/*
    * Copyright (C) 2007-2012 Argeo GmbH
    *
    * Licensed under the Apache License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    *
    *         http://www.apache.org/licenses/LICENSE-2.0
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.argeo.cms.ui.widgets.auth;
  
  import java.io.IOException;
  import java.util.Arrays;
  
  import javax.security.auth.callback.Callback;
  import javax.security.auth.callback.CallbackHandler;
  import javax.security.auth.callback.NameCallback;
  import javax.security.auth.callback.PasswordCallback;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.eclipse.core.runtime.IProgressMonitor;
  import org.eclipse.core.runtime.NullProgressMonitor;
  import org.eclipse.jface.dialogs.IDialogConstants;
  import org.eclipse.jface.dialogs.TrayDialog;
  import org.eclipse.jface.operation.IRunnableWithProgress;
  import org.eclipse.jface.operation.ModalContext;
  import org.eclipse.swt.events.SelectionEvent;
  import org.eclipse.swt.events.SelectionListener;
  import org.eclipse.swt.widgets.Button;
  import org.eclipse.swt.widgets.Display;
  import org.eclipse.swt.widgets.Shell;
  import org.osgi.framework.FrameworkUtil;
  
  /** Base for login dialogs */
  public abstract class AbstractLoginDialog extends TrayDialog implements CallbackHandler {
  	private static final long serialVersionUID = -8046708963512717709L;
  
  	private final static Log log = LogFactory.getLog(AbstractLoginDialog.class);
  
  	private Thread modalContextThread = null;
  	boolean processCallbacks = false;
  	boolean isCancelled = false;
  	Callback[] callbackArray;
  
  	protected final Callback[] getCallbacks() {
  		return this.callbackArray;
  	}
  
  	public abstract void internalHandle();
  
  	public boolean isCancelled() {
  		return isCancelled;
  	}
  
  	protected AbstractLoginDialog(Shell parentShell) {
  		super(parentShell);
  	}
  
  	/*
  	 * (non-Javadoc)
  	 * 
  	 * @see
  	 * javax.security.auth.callback.CallbackHandler#handle(javax.security.auth
  	 * .callback.Callback[])
  	 */
  	public void handle(final Callback[] callbacks) throws IOException {
  		// clean previous usage
  		if (processCallbacks) {
  			// this handler was already used
  			processCallbacks = false;
  		}
  
  		if (modalContextThread != null) {
  			try {
  				modalContextThread.join(1000);
  			} catch (InterruptedException e) {
  				// silent
  			}
  			modalContextThread = null;
  		}
  
  		// initialize
  		this.callbackArray = callbacks;
  		final Display display = Display.getDefault();
  		display.syncExec(new Runnable() {
  
  			public void run() {
  				isCancelled = false;
  				setBlockOnOpen(false);
  				open();
  
  				final Button okButton = getButton(IDialogConstants.OK_ID);
 				okButton.setText("Login");
 				okButton.addSelectionListener(new SelectionListener() {
 					private static final long serialVersionUID = -200281625679096775L;
 
 					public void widgetSelected(final SelectionEvent event) {
 						processCallbacks = true;
 					}
 
 					public void widgetDefaultSelected(final SelectionEvent event) {
 						// nothing to do
 					}
 				});
 				final Button cancel = getButton(IDialogConstants.CANCEL_ID);
 				cancel.addSelectionListener(new SelectionListener() {
 					private static final long serialVersionUID = -3826030278084915815L;
 
 					public void widgetSelected(final SelectionEvent event) {
 						isCancelled = true;
 						processCallbacks = true;
 					}
 
 					public void widgetDefaultSelected(final SelectionEvent event) {
 						// nothing to do
 					}
 				});
 			}
 		});
 		try {
 			ModalContext.setAllowReadAndDispatch(true); // Works for now.
 			ModalContext.run(new IRunnableWithProgress() {
 
 				public void run(final IProgressMonitor monitor) {
 					modalContextThread = Thread.currentThread();
 					// Wait here until OK or cancel is pressed, then let it rip.
 					// The event
 					// listener
 					// is responsible for closing the dialog (in the
 					// loginSucceeded
 					// event).
 					while (!processCallbacks && (modalContextThread != null)
 							&& (modalContextThread == Thread.currentThread())
 							&& FrameworkUtil.getBundle(AbstractLoginDialog.class).getBundleContext() != null) {
 						// Note: SecurityUiPlugin.getDefault() != null is false
 						// when the OSGi runtime is shut down
 						try {
 							Thread.sleep(100);
 							// if (display.isDisposed()) {
 							// log.warn("Display is disposed, killing login
 							// dialog thread");
 							// throw new ThreadDeath();
 							// }
 						} catch (final Exception e) {
 							// do nothing
 						}
 					}
 					processCallbacks = false;
 					// Call the adapter to handle the callbacks
 					if (!isCancelled())
 						internalHandle();
 					else
 						// clear callbacks are when cancelling
 						for (Callback callback : callbacks)
 							if (callback instanceof PasswordCallback) {
 								char[] arr = ((PasswordCallback) callback).getPassword();
 								if (arr != null) {
 									Arrays.fill(arr, '*');
 									((PasswordCallback) callback).setPassword(null);
 								}
 							} else if (callback instanceof NameCallback)
 								((NameCallback) callback).setName(null);
 				}
 			}, true, new NullProgressMonitor(), Display.getDefault());
 		} catch (ThreadDeath e) {
 			isCancelled = true;
 			log.debug("Thread " + Thread.currentThread().getId() + " died");
 			throw e;
 		} catch (Exception e) {
 			isCancelled = true;
 			IOException ioe = new IOException("Unexpected issue in login dialog, see root cause for more details");
 			ioe.initCause(e);
 			throw ioe;
 		} finally {
 			// so that the modal thread dies
 			processCallbacks = true;
 			// try {
 			// // wait for the modal context thread to gracefully exit
 			// modalContextThread.join();
 			// } catch (InterruptedException ie) {
 			// // silent
 			// }
 			modalContextThread = null;
 		}
 	}
 
 	protected void configureShell(Shell shell) {
 		super.configureShell(shell);
 		shell.setText("Authentication");
 	}
 }