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

namespace BracerLib.Utility
{
    [ExcludeFromCoverage]
    public static class UIUtility
    {
        private static bool performRefresh;
        private static PointerEventData eventBuffer = new PointerEventData(EventSystem.current);
        private static List<RaycastResult> raycastResultBuffer = new List<RaycastResult>(4);

        static UIUtility()
        {
            SceneManager.activeSceneChanged += (before, after) => Refresh();
        }

        public static bool IsMouseOverUI(Vector2 position, int uiLayer)
        {
            var eventSystem = EventSystem.current;
            eventBuffer.position = position;
            eventSystem.RaycastAll(eventBuffer, raycastResultBuffer);

            for (var i = 0; i < raycastResultBuffer.Count; i++)
            {
                var raycastResult = raycastResultBuffer[i];

                if (raycastResult.gameObject.layer == uiLayer)
                    return true;
            }

            return false;
        }

        private static void Refresh()
        {
            var current = EventSystem.current;

            if (current == null)
                return;

            eventBuffer = new PointerEventData(EventSystem.current);
        }
    }
}