/* AbstractCallbackHandler.java -- base callback handler implementation.
   Copyright (C) 2004  Free Software Foundation, Inc.

This file is a part of GNU Crypto.

GNU Crypto is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 2 of the License, or (at your
option) any later version.

GNU Crypto 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
General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Crypto; if not, write to the Free Software Foundation,
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
conditions of the GNU General Public License cover the whole
combination.

As a special exception, the copyright holders of this library give
you permission to link this library with independent modules to
produce an executable, regardless of the license terms of these
independent modules, and to copy and distribute the resulting
executable under terms of your choice, provided that you also meet,
for each linked independent module, the terms and conditions of the
license of that module.  An independent module is a module which is
not derived from or based on this library.  If you modify this
library, you may extend this exception to your version of the
library, but you are not obligated to do so.  If you do not wish to
do so, delete this exception statement from your version.  */


package gnu.crypto.auth.callback;

import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.util.PropertyResourceBundle;
import java.util.ResourceBundle;

import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.Provider;
import java.security.Security;

import javax.security.auth.callback.Callback;
import javax.security.auth.callback.CallbackHandler;
import javax.security.auth.callback.ChoiceCallback;
import javax.security.auth.callback.ConfirmationCallback;
import javax.security.auth.callback.LanguageCallback;
import javax.security.auth.callback.NameCallback;
import javax.security.auth.callback.PasswordCallback;
import javax.security.auth.callback.TextInputCallback;
import javax.security.auth.callback.TextOutputCallback;
import javax.security.auth.callback.UnsupportedCallbackException;

public abstract class AbstractCallbackHandler implements CallbackHandler
{

  // Fields.
  // -------------------------------------------------------------------------

  private static final String SERVICE = "CallbackHandler";

  protected final ResourceBundle messages;

  // Constructors.
  // -------------------------------------------------------------------------

  protected AbstractCallbackHandler()
  {
    super();
    messages = PropertyResourceBundle.getBundle("gnu/crypto/auth/callback/MessagesBundle");
  }

  // Class methods.
  // -------------------------------------------------------------------------

  public static CallbackHandler getInstance(String type)
    throws NoSuchAlgorithmException
  {
    Provider[] p = Security.getProviders();
    for (int i = 0; i < p.length; i++)
      {
        try
          {
            return getInstance(type, p[i]);
          }
        catch (NoSuchAlgorithmException ignored)
          {
          }
      }
    throw new NoSuchAlgorithmException(type);
  }

  public static CallbackHandler getInstance(String type, String provider)
    throws NoSuchAlgorithmException, NoSuchProviderException
  {
    Provider p = Security.getProvider(provider);
    if (p == null)
      {
        throw new NoSuchProviderException(provider);
      }
    return getInstance(type, p);
  }

  public static CallbackHandler getInstance(String type, Provider provider)
    throws NoSuchAlgorithmException
  {
    try
      {
        return (CallbackHandler) Engine.getInstance(SERVICE, type, provider);
      }
    catch (InvocationTargetException ite)
      {
        Throwable cause = ite.getCause();
        if (cause instanceof NoSuchAlgorithmException)
          throw (NoSuchAlgorithmException) cause;
        NoSuchAlgorithmException nsae = new NoSuchAlgorithmException(type);
        if (cause != null)
          nsae.initCause (cause);
        throw nsae;
      }
    catch (ClassCastException cce)
      {
        NoSuchAlgorithmException nsae = new NoSuchAlgorithmException(type);
        nsae.initCause (cce);
        throw nsae;
      }
  }

  // Instance methods.
  // -------------------------------------------------------------------------

  public void handle(Callback[] callbacks)
    throws IOException, UnsupportedCallbackException
  {
    if (callbacks == null)
      throw new NullPointerException();
    for (int i = 0; i < callbacks.length; i++)
      {
        if (callbacks[i] == null)
          continue;
        if (callbacks[i] instanceof ChoiceCallback)
          handleChoice((ChoiceCallback) callbacks[i]);
        else if (callbacks[i] instanceof ConfirmationCallback)
          handleConfirmation((ConfirmationCallback) callbacks[i]);
        else if (callbacks[i] instanceof LanguageCallback)
          handleLanguage((LanguageCallback) callbacks[i]);
        else if (callbacks[i] instanceof NameCallback)
          handleName((NameCallback) callbacks[i]);
        else if (callbacks[i] instanceof PasswordCallback)
          handlePassword((PasswordCallback) callbacks[i]);
        else if (callbacks[i] instanceof TextInputCallback)
          handleTextInput((TextInputCallback) callbacks[i]);
        else if (callbacks[i] instanceof TextOutputCallback)
          handleTextOutput((TextOutputCallback) callbacks[i]);
        else
          handleOther(callbacks[i]);
      }
  }

  // Abstract methods.
  // -------------------------------------------------------------------------

  /**
   * Handles a {@link ChoiceCallback}.
   *
   * @param callback The choice callback.
   * @throws IOException If an I/O error occurs.
   */
  protected abstract void handleChoice(ChoiceCallback callback)
    throws IOException;

  /**
   * Handles a {@link ConfirmationCallback}.
   *
   * @param callback The confirmation callback.
   * @throws IOException If an I/O error occurs.
   */
  protected abstract void handleConfirmation(ConfirmationCallback callback)
    throws IOException;

  /**
   * Handles a {@link LanguageCallback}.
   *
   * @param callback The language callback.
   * @throws IOException If an I/O error occurs.
   */
  protected abstract void handleLanguage(LanguageCallback callback)
    throws IOException;

  /**
   * Handles a {@link NameCallback}.
   *
   * @param callback The name callback.
   * @throws IOException If an I/O error occurs.
   */
  protected abstract void handleName(NameCallback callback)
    throws IOException;

  /**
   * Handles a {@link PasswordCallback}.
   *
   * @param callback The password callback.
   * @throws IOException If an I/O error occurs.
   */
  protected abstract void handlePassword(PasswordCallback callback)
    throws IOException;

  /**
   * Handles a {@link TextInputCallback}.
   *
   * @param callback The text input callback.
   * @throws IOException If an I/O error occurs.
   */
  protected abstract void handleTextInput(TextInputCallback callback)
    throws IOException;

  /**
   * Handles a {@link TextOutputCallback}.
   *
   * @param callback The text output callback.
   * @throws IOException If an I/O error occurs.
   */
  protected abstract void handleTextOutput(TextOutputCallback callback)
    throws IOException;

  /**
   * Handles an unknown callback. The default implementation simply throws
   * an {@link UnsupportedCallbackException}.
   *
   * @param callback The callback to handle.
   * @throws IOException If an I/O error occurs.
   * @throws UnsupportedCallbackException If the specified callback is not
   *   supported.
   */
  protected void handleOther(Callback callback)
    throws IOException, UnsupportedCallbackException
  {
    throw new UnsupportedCallbackException(callback);
  }
}
