/*
 *    GeoTools - The Open Source Java GIS Toolkit
 *    http://geotools.org
 *    
 *    (C) 2001-2006  Vivid Solutions
 *    (C) 2001-2008, Open Source Geospatial Foundation (OSGeo)
 *    
 *    This library is free software; you can redistribute it and/or
 *    modify it under the terms of the GNU Lesser General Public
 *    License as published by the Free Software Foundation;
 *    version 2.1 of the License.
 *
 *    This library is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *    Lesser General Public License for more details.
 */
package org.geotools.geometry.iso.topograph2D;


/**
 * A TopologyLocation is the labelling of a GraphComponent's topological
 * relationship to a single Geometry.
 * <p>
 * If the parent component is an area edge, each side and the edge itself have a
 * topological location. These locations are named
 * <ul>
 * <li> ON: on the edge
 * <li> LEFT: left-hand side of the edge
 * <li> RIGHT: right-hand side
 * </ul>
 * If the parent component is a line edge or node, there is a single topological
 * relationship attribute, ON.
 * <p>
 * The possible values of a topological location are {Location.NONE,
 * Location.EXTERIOR, Location.BOUNDARY, Location.INTERIOR}
 * <p>
 * The labelling is stored in an array location[j] where where j has the values
 * ON, LEFT, RIGHT
 *
 *
 *
 * @source $URL$
 */
public class TopologyLocation {

	int location[];

	public TopologyLocation(int[] location) {
		init(location.length);
	}

	/**
	 * Constructs a TopologyLocation specifying how points on, to the left of,
	 * and to the right of some GraphComponent relate to some Geometry. Possible
	 * values for the parameters are Location.NULL, Location.EXTERIOR,
	 * Location.BOUNDARY, and Location.INTERIOR.
	 * 
	 * @see Location
	 */
	public TopologyLocation(int on, int left, int right) {
		init(3);
		location[Position.ON] = on;
		location[Position.LEFT] = left;
		location[Position.RIGHT] = right;
	}

	public TopologyLocation(int on) {
		init(1);
		location[Position.ON] = on;
	}

	public TopologyLocation(TopologyLocation gl) {
		init(gl.location.length);
		if (gl != null) {
			for (int i = 0; i < location.length; i++) {
				location[i] = gl.location[i];
			}
		}
	}

	private void init(int size) {
		location = new int[size];
		setAllLocations(Location.NONE);
	}

	public int get(int posIndex) {
		if (posIndex < location.length)
			return location[posIndex];
		return Location.NONE;
	}

	/**
	 * @return true if all locations are NULL
	 */
	public boolean isNull() {
		for (int i = 0; i < location.length; i++) {
			if (location[i] != Location.NONE)
				return false;
		}
		return true;
	}

	/**
	 * @return true if any locations are NULL
	 */
	public boolean isAnyNull() {
		for (int i = 0; i < location.length; i++) {
			if (location[i] == Location.NONE)
				return true;
		}
		return false;
	}

	public boolean isEqualOnSide(TopologyLocation le, int locIndex) {
		return location[locIndex] == le.location[locIndex];
	}

	public boolean isArea() {
		return location.length > 1;
	}

	public boolean isLine() {
		return location.length == 1;
	}

	public void flip() {
		if (location.length <= 1)
			return;
		int temp = location[Position.LEFT];
		location[Position.LEFT] = location[Position.RIGHT];
		location[Position.RIGHT] = temp;
	}

	public void setAllLocations(int locValue) {
		for (int i = 0; i < location.length; i++) {
			location[i] = locValue;
		}
	}

	public void setAllLocationsIfNull(int locValue) {
		for (int i = 0; i < location.length; i++) {
			if (location[i] == Location.NONE)
				location[i] = locValue;
		}
	}

	public void setLocation(int locIndex, int locValue) {
		location[locIndex] = locValue;
	}

	public void setLocation(int locValue) {
		setLocation(Position.ON, locValue);
	}

	public int[] getLocations() {
		return location;
	}

	public void setLocations(int on, int left, int right) {
		location[Position.ON] = on;
		location[Position.LEFT] = left;
		location[Position.RIGHT] = right;
	}

	public boolean allPositionsEqual(int loc) {
		for (int i = 0; i < location.length; i++) {
			if (location[i] != loc)
				return false;
		}
		return true;
	}

	/**
	 * merge updates only the NULL attributes of this object with the attributes
	 * of another.
	 */
	public void merge(TopologyLocation gl) {
		// if the src is an Area label & and the dest is not, increase the dest
		// to be an Area
		if (gl.location.length > location.length) {
			int[] newLoc = new int[3];
			newLoc[Position.ON] = location[Position.ON];
			newLoc[Position.LEFT] = Location.NONE;
			newLoc[Position.RIGHT] = Location.NONE;
			location = newLoc;
		}
		for (int i = 0; i < location.length; i++) {
			if (location[i] == Location.NONE && i < gl.location.length)
				location[i] = gl.location[i];
		}
	}

	public String toString() {
		StringBuffer buf = new StringBuffer();
		if (location.length > 1)
			buf.append(Location.toLocationSymbol(location[Position.LEFT]));
		buf.append(Location.toLocationSymbol(location[Position.ON]));
		if (location.length > 1)
			buf.append(Location.toLocationSymbol(location[Position.RIGHT]));
		return buf.toString();
	}
}