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

namespace InfernalRobotics.Gui
{
    public class PanelResizer : MonoBehaviour, IPointerDownHandler, IDragHandler
    {
        public Vector2 minSize;
        public Vector2 maxSize;

        public RectTransform rectTransform;
        private Vector2 currentPointerPosition;
        private Vector2 previousPointerPosition;
        
        public void OnPointerDown(PointerEventData data)
        {
            rectTransform.SetAsLastSibling();
            RectTransformUtility.ScreenPointToLocalPointInRectangle(rectTransform, data.position, data.pressEventCamera, out previousPointerPosition);
        }

        public void OnDrag(PointerEventData data)
        {
            if (rectTransform == null)
                return;

            Vector2 sizeDelta = rectTransform.sizeDelta;

            RectTransformUtility.ScreenPointToLocalPointInRectangle(rectTransform, data.position, data.pressEventCamera, out currentPointerPosition);
            Vector2 resizeValue = currentPointerPosition - previousPointerPosition;

            sizeDelta += new Vector2(resizeValue.x, -resizeValue.y);
            sizeDelta = new Vector2(
                Mathf.Clamp(sizeDelta.x, minSize.x, maxSize.x),
                Mathf.Clamp(sizeDelta.y, minSize.y, maxSize.y)
                );

            rectTransform.sizeDelta = sizeDelta;

            previousPointerPosition = currentPointerPosition;
        }
    }
}
