public class StringTester {
// Develops and tests a few common string manipulation methods.
// Exercises the String class methods and the idea of recursion.

   static String readText(String fileName) {
   // read an entire text file, concatenate the lines together
   // to form one long string and return that string.  Adds an
   // extra blank between lines, and uses pseudoKeyboard class.
      pseudoKeyboard k = new pseudoKeyboard(fileName);
      String temp = "";
      String line = k.readString();   // a single line of text
      while (!k.eof()) {
         temp = temp + line + " "; 
         line = k.readString();       
      }      
      return temp;
   }

   static String nextWord (String s, int i) {
   // returns the next word in the text s, beginning at positon i, 
   // passing over blanks.  If no next word in s, return ""
      while (i < s.length() &&  s.charAt(i) == ' ') 
         i = i + 1;    // pass over leading blanks
      // now i is at the beginning of the word, or else there
      // is no next word in s.
      if (i >= s.length())
         return "";
      else        // end of the word is at the blank that trails it
         return s.substring(i, s.indexOf(" ", i));
   }
   
   static void displayWords (String s) {
   // Display all the words in a string, one word per line.
   // Use nextWord.  Assumes no extra blanks between words
      int i = 0;        // i marks the beginning of a word in s
      String t = nextWord(s, i);
      while ( !t.equals("") ) {
         System.out.println(t);
         i = i + t.length() + 1;   
         t = nextWord(s, i);
      } 
   }
   
   static String deleteExtraBlanks (String s) {
   // returns the result of deleting all but one blank between each
   // pair of words in s, as well as leading and trailing blanks
      int i = s.indexOf("  ");
      while (i >= 0) {      // squeeze out one blank at a time
         s = s.substring(0, i) + s.substring(i + 1); 
         i = s.indexOf("  ");
      }
      return s;  
   }
   
    static String deleteExtraBlanks (String s, int from) {
   // recursive version
      int i = s.indexOf("  ", from);  // find a pair of blanks
      if (i < 0)                      // base case -- none there
         return s;
      else                            // recursive case; delete one
         return s.substring(0, i) + deleteExtraBlanks(s, i + 1);   
   }
   
   static int countWords (String s) {
   // recursively counts the number of words in a string.  Assumes
   // there is exactly one blank between adjacent words.
      String t = nextWord(s, 0);    // find the next word
      if (t.equals(""))  			// base case -- none there
         return 0;                     
      else 							// recursive case; count it
         return 1 + countWords(s.substring(t.length() + 1));
   }

   public static void main (String[] argv) {
      String fileName;

	  // Locate a text with the user's help and read it
      System.out.println("Enter the name of a text file: ");
      fileName = Keyboard.readString();
      String s = readText(fileName);
      
      // display the text in 60-character lines
      System.out.println("\nOriginal text in 60-character chunks:");
      for (int i=0; i<s.length(); i = i + 60) {
          if (i+60 < s.length())
             System.out.println(s.substring(i, i + 60));
          else
             System.out.println(s.substring(i));
      }
      
      // Now delete all extra blanks from the text 
      s = deleteExtraBlanks(s);

      // display the text again
      System.out.println("\nText without extra blanks:");
      for (int i=0; i<s.length(); i = i + 60) {
          if (i+60 < s.length())
             System.out.println(s.substring(i, i + 60));
          else
             System.out.println(s.substring(i));
      }
      
      // Now display the words in the text in a column
      System.out.println("\nWord list:");      
      displayWords(s);
      
      // Now compute and display the word count
      System.out.println("\nWord count for the text is: " + countWords(s));
              
   }

}