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

/* Java application having as its purpose to test the methods of one
** or more classes that implement the MaxSegSum interface.
*/

public class MaxSegSumTester {

   public static void main(String[] args) {
      int aryLen;     // length of array to test
      int lowerBound; // array elements no less than this
      int upperBound; // array elements no greater than this
      int randSeed;   // seed for Random object

      if (args.length == 0) {   // User must provide inputs
         Scanner keyboard = new Scanner(System.in);
         aryLen = getInt(keyboard, "Enter desired array length:");
         lowerBound = getInt(keyboard, "Enter element lower bound:");
         upperBound = getInt(keyboard, "Enter element upper bound:");
         randSeed = getInt(keyboard, "Enter seed for random # generation:");
      }
      else {   // interpret the command-line arguments as the inputs
         aryLen = Integer.parseInt(args[0]);
         lowerBound = Integer.parseInt(args[1]);
         upperBound = Integer.parseInt(args[2]);
         randSeed = Integer.parseInt(args[3]);
         System.out.println("Inputs:");
         System.out.printf("array length = %d\n", aryLen);
         System.out.printf("lower bound = %d\n", lowerBound);
         System.out.printf("upper bound = %d\n", upperBound);
         System.out.printf("randomization seed = %d\n", randSeed);
      }

      // Create an array containing pseudorandom values in the range
      // specified by the user.
      Random rand = new Random(randSeed);
      RandomIntAryGenerator riag = new RandomIntAryGenerator(rand);
      int[] a = riag.randomArray(aryLen, lowerBound, upperBound); 

      System.out.println("\nArray generated:");
      printWithLineBreaks(Arrays.toString(a), ',', 80);
      //System.out.println(Arrays.toString(a));
      System.out.println();
      System.out.println();

      // Now compute the maximum segment sum of that array, using objects 
      // of two different classes that implement the MaxSegSum interface
      // Report differences in the results.

      MaxSegSum mssPref = new MaxSegSumViaPrefixSums();
      compute(mssPref, a, "Using prefix sums: ");
      
      MaxSegSum mssRec = new MaxSegSumViaRec();
      compute(mssRec, a, "Using recursion: ");

      if (mssRec.maxSegSumVal() != mssPref.maxSegSumVal()) {
         System.out.println("**WARNING: DISAGREEMENT");
      }
   }

   /* Applies the maxSegSum() method of the given MaxSegSum object to
   ** the given array and reports the results.
   */
   private static void compute(MaxSegSum mss, int[] b, String message) {
      System.out.print(message);
      int result = mss.maxSegSum(b);
      System.out.printf("Max segment sum is %d; work measure is %d\n", 
                        mss.maxSegSumVal(), mss.measureOfWork());
      if (result != mss.maxSegSumVal()) {
         System.out.println("**ERROR: maxSegSumVal() and maxSegSum() " +
                            "yield different values, namely " +
                            mss.maxSegSumVal() + " and " + result);
      }
   }

   /* Prints the given prompt and returns the user's response, interpreted
   ** to be an integer.
   */
   private static int getInt(Scanner scanner, String prompt) {
      System.out.print(prompt);
      return scanner.nextInt();
   }

   /* Prints the given string, splitting it so that no printed line
   ** exceeds the specified # of characters and so that each line
   ** ends with the specified separator (which is assumed to appear
   ** frequently in the string).
   */
   private static void printWithLineBreaks(String s, 
                                           char separator, 
                                           int lineWidth) {
      int lineStart = 0;
      while (lineStart + lineWidth < s.length()) {
         int stop = s.lastIndexOf(separator, lineStart + lineWidth-1);
         if (stop < lineStart) {  // no occurrences of separator
            printSubstring(s, lineStart, lineStart + lineWidth);
            lineStart = lineStart + lineWidth;
         }
         else {
            printSubstring(s, lineStart, stop+1);
            lineStart = stop + 1;
         }
         System.out.println();
      }
      printSubstring(s, lineStart, s.length());
   }

   /* Prints s[low..high).
   */
   private static void printSubstring(String s, int low, int high) {
      high = Math.min(high, s.length());
      while (low != high) {
         System.out.print(s.charAt(low));
         low = low + 1;
      }
   }

}