using System.Collections.Generic;
using UnityEngine.EventSystems;

// ActionDice 처럼 SLUIButton 사용하지 않는 경우용 임시, 남용하지 마시에
namespace Superlazy.UI
{
    public class SLUIDragClick : SLUIComponent, IBeginDragHandler, IDragHandler, IEndDragHandler
    {
        public string cancelCommand;
        public SLValueComparison comparison;

        private bool draggable = true;
        private bool dragging = false;
        private PointerEventData currentPoint;

        protected override void Validate()
        {
        }

        protected override void Init()
        {
        }

        protected override void Enable()
        {
            if (comparison.useCheckValue) comparison.OnEnable(bindParent.BindPath, OnChange);
        }

        protected override void Disable()
        {
            if (comparison.useCheckValue) comparison.OnDisable();

            if (dragging)
            {
                EndDrag(); // Dragged == false 체크 이미 되어있음
            }
        }

        private void OnChange()
        {
            if (bindParent.Active == false) return;

            var result = comparison.Result;//

            if (draggable && comparison.useCheckValue && comparison.Result == false)
            {
                EndDrag();
            }

            draggable = result;
        }

        private void BeginDrag()
        {
            dragging = true;

            if (comparison.useCheckValue && comparison.Result == false) return;

            // ExecuteEvent 때문에 드래그가 무효가 되기 때문에 버튼을 직접 핸들링
            ExecuteEvents.Execute(gameObject, currentPoint, ExecuteEvents.pointerClickHandler);
        }

        private void Drag()
        {
            if (comparison.useCheckValue && comparison.Result == false) return;
            if (dragging == false) return;
        }

        private void EndDrag()
        {
            if (dragging == false) return;

            var pointerData = new PointerEventData(EventSystem.current)
            {
                position = currentPoint.position,
                pointerId = currentPoint.pointerId,
                pointerEnter = currentPoint.pointerEnter,
                eligibleForClick = true
            };

            var results = new List<RaycastResult>();

            EventSystem.current.RaycastAll(pointerData, results);

            var canceled = true;
            foreach (var result in results)
            {
                var targetObject = result.gameObject;
                if (targetObject == gameObject) // 드래그를 넘 멀리 안했다면 짧은 클릭으로 인식
                {
                    dragging = false;
                    return;
                }
                else if (targetObject.TryGetComponent<SLUIDragClickTarget>(out var target))
                {
                    if (target.CanClick())
                    {
                        // target.Click 에서 EndDrag가 또 불리지 않게끔 미리 드래그 해제
                        currentPoint = null;
                        SLUIDragButton.currentDragCancelCommand = null;
                        SLUIDragButton.currentDragObject = null;
                        SLUIDragButton.globalDragging = false;

                        target.Click();
                        canceled = false;
                    }

                    break;
                }
            }

            if (canceled)
            {
                SLGame.Command(cancelCommand, bindParent.BindPath);
            }

            dragging = false;
            currentPoint = null;
        }

        public void OnBeginDrag(PointerEventData eventData)
        {
            currentPoint = eventData;
            BeginDrag();
        }

        public void OnDrag(PointerEventData eventData)
        {
            currentPoint = eventData;
            Drag();
        }

        public void OnEndDrag(PointerEventData eventData)
        {
            currentPoint = eventData;
            EndDrag();
        }
    }
}