using System.Collections.Generic;
using TriangleNet.Geometry;

namespace TriangleNet.Topology.DCEL
{
	public class Face
	{
		public static readonly Face Empty;

		internal int id;

		internal Point generator;

		internal HalfEdge edge;

		internal bool bounded;

		public int ID
		{
			get
			{
				return id;
			}
			set
			{
				id = value;
			}
		}

		public HalfEdge Edge
		{
			get
			{
				return edge;
			}
			set
			{
				edge = value;
			}
		}

		public bool Bounded
		{
			get
			{
				return bounded;
			}
			set
			{
				bounded = value;
			}
		}

		static Face()
		{
			Empty = new Face(null);
			Empty.id = -1;
		}

		public Face(Point generator)
			: this(generator, null)
		{
		}

		public Face(Point generator, HalfEdge edge)
		{
			this.generator = generator;
			this.edge = edge;
			bounded = true;
			if (generator != null)
			{
				id = generator.ID;
			}
		}

		public IEnumerable<HalfEdge> EnumerateEdges()
		{
			HalfEdge edge = Edge;
			int first = edge.ID;
			do
			{
				yield return edge;
				edge = edge.Next;
			}
			while (edge.ID != first);
		}

		public override string ToString()
		{
			return $"F-ID {id}";
		}
	}
}