import java.util.Arrays; 
import java.util.Scanner;

/* This Java application program is for the purpose of testing the
** ParallelArySummer class.
**
** Author: R. McCloskey
** Date: May 9, 2023
*/
public class ParArySumTester {

   public static void main(String[] args) {

      Scanner keyboard = new Scanner(System.in);
      int aryLen = getIntInput(keyboard, "Enter array length: ");
      int lowBound = getIntInput(keyboard, "Enter lower bound value: ");
      int upperBound = getIntInput(keyboard, "Enter upper bound value: ");
      int seed = getIntInput(keyboard, "Enter random seed: ");

      RandIntArrayMaker riam = new RandIntArrayMaker();

      // Make an array filled with random integers in accord with
      // parameters entered by user.
      int[] ary = riam.randomIntArray(aryLen, lowBound, upperBound, seed);

      // Display the array
      System.out.printf("Array: %s\n", Arrays.toString(ary));

      // Compute the sum of the array's elements using an object of the 
      // ParallelArySummer class.
      ParallelArySummer pas = new ParallelArySummer(ary);
      pas.computeSum();

      System.out.println("\nParallelArySummer reports a sum of " + pas.sumOf());

      // Verify that the sum computed by the instance of ParallelArySummer
      // is correct.
      int correctSum = segmentSum(ary, 0, ary.length);
      if (pas.sumOf() != correctSum) {
         System.out.printf("***ERROR; correct sum is %d\n", correctSum);
      }
   }

   /* Returns the sum of the elements in b[floor..ceiling).
   ** pre: 0 <= floor <= ceiling <= b.length
   */
   private static int segmentSum(int[] b, int floor, int ceiling) {
      int sumSoFar = 0;
      // loop invariant: 
      //    sumSoFar = sum of elements in b[floor..i)
      for (int i = floor; i != ceiling; i++) {
         sumSoFar = sumSoFar + b[i];
      }
      return sumSoFar;
   }


   /* Displays the specified prompt and then returns the response read
   ** from the specified Scanner (which is assumed to be in a form that 
   ** can be interpreted as an integer).
   */
   private static int getIntInput(Scanner scanner, String prompt) {
      System.out.print(prompt);
      return scanner.nextInt();
   }

}