EDIT

package eu.etaxonomy.vaadin.mvp;

import java.io.Serializable;

import org.apache.log4j.Logger;

import org.hibernate.Session;

import org.hibernate.engine.spi.SessionImplementor;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.beans.factory.annotation.Qualifier;

import org.springframework.security.core.context.SecurityContext;

import org.springframework.security.core.context.SecurityContextHolder;

import org.springframework.transaction.IllegalTransactionStateException;

import com.vaadin.server.ServletPortletHelper;

import com.vaadin.server.VaadinRequest;

import com.vaadin.server.VaadinService;

import com.vaadin.server.VaadinSession;

import com.vaadin.ui.UI;

import eu.etaxonomy.cdm.api.application.CdmRepository;

import eu.etaxonomy.cdm.vaadin.server.CdmSpringVaadinServletService;

import eu.etaxonomy.cdm.vaadin.server.RequestStartListener;

import eu.etaxonomy.cdm.vaadin.session.IntraViewConversationDirector;

import eu.etaxonomy.cdm.vaadin.session.ViewScopeConversationHolder;

import eu.etaxonomy.vaadin.ui.navigation.NavigationManager;

import eu.etaxonomy.vaadin.ui.navigation.NavigationManagerBean;

/**

 * AbstractPresenter is the base class of all presenter components. Presenter's

 * role is to govern the view and control the complex UI logic based on

 * notifications presenter receives from its view.

 *

 * @author Peter / Vaadin

 *

 * @param <V>

 *            type of the view this presenter governs

 */

public abstract class AbstractPresenter<V extends ApplicationView> implements Serializable, IntraViewConversationDirector, RequestStartListener {

    private static final long serialVersionUID = 5260910510283481832L;

    public static final Logger logger = Logger.getLogger(AbstractPresenter.class);

	private V view;

	protected V getView() {

	    if(view == null){

            Logger.getLogger(this.getClass()).warn("CDM-VAADIN#6562: presenter " + toString() + " without view.");

        }

		return view;

	}

	@Autowired

	@Qualifier("cdmRepository")

	private CdmRepository repo;

	@Autowired

	private NavigationManager navigationManager;

	@Autowired

	private ViewScopeConversationHolder conversationHolder;

    protected boolean conversationBound;

	/**

	 * @return the repo

	 */

	public CdmRepository getRepo() {

	    if(!conversationBound){

	        // this is the central access point for getting access to the service layer.

	        // In case the presenter needs access to the repository, it most probably will use

	        // a service, so it is a good idea to bind the conversation at this point.

	        bindConversation();

	    }

	    return repo;

	}

	/**

     * @return

     *

     * FIXME is it ok to use the SecurityContextHolder or do we need to hold the context in the vaadin session?

     */

    protected SecurityContext currentSecurityContext() {

        return SecurityContextHolder.getContext();

    }

    /**

     * @return

     */

    protected Session getSession() {

        Session session = conversationHolder.getSession();

        logger.trace(this._toString() + ".getSession() - session:" + session.hashCode() +", persistenceContext: " + ((SessionImplementor)session).getPersistenceContext() + " - " + session.toString());

        return session;

    }

    protected String _toString(){

        return this.getClass().getSimpleName() + "@" + this.hashCode();

    }

	/**

	 * Notifies the presenter that its view is initialized so that presenter can

	 * start its own initialization if required.

	 *

	 * @param view

	 */

	protected final void init(V view) {

	    logger.trace(String.format("Presenter %s init()", _toString()));

		this.view = view;

		// bind the conversation to the thread of the first request send to the according View

		// all other requests are handled in onRequestStart()

		// logger.trace(String.format(">>>>> %s init() bind()", _toString()));

	    ensureBoundConversation();

	    // register as request start and end listener

	    VaadinService service = UI.getCurrent().getSession().getService();

	    if(service instanceof CdmSpringVaadinServletService){

	        logger.trace(String.format("~~~~~ %s register as request listener", _toString()));

	        ((CdmSpringVaadinServletService)service).addRequestEndListener(this);

	        if(logger.isTraceEnabled()){

	            ((CdmSpringVaadinServletService)service).addRequestStartListener(this);

	        }

	    } else {

	        throw new RuntimeException("Using the CdmSpringVaadinServletService is required for proper per view conversation handling");

	    }

		onPresenterReady();

	}

	/**

	 * Returns <code>true</code> for:

	 * <ul>

	 *   <li>..</li>

	 * <ul>

	 *

	 * Return <code>false</code> for:

	 *

	 * <ul>

     *   <li>UILD request in a existing view, like clicking on a button</li>

     * <ul>

     *

	 * @return

	protected boolean isActiveView(){

        return UI.getCurrent() != null && getView() != null && getView() == navigationManager.getCurrentView();

    }

	 */

    /**

     *

     */

	protected void bindConversation() {

        logger.trace(String.format(">>>>> %s bind()", _toString()));

        conversationHolder.bind();

        conversationBound = true;

    }

    @Override

    public void ensureBoundConversation() {

        if(!conversationBound){

            bindConversation();

        }

        if(!conversationHolder.isTransactionActive()){

            logger.trace(String.format(">>   %s starting transaction ", _toString()));

            conversationHolder.startTransaction();

        }

    }

    /**

     *

     */

    protected void unbindConversation() {

        logger.trace(String.format("<<<<< %s unbind()", _toString()));

        conversationHolder.unbind();

        // FIXME conversationHolder.isTransactionActive() always returns true

        // see https://dev.e-taxonomy.eu/redmine/issues/6780

        if(false && conversationHolder.isTransactionActive()){

            logger.trace(String.format("<<    %s comitting transaction ", _toString()));

            try{

                conversationHolder.commit(false);

            } catch (IllegalTransactionStateException | IllegalStateException e){

                // log this exception, but stop from propagating

                // FIXME remove this catch once https://dev.e-taxonomy.eu/redmine/issues/6780 is fixed

                logger.error(e.getMessage());

            }

        }

        conversationBound = false;

    }

    /**

	 * Extending classes should overwrite this method in order to perform logic

	 * after presenter has finished initializing.

	 */

	protected void onPresenterReady() {

	    logger.trace(String.format("Presenter %s ready", _toString()));

	}

    /**

     * <b>ONLY USED FOR LOGGING</b> when Level==TRACE

     * {@inheritDoc}

     */

    @Override

    public void onRequestStart(VaadinRequest request){

        if( ! requestNeedsConversation(request) ){

            // ignore hartbeat, fileupload, push etc

            logger.trace("ignoring request:" + request.getPathInfo());

            return;

        }

        logger.trace("onRequestStart() " + request.getPathInfo() + " " + _toString());

    }

    /**

     * @param request

     * @return

     */

    protected boolean requestNeedsConversation(VaadinRequest request) {

        return !(

                ServletPortletHelper.isAppRequest(request) // includes published file request

             || ServletPortletHelper.isFileUploadRequest(request)

             || ServletPortletHelper.isHeartbeatRequest(request)

             || ServletPortletHelper.isPushRequest(request)

             );

    }

    @Override

    public void onRequestEnd(VaadinRequest request, VaadinSession session){

        if( ! requestNeedsConversation(request) ){

            // ignore hartbeat, fileupload, push etc

            logger.trace("ignoring request:" + request.getPathInfo());

            return;

        }

        // always unbind at the end of a request to clean up the threadLocal variables in the

        // TransactionManager. This is crucial since applications containers manage threads in a pool

        // and the recycled threads may still have a reference to a SessionHolder from the processing

        // of a former request

        logger.trace("onRequestEnd() " + request.getPathInfo() + " " + _toString());

        if(conversationBound){

            unbindConversation();

        }

    }

    public final void onViewEnter() {

	    logger.trace(String.format("%s onViewEnter()", _toString()));

	    handleViewEntered();

	}

	public final void onViewExit() {

	    logger.trace(String.format("%s onViewExit()", _toString()));

	    // un-register as request start and end listener

	    if(conversationBound){

    	    logger.trace(String.format("<<<<< %s onViewExit() unbind()", _toString()));

            conversationHolder.unbind();

            conversationBound = false;

	    }

        VaadinService service = UI.getCurrent().getSession().getService();

        if(service instanceof CdmSpringVaadinServletService){

            logger.trace(String.format("~~~~~ %s un-register as request listener", _toString()));

            ((CdmSpringVaadinServletService)service).removeRequestEndListener(this);

            if(logger.isTraceEnabled()){

                ((CdmSpringVaadinServletService)service).removeRequestStartListener(this);

            }

        } else {

            throw new RuntimeException("Using the CdmSpringVaadinServletService is required for proper per view conversation handling");

        }

	    handleViewExit();

	}

	/**

	 * Extending classes should overwrite this method to react to the event when

	 * user has navigated into the view that this presenter governs.

	 * For implementations of {@link AbstractPopupEditor AbstractPopupEditors} this is usually

	 * called before the data item has been bound. This order is guaranteed since popup editors

	 * are managed through the {@link NavigationManagerBean}

	 */

	public void handleViewEntered() {

	}

    /**

     * Extending classes may overwrite this method to react to

     * the event when user leaves the view that this presenter

     * governs.

     */

    public void handleViewExit() {

    }

    /**

     * @return the navigationManager

     */

    public NavigationManager getNavigationManager() {

        return navigationManager;

    }

    protected ViewScopeConversationHolder getConversationHolder(){

        return conversationHolder;

    }

    /**

     * @param repo the repo to set

     */

    protected void setRepo(CdmRepository repo) {

        this.repo = repo;

    }

    /**

     * @param navigationManager the navigationManager to set

     */

    protected void setNavigationManager(NavigationManager navigationManager) {

        this.navigationManager = navigationManager;

    }

}