// Allison Obourn
// CSE 143 - lecture 12
// This program reads a Graphviz graph file of friendships and allows the user
// to find the distance between two people in the graph.

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

public class Friends {
   public static void main(String[] args) throws FileNotFoundException {
      System.out.println("Welcome to the cse143 friend finder.");
      Scanner input = new Scanner(new File("friends.dot"));
      
      // How to model friendships?
      // Map: person -> their friends
      // key: person's name (String)
      // value: collection of friends (Set<String>)
      //    why set? all values must be unique; order doesn't matter; 
      //    contains, add, get should be fast
      Map<String, Set<String>> friends = readFile(input);
      System.out.println(friends);
      
      Scanner console = new Scanner(System.in);
      System.out.print("starting name? ");
      String name1 = console.next();
      System.out.print("target name? ");
      String name2 = console.next();
      showMatches(friends, name1, name2);
   }
    
   // pre : input is open and contains a legal Graphviz file of friendship
   //       connections where each friend is listed as a single token
   // post: returns a map that contains for each person the set of friends for
   //       that person
   public static Map<String, Set<String>> readFile (Scanner input) {
      Map<String, Set<String>> friends = new TreeMap<String, Set<String>>();
      while(input.hasNextLine()) {
         String line = input.nextLine();
         if(line.contains("--")) {
            Scanner lineData = new Scanner(line);
            String name1 = lineData.next();
            lineData.next();
            String name2 = lineData.next();
            
            addTo(friends, name1, name2);
            addTo(friends, name2, name1);
            
         }
      }
      return friends;
   }

   // post: records a friendship for name1.  If name1 is not in the map, a new
   //       set is added to the map
   public static void addTo(Map<String, Set<String>> friends, String name1, String name2) {
      if(!friends.containsKey(name1)) {
         friends.put(name1, new TreeSet<String>());
      }
      friends.get(name1).add(name2);
   }

   // WARNING: this method is incomplete! We will finish it on Wednesday.
   // post: computes the distance between two people, printing the various
   //       lists of friends with their distance from name1
   public static void showMatches(Map<String, Set<String>> friends, String name1, String name2) {
                
      System.out.println();
      System.out.println("Starting with " + name1);
      distance = 1;
      Set<String> currentGroup = new TreeSet<String>();
      
      while(/* we haven't found name2 */) {
         distance++;
      }
   }
}