/*
    * Zemucan: A Syntax Assistant for DB2
    * Copyright (C) 2009, 2010 Andres Gomez Casanova
    *
    * This file is part of Zemucan.
    *
    * Zemucan is free software: you can redistribute it and/or modify
    * it under the terms of the GNU Lesser General Public License as published by
    * the Free Software Foundation; either version 3 of the License, or
   * (at your option) any later version.
   *
   * Zemucan is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public License
   * along with this library; if not, see <http://www.gnu.org/licenses/>.
   *
   * Contact:
   * a n g o c a  at  y a h o o  dot  c o m
   * Cra. 45 No 61 - 31, Bogota, Colombia.
   *
   * Author:   $LastChangedBy: angoca $:
   * Date:     $LastChangedDate: 2011-03-06 23:10:20 -0500 (dom, 06 mar 2011) $:
   * Revision: $LastChangedRevision: 1917 $:
   * URL:      $HeadURL: https://zemucan.svn.sourceforge.net/svnroot/zemucan/branches/zemucan_v1/source-code/uiImplJLine/src/main/java/name/angoca/zemucan/ui/impl/jline/ZemucanCompletionHandler.java $:
   */
  package name.angoca.zemucan.ui.impl.jline;
  
  import java.io.IOException;
  import java.text.MessageFormat;
  import java.util.Collection;
  import java.util.List;
  
  import jline.CompletionHandler;
  import jline.ConsoleReader;
  import name.angoca.zemucan.tools.messages.jline.Messages;
  
  /**
   * This is the implementation of a JLine CompletionHandler. This class is almost
   * the same implementation of CandidateListCompletionHandler but it does not
   * process the candidates, just show them.
   * <p>
   * This class is completely based in CandidateListCompletionHandler and that
   * code has a BSD license.
   * <p>
   * <b>Control Version</b>
   * <p>
   * <ul>
   * <li>1.0.0 Class creation.</li>
   * </ul>
   *
   * @author Andres Gomez Casanova <a
   *         href="mailto:a n g o c a at y a h o o dot c o m" >(AngocA)</a>
   * @version 1.0.0 2010-05-15
   */
  public final class ZemucanCompletionHandler implements CompletionHandler {
  
      /**
       * Print out the candidates. If the size of the candidates is greater than
       * the {@link getAutoprintThreshhold}, they prompt with a warning.
       *
       * @param reader
       *            Console that prints out the output.
       * @param candidates
       *            List of candidates to print.
       * @throws IOException
       *             If there is a problem writing the output.
       */
      private static void printCandidates(final ConsoleReader/* ! */reader,
              final Collection<Object>/* ! */candidates) throws IOException {
          assert reader != null;
          assert candidates != null;
  
          boolean printCandidates = false;
  
          // Prints a message that indicates that there are a lot of
          // candidates, and asks if the user wants to see all of them.
          if (candidates.size() > reader.getAutoprintThreshhold()) {
              // Asks the user.
              reader.printNewline();
              reader.printString(MessageFormat.format(
                      Messages.getString("SACompletionHandler"
                              + ".DisplayCandidates"),
                      new Object[] { new Integer(candidates.size()) })
                      + " ");
  
              reader.flushConsole();
  
              final String noOpt = Messages
                      .getString("SACompletionHandler.DisplayCandidatesYes");
              final String yesOpt = Messages
                      .getString("SACompletionHandler.DisplayCandidatesNo");
  
              // Process the user's answer.
              int c = -1;
              boolean exit = false;
              do {
                 // Read the user's answer.
                 c = reader.readCharacter(new char[] { yesOpt.charAt(0),
                         noOpt.charAt(0) });
 
                 // Not show options.
                 if (noOpt.startsWith(new String(new char[] { (char) c }))) {
                     reader.printNewline();
                     exit = true;
                 } else
                 // Show options
                 if (yesOpt.startsWith(new String(new char[] { (char) c }))) {
                     printCandidates = true;
                 } else {
                     // Invalid option taped.
                     reader.beep();
                 }
 
             } while ((c != -1) && !exit && !printCandidates);
 
         } else {
             printCandidates = true;
         }
 
         // If the candidates have to be printed.
         if (printCandidates) {
             reader.printNewline();
             reader.printColumns(candidates);
         }
     }
 
     /**
      * Prints the command line and position the cursor.
      *
      * @param reader
      *            Console that prints the output.
      * @param value
      *            New value in the command line.
      * @param offset
      *            cursor position.
      * @throws IOException
      *             if problem while moving back.
      */
     private static void setBuffer(final ConsoleReader/* ! */reader,
             final String/* ! */value, final int offset) throws IOException {
         assert reader != null;
         assert value != null;
 
         while ((reader.getCursorBuffer().cursor > offset) && reader.backspace()) {
             // Nothing.
             System.currentTimeMillis();
         }
 
         // Prints the line and the cursor in the right position.
         reader.putString(value);
         reader.setCursorPosition(offset + value.length());
     }
 
     /**
      * Completes a phrase. This implementation modifies the normal behavior of
      * this interface. The first candidate is the phrase to add in the command
      * line, the others, if they exists are the real candidates.
      *
      * @see jline.CompletionHandler#complete(jline.ConsoleReader,
      *      java.util.List, int)
      */
     @SuppressWarnings("unchecked")
     @Override
     public boolean complete(final ConsoleReader/* ! */reader,
             @SuppressWarnings("rawtypes") final List/* <!>! */candidates, final int position)
             throws IOException {
         assert reader != null;
         assert candidates != null;
         boolean assertsEnabled = false;
         // Intentional side-effect!
         assert assertsEnabled = true;
         if (assertsEnabled) {
             for (final Object object : candidates) {
                 assert object != null;
                 assert object instanceof String;
             }
         }
         assert candidates.size() >= 1;
 
         final String newPhrase = candidates.remove(0).toString();
         ZemucanCompletionHandler.setBuffer(reader, newPhrase, position);
 
         ZemucanCompletionHandler.printCandidates(reader, candidates);
 
         // Redraws the current console buffer.
         reader.drawLine();
 
         return true;
     }
 }