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

public class ScrollRectGroup : MonoBehaviour, IInitializePotentialDragHandler, IBeginDragHandler, IEndDragHandler, IDragHandler
{
    [SerializeField] ScrollRect[] m_ScrollRects;
    [SerializeField] Direction m_OnlyDirection;
    [SerializeField] float m_Offset = 100f;

    Dictionary<Direction, ScrollRect> scrollRects = new Dictionary<Direction, ScrollRect>();

    Direction m_Direction = Direction.None;
    Direction direction
    {
        get { return m_Direction; }
        set
        {
            if (value != m_Direction)
            {
                m_Direction = value;

                scrollRects[Direction.Horizontal].horizontal = direction == Direction.Horizontal
                    || direction == Direction.Both;
                scrollRects[Direction.Vertical].vertical = direction == Direction.Vertical
                    || direction == Direction.Both;
                scrollRects[Direction.Both].horizontal = direction == Direction.Horizontal
                    || direction == Direction.Both;
                scrollRects[Direction.Both].vertical = direction == Direction.Vertical
                    || direction == Direction.Both;
            }
        }
    }

    Vector2 m_StartPosition = Vector2.zero;



    private void Awake()
    {
        for (int i = 0; i < m_ScrollRects.Length; i++)
        {
            var scrollRect = m_ScrollRects[i];
            if (scrollRect.horizontal && scrollRect.vertical)
            {
                scrollRects.Add(Direction.Both, scrollRect);
            }
            else if (scrollRect.horizontal)
            {
                scrollRects.Add(Direction.Horizontal, scrollRect);
            }
            else
            {
                scrollRects.Add(Direction.Vertical, scrollRect);
            }
        }

        Initialize();
    }

    public void Initialize()
    {
        direction = Direction.Both;

        scrollRects[Direction.Both].horizontalNormalizedPosition = 0f;
        scrollRects[Direction.Both].verticalNormalizedPosition = 1f;
        scrollRects[Direction.Horizontal].horizontalNormalizedPosition = 0f;
        scrollRects[Direction.Vertical].verticalNormalizedPosition = 1f;
    }

    public void OnBeginDrag(PointerEventData eventData)
    {
        direction = Direction.Both;

        foreach (var scrollRect in m_ScrollRects)
        {
            scrollRect.OnBeginDrag(eventData);
        }

        m_StartPosition = eventData.position;
    }

    public void OnDrag(PointerEventData eventData)
    {
        var position = eventData.position;
        if (direction == Direction.Both)
        {
            if (m_OnlyDirection == Direction.Both)
            {
                var horizontal = Mathf.Abs(position.x - m_StartPosition.x) > m_Offset;
                var vertical = !horizontal && Mathf.Abs(position.y - m_StartPosition.y) > m_Offset;
                if (horizontal || vertical)
                {
                    var _direction = horizontal ? Direction.Horizontal : Direction.Vertical;
                    if (_direction != direction)
                    {
                        direction = _direction;
                        foreach (var scrollRect in m_ScrollRects)
                        {
                            scrollRect.OnBeginDrag(eventData);
                        }
                    }
                }
            }
            else
            {
                direction = m_OnlyDirection;
            }
        }

        if (direction != Direction.Both)
        {
            foreach (var scrollRect in m_ScrollRects)
            {
                scrollRect.OnDrag(eventData);
            }
        }
    }

    public void OnEndDrag(PointerEventData eventData)
    {
        foreach (var scrollRect in m_ScrollRects)
        {
            scrollRect.OnEndDrag(eventData);
        }
    }

    public void OnInitializePotentialDrag(PointerEventData eventData)
    {
        foreach (var scrollRect in m_ScrollRects)
        {
            scrollRect.OnInitializePotentialDrag(eventData);
        }
    }

#if UNITY_EDITOR
    [ContextMenu("CloseRayAccepter")]
    void BatchCloseRayAccepter()
    {
        var componenst = transform.GetComponentsInChildren<Graphic>(true);
        for (int i = 0; i < componenst.Length; i++)
        {
            componenst[i].raycastTarget = false;
        }
    }
#endif

    enum Direction
    {
        None,
        Horizontal,
        Vertical,
        Both,
    }
}