using TriangleNet.Geometry;
using TriangleNet.Tools;
using TriangleNet.Topology.DCEL;

namespace TriangleNet.Voronoi
{
	public class BoundedVoronoi : VoronoiBase
	{
		private int offset;

		public BoundedVoronoi(Mesh mesh)
			: this(mesh, new DefaultVoronoiFactory(), RobustPredicates.Default)
		{
		}

		public BoundedVoronoi(Mesh mesh, IVoronoiFactory factory, IPredicates predicates)
			: base(mesh, factory, predicates, generate: true)
		{
			offset = vertices.Count;
			vertices.Capacity = offset + mesh.hullsize;
			PostProcess();
			ResolveBoundaryEdges();
		}

		private void PostProcess()
		{
			foreach (HalfEdge ray in rays)
			{
				HalfEdge twin = ray.twin;
				TriangleNet.Geometry.Vertex vertex = (TriangleNet.Geometry.Vertex)ray.face.generator;
				TriangleNet.Geometry.Vertex vertex2 = (TriangleNet.Geometry.Vertex)twin.face.generator;
				if (predicates.CounterClockwise(vertex, vertex2, ray.origin) <= 0.0)
				{
					HandleCase1(ray, vertex, vertex2);
				}
				else
				{
					HandleCase2(ray, vertex, vertex2);
				}
			}
		}

		private void HandleCase1(HalfEdge edge, TriangleNet.Geometry.Vertex v1, TriangleNet.Geometry.Vertex v2)
		{
			TriangleNet.Topology.DCEL.Vertex origin = edge.twin.origin;
			origin.x = (v1.x + v2.x) / 2.0;
			origin.y = (v1.y + v2.y) / 2.0;
			TriangleNet.Topology.DCEL.Vertex vertex = factory.CreateVertex(v1.x, v1.y);
			HalfEdge halfEdge = factory.CreateHalfEdge(edge.twin.origin, edge.face);
			HalfEdge halfEdge2 = factory.CreateHalfEdge(vertex, edge.face);
			edge.next = halfEdge;
			halfEdge.next = halfEdge2;
			halfEdge2.next = edge.face.edge;
			vertex.leaving = halfEdge2;
			edge.face.edge = halfEdge2;
			edges.Add(halfEdge);
			edges.Add(halfEdge2);
			halfEdge2.id = (halfEdge.id = edges.Count) + 1;
			vertex.id = offset++;
			vertices.Add(vertex);
		}

		private void HandleCase2(HalfEdge edge, TriangleNet.Geometry.Vertex v1, TriangleNet.Geometry.Vertex v2)
		{
			Point c = edge.origin;
			Point c2 = edge.twin.origin;
			HalfEdge next = edge.twin.next;
			HalfEdge next2 = next.twin.next;
			IntersectionHelper.IntersectSegments(v1, v2, next.origin, next.twin.origin, ref c2);
			IntersectionHelper.IntersectSegments(v1, v2, next2.origin, next2.twin.origin, ref c);
			next.twin.next = edge.twin;
			edge.twin.next = next2;
			edge.twin.face = next2.face;
			next.origin = edge.twin.origin;
			edge.twin.twin = null;
			edge.twin = null;
			TriangleNet.Topology.DCEL.Vertex vertex = factory.CreateVertex(v1.x, v1.y);
			HalfEdge halfEdge = (edge.next = factory.CreateHalfEdge(vertex, edge.face));
			halfEdge.next = edge.face.edge;
			edge.face.edge = halfEdge;
			edges.Add(halfEdge);
			halfEdge.id = edges.Count;
			vertex.id = offset++;
			vertices.Add(vertex);
		}
	}
}