/modules/unsupported/geometry/src/main/java/org/geotools/geometry/iso/topograph2D/util/CoordinateArrays.java

/*
 *    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.util;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Comparator;
import java.util.List;

import org.geotools.geometry.iso.coordinate.DirectPositionImpl;
import org.geotools.geometry.iso.coordinate.PositionImpl;
import org.geotools.geometry.iso.topograph2D.Coordinate;
import org.geotools.geometry.iso.topograph2D.CoordinateList;
import org.opengis.geometry.DirectPosition;
import org.opengis.geometry.coordinate.Position;
import org.opengis.referencing.crs.CoordinateReferenceSystem;

/**
 * Useful utility functions for handling Coordinate arrays
 *
 * @source $URL$
 */
public class CoordinateArrays {

	private final static Coordinate[] coordArrayType = new Coordinate[0];

	/**
	 * Finds a point in a list of points which is not contained in another list
	 * of points
	 * 
	 * @param testPts
	 *            the {@link Coordinate}s to test
	 * @param pts
	 *            an array of {@link Coordinate}s to test the input points
	 *            against
	 * @return a {@link Coordinate} from <code>testPts</code> which is not in
	 *         <code>pts</code>, ' or <code>null</code>
	 */
	public static Coordinate ptNotInList(Coordinate[] testPts, Coordinate[] pts) {
		for (int i = 0; i < testPts.length; i++) {
			Coordinate testPt = testPts[i];
			if (CoordinateArrays.indexOf(testPt, pts) < 0)
				return testPt;
		}
		return null;
	}

	/**
	 * Compares two {@link Coordinate} arrays in the forward direction of their
	 * coordinates, using lexicographic ordering.
	 * 
	 * @param pts1
	 * @param pts2
	 * @return
	 */
	public static int compare(Coordinate[] pts1, Coordinate[] pts2) {
		int i = 0;
		while (i < pts1.length && i < pts2.length) {
			int compare = pts1[i].compareTo(pts2[i]);
			if (compare != 0)
				return compare;
			i++;
		}
		// handle situation when arrays are of different length
		if (i < pts2.length)
			return -1;
		if (i < pts1.length)
			return 1;

		return 0;
	}

	/**
	 * A {@link Comparator} for {@link Coordinate} arrays in the forward
	 * direction of their coordinates, using lexicographic ordering.
	 */
	public static class ForwardComparator implements Comparator {
		public int compare(Object o1, Object o2) {
			Coordinate[] pts1 = (Coordinate[]) o1;
			Coordinate[] pts2 = (Coordinate[]) o2;

			return CoordinateArrays.compare(pts1, pts2);
		}
	}

	/**
	 * Determines which orientation of the {@link Coordinate} array is (overall)
	 * increasing. In other words, determines which end of the array is
	 * "smaller" (using the standard ordering on {@link Coordinate}). Returns
	 * an integer indicating the increasing direction. If the sequence is a
	 * palindrome, it is defined to be oriented in a positive direction.
	 * 
	 * @param pts
	 *            the array of Coordinates to test
	 * @return <code>1</code> if the array is smaller at the start or is a
	 *         palindrome, <code>-1</code> if smaller at the end
	 */
	public static int increasingDirection(Coordinate[] pts) {
		for (int i = 0; i < pts.length / 2; i++) {
			int j = pts.length - 1 - i;
			// skip equal points on both ends
			int comp = pts[i].compareTo(pts[j]);
			if (comp != 0)
				return comp;
		}
		// array must be a palindrome - defined to be in positive direction
		return 1;
	}

	/**
	 * Determines whether two {@link Coordinate} arrays of equal length are
	 * equal in opposite directions.
	 * 
	 * @param pts1
	 * @param pts2
	 * @return <code>true</code> if the two arrays are equal in opposite
	 *         directions.
	 */
	private static boolean isEqualReversed(Coordinate[] pts1, Coordinate[] pts2) {
		for (int i = 0; i < pts1.length; i++) {
			Coordinate p1 = pts1[i];
			Coordinate p2 = pts2[pts1.length - i - 1];
			if (p1.compareTo(p2) != 0)
				return false;
		}
		return true;
	}

	/**
	 * A {@link Comparator} for {@link Coordinate} arrays modulo their
	 * directionality. E.g. if two coordinate arrays are identical but reversed
	 * they will compare as equal under this ordering. If the arrays are not
	 * equal, the ordering returned is the ordering in the forward direction.
	 * 
	 */
	public static class BidirectionalComparator implements Comparator {
		public int compare(Object o1, Object o2) {
			Coordinate[] pts1 = (Coordinate[]) o1;
			Coordinate[] pts2 = (Coordinate[]) o2;

			if (pts1.length < pts2.length)
				return -1;
			if (pts1.length > pts2.length)
				return 1;

			if (pts1.length == 0)
				return 0;

			int forwardComp = CoordinateArrays.compare(pts1, pts2);
			boolean isEqualRev = isEqualReversed(pts1, pts2);
			if (isEqualRev)
				return 0;
			return forwardComp;
		}

		public int OLDcompare(Object o1, Object o2) {
			Coordinate[] pts1 = (Coordinate[]) o1;
			Coordinate[] pts2 = (Coordinate[]) o2;

			if (pts1.length < pts2.length)
				return -1;
			if (pts1.length > pts2.length)
				return 1;

			if (pts1.length == 0)
				return 0;

			int dir1 = increasingDirection(pts1);
			int dir2 = increasingDirection(pts2);

			int i1 = dir1 > 0 ? 0 : pts1.length - 1;
			int i2 = dir2 > 0 ? 0 : pts1.length - 1;

			for (int i = 0; i < pts1.length; i++) {
				int comparePt = pts1[i1].compareTo(pts2[i2]);
				if (comparePt != 0)
					return comparePt;
				i1 += dir1;
				i2 += dir2;
			}
			return 0;
		}

	}

	/**
	 * Creates a deep copy of the argument {@link Coordinate) array.
	 * 
	 * @param coordinates
	 *            an array of Coordinates
	 * @return a deep copy of the input
	 */
	public static Coordinate[] copyDeep(Coordinate[] coordinates) {
		Coordinate[] copy = new Coordinate[coordinates.length];
		for (int i = 0; i < coordinates.length; i++) {
			copy[i] = new Coordinate(coordinates[i]);
		}
		return copy;
	}

	/**
	 * Converts the given Collection of Coordinates into a Coordinate array.
	 */
	public static Coordinate[] toCoordinateArray(Collection coordList) {
		return (Coordinate[]) coordList.toArray(coordArrayType);
	}

	/**
	 * Returns whether #equals returns true for any two consecutive Coordinates
	 * in the given array.
	 */
	public static boolean hasRepeatedPoints(Coordinate[] coord) {
		for (int i = 1; i < coord.length; i++) {
			if (coord[i - 1].equals(coord[i])) {
				return true;
			}
		}
		return false;
	}

	/**
	 * Returns either the given coordinate array if its length is greater than
	 * the given amount, or an empty coordinate array.
	 */
	public static Coordinate[] atLeastNCoordinatesOrNothing(int n,
			Coordinate[] c) {
		return c.length >= n ? c : new Coordinate[] {};
	}

	/**
	 * If the coordinate array argument has repeated points, constructs a new
	 * array containing no repeated points. Otherwise, returns the argument.
	 * 
	 * @see #hasRepeatedPoints(Coordinate[])
	 */
	public static Coordinate[] removeRepeatedPoints(Coordinate[] coord) {
		if (!hasRepeatedPoints(coord))
			return coord;
		CoordinateList coordList = new CoordinateList(coord, false);
		return coordList.toCoordinateArray();
	}

	/**
	 * Reverses the coordinates in an array in-place.
	 */
	public static void reverse(Coordinate[] coord) {
		int last = coord.length - 1;
		int mid = last / 2;
		for (int i = 0; i <= mid; i++) {
			Coordinate tmp = coord[i];
			coord[i] = coord[last - i];
			coord[last - i] = tmp;
		}
	}

	/**
	 * Returns true if the two arrays are identical, both null, or pointwise
	 * equal (as compared using Coordinate#equals)
	 * 
	 * @see Coordinate#equals(Object)
	 */
	public static boolean equals(Coordinate[] coord1, Coordinate[] coord2) {
		if (coord1 == coord2)
			return true;
		if (coord1 == null || coord2 == null)
			return false;
		if (coord1.length != coord2.length)
			return false;
		for (int i = 0; i < coord1.length; i++) {
			if (!coord1[i].equals(coord2[i]))
				return false;
		}
		return true;
	}

	/**
	 * Returns true if the two arrays are identical, both null, or pointwise
	 * equal, using a user-defined {@link Comparator} for {@link Coordinate} s
	 * 
	 * @param coord1
	 *            an array of Coordinates
	 * @param coord2
	 *            an array of Coordinates
	 * @param coordinateComparator
	 *            a Comparator for Coordinates
	 */
	public static boolean equals(Coordinate[] coord1, Coordinate[] coord2,
			Comparator coordinateComparator) {
		if (coord1 == coord2)
			return true;
		if (coord1 == null || coord2 == null)
			return false;
		if (coord1.length != coord2.length)
			return false;
		for (int i = 0; i < coord1.length; i++) {
			if (coordinateComparator.compare(coord1[i], coord2[i]) != 0)
				return false;
		}
		return true;
	}

	/**
	 * Returns the minimum coordinate, using the usual lexicographic comparison.
	 * 
	 * @param coordinates
	 *            the array to search
	 * @return the minimum coordinate in the array, found using
	 *         <code>compareTo</code>
	 * @see Coordinate#compareTo(Object)
	 */
	public static Coordinate minCoordinate(Coordinate[] coordinates) {
		Coordinate minCoord = null;
		for (int i = 0; i < coordinates.length; i++) {
			if (minCoord == null || minCoord.compareTo(coordinates[i]) > 0) {
				minCoord = coordinates[i];
			}
		}
		return minCoord;
	}

	/**
	 * Shifts the positions of the coordinates until
	 * <code>firstCoordinate</code> is first.
	 * 
	 * @param coordinates
	 *            the array to rearrange
	 * @param firstCoordinate
	 *            the coordinate to make first
	 */
	public static void scroll(Coordinate[] coordinates,
			Coordinate firstCoordinate) {
		int i = indexOf(firstCoordinate, coordinates);
		if (i < 0)
			return;
		Coordinate[] newCoordinates = new Coordinate[coordinates.length];
		System.arraycopy(coordinates, i, newCoordinates, 0, coordinates.length
				- i);
		System.arraycopy(coordinates, 0, newCoordinates,
				coordinates.length - i, i);
		System.arraycopy(newCoordinates, 0, coordinates, 0, coordinates.length);
	}

	/**
	 * Returns the index of <code>coordinate</code> in
	 * <code>coordinates</code>. The first position is 0; the second, 1; etc.
	 * 
	 * @param coordinate
	 *            the <code>Coordinate</code> to search for
	 * @param coordinates
	 *            the array to search
	 * @return the position of <code>coordinate</code>, or -1 if it is not
	 *         found
	 */
	public static int indexOf(Coordinate coordinate, Coordinate[] coordinates) {
		for (int i = 0; i < coordinates.length; i++) {
			if (coordinate.equals(coordinates[i])) {
				return i;
			}
		}
		return -1;
	}

	/**
	 * Extracts a subsequence of the input {@link Coordinate} array from indices
	 * <code>start</code> to <code>end</code> (inclusive).
	 * 
	 * @param pts
	 *            the input array
	 * @param start
	 *            the index of the start of the subsequence to extract
	 * @param end
	 *            the index of the end of the subsequence to extract
	 * @return a subsequence of the input array
	 */
	public static Coordinate[] extract(Coordinate[] pts, int start, int end) {
		int len = end - start + 1;
		Coordinate[] extractPts = new Coordinate[len];
		int iPts = 0;
		for (int i = start; i <= end; i++) {
			extractPts[iPts++] = pts[i];
		}
		return extractPts;
	}

	/**
	 * SJ TODO faellt evtl weg, wenn coordinate durch DirectPosition
	 * ausgetauscht wird
	 * 
	 * @param aPositions
	 * @return
	 */
	public static Coordinate[] toCoordinateArray(
			List<DirectPosition> aPositions) {

		Coordinate[] rCoords = new Coordinate[aPositions.size()];

		for (int i = 0; i < aPositions.size(); i++) {
			rCoords[i] = new Coordinate(aPositions.get(i).getCoordinates());
		}

		return rCoords;

	}

	/**
	 * Converts a Coordinate array into a list of Positions
	 * 
	 * SJ: faellt evtl weg, wenn coordinate durch DirectPosition
	 * ausgetauscht wird
	 * 
	 * @param coordArray
	 * @return
	 */
	public static List<Position> toPositionList(
			CoordinateReferenceSystem crs, Coordinate[] coordArray) {
		List<Position> rList = new ArrayList<Position>();
		for (int i = 0; i < coordArray.length; i++) {
			DirectPositionImpl position = new DirectPositionImpl( crs, coordArray[i].getCoordinates() );
			rList.add( new PositionImpl((DirectPosition)position.clone()) );
			//rList.add(coordinateFactory.createPosition(coordArray[i].getCoordinates()));
		}
		return rList;
	}
	
	/**
 	 * Converts a Coordinate array into a list of DirectPositions
	 * 
	 * @param crs
	 * @param coordArray
	 * @return
	 */
	public static List<DirectPositionImpl> toDirectPositionList(
			CoordinateReferenceSystem crs, Coordinate[] coordArray) {
		List<DirectPositionImpl> rList = new ArrayList<DirectPositionImpl>();
		for (int i = 0; i < coordArray.length; i++) {
			rList.add(new DirectPositionImpl( crs, coordArray[i].getCoordinates() ));
		}
		return rList;
	}

}