using System;
using TriangleNet.Geometry;
using TriangleNet.Topology.DCEL;
using TriangleNet.Voronoi;

namespace TriangleNet.Smoothing
{
	internal class VoronoiFactory : IVoronoiFactory
	{
		private class ObjectPool<T> where T : class
		{
			private int index;

			private int count;

			private T[] pool;

			public int Count => count;

			public int Capacity
			{
				get
				{
					return pool.Length;
				}
				set
				{
					Resize(value);
				}
			}

			public ObjectPool(int capacity = 3)
			{
				index = 0;
				count = 0;
				pool = new T[capacity];
			}

			public ObjectPool(T[] pool)
			{
				index = 0;
				count = 0;
				this.pool = pool;
			}

			public bool TryGet(out T obj)
			{
				if (index < count)
				{
					obj = pool[index++];
					return true;
				}
				obj = null;
				return false;
			}

			public void Put(T obj)
			{
				int num = pool.Length;
				if (num <= count)
				{
					Resize(2 * num);
				}
				pool[count++] = obj;
				index++;
			}

			public void Release()
			{
				index = 0;
			}

			private void Resize(int size)
			{
				if (size > count)
				{
					Array.Resize(ref pool, size);
				}
			}
		}

		private ObjectPool<TriangleNet.Topology.DCEL.Vertex> vertices;

		private ObjectPool<HalfEdge> edges;

		private ObjectPool<Face> faces;

		public VoronoiFactory()
		{
			vertices = new ObjectPool<TriangleNet.Topology.DCEL.Vertex>();
			edges = new ObjectPool<HalfEdge>();
			faces = new ObjectPool<Face>();
		}

		public void Initialize(int vertexCount, int edgeCount, int faceCount)
		{
			vertices.Capacity = vertexCount;
			edges.Capacity = edgeCount;
			faces.Capacity = faceCount;
			for (int i = vertices.Count; i < vertexCount; i++)
			{
				vertices.Put(new TriangleNet.Topology.DCEL.Vertex(0.0, 0.0));
			}
			for (int j = edges.Count; j < edgeCount; j++)
			{
				edges.Put(new HalfEdge(null));
			}
			for (int k = faces.Count; k < faceCount; k++)
			{
				faces.Put(new Face(null));
			}
			Reset();
		}

		public void Reset()
		{
			vertices.Release();
			edges.Release();
			faces.Release();
		}

		public TriangleNet.Topology.DCEL.Vertex CreateVertex(double x, double y)
		{
			if (vertices.TryGet(out var obj))
			{
				obj.x = x;
				obj.y = y;
				obj.leaving = null;
				return obj;
			}
			obj = new TriangleNet.Topology.DCEL.Vertex(x, y);
			vertices.Put(obj);
			return obj;
		}

		public HalfEdge CreateHalfEdge(TriangleNet.Topology.DCEL.Vertex origin, Face face)
		{
			if (edges.TryGet(out var obj))
			{
				obj.origin = origin;
				obj.face = face;
				obj.next = null;
				obj.twin = null;
				if (face != null && face.edge == null)
				{
					face.edge = obj;
				}
				return obj;
			}
			obj = new HalfEdge(origin, face);
			edges.Put(obj);
			return obj;
		}

		public Face CreateFace(TriangleNet.Geometry.Vertex vertex)
		{
			if (faces.TryGet(out var obj))
			{
				obj.id = vertex.id;
				obj.generator = vertex;
				obj.edge = null;
				return obj;
			}
			obj = new Face(vertex);
			faces.Put(obj);
			return obj;
		}
	}
}