/*
 * 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.security.ui.rap;

import java.security.AccessControlContext;
import java.security.AccessController;
import java.security.PrivilegedAction;

import javax.security.auth.Subject;
import javax.security.auth.login.CredentialNotFoundException;
import javax.security.auth.login.FailedLoginException;
import javax.security.auth.login.LoginContext;
import javax.security.auth.login.LoginException;
import javax.security.auth.x500.X500Principal;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.argeo.cms.CmsException;
import org.argeo.cms.auth.AuthConstants;
import org.argeo.cms.auth.ThreadDeathLoginException;
import org.argeo.cms.widgets.auth.DefaultLoginDialog;
import org.argeo.eclipse.ui.dialogs.ErrorFeedback;
import org.eclipse.jface.dialogs.MessageDialog;
import org.eclipse.rap.rwt.RWT;
import org.eclipse.rap.rwt.application.EntryPoint;
import org.eclipse.swt.widgets.Display;
import org.eclipse.ui.PlatformUI;

/**
 * RAP entry point with login capabilities. Once the user has been
 * authenticated, the workbench is run as a privileged action by the related
 * subject.
 */
@Deprecated
public class SecureEntryPoint implements EntryPoint {
	final static String ACCESS_CONTROL_CONTEXT = "org.argeo.node.accessControlContext";
	private final static Log log = LogFactory.getLog(SecureEntryPoint.class);

	/**
	 * How many seconds to wait before invalidating the session if the user has
	 * not yet logged in.
	 */
	private Integer loginTimeout = 1 * 60;
	// TODO make it configurable
	/** Default session timeout is 8 hours (European working day length) */
	private Integer sessionTimeout = 8 * 60 * 60;

	/** Override to provide an application specific workbench advisor */
	protected RapWorkbenchAdvisor createRapWorkbenchAdvisor(String username) {
		return new RapWorkbenchAdvisor(username);
	}

	@Override
	public final int createUI() {
		// Short login timeout so that the modal dialog login doesn't hang
		// around too long
		RWT.getRequest().getSession().setMaxInactiveInterval(loginTimeout);

		final Display display = PlatformUI.createDisplay();

		// load context from session
		HttpServletRequest httpRequest = RWT.getRequest();
		final HttpSession httpSession = httpRequest.getSession();
		AccessControlContext acc = (AccessControlContext) httpSession
				.getAttribute(ACCESS_CONTROL_CONTEXT);

		final Subject subject;
		if (acc != null
				&& Subject.getSubject(acc).getPrincipals(X500Principal.class)
						.size() == 1) {
			subject = Subject.getSubject(acc);
		} else {
			subject = new Subject();

			final LoginContext loginContext;
			DefaultLoginDialog callbackHandler;
			try {
				callbackHandler = new DefaultLoginDialog(
						display.getActiveShell());
				loginContext = new LoginContext(
						AuthConstants.LOGIN_CONTEXT_USER, subject,
						callbackHandler);
			} catch (LoginException e1) {
				throw new CmsException("Cannot initialize login context", e1);
			}

			tryLogin: while (subject.getPrincipals(X500Principal.class).size() == 0) {
				try {
					loginContext.login();
					if (subject.getPrincipals(X500Principal.class).size() == 0)
						throw new CmsException("Login succeeded but no auth");// fatal

					// add thread locale to RWT session
					// if (log.isTraceEnabled())
					// log.trace("Locale " + LocaleUtils.threadLocale.get());
					// RWT.setLocale(LocaleUtils.threadLocale.get());

					// once the user is logged in, longer session timeout
					RWT.getRequest().getSession()
							.setMaxInactiveInterval(sessionTimeout);

					if (log.isDebugEnabled())
						log.debug("Authenticated " + subject);
				} catch (FailedLoginException e) {
					MessageDialog.openInformation(display.getActiveShell(),
							"Bad Credentials", e.getMessage());
					// retry login
					continue tryLogin;
				} catch (CredentialNotFoundException e) {
					MessageDialog.openInformation(display.getActiveShell(),
							"No Credentials", e.getMessage());
					// retry login
					continue tryLogin;
				} catch (LoginException e) {
					callbackHandler.getShell().dispose();
					return processLoginDeath(display, e);
				}
			}
		}
		final String username = subject.getPrincipals(X500Principal.class)
				.iterator().next().getName();
		// Logout callback when the display is disposed
		display.disposeExec(new Runnable() {
			public void run() {
				if (log.isTraceEnabled())
					log.trace("Display disposed");
				try {
					LoginContext loginContext = new LoginContext(
							AuthConstants.LOGIN_CONTEXT_USER, subject);
					loginContext.logout();
				} catch (LoginException e) {
					log.error("Error when logging out", e);
				}
			}
		});

		//
		// RUN THE WORKBENCH
		//
		Integer returnCode = null;
		try {
			returnCode = Subject.doAs(subject, new PrivilegedAction<Integer>() {
				public Integer run() {
					// add security context to session
					httpSession.setAttribute(ACCESS_CONTROL_CONTEXT,
							AccessController.getContext());

					// start workbench
					RapWorkbenchAdvisor workbenchAdvisor = createRapWorkbenchAdvisor(username);
					int result = PlatformUI.createAndRunWorkbench(display,
							workbenchAdvisor);
					return new Integer(result);
				}
			});
			// Explicit exit from workbench
			fullLogout(subject, username);
		} finally {
			display.dispose();
		}
		return returnCode;
	}

	private Integer processLoginDeath(Display display, Throwable e) {
		// check thread death
		ThreadDeath td = wasCausedByThreadDeath(e);
		if (td != null) {
			display.dispose();
			throw td;
		}
		if (!display.isDisposed()) {
			ErrorFeedback.show("Unexpected exception during authentication", e);
			// this was not just bad credentials or death thread
			RWT.getRequest().getSession().setMaxInactiveInterval(1);
			display.dispose();
			return -1;
		} else {
			throw new CmsException(
					"Unexpected exception during authentication", e);
		}

	}

	/**
	 * If there is a {@link ThreadDeath} in the root causes, rethrow it
	 * (important for RAP cleaning mechanism)
	 */
	protected ThreadDeath wasCausedByThreadDeath(Throwable t) {
		if (t instanceof ThreadDeath)
			return (ThreadDeath) t;
		if (t instanceof ThreadDeathLoginException)
			return ((ThreadDeathLoginException) t).getThreadDeath();
		if (t.getCause() != null)
			return wasCausedByThreadDeath(t.getCause());
		else
			return null;
	}

	private void fullLogout(Subject subject, String username) {
		try {
			LoginContext loginContext = new LoginContext(
					AuthConstants.LOGIN_CONTEXT_USER, subject);
			loginContext.logout();
			HttpServletRequest httpRequest = RWT.getRequest();
			HttpSession httpSession = httpRequest.getSession();
			httpSession.setAttribute(ACCESS_CONTROL_CONTEXT, null);
			RWT.getRequest().getSession().setMaxInactiveInterval(1);
			log.info("Logged out " + (username != null ? username : "")
					+ " (THREAD=" + Thread.currentThread().getId() + ")");
		} catch (LoginException e) {
			log.error("Error when logging out", e);
		}
	}
}