/* Poly2Tri
 * Copyright (c) 2009-2010, Poly2Tri Contributors
 * http://code.google.com/p/poly2tri/
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * * Redistributions of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
 * * Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 * * Neither the name of Poly2Tri nor the names of its contributors may be
 *   used to endorse or promote products derived from this software without specific
 *   prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
/**
 * Forces a triangle edge between two points p and q
 * when triangulating. For example used to enforce
 * Polygon Edges during a polygon triangulation.
 * 
 * @author Thomas Åhlén, thahlen@gmail.com
 */
using System;


namespace WPM.Poly2Tri {
	public class Edge {
		protected Point2D mP = null;
		protected Point2D mQ = null;

		public Point2D EdgeStart { get { return mP; } set { mP = value; } }

		public Point2D EdgeEnd { get { return mQ; } set { mQ = value; } }

		public Edge () {
			mP = null;
			mQ = null;
		}

		public Edge (Point2D edgeStart, Point2D edgeEnd) {
			mP = edgeStart;
			mQ = edgeEnd;
		}
	}
 
	public class TriangulationConstraint : Edge {
		private uint mContraintCode = 0;

		public TriangulationPoint P {
			get { return mP as TriangulationPoint; } 
			set {
				// Note:  intentionally use != instead of !Equals() because we
				// WANT to compare pointer values here rather than VertexCode values
				if (value != null && mP != value) {
					mP = value;
					CalculateContraintCode ();
				}
			}
		}

		public TriangulationPoint Q {
			get { return mQ as TriangulationPoint; }
			set {
				// Note:  intentionally use != instead of !Equals() because we
				// WANT to compare pointer values here rather than VertexCode values
				if (value != null && mQ != value) {
					mQ = value;
					CalculateContraintCode ();
				}
			}
		}

		public uint ConstraintCode { get { return mContraintCode; } }


		/// <summary>
		/// Give two points in any order. Will always be ordered so
		/// that q.y > p.y and q.x > p.x if same y value 
		/// </summary>
		public TriangulationConstraint (TriangulationPoint p1, TriangulationPoint p2) {
			mP = p1;
			mQ = p2;
			if (p1.Y > p2.Y) {
				mQ = p1;
				mP = p2;
			} else if (p1.Y == p2.Y) {
				if (p1.X > p2.X) {
					mQ = p1;
					mP = p2;
				} else if (p1.X == p2.X) {
					//                logger.info( "Failed to create constraint {}={}", p1, p2 );
					//                throw new DuplicatePointException( p1 + "=" + p2 );
					//                return;
				}
			}
			CalculateContraintCode ();
		}

		public override string ToString () {
			return "[P=" + P.ToString () + ", Q=" + Q.ToString () + " : {" + mContraintCode.ToString () + "}]";
		}
        
		public void CalculateContraintCode () {
			mContraintCode = TriangulationConstraint.CalculateContraintCode (P, Q);
		}

		public static uint CalculateContraintCode (TriangulationPoint p, TriangulationPoint q) {
			if (p == null || p == null) {
				throw new ArgumentNullException ();
			}

			uint constraintCode = MathUtil.Jenkins32Hash (BitConverter.GetBytes (p.VertexCode), 0);
			constraintCode = MathUtil.Jenkins32Hash (BitConverter.GetBytes (q.VertexCode), constraintCode);

			return constraintCode;
		}

	}
}