/**
 * Class:       PositiveWeightedGraphDemo
 * Author:      Peter Williams
 * LastEdit:	Wed May 29 09:51:47 2002
 * Purpose:     To demonstrate shortest path algorithm
 */

import DataStructures.*;
import java.io.*;
import java.util.*;

public class PositiveWeightedGraphDemo {

    public static void main(String[] args) throws IOException {

        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));

        String filename;
        System.out.print("graph file name: ");
        filename = in.readLine();
    
        PositiveWeightedGraph g = new PositiveWeightedGraph();
        g.readGraphTxtFile(filename);
        if (g.nrArcs() <= 24) {
            Iterator i = g.arcs();
            while (i.hasNext()) {
                WeightedGraph.Arc a = (WeightedGraph.Arc) i.next();
                System.out.println
                    (a.tail() + " -> " + a.head() + " " + a.weight());
            }
        }

        System.out.println("graph has " + g.nrNodes() + " nodes" 
                           + " and " + g.nrArcs() + " arcs");
    
        String reply;
        boolean running;
    
        do {
            String origin, destination;
            do {
                System.out.print("origin: ");
                origin = in.readLine();
            } while (!g.contains(origin));
            do {
                System.out.print("destination: ");
                destination = in.readLine();
            } while (!g.contains(destination));
            if (g.pathExists(origin, destination)) {
                Enumeration path = g.shortestPath(origin, destination);
                System.out.print(path.nextElement());
                while (path.hasMoreElements()) {
                    System.out.print(" -> " + path.nextElement());
                }
                System.out.println
                    (" (" + g.shortestPathLength(origin, destination) + ")");
            } else {
                System.out.println
                    ("no path exists between "+ origin + " and " + destination);
            }
            System.out.print("continue (y/n)? ");
            reply = in.readLine();
            running = (reply.length() > 0 &&
		       (Character.toLowerCase(reply.charAt(0)) == 'y'));
        } while (running);
     
    }

}