/* 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.
 */

/// Changes from the Java version
///   Removed BST code, but not all artifacts of it
/// Future possibilities
///   Eliminate Add/RemoveNode ?
///   Comments comments and more comments!
using System.Text;
using System;

namespace WPM.Poly2Tri {
	/**
     * @author Thomas Åhlen (thahlen@gmail.com)
     */
	public class AdvancingFront {
		public AdvancingFrontNode Head;
		public AdvancingFrontNode Tail;
		protected AdvancingFrontNode Search;

		public AdvancingFront (AdvancingFrontNode head, AdvancingFrontNode tail) {
			this.Head = head;
			this.Tail = tail;
			this.Search = head;
//			AddNode (head);
//			AddNode (tail);
		}
//
//		public void AddNode (AdvancingFrontNode node) {
//		}
//
//		public void RemoveNode (AdvancingFrontNode node) {
//		}

		public override string ToString () {
			StringBuilder sb = new StringBuilder ();
			AdvancingFrontNode node = Head;
			while (node != Tail) {
				sb.Append (node.Point.X).Append ("->");
				node = node.Next;
			}
			sb.Append (Tail.Point.X);
			return sb.ToString ();
		}

		/// <summary>
		/// MM:  This seems to be used by LocateNode to guess a position in the implicit linked list of AdvancingFrontNodes near x
		///      Removed an overload that depended on this being exact
		/// </summary>
		private AdvancingFrontNode FindSearchNode (double x) {
			return Search;
		}

		/// <summary>
		/// We use a balancing tree to locate a node smaller or equal to given key value (in theory)
		/// </summary>
		public AdvancingFrontNode LocateNode (TriangulationPoint point) {
			return LocateNode (point.X);
		}

		private AdvancingFrontNode LocateNode (double x) {
			AdvancingFrontNode node = FindSearchNode (x);
			if (x < node.Value) { // - Point2D.PRECISION) {
				while ((node = node.Prev) != null) {
					if (x >= node.Value) { // - Point2D.PRECISION) {
						Search = node;
						return node;
					}
				}
			} else {
				while ((node = node.Next) != null) {
					if (x < node.Value) { // - Point2D.PRECISION) {
						Search = node.Prev;
						return node.Prev;
					}
				}
			}

			return null;
		}


		/// <summary>
		/// This implementation will use simple node traversal algorithm to find a point on the front
		/// </summary>
		public AdvancingFrontNode LocatePoint (TriangulationPoint point) {
			double px = point.X;
			AdvancingFrontNode node = FindSearchNode (px);
			double nx = node.Point.X;

			if (px == nx) { // Changed by Kronnect Games == nx) {
				if (point != node.Point) {
					// We might have two nodes with same x value for a short time
					if (point == node.Prev.Point) {
						node = node.Prev;
					} else if (point == node.Next.Point) {
						node = node.Next;
					} else {
						throw new Exception ("Failed to find Node for given afront point");
					}
				}
			} else if (px < nx) { // Changes by Kronnect Games
				while ((node = node.Prev) != null) {
					if (point == node.Point) {
						break;
					}
				}
			} else {
				while ((node = node.Next) != null) {
					if (point == node.Point) {
						break;
					}
				}
			}
			Search = node;

			return node;
		}
	}
}