/* AbstractCallbackHandler.java -- 
   Copyright (C) 2005, 2006  Free Software Foundation, Inc.

This file is a part of GNU Classpath.

GNU Classpath 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 Classpath 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 Classpath; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, 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
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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
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independent module, the terms and conditions of the license of that
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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
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exception statement from your version.  */


package gnu.javax.security.auth.callback;

import gnu.java.security.Engine;

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;

  private final String name;

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

  protected AbstractCallbackHandler (final String name)
  {
    super();
    messages = PropertyResourceBundle.getBundle("gnu/javax/security/auth/callback/MessagesBundle");
    this.name = name;
  }

  // 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]);
      }
  }

  public final String getName ()
  {
    return name;
  }

  // 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);
  }
}