/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.apache.myfaces.extensions.cdi.jsf2.impl.navigation;

import org.apache.myfaces.extensions.cdi.core.api.config.view.DefaultErrorView;
import org.apache.myfaces.extensions.cdi.core.api.config.view.ViewConfig;
import org.apache.myfaces.extensions.cdi.jsf.api.config.view.Page;
import org.apache.myfaces.extensions.cdi.jsf.api.config.view.ViewConfigDescriptor;
import org.apache.myfaces.extensions.cdi.jsf.impl.config.view.ViewConfigCache;
import org.apache.myfaces.extensions.cdi.jsf.impl.navigation.ViewConfigAwareNavigationHandler;
import org.apache.myfaces.extensions.cdi.jsf.api.config.JsfModuleConfig;
import org.apache.myfaces.extensions.cdi.core.api.activation.Deactivatable;
import org.apache.myfaces.extensions.cdi.core.impl.util.ClassDeactivation;
import org.apache.myfaces.extensions.cdi.core.impl.util.CodiUtils;

import javax.faces.application.ConfigurableNavigationHandler;
import javax.faces.application.NavigationHandler;
import javax.faces.application.NavigationCase;
import javax.faces.context.FacesContext;
import java.util.Set;
import java.util.Map;
import java.util.HashMap;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.CopyOnWriteArraySet;

import static org.apache.myfaces.extensions.cdi.core.api.util.ClassUtils.tryToLoadClassForName;

/**
 * We have to ensure the invocation order for the type-safe navigation feature/s.
 */
public class CodiNavigationHandler extends ConfigurableNavigationHandler implements Deactivatable
{
    private Set<String> otherOutcomes = new CopyOnWriteArraySet<String>();

    private Map<String, NavigationCase> viewConfigBasedNavigationCaseCache
        = new ConcurrentHashMap<String, NavigationCase>();

    private final NavigationHandler wrapped;
    private final boolean deactivated;
    private final boolean addViewConfigsAsNavigationCase;

    /**
     * Constructor for wrapping the given {@link NavigationHandler}
     * @param navigationHandler navigation-handler which should be wrapped
     */
    public CodiNavigationHandler(NavigationHandler navigationHandler)
    {
        this.wrapped = navigationHandler;
        this.deactivated = !isActivated();

        if(!this.deactivated)
        {
            this.addViewConfigsAsNavigationCase = isAddViewConfigsAsNavigationCaseActivated();
        }
        else
        {
            this.addViewConfigsAsNavigationCase = false;
        }
    }

    /**
     * {@inheritDoc}
     */
    public void handleNavigation(FacesContext context, String fromAction, String outcome)
    {
        if(this.deactivated || isUnhandledExceptionQueued(context))
        {
            this.wrapped.handleNavigation(context, fromAction, outcome);
        }

        //allow multiple redirects via view-configs.
        //in addition some component libs use a different order (which isn't spec. conform),
        //but it might be useful to use the ViewConfigAwareNavigationHandler
        else if (context.getRenderResponse() /*see EXTCDI-92*/ || context.getViewRoot() == null)
        {
            new ViewConfigAwareNavigationHandler(this.wrapped, true).handleNavigation(context, fromAction, outcome);
        }
        else
        {
            //don't refactor it - currently we need the lazy wrapping due to special jsf2 constellations
            getWrappedNavigationHandler().handleNavigation(context, fromAction, outcome);
        }
    }

    private boolean isUnhandledExceptionQueued(FacesContext context)
    {
        return context.getExceptionHandler().getUnhandledExceptionQueuedEvents() != null &&
                context.getExceptionHandler().getUnhandledExceptionQueuedEvents().iterator().hasNext();
    }

    private NavigationHandler getWrappedNavigationHandler()
    {
        ViewConfigAwareNavigationHandler viewConfigAwareNavigationHandler =
                new ViewConfigAwareNavigationHandler(this.wrapped, true);

        return new AccessScopeAwareNavigationHandler(viewConfigAwareNavigationHandler);
    }

    /**
     * {@inheritDoc}
     */
    public NavigationCase getNavigationCase(FacesContext context, String action, String outcome)
    {
        if (this.wrapped instanceof ConfigurableNavigationHandler)
        {
            if(action == null && outcome != null && outcome.contains(".") && outcome.startsWith("class ") &&
                    !otherOutcomes.contains(outcome))
            {
                String originalOutcome = outcome;

                NavigationCase navigationCase = this.viewConfigBasedNavigationCaseCache.get(originalOutcome);

                if (navigationCase != null)
                {
                    return navigationCase;
                }

                outcome = outcome.substring(6);

                ViewConfigDescriptor entry = null;

                if(DefaultErrorView.class.getName().equals(originalOutcome))
                {
                    entry = ViewConfigCache.getDefaultErrorViewConfigDescriptor();
                }

                if(entry == null)
                {
                    Object loadedClass = tryToLoadClassForName(outcome);

                    if(loadedClass == null)
                    {
                        this.otherOutcomes.add(originalOutcome);
                    }
                    else if(ViewConfig.class.isAssignableFrom((Class)loadedClass))
                    {
                        //noinspection unchecked
                        entry = ViewConfigCache.getViewConfigDescriptor((Class<? extends ViewConfig>) loadedClass);
                    }
                }

                if(entry != null)
                {
                    navigationCase = new NavigationCase("*",
                                                        null,
                                                        null,
                                                        null,
                                                        entry.getViewId(),
                                                        null,
                                                        Page.NavigationMode.REDIRECT.equals(entry.getNavigationMode()),
                                                        false);
                    this.viewConfigBasedNavigationCaseCache.put(originalOutcome, navigationCase);
                    return navigationCase;
                }
            }
            return ((ConfigurableNavigationHandler) this.wrapped).getNavigationCase(context, action, outcome);
        }
        //TODO add support for implicit navigation in combination with view-config based typesafe navigation
        return null;
    }

    /**
     * {@inheritDoc}
     */
    public Map<String, Set<NavigationCase>> getNavigationCases()
    {
        Map<String, Set<NavigationCase>> result = null;

        if (this.wrapped instanceof ConfigurableNavigationHandler)
        {
            result = ((ConfigurableNavigationHandler) this.wrapped).getNavigationCases();
        }

        if(result == null)
        {
            result = new HashMap<String, Set<NavigationCase>>();
        }

        if(!this.addViewConfigsAsNavigationCase || this.deactivated)
        {
            return result;
        }

        return new NavigationCaseMapWrapper(result);
    }

    /**
     * {@inheritDoc}
     */
    public boolean isActivated()
    {
        return ClassDeactivation.isClassActivated(getClass());
    }

    private boolean isAddViewConfigsAsNavigationCaseActivated()
    {
        JsfModuleConfig config = CodiUtils.getContextualReferenceByClass(JsfModuleConfig.class);

        return config.isUseViewConfigsAsNavigationCasesEnabled();
    }
}