using UnityEngine;

namespace DebuggingEssentials
{
	public class ScrollViewCullDrawOnce
	{
		public bool active = true;

		public bool recalc;

		private FastList<float> elements1 = new FastList<float>();

		private FastList<float> elements2 = new FastList<float>();

		private Vector2 scrollView;

		private bool eventLayout;

		private bool eventRepaint;

		private bool hasCalc;

		private bool calcHeights;

		private int startElementCull;

		private float spaceEnd;

		private float scrollViewStartHeight;

		private float scrollViewEndHeight;

		public void ResetAndRecalc()
		{
			recalc = true;
			scrollView.y = 0f;
		}

		public void BeginScrollView(float heightOffset = 0f)
		{
			Event current = Event.current;
			eventLayout = current.type == EventType.Layout;
			eventRepaint = current.type == EventType.Repaint;
			if (recalc && eventLayout)
			{
				hasCalc = false;
				recalc = false;
				elements1.FastClear();
				elements2.FastClear();
			}
			startElementCull = 0;
			calcHeights = !hasCalc && eventRepaint;
			spaceEnd = 0f;
			GUILayout.Space(0f);
			float y = GUILayoutUtility.GetLastRect().y;
			if (calcHeights)
			{
				scrollViewStartHeight = y;
			}
			scrollView = GUILayout.BeginScrollView(scrollView);
			if (!hasCalc || !active)
			{
				return;
			}
			int num = Helper.BinarySearch(elements2.items, elements2.Count, scrollView.y);
			float num2 = 0f;
			float num3 = elements2.items[num];
			if (num3 < scrollView.y)
			{
				num2 = num3;
			}
			else if (num > 0)
			{
				num3 = elements2.items[num - 1];
				if (num3 < scrollView.y)
				{
					num2 = num3;
				}
			}
			if (num2 > 0f)
			{
				GUILayout.Space(num2 + 4f);
			}
		}

		public void EndScrollView()
		{
			if (hasCalc && active)
			{
				GUILayout.Space((spaceEnd != 0f) ? (elements2.items[elements2.Count - 1] - spaceEnd) : 0f);
			}
			GUILayout.EndScrollView();
			if (calcHeights)
			{
				hasCalc = true;
			}
			GUILayout.Space(0f);
			float y = GUILayoutUtility.GetLastRect().y;
			if (calcHeights)
			{
				scrollViewEndHeight = y;
			}
		}

		public bool StartCull()
		{
			if (!hasCalc || !active)
			{
				return true;
			}
			if (startElementCull >= elements1.items.Length)
			{
				return true;
			}
			float num = elements1.items[startElementCull];
			if (elements2.items[startElementCull++] < scrollView.y && active)
			{
				return false;
			}
			if (num > scrollViewEndHeight - scrollViewStartHeight + scrollView.y && active)
			{
				if (spaceEnd == 0f)
				{
					spaceEnd = num;
				}
				return false;
			}
			return true;
		}

		public void EndCull()
		{
			if (calcHeights)
			{
				Rect lastRect = GUILayoutUtility.GetLastRect();
				elements1.Add(lastRect.yMin);
				elements2.Add(lastRect.yMax);
			}
		}
	}
}