/*
    * Copyright (c) 2002-2012, the original author or authors.
    *
    * This software is distributable under the BSD license. See the terms of the
    * BSD license in the documentation provided with this software.
    *
    * http://www.opensource.org/licenses/bsd-license.php
    */
   package jline.console;
  
  import static jline.internal.Preconditions.checkNotNull;
  
  /**
   * A holder for a {@link StringBuilder} that also contains the current cursor position.
   *
   * @author <a href="mailto:mwp1@cornell.edu">Marc Prud'hommeaux</a>
   * @author <a href="mailto:jason@planet57.com">Jason Dillon</a>
   * @since 2.0
   */
  public class CursorBuffer
  {
      private boolean overTyping = false;
  
      public int cursor = 0;
  
      public final StringBuilder buffer = new StringBuilder();
      
      public CursorBuffer copy () {
          CursorBuffer that = new CursorBuffer();
          that.overTyping = this.overTyping;
          that.cursor = this.cursor;
          that.buffer.append (this.toString());
          
          return that;
      }
  
      public boolean isOverTyping() {
          return overTyping;
      }
  
      public void setOverTyping(final boolean b) {
          overTyping = b;
      }
  
      public int length() {
          return buffer.length();
      }
  
      public char nextChar() {
          if (cursor == buffer.length()) {
              return 0;
          } else {
              return buffer.charAt(cursor);
          }
      }
  
      public char current() {
          if (cursor <= 0) {
              return 0;
          }
  
          return buffer.charAt(cursor - 1);
      }
  
      /**
       * Write the specific character into the buffer, setting the cursor position
       * ahead one. The text may overwrite or insert based on the current setting
       * of {@link #isOverTyping}.
       *
       * @param c the character to insert
       */
      public void write(final char c) {
          buffer.insert(cursor++, c);
          if (isOverTyping() && cursor < buffer.length()) {
              buffer.deleteCharAt(cursor);
          }
      }
  
      /**
       * Insert the specified chars into the buffer, setting the cursor to the end of the insertion point.
       */
      public void write(final CharSequence str) {
          checkNotNull(str);
  
          if (buffer.length() == 0) {
              buffer.append(str);
          }
          else {
              buffer.insert(cursor, str);
          }
  
          cursor += str.length();
  
          if (isOverTyping() && cursor < buffer.length()) {
              buffer.delete(cursor, (cursor + str.length()));
          }
      }
  
      public boolean clear() {
         if (buffer.length() == 0) {
             return false;
         }
 
         buffer.delete(0, buffer.length());
         cursor = 0;
         return true;
     }
 
     public String upToCursor() {
         if (cursor <= 0) {
             return "";
         }
 
         return buffer.substring(0, cursor);
     }
 
     @Override
     public String toString() {
         return buffer.toString();
     }
 }