/* 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.

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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.

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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
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permission to link this library with independent modules to produce an
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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;
  }

  /**
   * Create an instance of <code>CallbackHandler</code> of the designated
   * <code>type</code> from the first Security Provider which offers it.
   * 
   * @param type the type of callback handler to create.
   * @return a newly created instance of <code>ClassbackHandler</code>.
   * @throws NoSuchAlgorithmException if no security provider is found to offer
   *           an implementation of <code>CallbackHandler</code> of the
   *           designated <code>type</code>.
   */
  public static CallbackHandler getInstance(String type)
      throws NoSuchAlgorithmException
  {
    Provider[] p = Security.getProviders();
    NoSuchAlgorithmException lastException = null;
    for (int i = 0; i < p.length; i++)
      try
        {
          return getInstance(type, p[i]);
        }
      catch (NoSuchAlgorithmException x)
        {
          lastException = x;
        }
    if (lastException != null)
      throw lastException;
    throw new NoSuchAlgorithmException(type);
  }

  /**
   * Create an instance of <code>CallbackHandler</code> of the designated
   * <code>type</code> from the named security <code>provider</code>.
   * 
   * @param type the type of callback handler to create.
   * @param provider a named security provider to use.
   * @return a newly created instance of <code>ClassbackHandler</code>.
   * @throws NoSuchAlgorithmException if no security provider is found to offer
   *           an implementation of <code>CallbackHandler</code> of the
   *           designated <code>type</code>.
   * @throws IllegalArgumentException if either <code>type</code> or
   *           <code>provider</code> is <code>null</code>, or if
   *           <code>type</code> is an empty string.
   */
  public static CallbackHandler getInstance(String type, String provider)
      throws NoSuchAlgorithmException, NoSuchProviderException
  {
    if (provider == null)
      throw new IllegalArgumentException("provider MUST NOT be null");
    Provider p = Security.getProvider(provider);
    if (p == null)
      throw new NoSuchProviderException(provider);
    return getInstance(type, p);
  }

  /**
   * Create an instance of <code>CallbackHandler</code> of the designated
   * <code>type</code> from the designated security <code>provider</code>.
   * 
   * @param type the type of callback handler to create.
   * @param provider a security provider to use.
   * @return a newly created instance of <code>ClassbackHandler</code>.
   * @throws NoSuchAlgorithmException if no security provider is found to offer
   *           an implementation of <code>CallbackHandler</code> of the
   *           designated <code>type</code>.
   * @throws IllegalArgumentException if either <code>type</code> or
   *           <code>provider</code> is <code>null</code>, or if
   *           <code>type</code> is an empty string.
   */
  public static CallbackHandler getInstance(String type, Provider provider)
    throws NoSuchAlgorithmException
  {
    StringBuilder sb = new StringBuilder("CallbackHandler of type [")
        .append(type).append("] from provider[")
        .append(provider).append("] could not be created");
    Throwable cause;
    try
      {
        return (CallbackHandler) Engine.getInstance(SERVICE, type, provider);
      }
    catch (InvocationTargetException x)
      {
        cause = x.getCause();
        if (cause instanceof NoSuchAlgorithmException)
          throw (NoSuchAlgorithmException) cause;
        if (cause == null)
          cause = x;
      }
    catch (ClassCastException x)
      {
        cause = x;
      }
    NoSuchAlgorithmException x = new NoSuchAlgorithmException(sb.toString());
    x.initCause(cause);
    throw x;
  }

  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);
  }
}