/*
 * 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.empire.jsf2.pages;

import java.util.Map;

import javax.faces.component.UIViewRoot;
import javax.faces.context.FacesContext;
import javax.faces.event.PhaseEvent;
import javax.faces.event.PhaseId;
import javax.faces.event.PhaseListener;

import org.apache.commons.beanutils.BeanUtils;
import org.apache.empire.exceptions.InternalException;
import org.apache.empire.exceptions.ObjectNotValidException;
import org.apache.empire.jsf2.app.FacesUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class PagePhaseListener implements PhaseListener
{
    private static final long   serialVersionUID       = 1L;
    private static final Logger log                    = LoggerFactory.getLogger(PagePhaseListener.class);

    private static final String LAST_PAGE_VIEW_ID      = "lastPageViewId";
    
    // FORWARD_PAGE_PARAMS used by PageNavigationHandler
    public  static final String FORWARD_PAGE_PARAMS    = "forwardPageParams";

    public PagePhaseListener()
    {
        log.trace("PagePhaseListener created.");
    }

    @Override
    public PhaseId getPhaseId()
    {
        return PhaseId.ANY_PHASE;
    }

    @Override
    public void beforePhase(PhaseEvent pe)
    {
        PhaseId phaseId = pe.getPhaseId();
        if (log.isTraceEnabled())
            log.trace("Processing Phase {}.", phaseId);

        FacesContext fc = pe.getFacesContext();
        UIViewRoot vr = fc.getViewRoot();
        if (vr == null)
        {
            /*
            PartialViewContext pvc = fc.getPartialViewContext(); 
            boolean ajax = pvc.isAjaxRequest();
            boolean part = pvc.isPartialRequest();
            if (!part && !ajax)
            {
                HttpServletRequest req = FacesUtils.getHttpRequest(fc);
                String reqURI = req.getRequestURI();
                log.info("No View Root for request to '"+reqURI+"' in Phase "+String.valueOf(phaseId));
            }
            */
            return;
        }

        // Get the view Id
        String viewId = vr.getViewId();
        if (viewId==null)
        {   // Error: No viewId!
            log.warn("No viewId provided for PagePhaseEvent in phase {}.", phaseId);
            return;
        }
        
        // Detect view change
        Map<String, Object> sessionMap = fc.getExternalContext().getSessionMap();
        Object lastViewId = sessionMap.get(LAST_PAGE_VIEW_ID);
        if (lastViewId == null || !(((String) lastViewId).equalsIgnoreCase(viewId)))
        { // view changes
            FacesUtils.getWebApplication().onChangeView(fc, viewId);
            if (fc.getResponseComplete())
                return;
            // set view Id
            sessionMap.put(LAST_PAGE_VIEW_ID, viewId);
        }

        // Get Page Definition
        PageDefinition pageDef = PageDefinitions.getInstance().getPageFromViewId(viewId);
        if (pageDef == null)
        {   // No page definition available
            if (log.isDebugEnabled())
                log.debug("No page definition available for viewId {}.", viewId);
            return;
        }    

        // Check Request context path 
        /*
        if (viewChanged)
        {
            log.debug("Checking view context path");
            HttpServletRequest req = FacesUtils.getHttpRequest(fc);
            String reqURI = req.getRequestURI();
            viewId = pageDef.getPath();
            int vix = viewId.lastIndexOf('.');
            int rix = reqURI.lastIndexOf('.');
            if (rix<vix || !viewId.regionMatches(true, 0, reqURI, rix-vix, vix))
            {   // redirect to view page
                String ctxPath = fc.getExternalContext().getRequestContextPath();
                String pageURI = ctxPath + viewId.substring(0,vix) + ".iface";
                log.warn("Invalid RequestURI '" + reqURI + "'. Redirecting to '"+pageURI+"'.");
                FacesUtils.redirectDirectly(fc, pageURI);
                return;
            }
            // Save current viewId
        }
        */
        
        // Obtain PageBean from BeanManager
        String name = pageDef.getPageBeanName();
        Map<String, Object> viewMap = vr.getViewMap();
        Page pageBean = (Page) viewMap.get(name);
        if (pageBean == null)
        {   // Not available yet
            Class<? extends Page> pageClass = pageDef.getPageBeanClass();
            if (log.isDebugEnabled())
                log.debug("Creating page bean {} for {} in Phase {}.", new Object[] { pageClass.getName(), viewId, pe.getPhaseId() });
            // Use Bean Manager
            pageBean = (Page)FacesUtils.getManagedBean(fc, name);
            if (pageBean==null)
            {   // Create Instance ourselves
                log.warn("Unable to obtain page bean '{}' from BeanManager. Page bean probably not registered. Creating new instance but Injection might not work! ", name);
                try
                {   // Create Instance
                    pageBean = pageClass.newInstance();
                    viewMap.put(name, pageBean);
                }
                catch (Exception e)
                {
                    log.error("Error creating instance of page bean " + pageClass.getName(), e);
                    throw new InternalException(e);
                }
            }
            else if (!pageClass.isInstance(pageBean))
            {   // Wrong class
                log.warn("Page bean '"+name+"' is not an instance of class {} as expected. Detected class is {}", pageClass.getName(), pageBean.getClass().getName());
            }
            // Add 'page' to map 
            viewMap.put("page", pageBean);
        }
        // set definition
        pageBean.setPageDefinition(pageDef);

        // Init PageBean
        if (pe.getPhaseId() == PhaseId.RENDER_RESPONSE)
            initPageBean(pageBean, fc, viewMap);

        /*
        Collection<UIViewParameter> params = ViewMetadata.getViewParameters(vr);
        for (UIViewParameter p : params)
        {
            log.info("p {} = {}", p.getName(), p.getValue());
        }
        */
    }

    private void initPageBean(Page pageBean, FacesContext fc, Map<String, Object> viewMap)
    {
        if (!pageBean.isInitialized())
        { // Not yet initialized 
            if (!PageNavigationHandler.isInitialized())
            { // Probably missing declaration in faces-config.xml 
                log.error("PageNavigationHandler has not been initialized. Forward operations will not work!");
            }
            // Check for forward page params
            if (viewMap.containsKey(FORWARD_PAGE_PARAMS))
            {
                @SuppressWarnings("unchecked")
                Map<String, String> pageParams = (Map<String, String>) viewMap.remove(FORWARD_PAGE_PARAMS);
                // TODO: Set view metadata
                if (!setViewMetadata(pageParams))
                { // instead set properties directly
                    for (String name : pageParams.keySet())
                    {
                        String value = pageParams.get(name);
                        try
                        {
                            BeanUtils.setProperty(pageBean, name, value);
                        }
                        catch (Exception e)
                        {
                            log.error("Unable to set PageParam " + name + " on " + pageBean.getClass().getName() + ".", e);
                        }
                    }
                }
            }
            // page prepared
        }
        // Init now
        pageBean.preRenderPage(fc);
    }

    /**
     * TODO: Find a way to set the view Metadata. Don't know how to do it.
     * 
     * @param pageParams
     * @return
     */
    private boolean setViewMetadata(Map<String, String> pageParams)
    {
        // Getting the metadata facet of the view
        /*
        FacesContext fc = FacesContext.getCurrentInstance();
        UIViewRoot   vr = fc.getViewRoot();
        UIComponent metadataFacet = vr.getFacet(UIViewRoot.METADATA_FACET_NAME);
        */

        /*
        String viewId = vr.getViewId();        
        ViewDeclarationLanguage vdl = fc.getApplication().getViewHandler().getViewDeclarationLanguage(fc, viewId);
        ViewMetadata viewMetadata = vdl.getViewMetadata(fc, viewId);
        Collection<UIViewParameter> viewParams = ViewMetadata.getViewParameters(vr);
        for (UIComponent child : metadataFacet.getChildren())
        */

        /*
        UIComponent metadata = vr.getFacet(UIViewRoot.METADATA_FACET_NAME);
        if (metadata == null)
        {
            metadata = fc.getApplication().createComponent(UIPanel.COMPONENT_TYPE);
            vr.getFacets().put(UIViewRoot.METADATA_FACET_NAME, metadata);

            Collection<UIViewParameter> viewParams = ViewMetadata.getViewParameters(vr);
            int size = viewParams.size();
            
            for (String name : pageParams.keySet())
            {
                String value = pageParams.get(name);
                UIViewParameter uivp = new UIViewParameter();
                uivp.setName(name);
                uivp.setValue(value);
                // uivp.setParent(vr);
                metadata.getChildren().add(uivp);
            }
        }
        for (UIComponent child : metadata.getChildren())
        {
            if (child instanceof UIViewParameter)
            {
                UIViewParameter viewParam = (UIViewParameter) child;
                String value = pageParams.get(viewParam.getName());
                if (value != null)
                    viewParam.setValue(value);
            }
        }
        */

        return false;
    }

    @Override
    public void afterPhase(PhaseEvent pe)
    {
        if (pe.getPhaseId() != PhaseId.RENDER_RESPONSE)
            return;
        // Get the view
        UIViewRoot vr = pe.getFacesContext().getViewRoot();
        if (vr==null)
            return;
        // Check Page Bean
        Map<String, Object> viewMap = vr.getViewMap();
        Page pageBean = (Page) viewMap.get("page");
        if (pageBean != null && !pageBean.isInitialized())
        {
            log.warn("PageBean was not initialized!");
            throw new ObjectNotValidException(pageBean);
        }
        // FacesUtils.getFin2Application().releaseConnection(true);
        log.trace("PagePhase complete.");
    }

}