package multdrill;
/**
 * @author Jeff Offutt
 *         Date: June, 2011
 */

import java.io.*;
import java.util.*;

/* A multiplication Problem has three fields:
 * left -- left hand side (int)
 * right -- right hand side (int)
 * actualAnswer -- computed answer (int)
 * userAnswer -- answer from the user, initially -1 (int)
*/

public class Problem
{
   private int left;
   private int right;
   private int actualAnswer;
   private int userAnswer;
   private String errMsg;

   public Problem ()
   {
      left = 0;
      right = 0;
      actualAnswer = 0;
      userAnswer = -1;
      errMsg = "";
   }

   public Problem (int l, int r)
   {
      left = l;
      right = r;
      actualAnswer = left * right;
      userAnswer = -1;
      errMsg = "";
   }

   // set and get userAnswer
   public void setUserAnswer (int ans)
   {
      userAnswer = ans;
      checkAnswer();
   }
   public void setUserAnswer (String ans)
   {  // Passed a string, check and convert
      if (ans != null && ans.length() != 0)
      {  // Convert to integer if not null.
         try
         {
            userAnswer = (Integer.parseInt (ans));
            checkAnswer();
         }
         catch (NumberFormatException ex)
         {
            userAnswer = -1;
            errMsg = "Sorry, I only understand numbers.";
         }
      }
   }
   public int getUserAnswer()
   {
      return userAnswer;
   }

   //get left
   public int getLeft()
   {
      return left;
   }

   //get right
   public int getRight()
   {
      return right;
   }

   //get actualAnswer
   public int getActualAnswer()
   {
      return actualAnswer;
   }

   //get error
   public String getErrMsg()
   {
      return errMsg;
   }

   // Check the answer
   private void checkAnswer()
   {  // called from setUserAnswer()
      int tmp;
      if (userAnswer == actualAnswer)
      {
         errMsg = "Great, " + userAnswer + " is right!";
      }
      else if (userAnswer == left*right-1 || userAnswer == left*right+1)
      {
         errMsg = "Close, but your answer is one number off.";
      }
      else if (userAnswer == left+right)
      {
         errMsg = "Close, but did you add the numbers instead of multiply?";
      }
      else if (userAnswer == left-right)
      {
         errMsg = "Close, but did you subtract the numbers instead of multiply?";
      }
      else if (userAnswer == left*(right+1))
      {
         tmp = right+1;
         errMsg = "Close, but did you multiply " + left
         + " * " + tmp + " instead of " + left + " * " + right + "?";
      }
      else if (userAnswer == left*(right-1))
      {
         tmp = right-1;
         errMsg = "Close, but did you multiply " + left
         + " * " + tmp + " instead of " + left + " * " + right + "?";
      }
      else if (userAnswer == (left+1)*right)
      {
         tmp = left+1;
         errMsg = "Close, but did you multiply " + tmp
         + " * " + right + " instead of " + left + " * " + right + "?";
      }
      else if (userAnswer == (left-1)*right)
      {
         tmp = left-1;
         errMsg = "Close, but did you multiply " + tmp
         + " * " + right + " instead of " + left + " * " + right + "?";
      }
      else
      {
         errMsg = "Sorry, that is not the correct answer.";
      }
   }
}