import java.util.Comparator;
import java.util.Scanner;
import java.io.File;
import java.io.FileNotFoundException;

/* Java program having as its purpose to build (and afterwards, display)
** several lists, all containing the same StateInUSA objects, but
** each list ordered by a different criterion as defined by an instance
** of a class that implements the java.util.Comparator interface.
**
** Author: R. McCloskey
** Date: April 2026
*/
public class Tester {

   private static String fileName;

   public static void main(String[] args) {
      fileName = args[0];   // name of input file
   
      System.out.println("Ordered by name:");
      test(new CompareByName());

      System.out.println("\n\nOrdered by area:");
      test(new CompareByArea());

      System.out.println("\n\nOrdered by electoral votes:");
      test(new CompareByElectVotes());

      System.out.println("\n\nOrdered by electoral votes with name tie-breaker:");
      test(new CompareByElectVotesAndName());

      System.out.println("\nGoodbye.");

   }


   /* Builds and then displays an OrderedIndexedList of StateInUSA
   ** objects whose descriptions are read from a file.  The list's elements
   ** are intended to be in ascending order in accord with the Comparator
   ** provided via this method's parameter.  If they are not, an error
   ** message is displayed.
   */
   private static void test(Comparator<StateInUSA> comparator) {
      // Set up a Scanner to read from the input file descriptions of
      // StateInUSA objects.  The file's first line is skipped
      // over.  Subsequent lines have the form of CSV-strings with three
      // fields: name, area, and number of electoral votes.
      Scanner input = null;
      try {
         input = new Scanner(new File(fileName));
      }
      catch (FileNotFoundException e) {
         e.printStackTrace(System.out);
         System.out.println("Program aborting");
         System.exit(0);
      }
      input.nextLine();  // skip first line

      // Make an empty OrderedIndexedList capable of holding instances
      // of the StateInUSA class.
      OrderedIndexedList<StateInUSA> list;
      list = new OrderedIndexedList<StateInUSA>(comparator);

      // Populate the list with the regions described in the input file
      while (input.hasNextLine()) {
         String line = input.nextLine();
         StateInUSA region = parseString(line);
         // System.out.println("Inserting: " + region);
         list.insert(region);
      }

      // Display the list
      list.printList();   // System.out.println(list);

      // See if the list's elements really are in ascending order;
      // if not, display an error message.
      if (!isAscending(list, comparator)) {
         System.out.println("** ERROR: List elements are not in ascending order!");
      }
   }

   /* Given a CSV-string describing a state in the USa (with three fields 
   ** that provide a name, area, and # of electoral votes respectively),
   ** returns a  corresponding new instance of the StateInUSA class.
   */
   private static StateInUSA parseString(String s) {
      Scanner scanner = new Scanner(s);
      scanner.useDelimiter(",");
      String name = scanner.next();
      int area = scanner.nextInt();
      int electoralVotes = scanner.nextInt();
      return new StateInUSA(name, area, electoralVotes);
   }

   /* Returns true iff the elements of the given list are in ascending
   ** order with respect to the ordering defined by the given Comparator.
   */
   private static boolean isAscending(OrderedIndexedList<StateInUSA> list,
                                      Comparator<StateInUSA> c) {
      boolean goodSoFar = true;
      if (list.size() < 2) { }
      else {
         int i = 1;
         StateInUSA prev = list.get(0);
         while (i != list.size()  &&  goodSoFar) {
            StateInUSA current = list.get(i);
            if (c.compare(prev, current) > 0) {
               goodSoFar = false;
            }
            else {
               prev = current;
            }
            i = i+1;
         }
      }
      return goodSoFar;
   }

}