/*
 * Southampton University Map App
 * Copyright (C) 2011  Christopher Baines
 * 
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * 
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

package net.cbaines.suma;

import java.util.Comparator;

public class StringPOIDistanceComparator implements Comparator<POI> {
	private String userString;

	// private static final String TAG = "StringDistanceComparator";

	public StringPOIDistanceComparator(String userString) {
		super();
		this.userString = userString;
	}

	public int compare(POI poi1, POI poi2) {
		int distTo1 = Math.min(LD(userString, poi1.toString()), LD(userString, poi1.id));
		// Log.i(TAG, "Comparing " + userString + " and " + poi1.toString() +
		// " got dist " + distTo1);
		int distTo2 = Math.min(LD(userString, poi2.toString()), LD(userString, poi2.id));
		// Log.i(TAG, "Comparing " + userString + " and " + poi2.toString() +
		// " got dist " + distTo2);
		return distTo1 - distTo2;
	}

	// Below is public domain code from http://www.merriampark.com/ld.htm

	// ****************************
	// Get minimum of three values
	// ****************************

	private int Minimum(int a, int b, int c) {
		int mi;

		mi = a;
		if (b < mi) {
			mi = b;
		}
		if (c < mi) {
			mi = c;
		}
		return mi;

	}

	// *****************************
	// Compute Levenshtein distance
	// *****************************

	public int LD(String s, String t) {
		int d[][]; // matrix
		int n; // length of s
		int m; // length of t
		int i; // iterates through s
		int j; // iterates through t
		char s_i; // ith character of s
		char t_j; // jth character of t
		int cost; // cost

		// Step 1

		n = s.length();
		m = t.length();
		if (n == 0) {
			return m;
		}
		if (m == 0) {
			return n;
		}
		d = new int[n + 1][m + 1];

		// Step 2

		for (i = 0; i <= n; i++) {
			d[i][0] = i;
		}

		for (j = 0; j <= m; j++) {
			d[0][j] = j;
		}

		// Step 3

		for (i = 1; i <= n; i++) {

			s_i = s.charAt(i - 1);

			// Step 4

			for (j = 1; j <= m; j++) {

				t_j = t.charAt(j - 1);

				// Step 5

				if (s_i == t_j) {
					cost = 0;
				} else {
					cost = 1;
				}

				// Step 6

				d[i][j] = Minimum(d[i - 1][j] + 1, d[i][j - 1] + 1, d[i - 1][j - 1] + cost);

			}

		}

		// Step 7

		return d[n][m];

	}

}