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

/* Java application having as its purpose to test the methods of the
** MaxHeapOfInt class.
**
** Author: R. McCloskey
** Date: May 2022
*/

public class HeapTester {

   private static Scanner input;
   private static boolean echo;
   private static MaxHeapOfInt heap;

   public static void main(String[] args) throws FileNotFoundException {
      // Establish whether input comes from the keyboard or from a file 
      // whose name is specified by the first command line argument.
      if (args.length == 0) {
         input = new Scanner(System.in);
         echo = false;
      }
      else {
         input = new Scanner(new File(args[0]));
         echo = true;
      }

      System.out.println("Welcome to the Heap Tester program.");

      doTesting();

      System.out.println("Goodbye from the Heap Tester program.");
   }

   /* Performs testing upon a heap.
   */
   private static void doTesting() {
      heap = new MaxHeapOfInt();  // initialize heap to being empty

      boolean keepGoing = true;
      while (keepGoing) {
         System.out.println();
         printMenu();
         int choice = getInt("> ");
         if (choice == 1) { heap = new MaxHeapOfInt(); heap.isValid(true); }
         else if (choice == 2) { heap = loadHeap(); heap.isValid(true); }
         else if (choice == 3) { insert(); heap.isValid(true); }
         else if (choice == 4) { System.out.println(heap.getMax()); }
         else if (choice == 5) { heap.deleteMax(); heap.isValid(true); }
         else if (choice == 6) { heap.print(); }
         else if (choice == 7) { keepGoing = false; }
         else { System.out.println("** Invalid choice **"); }
      }
   }


   private static void printMenu() {
      System.out.println("(1) Create new empty heap");
      System.out.println("(2) Load some values into a new heap");
      System.out.println("(3) Insert value into heap");
      System.out.println("(4) Show max value in heap");
      System.out.println("(5) Delete max value from heap");
      System.out.println("(6) Display heap");
      System.out.println("(7) Quit");
   }

   /* Prompts the user to enter an integer and returns the response.  If the 
   ** response entered cannot be translated to an int by Integer.parseInt(),
   ** the prompt it repeated.  This continues until a valid response is given.
   */
   private static int getInt(String prompt) {
      int result = -99;
      boolean keepTrying = true;
      while (keepTrying) {
         try {
            System.out.print(prompt);
            result = Integer.parseInt(input.nextLine().trim());
            if (echo) { System.out.printf("%d\n", result); }
            keepTrying = false;
         }
         catch (Exception e) {
            System.out.println("** Invalid response; expecting an integer! **");
         }
      }
      return result;
   }


   /* Prompts user to enter values to be loaded into a new heap.
   */
   private static MaxHeapOfInt loadHeap() {
      System.out.print("Enter (one or more) values to load into a new heap: ");
      String response = input.nextLine().trim();
      if (response.length() == 0) {
         // Return an empty heap.
         return new MaxHeapOfInt();
      }
      else {
         int[] ary = stringToIntAry(response);
         return new MaxHeapOfInt(ary);
      }
   } 
   
   /* Returns an array of type int[] containing the translations, into int
   ** values, of tokens of the given string.
   */
   private static int[] stringToIntAry(String s) {
      Scanner valScanner = new Scanner(s);
      // Count how many int tokens are in the String
      int cntr = 0;
      while (valScanner.hasNextInt()) {
         valScanner.nextInt();
         cntr = cntr + 1;
      }
      int[] result = new int[cntr];
      valScanner = new Scanner(s);
      for (int i=0; i != cntr; i++) {
         result[i] = valScanner.nextInt();
      }
      return result;
   }

   /* Prompts user to enter a number to insert into the heap, and
   ** does so.
   */
   private static void insert() {
      int val = getInt("Enter a number to insert: ");
      heap.insert(val);
   }

}