import java.util.Scanner;
import java.util.Random;

/** Java application whose purpose is to make a simple test of either 
**  StackViaArray or StackViaLink1, at the choice of the user. 
*/

public class StackTestApp {

   private static Scanner keyboard = new Scanner(System.in);

   public static void main(String[] args) {
      System.out.print("Enter 1 to test StackViaArray, " +
                       "2 to test StackViaLink1:"); 
      int choice = keyboard.nextInt();
      
      Stack<Integer> stack = null;
      if (choice == 1) { stack = new StackViaArray<Integer>(4); }
      else if (choice == 2) { stack = new StackViaLink1<Integer>(); }
      else {
         System.out.println("Invalid response; program aborting!");
         System.exit(1);
      }

      performTest(stack, 6, 0.6);
      System.out.println("Goodbye.");
   }

   private static void performTest(Stack<Integer> stk,
                                   int initSize, 
                                   double deleteProb) {
      final int maxRand = 20;
      Random rand = new Random();

      for (int i=0; i != initSize; i++) {
         stk.push(rand.nextInt(maxRand));
      }

      System.out.println("Stack initially: " + stk);

      while (!stk.isEmpty()) {
         if (rand.nextDouble() < deleteProb) {
            int m = stk.pop();
            System.out.println("After popping " + m + ": " + stk);
         }
         else {
            int m = rand.nextInt(maxRand);
            stk.push(m);
            System.out.println("After pushing " + m + ": " + stk);
         }
      }
   }
}