ConsoleDialog

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 * must also contain a copy of this document.
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 *
 * Copyright 2000-2001 (C) Intalio, Inc. All Rights Reserved.
 *
 * $Id$
 */
package org.exolab.castor.util.dialog;

/**
 * A simple utility class to handle command line dialogs
 *
 * @author <a href="mailto:nsgreen@thazar.com">Nathan Green</a>
 * @author <a href="mailto:kvisco@intalio.com">Keith Visco</a>
 */
public class ConsoleDialog implements Dialog {

  /**
   * Creates a new Console Dialog
   */
  public ConsoleDialog() {
    super();
  } // -- ConsoleDialog

  /**
   * Presents a confirmation prompt with the given message.
   *
   * @param message the confirmation prompt message to display
   * @return true if the user has selected a positive confirmation, otherwise false
   */
  public boolean confirm(final String message) {
    try {
      while (true) {
        System.out.println();
        System.out.print(message);
        System.out.print("(y|n|?) : ");

        int ch = getChar();

        System.out.println();

        // -- check ch
        switch (ch) {
          case 'y':
            return true;
          case 'n':
            return false;
          case '?':
            System.out.println("y = yes, n = no");
            break;
          default:
            System.out.print("invalid input, expecting ");
            System.out.println("'y', 'n', or '?'.");
            break;
        }
      }
    } catch (java.io.IOException ix) {
      System.out.println(ix);
    }
    return false;
  } // -- confirm

  /**
   * Returns a single char from System.in.
   *
   * @return the character entered, or null if more than one was entered (not including EOLs)
   * @throws java.io.IOException if one is encountered in System.in.read()
   */
  private int getChar() throws java.io.IOException {
    int ch = System.in.read();

    // -- read eoln, or extra characters
    while (System.in.available() > 0) {
      switch (System.in.read()) {
        case '\n':
        case '\r':
          break;
        default:
          ch = '\0';
      }
    }
    return ch;
  }

  /**
   * Presents a confirmation prompt for values with the given messge.
   *
   * @param message the confirmation prompt to display
   * @param values a list of valid characters to accept
   * @return whatever character the user presses
   */
  public char confirm(final String message, final String values) {
    return confirm(message, values, "no help available...");
  }

  /**
   * Presents a confirmation prompt for values with the given messge
   *
   * @param message the confirmation prompt to display
   * @param values a list of valid characters to accept
   * @param help a help message when the user presses '?'
   * @return whatever character the user presses
   */
  public char confirm(final String message, final String values, final String help) {
    String prompt = makeList(values);

    try {
      while (true) {
        System.out.println();
        System.out.print(message + prompt);

        int ch = getChar();

        System.out.println();

        // -- check ch
        if (values.indexOf(ch) != -1) {
          return (char) ch;
        }

        if (ch == '?') {
          System.out.println(help);
        } else {
          System.out.print("invalid input, expecting ");
          System.out.println(listInput(values));
        }
      }
    } catch (java.io.IOException ix) {
      System.out.println(ix);
    }
    return '\0';
  }

  /**
   * Displays the given message to the user. No input is returned from the user.
   *
   * @param message the message to display to the user
   */
  public void notify(final String message) {
    System.out.println(message);
  } // -- notify

  /**
   * Converts a list of characters into a delimited prompt. A '?' is automatically put at the end.
   *
   * @param values a list of valid characters to accept
   * @return each character separated by a pipe and in parenthesis
   */
  private String makeList(final String values) {
    StringBuilder sb = new StringBuilder(values.length() * 2).append('(');
    for (int i = 0; i < values.length(); i++) {
      sb.append(values.charAt(i)).append('|');
    }
    sb.append("?)");
    return sb.toString();
  }

  /**
   * Creates a list of valid input options to give a better explanation to the user.
   *
   * @param values a list of valid characters to accept
   * @return each character in single quotes, comma separated
   */
  private String listInput(final String values) {
    StringBuilder sb = new StringBuilder(values.length() * 4);
    for (int i = 0; i < values.length(); i++) {
      sb.append('\'').append(values.charAt(i)).append("', ");
    }
    sb.append("or '?'");
    return sb.toString();
  }

} // -- Dialog