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/**

* Copyright (C) 2017 EDIT

* European Distributed Institute of Taxonomy

* http://www.e-taxonomy.eu

*

* The contents of this file are subject to the Mozilla Public License Version 1.1

* See LICENSE.TXT at the top of this package for the full license terms.

*/

package eu.etaxonomy.cdm.vaadin.view;

import java.net.MalformedURLException;

import java.net.URL;

import java.util.ArrayList;

import java.util.List;

import java.util.concurrent.CountDownLatch;

import java.util.concurrent.ExecutionException;

import java.util.concurrent.TimeUnit;

import javax.mail.internet.AddressException;

import org.apache.commons.lang.StringUtils;

import org.apache.logging.log4j.LogManager;

import org.apache.logging.log4j.Logger;

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

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

import org.springframework.core.env.Environment;

import org.springframework.mail.MailException;

import org.springframework.security.authentication.AuthenticationManager;

import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;

import org.springframework.security.core.Authentication;

import org.springframework.security.core.AuthenticationException;

import org.springframework.util.concurrent.ListenableFuture;

import org.vaadin.spring.events.Event;

import org.vaadin.spring.events.EventBus;

import org.vaadin.spring.events.EventBusListener;

import org.vaadin.spring.events.annotation.EventBusListenerMethod;

import com.vaadin.data.validator.AbstractStringValidator;

import com.vaadin.spring.annotation.SpringComponent;

import com.vaadin.spring.annotation.ViewScope;

import com.vaadin.ui.themes.ValoTheme;

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

import eu.etaxonomy.cdm.api.config.CdmConfigurationKeys;

import eu.etaxonomy.cdm.api.service.security.AccountSelfManagementException;

import eu.etaxonomy.cdm.api.service.security.EmailAddressNotFoundException;

import eu.etaxonomy.cdm.vaadin.event.AuthenticationAttemptEvent;

import eu.etaxonomy.cdm.vaadin.event.AuthenticationSuccessEvent;

import eu.etaxonomy.cdm.vaadin.event.UserAccountEvent;

import eu.etaxonomy.cdm.vaadin.ui.UserAccountSelfManagementUI;

import eu.etaxonomy.cdm.vaadin.util.VaadinServletUtilities;

import eu.etaxonomy.vaadin.mvp.AbstractPresenter;

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

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

/**

 * The {@link LoginView} is used as replacement view in the scope of other views.

 * Therefore the LoginPresenter must be in <b>UIScope</b> so that the LoginPresenter

 * is available to all Views.

 * <p>

 * The LoginPresenter offers a <b>auto login feature for developers</b>. To activate the auto login

 * you need to provide the <code>user name</code> and <code>password</code> using the environment variables

 * <code>cdm-vaadin.login.usr</code> and <code>cdm-vaadin.login.pwd</code>, e.g.:

 * <pre>

 * -Dcdm-vaadin.login.usr=admin -Dcdm-vaadin.login.pwd=00000

 * </pre>

 *

 * @author a.kohlbecker

 * @since Apr 25, 2017

 *

 */

@SpringComponent

@ViewScope

public class LoginPresenter extends AbstractPresenter<LoginView> implements EventBusListener<AuthenticationAttemptEvent> {

    private static final long serialVersionUID = 4020699735656994791L;

    private final static Logger logger = LogManager.getLogger();

    private final static String PROPNAME_USER = "cdm-vaadin.login.usr";

    private final static String PROPNAME_PASSWORD = "cdm-vaadin.login.pwd";

    private String redirectToState;

    protected EventBus.UIEventBus uiEventBus;

    @Autowired

    @Qualifier("cdmRepository")

    private ICdmRepository repo;

    @Autowired

    protected Environment env;

//    @Override

//    protected void eventViewBusSubscription(ViewEventBus viewEventBus) {

//        viewEventBus.subscribe(this);

//    }

    @Autowired

    protected void setUIEventBus(EventBus.UIEventBus uiEventBus){

        this.uiEventBus = uiEventBus;

        uiEventBus.subscribe(this);

    }

    public boolean authenticate(String userName, String password) {

        getView().clearMessage();

        UsernamePasswordAuthenticationToken token = new UsernamePasswordAuthenticationToken(userName, password);

        AuthenticationManager authenticationManager = getRepo().getAuthenticationManager();

        try {

            Authentication authentication = authenticationManager.authenticate(token);

            if(authentication != null && authentication.isAuthenticated()) {

                logger.debug("user '" + userName + "' authenticated");

                currentSecurityContext().setAuthentication(authentication);

                if(NavigationManager.class.isAssignableFrom(getNavigationManager().getClass())){

                    uiEventBus.publish(this, new AuthenticationSuccessEvent(userName));

                    logger.debug("redirecting to " + redirectToState);

                    uiEventBus.publish(this, new NavigationEvent(redirectToState));

                }

            }

        } catch (AuthenticationException e){

            getView().showErrorMessage("Login failed! Please check your username and password.");

        }

        return false;

    }

    @Override

    public void handleViewEntered() {

        List<String> redirectToStateTokens = getNavigationManager().getCurrentViewParameters();

        String currentViewName = getNavigationManager().getCurrentViewName();

        if(currentViewName.equals(LoginViewBean.NAME) && redirectToStateTokens.isEmpty()){

            // login view is shown in turn to an explicit login request of the user (e.g. login button pressed)

            // use the redirectToStateTokens 1-n as redirectToState

            //FIXME implement : redirectToState = UserView.NAME

        } else {

            // the login view is shown instead of the requested view for which the user needs to login

            redirectToState = String.join("/", redirectToStateTokens);

        }

        getView().getLoginDialog().getEmail().addValidator(new AbstractStringValidator("An account for this email address already exits. You may want to use the \"Password Revovery\" tab intsead?") {

            private static final long serialVersionUID = 1L;

            @Override

            protected boolean isValidValue(String value) {

                return !repo.getAccountRegistrationService().emailAddressExists(value);

            }

        });

        // attempt to auto login

        if(StringUtils.isNotEmpty(System.getProperty(PROPNAME_USER)) && StringUtils.isNotEmpty(System.getProperty(PROPNAME_PASSWORD))){

            logger.warn("Performing autologin with user " + System.getProperty(PROPNAME_USER));

            authenticate(System.getProperty(PROPNAME_USER), System.getProperty(PROPNAME_PASSWORD));

        }

    }

    @Override

    public void onEvent(Event<AuthenticationAttemptEvent> event) {

        if(getView()!= null){

            authenticate(event.getPayload().getUserName(), getView().getLoginDialog().getPassword().getValue());

        } else {

            logger.info("view is NULL, not yet disposed LoginPresenter?");

        }

    }

    @EventBusListenerMethod

    public void onPasswordRevoveryEvent(UserAccountEvent event) throws MalformedURLException, ExecutionException, MailException, AddressException, AccountSelfManagementException {

        if(event.getAction().equals(UserAccountEvent.UserAccountAction.REQUEST_PASSWORD_RESET)) {

            requestPasswordReset();

        } else if(event.getAction().equals(UserAccountEvent.UserAccountAction.REGISTER_ACCOUNT)) {

            requestAccountCreation();

        }

    }

    private void requestPasswordReset() throws MalformedURLException, ExecutionException {

        String userNameOrEmail = getView().getLoginDialog().getUserNameOrEmail().getValue();

        URL servletBaseUrl = VaadinServletUtilities.getServletBaseUrl();

        logger.debug("UserAccountAction.REQUEST_PASSWORD_RESET for " + servletBaseUrl + ", userNameOrEmail:" + userNameOrEmail);

        // Implementation note: UI modifications allied in the below callback methods will not affect the UI

        // immediately, therefore we use a CountDownLatch

        CountDownLatch finshedSignal = new CountDownLatch(1);

        List<Throwable> asyncException = new ArrayList<>(1);

        ListenableFuture<Boolean> futureResult = repo.getPasswordResetService().emailResetToken(

                userNameOrEmail,

                servletBaseUrl.toString() + "/app/" + UserAccountSelfManagementUI.NAME + "#!" + PasswordResetViewBean.NAME + "/%s");

        futureResult.addCallback(

                    successFuture -> {

                        finshedSignal.countDown();

                    },

                    exception -> {

                        // possible MailException

                        asyncException.add(exception);

                        finshedSignal.countDown();

                    }

                );

        boolean asyncTimeout = false;

        Boolean result = false;

        try {

            finshedSignal.await(2, TimeUnit.SECONDS);

            result = futureResult.get();

        } catch (InterruptedException e) {

            asyncTimeout = true;

        } catch (Exception e) {

            // in case executing getUserNameOrEmail() causes an exception faster

            // than futureResult.addCallback( can be processed, the exception

            // can not be caught asynchronously

            // so we are adding all these exceptions here

            asyncException.add(e);

        }

        if(!asyncException.isEmpty()) {

            String messageText = "An unknown error has occurred.";

            if(asyncException.get(0) instanceof MailException) {

                String supportText = "the support";

                String supportEmail = env.getProperty(CdmConfigurationKeys.MAIL_ADDRESS_SUPPORT);

                if(supportEmail != null) {

                    supportText = "<a href=\"mailto:" + supportEmail +"\">" + supportEmail + "</a>";

                }

                messageText = "Sending the password reset email to you has failed. Please try again later or contact " + supportText + " in case this error persists.";

            }

            if(asyncException.get(0) instanceof EmailAddressNotFoundException) {

                messageText = "There is no user accout for this email address.";

            }

            getView().getLoginDialog().getMessageSendRecoveryEmailLabel().setValue(messageText);

            getView().getLoginDialog().getMessageSendRecoveryEmailLabel().setStyleName(ValoTheme.LABEL_FAILURE);

        } else {

            if(!asyncTimeout && result) {

                getView().getLoginDialog().getMessageSendRecoveryEmailLabel().setValue("An email with a password reset link has been sent to you.");

                getView().getLoginDialog().getMessageSendRecoveryEmailLabel().setStyleName(ValoTheme.LABEL_SUCCESS);

                getView().getLoginDialog().getSendOnetimeLogin().setEnabled(false);

                getView().getLoginDialog().getUserNameOrEmail().setEnabled(false);

                getView().getLoginDialog().getUserNameOrEmail().setReadOnly(true);

            } else {

                getView().getLoginDialog().getMessageSendRecoveryEmailLabel().setValue("A timeout has occured, please try again.");

                getView().getLoginDialog().getMessageSendRecoveryEmailLabel().setStyleName(ValoTheme.LABEL_FAILURE);

            }

        }

    }

    private void requestAccountCreation() throws MalformedURLException, MailException, AddressException, AccountSelfManagementException, ExecutionException {

        String emailAddress = getView().getLoginDialog().getEmail().getValue();

        URL servletBaseUrl = VaadinServletUtilities.getServletBaseUrl();

        logger.debug("UserAccountAction.REGISTER_ACCOUNT for " + servletBaseUrl + ", emailAddress:" + emailAddress);

        CountDownLatch finshedSignal = new CountDownLatch(1);

        List<Throwable> asyncException = new ArrayList<>(1);

        ListenableFuture<Boolean> futureResult = repo.getAccountRegistrationService().emailAccountRegistrationRequest(emailAddress,

                servletBaseUrl.toString() + "/app/" + UserAccountSelfManagementUI.NAME + "#!" + AccountRegistrationViewBean.NAME + "/%s");

        futureResult.addCallback(

                    successFuture -> {

                        finshedSignal.countDown();

                    },

                    exception -> {

                        // possible MailException

                        asyncException.add(exception);

                        finshedSignal.countDown();

                    }

                );

        boolean asyncTimeout = false;

        Boolean result = false;

        try {

            finshedSignal.await(2, TimeUnit.SECONDS);

            result = futureResult.get();

        } catch (InterruptedException e) {

            asyncTimeout = true;

        } catch (Exception e) {

            // in case executing emailAccountRegistrationRequest() causes an exception faster

            // than futureResult.addCallback( can be processed, the exception

            // can not be caught asynchronously

            // so we are adding all these exceptions here

            asyncException.add(e);

        }

        if(!asyncException.isEmpty()) {

            getView().getLoginDialog().getRegisterMessageLabel()

            .setValue("Sending the account registration email to you has failed. Please try again later or contect the support in case this error persists.");

            getView().getLoginDialog().getRegisterMessageLabel().setStyleName(ValoTheme.LABEL_FAILURE);

        } else {

            if(!asyncTimeout && result) {

                getView().getLoginDialog().getRegisterMessageLabel().setValue("An email with with further instructions has been sent to you.");

                getView().getLoginDialog().getRegisterMessageLabel().setStyleName(ValoTheme.LABEL_SUCCESS);

                getView().getLoginDialog().getEmail().setEnabled(false);

                getView().getLoginDialog().getRegisterButton().setEnabled(false);

            } else {

                getView().getLoginDialog().getRegisterMessageLabel().setValue("A timeout has occured, please try again.");

                getView().getLoginDialog().getRegisterMessageLabel().setStyleName(ValoTheme.LABEL_FAILURE);

            }

        }

    }

}