using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using UnityEngine;
using UnityEditor;
using Object = UnityEngine.Object;

namespace UnityEditorInternal
{
	internal class RectUtils
	{
		public static bool Contains(Rect a, Rect b)
		{
			if (a.xMin > b.xMin)
				return false;
			if (a.xMax < b.xMax)
				return false;

			if (a.yMin > b.yMin)
				return false;
			if (a.yMax < b.yMax)
				return false;

			return true;
		}

		public static Rect Encompass(Rect a, Rect b)
		{
			Rect newRect = a;
			newRect.xMin = Math.Min(a.xMin, b.xMin);
			newRect.yMin = Math.Min(a.yMin, b.yMin);
			newRect.xMax = Math.Max(a.xMax, b.xMax);
			newRect.yMax = Math.Max(a.yMax, b.yMax);
			return newRect;
		}

		public static Rect Inflate(Rect a, float factor)
		{
			return Inflate(a, factor, factor);
		}

		public static Rect Inflate(Rect a, float factorX, float factorY)
		{
			float newWidth = a.width * factorX;
			float newHeight = a.height * factorY;

			float offsetWidth = (newWidth - a.width) / 2.0f;
			float offsetHeight = (newHeight - a.height) / 2.0f;

			Rect r = a;
			r.xMin -= offsetWidth;
			r.yMin -= offsetHeight;
			r.xMax += offsetWidth;
			r.yMax += offsetHeight;
			return r;
		}

		public static bool Intersects(Rect r1, Rect r2)
		{
			if (!r1.Overlaps(r2) && !r2.Overlaps(r1))
				return false;
			return true;
		}

		public static bool Intersection(Rect r1, Rect r2, out Rect intersection)
		{
			if (!r1.Overlaps(r2) && !r2.Overlaps(r1))
			{
				intersection = new Rect(0, 0, 0, 0);
				return false;
			}

			float left = Mathf.Max(r1.xMin, r2.xMin);
			float top = Mathf.Max(r1.yMin, r2.yMin);

			float right = Mathf.Min(r1.xMax, r2.xMax);
			float bottom = Mathf.Min(r1.yMax, r2.yMax);

			intersection = new Rect(left, top, right - left, bottom - top);
			return true;
		}

		public static bool IntersectsSegment(Rect rect, Vector2 p1, Vector2 p2)
		{
			float minX = Mathf.Min(p1.x, p2.x);
			float maxX = Mathf.Max(p1.x, p2.x);

			if (maxX > rect.xMax)
			{
				maxX = rect.xMax;
			}

			if (minX < rect.xMin)
			{
				minX = rect.xMin;
			}

			if (minX > maxX)
			{
				return false;
			}

			float minY = Mathf.Min(p1.y, p2.y);
			float maxY = Mathf.Max(p1.y, p2.y);

			float dx = p2.x - p1.x;

			if (Mathf.Abs(dx) > 0.0000001f)
			{
				float a = (p2.y - p1.y) / dx;
				float b = p1.y - a * p1.x;
				minY = a * minX + b;
				maxY = a * maxX + b;
			}

			if (minY > maxY)
			{
				float tmp = maxY;
				maxY = minY;
				minY = tmp;
			}

			if (maxY > rect.yMax)
			{
				maxY = rect.yMax;
			}

			if (minY < rect.yMin)
			{
				minY = rect.yMin;
			}

			if (minY > maxY)
			{
				return false;
			}

			return true;
		}

		public static Rect OffsetX(Rect r, float offsetX)
		{
			return Offset(r, offsetX, 0.0f);
		}

		public static Rect Offset(Rect r, float offsetX, float offsetY)
		{
			Rect nr = r;
			nr.xMin += offsetX;
			nr.yMin += offsetY;
			return nr;
		}

		public static Rect Offset(Rect a, Rect b)
		{
			Rect nr = a;
			nr.xMin += b.xMin;
			nr.yMin += b.yMin;
			return nr;
		}

		public static Rect Move(Rect r, Vector2 delta)
		{
			Rect nr = r;
			nr.xMin += delta.x;
			nr.yMin += delta.y;
			nr.xMax += delta.x;
			nr.yMax += delta.y;
			return nr;
		}
	}

	internal interface IBounds
	{
		Rect boundingRect { get; }
	}

	internal class QuadTreeNode<T> where T : IBounds
	{
		private Rect m_BoundingRect;
		private static Color m_DebugFillColor = new Color(1.0f, 1.0f, 1.0f, 0.01f);
		private static Color m_DebugWireColor = new Color(1.0f, 0.0f, 0.0f, 0.5f);
		private static Color m_DebugBoxFillColor = new Color(1.0f, 0.0f, 0.0f, 0.01f);
		private const float kSmallestAreaForQuadTreeNode = 10.0f;

		List<T> m_Elements = new List<T>();
		List<QuadTreeNode<T>> m_ChildrenNodes = new List<QuadTreeNode<T>>(4);

		public QuadTreeNode(Rect r)
		{
			m_BoundingRect = r;
		}

		public bool IsEmpty { get { return (m_BoundingRect.width == 0 && m_BoundingRect.height == 0) || m_ChildrenNodes.Count == 0; } }
		public Rect BoundingRect { get { return m_BoundingRect; } }

		public int CountItemsIncludingChildren()
		{
			return Count (true);
		}
		
		public int CountLocalItems()
		{
			return Count(false);
		}

		private int Count(bool recursive)
		{
			int count = m_Elements.Count;

			if (recursive)
			{
					foreach (QuadTreeNode<T> node in m_ChildrenNodes)
						count += node.Count(recursive);
			}
			return count;
		}

		public List<T> GetElementsIncludingChildren()
		{
			return Elements (true);
		}

		public List<T> GetElements()
		{
			return Elements(false);
		}

		private List<T> Elements(bool recursive)
		{
			List<T> results = new List<T>();

			if (recursive)
			{
					foreach (QuadTreeNode<T> node in m_ChildrenNodes)
						results.AddRange(node.Elements(recursive));
			}

			results.AddRange(m_Elements);
			return results;
		}

		public List<T> IntersectsWith(Rect queryArea)
		{
			List<T> results = new List<T>();
			
			foreach (T item in m_Elements)
			{
				if (RectUtils.Intersects(item.boundingRect, queryArea))
				{
					results.Add(item);
				}
			}

			foreach (QuadTreeNode<T> node in m_ChildrenNodes)
			{
				if (node.IsEmpty)
					continue;

				if (RectUtils.Intersects(node.BoundingRect, queryArea))
				{
					// the node completely contains the queryArea
					// recurse down and stop
					results.AddRange(node.IntersectsWith(queryArea));
					break;
				}
			}

			return results;

		}


		public List<T> ContainedBy(Rect queryArea)
		{
			List<T> results = new List<T>();

			foreach (T item in m_Elements)
			{
					if (RectUtils.Contains(item.boundingRect, queryArea))
					{
						results.Add(item);
					}
					else if (queryArea.Overlaps(item.boundingRect))
					{
						results.Add(item);
					}
			}

			foreach (QuadTreeNode<T> node in m_ChildrenNodes)
			{
					if (node.IsEmpty)
						continue;

					if (RectUtils.Contains(node.BoundingRect, queryArea))
					{
						// the node completely contains the queryArea
						// recurse down and stop
						results.AddRange(node.ContainedBy(queryArea));
						break;
					}

					if (RectUtils.Contains(queryArea, node.BoundingRect))
					{
						// the queryArea completely contains this node
						// just add everything under this node, recursively
						results.AddRange(node.Elements(true));
						continue;
					}

					if (node.BoundingRect.Overlaps(queryArea))
					{
						// the node intesects
						// recurse and continue iterating siblings
						results.AddRange(node.ContainedBy(queryArea));
					}
			}

			return results;
		}

		public void Remove(T item)
		{
			m_Elements.Remove(item);
			foreach (QuadTreeNode<T> node in m_ChildrenNodes)
			{
				node.Remove(item);
			}
		}

		public void Insert(T item)
		{
			if (!RectUtils.Contains(m_BoundingRect, item.boundingRect))
			{
				Rect intersection = new Rect();
				if (!RectUtils.Intersection(item.boundingRect, m_BoundingRect, out intersection))
				{
					// Ignore elements completely outside the quad tree
					return;
				}
			}

			if (m_ChildrenNodes.Count == 0)
					Subdivide();

			// insert into children nodes
			foreach (QuadTreeNode<T> node in m_ChildrenNodes)
			{
				if (RectUtils.Contains(node.BoundingRect, item.boundingRect))
				{
					node.Insert(item);
					return;
				}
			}

			// item is not completely contained in any of the children nodes
			// insert here
			this.m_Elements.Add(item);
		}

		private void Subdivide()
		{
			if ((m_BoundingRect.height * m_BoundingRect.width) <= kSmallestAreaForQuadTreeNode)
					return;

			float halfWidth = (m_BoundingRect.width / 2f);
			float halfHeight = (m_BoundingRect.height / 2f);

			m_ChildrenNodes.Add(new QuadTreeNode<T>(new Rect(m_BoundingRect.position.x, m_BoundingRect.position.y, halfWidth, halfHeight)));
			m_ChildrenNodes.Add(new QuadTreeNode<T>(new Rect(m_BoundingRect.xMin, m_BoundingRect.yMin + halfHeight, halfWidth, halfHeight)));
			m_ChildrenNodes.Add(new QuadTreeNode<T>(new Rect(m_BoundingRect.xMin + halfWidth, m_BoundingRect.yMin, halfWidth, halfHeight)));
			m_ChildrenNodes.Add(new QuadTreeNode<T>(new Rect(m_BoundingRect.xMin + halfWidth, m_BoundingRect.yMin + halfHeight, halfWidth, halfHeight)));
		}

		public void DebugDraw(Vector2 offset)
		{
			UnityEditor.Experimental.UIHelpers.ApplyWireMaterial();
			Rect screenSpaceRect = m_BoundingRect;
			screenSpaceRect.x += offset.x;
			screenSpaceRect.y += offset.y;

			Handles.DrawSolidRectangleWithOutline(screenSpaceRect, m_DebugFillColor, m_DebugWireColor);
			foreach (QuadTreeNode<T> node in m_ChildrenNodes)
			{
				node.DebugDraw(offset);
			}

			foreach (IBounds i in Elements(false))
			{
				Rect o = i.boundingRect;
				o.x += offset.x;
				o.y += offset.y;
				Handles.DrawSolidRectangleWithOutline(o, m_DebugBoxFillColor, Color.yellow);
			}
			
		}
	};

	internal class QuadTree<T> where T : IBounds
	{
		private QuadTreeNode<T> m_Root = null;
		private Rect m_Rectangle;
		private Vector2 m_ScreenSpaceOffset = Vector2.zero;
		
		public QuadTree()
		{
			Clear();
		}

		public Vector2 screenSpaceOffset
		{
			get { return m_ScreenSpaceOffset; }
			set
			{
				m_ScreenSpaceOffset = value;
			}
		}

		public Rect rectangle
		{
			get { return m_Rectangle; }
		}

		public void Clear()
		{
			SetSize(new Rect(0, 0, 1, 1));
		}

		public void SetSize(Rect rectangle)
		{
			m_Root = null;
			m_Rectangle = rectangle;
			m_Root = new QuadTreeNode<T>(m_Rectangle);
		}

		public int Count { get { return m_Root.CountItemsIncludingChildren(); } }

		public void Insert(List<T> items)
		{
			foreach (T i in items)
			{
					Insert(i);
			}
		}

		public void Insert(T item)
		{
			m_Root.Insert(item);
		}

		public void Remove(T item)
		{
			m_Root.Remove(item);
		}

		public List<T> IntersectsWith(Rect area)
		{
			area.x -= m_ScreenSpaceOffset.x;
			area.y -= m_ScreenSpaceOffset.y;
			return m_Root.IntersectsWith(area);
		}

		public List<T> ContainedBy(Rect area)
		{
			area.x -= m_ScreenSpaceOffset.x;
			area.y -= m_ScreenSpaceOffset.y;
			return m_Root.ContainedBy(area);
		}

		public List<T> Elements()
		{
			return m_Root.GetElementsIncludingChildren();
		}

		public void DebugDraw()
		{
			m_Root.DebugDraw(m_ScreenSpaceOffset);
		}
	}
}