using System;
using UnityEngine;
using UnityEngine.EventSystems;

internal class ScrapbookStickerDragProxy : MonoBehaviour
{
    [Serializable]
    private class Components
    {
        [SerializeField]
        internal RectTransform rectTransform;

        internal ScrapbookSticker scrapbookSticker;
    }
    [SerializeField]
    private Components _components;

    internal void Drag(ScrapbookSticker scrapbookSticker)
    {
        _components.scrapbookSticker = scrapbookSticker;
        base.gameObject.SetActive(true);
        _components.rectTransform.position = scrapbookSticker.RectTransform.position;
    }

    private void Update()
    {
        UpdateDrag();
        UpdateContainment();
    }

    private void UpdateDrag()
    {
        _components.rectTransform.position = Input.mousePosition;
    }

    private void UpdateContainment()
    {
        bool contained = false;
        Touch[] touches = Input.touches;
        foreach (Touch touch in touches)
        {
            bool contains = Contains(touch.position);
            if (contains)
            {
                contains = true;
                break;
            }
        }

        if(!contained)
            contained = Input.GetMouseButton(0) && Contains(Input.mousePosition);

        if (!contained)
            Drop();
    }

    private void Drop()
    {
        _components.scrapbookSticker.OnDrop();
        _components.scrapbookSticker = null;
        base.gameObject.SetActive(false);
    }

    private bool Contains(Vector2 position)
    {
        return RectTransformUtility.RectangleContainsScreenPoint(_components.rectTransform, position);
    }
}


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

internal class ScrapbookSticker : MonoBehaviour, IDragHandler
{
    [Serializable]
    private class Components
    {
        [SerializeField]
        internal RectTransform rectTransform;

        [SerializeField]
        internal ScrapbookStickerDragProxy scrapbookStickerDragProxy;
    }
    [SerializeField]
    private Components _components;

    internal RectTransform RectTransform => _components.rectTransform;

    [Serializable]
    private class Data
    {
        [SerializeField]
        internal bool dragging;
        [SerializeField]
        internal Vector3 startingPosition;
    }
    [SerializeField]
    private Data _data;

    private void OnDisable()
    {
        _data.dragging = false;
    }

    public void OnDrag(PointerEventData eventData)
    {
        if (!_data.dragging)
            _components.scrapbookStickerDragProxy.Drag(this);
        _data.dragging = true;

    }

    internal void OnDrop()
    {
        _data.dragging = false;
    }


}