MAGPIE4

/**
 * A program to carry on conversations with a human user.
 * This version:
 *<ul><li>
 *   Uses advanced search for keywords
 *</li><li>
 *   Will transform statements as well as react to keywords
 *</li></ul>
 * @author Laurie White
 * @version April 2012
 *
 */
public class Magpie4
{
 /**
  * Get a default greeting
  * @return a greeting
  */
 public String getGreeting()
 {
  return "Hello, let's talk.";
 }

 /**
  * Gives a response to a user statement
  *
  * @param statement
  *            the user statement
  * @return a response based on the rules given
  */
 public String getResponse(String statement)
 {
  String response = "";
  if (statement.length() == 0)
  {
   response = "Say something, please.";
  }

  else if (findKeyword(statement, "no") >= 0)
  {
   response = "Why so negative?";
  }
  else if (findKeyword(statement, "mother") >= 0
    || findKeyword(statement, "father") >= 0
    || findKeyword(statement, "sister") >= 0
    || findKeyword(statement, "brother") >= 0)
  {
   response = "Tell me more about your family.";
  }

  // Responses which require transformations
  else if (findKeyword(statement, "I want", 0) >= 0)
  {
   response = transformIWantToStatement(statement);
  }

  else
  {
   // Look for a two word (you <something> me)
   // pattern
   int psn = findKeyword(statement, "you", 0);

   if (psn >= 0
     && findKeyword(statement, "I", psn) >= 0)
   {
    response = transformYouMeStatement(statement);
   }
   else
   {
    response = getRandomResponse();
   }
  }
  return response;
 }

 /**
  * Take a statement with "I want to <something>." and transform it into
  * "What would it mean to <something>?"
  * @param statement the user statement, assumed to contain "I want to"
  * @return the transformed statement
  */
 private String transformIWantToStatement(String statement)
 {
  //  Remove the final period, if there is one
  statement = statement.trim();
  String lastChar = statement.substring(statement
    .length() - 1);
  if (lastChar.equals("."))
  {
   statement = statement.substring(0, statement
     .length() - 1);
  }
  int psn = findKeyword (statement, "I want", 0);
  String restOfStatement = statement.substring(psn + 9).trim();
  return "Would you really be happy if you had " + restOfStatement + "?";
 }



 /**
  * Take a statement with "you <something> me" and transform it into
  * "What makes you think that I <something> you?"
  * @param statement the user statement, assumed to contain "you" followed by "me"
  * @return the transformed statement
  */
 private String transformYouMeStatement(String statement)
 {
  //  Remove the final period, if there is one
  statement = statement.trim();
  String lastChar = statement.substring(statement
    .length() - 1);
  if (lastChar.equals("."))
  {
   statement = statement.substring(0, statement
     .length() - 1);
  }

  int psnOfYou = findKeyword (statement, "you", 0);
  int psnOfMe = findKeyword (statement, "I", psnOfYou + 3);

  String restOfStatement = statement.substring(psnOfYou + 3, psnOfMe).trim();
  return "Why do you " + restOfStatement + " me?";
 }





 /**
  * Search for one word in phrase.  The search is not case sensitive.
  * This method will check that the given goal is not a substring of a longer string
  * (so, for example, "I know" does not contain "no").
  * @param statement the string to search
  * @param goal the string to search for
  * @param startPos the character of the string to begin the search at
  * @return the index of the first occurrence of goal in statement or -1 if it's not found
  */
 private int findKeyword(String statement, String goal, int startPos)
 {
  String phrase = statement.trim();
  //  The only change to incorporate the startPos is in the line below
  int psn = phrase.toLowerCase().indexOf(goal.toLowerCase(), startPos);

  //  Refinement--make sure the goal isn't part of a word
  while (psn >= 0)
  {
   //  Find the string of length 1 before and after the word
   String before = " ", after = " ";
   if (psn > 0)
   {
    before = phrase.substring (psn - 1, psn).toLowerCase();
   }
   if (psn + goal.length() < phrase.length())
   {
    after = phrase.substring(psn + goal.length(), psn + goal.length() + 1).toLowerCase();
   }

   //  If before and after aren't letters, we've found the word
   if (((before.compareTo ("a") < 0 ) || (before.compareTo("z") > 0))  //  before is not a letter
     && ((after.compareTo ("a") < 0 ) || (after.compareTo("z") > 0)))
   {
    return psn;
   }

   //  The last position didn't work, so let's find the next, if there is one.
   psn = phrase.indexOf(goal.toLowerCase(), psn + 1);

  }

  return -1;
 }

 /**
  * Search for one word in phrase.  The search is not case sensitive.
  * This method will check that the given goal is not a substring of a longer string
  * (so, for example, "I know" does not contain "no").  The search begins at the beginning of the string.
  * @param statement the string to search
  * @param goal the string to search for
  * @return the index of the first occurrence of goal in statement or -1 if it's not found
  */
 private int findKeyword(String statement, String goal)
 {
  return findKeyword (statement, goal, 0);
 }



 /**
  * Pick a default response to use if nothing else fits.
  * @return a non-committal string
  */
 private String getRandomResponse()
 {
  final int NUMBER_OF_RESPONSES = 4;
  double r = Math.random();
  int whichResponse = (int)(r * NUMBER_OF_RESPONSES);
  String response = "";

  if (whichResponse == 0)
  {
   response = "Interesting, tell me more.";
  }
  else if (whichResponse == 1)
  {
   response = "Hmmm.";
  }
  else if (whichResponse == 2)
  {
   response = "Do you really think so?";
  }
  else if (whichResponse == 3)
  {
   response = "You don't say.";
  }

  return response;
 }

}