 예외
            if (index == newIndex) return;

            index = newIndex;

            snapping = true;
            // anchoredPosition은 -로 가기때문에 인덱스 자체는 -로 세팅해야함 // 나중에는 확장가능성 생각해서 추가 개선
            snapTargetPosition = scrollRect.horizontal
                ? new Vector2(-newIndex * itemSize, container.anchoredPosition.y)
                : new Vector2(container.anchoredPosition.x, -newIndex * itemSize);

            if (stateBind != string.Empty)
            {
                SLGame.SessionGet(bindParent.BindPath).Set(stateBind, "Snapping");
            }
        }

        public void ResetPage()
        {
            if (scrollRect.horizontal)
            {
                scrollRect.horizontalNormalizedPosition = 0;
            }
            else
            {
                scrollRect.verticalNormalizedPosition = 0;
            }
        }

        private void LateUpdate()
        {
            if (snapping)
            {
                scrollRect.StopMovement();
                container.anchoredPosition = Vector2.Lerp(container.anchoredPosition, snapTargetPosition, 0.5f);

                if (Vector3.Distance(container.anchoredPosition, snapTargetPosition) < 5f)
                {
                    container.anchoredPosition = snapTargetPosition;

                    snapping = false;

                    if (stateBind != string.Empty)
                    {
                        SLGame.SessionGet(bindParent.BindPath).Set(stateBind, "Idle");
                    }
                }
            }
        }

        public void OnBeginDrag(PointerEventData eventData)
        {
            if (snap == false) return;

            //positionOnDragStart = eventData.position;
        }

        public void OnEndDrag(PointerEventData eventData)
        {
            if (snap == false) return;

            dragging = false;

            if (bindParent.BindPath != string.Empty)
            {
                // 바인딩 패스가 있다면 값을 바꿔서 OnChange를 불리게하는쪽으로 일원화
                index = -1;
                // anchoredPosition은 -로 가기때문에 인덱스 자체는 -로 세팅해야함 // 나중에는 확장가능성 생각해서 추가 개선
                if (scrollRect.horizontal)
                {
                    SLGame.SessionGet(bindParent.BindPath).Set(indexBind, Mathf.Clamp(-Mathf.RoundToInt(container.anchoredPosition.x / itemSize), 0, container.sizeDelta.x / itemSize));
                }
                else
                {
                    SLGame.SessionGet(bindParent.BindPath).Set(indexBind, Mathf.Clamp(Mathf.RoundToInt(container.anchoredPosition.y / itemSize), 0, container.sizeDelta.y / itemSize));
                }
            }
            else
            {
                // 별도의 바인딩패스를 사용하지 않는 구성
                snapping = true;
                snapTargetPosition = scrollRect.horizontal
                    ? new Vector2(Mathf.Clamp(Mathf.Round(container.anchoredPosition.x / itemSize) * itemSize, -container.sizeDelta.x, 0), container.anchoredPosition.y)
                    : new Vector2(container.anchoredPosition.x, Mathf.Clamp(Mathf.Round(container.anchoredPosition.y / itemSize) * itemSize, 0, container.anchoredPosition.y));
            }
        }

        public void OnDrag(PointerEventData eventData)
        {
            if (snap == false) return;

            snapping = false;

            if (dragging == false)
            {
                OnBeginDrag(eventData);
                dragging = true;

                SLGame.SessionGet(bindParent.BindPath).Set(stateBind, "Dragging");
            }
        }

        public void StartScreenChange()
        {
        }
    }
}