/*
 * Copyright (c) 2006-2011 Nuxeo SA (http://nuxeo.com/) and others.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     bstefanescu
 */
package org.eclipse.ecr.runtime.api;

import java.util.Map;

import javax.security.auth.Subject;
import javax.security.auth.callback.CallbackHandler;
import javax.security.auth.login.LoginException;
import javax.security.auth.spi.LoginModule;

/**
 * A login module wrapper to overcome the class loading issues on OSGi frameworks.
 * <p>
 * A login module is specified using the class name - and when doing a login against that module
 * the login context will get a class instance for the module by using Clas.forName and the current
 * thread context class loader. This means in an OSGi application the class loader of the caller bundle
 * will be used to resolve the login module. But the caller bundle may not have any dependency on the login module
 * since it is not aware about which login module implementation is used underneath - so in most cases
 * the login module class will not be found.
 * <p>
 * For this reason all the contributed login modules will be wrapped using this class.
 * As almost any Nuxeo bundle have a dependency on runtime this class will be visible from almost any Nuxeo bundle.
 * So, the login context will instantiate this wrapper instead of the real login module and the wrapper
 * will use OSGi logic to instantiate the wrapped login module. (by using the bundle that contributed the login module)
 * <p>
 * <b>IMPORTANT</b>
 * <p>
 * This class is in org.eclipse.ecr.runtime.api package to be visible to any bundle that uses Nuxeo runtime.
 * This is because this package is imported by almost any bundle using Nuxeo runtime - so you don't
 * need to declare the import package in the OSGi manifest.
 * In the case you don't use runtime but you are doing logins in the context of your bundle you must import the package
 * <code>org.eclipse.ecr.runtime.api</code> in your manifest.
 *
 * @author <a href="mailto:bs@nuxeo.com">Bogdan Stefanescu</a>
 */
public class LoginModuleWrapper implements LoginModule {

    public static final String DELEGATE_CLASS_KEY = LoginModuleWrapper.class.getName()+".delegate";

    protected LoginModule delegate;


    protected void initDelegate(Map<String, ?> options) {
        if (delegate == null) {
            try {
                Class<?> clazz = (Class<?>)options.get(DELEGATE_CLASS_KEY);
                delegate = (LoginModule)clazz.newInstance();
            } catch (NullPointerException e) {
                throw new RuntimeException("Should be a bug: No DELEGATE_CLASS_KEY found in login module options", e);
            } catch (ClassCastException e) {
                throw new RuntimeException("Invalid login module class: "+options.get(DELEGATE_CLASS_KEY)+". Should implement LoginModule.", e);
            } catch (Exception e) {
                throw new RuntimeException("Cannot instantiate login module: "+options.get(DELEGATE_CLASS_KEY), e);
            }
        }
    }

    @Override
    public void initialize(Subject subject, CallbackHandler callbackHandler,
            Map<String, ?> sharedState, Map<String, ?> options) {
        initDelegate(options);
        delegate.initialize(subject, callbackHandler, sharedState, options);
    }

    @Override
    public boolean login() throws LoginException {
        return delegate.login();
    }

    @Override
    public boolean commit() throws LoginException {
        return delegate.commit();
    }

    @Override
    public boolean abort() throws LoginException {
        return delegate.abort();
    }

    @Override
    public boolean logout() throws LoginException {
        return delegate.logout();
    }

}