/*
 *  Copyright 2016 Anyware Services
 *
 *  Licensed 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.ametys.web.transformation.xslt;

import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.apache.avalon.framework.service.ServiceException;
import org.apache.avalon.framework.service.ServiceManager;
import org.apache.cocoon.components.ContextHelper;
import org.apache.cocoon.environment.Request;
import org.apache.cocoon.environment.Response;
import org.apache.commons.lang.StringUtils;
import org.apache.excalibur.source.SourceResolver;
import org.apache.excalibur.source.impl.FileSource;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

import org.ametys.cms.repository.Content;
import org.ametys.cms.transformation.ImageResolverHelper;
import org.ametys.core.right.RightManager;
import org.ametys.core.right.RightManager.RightResult;
import org.ametys.core.util.I18nUtils;
import org.ametys.core.util.dom.AmetysNodeList;
import org.ametys.core.util.dom.EmptyElement;
import org.ametys.core.util.dom.FileElement;
import org.ametys.core.util.dom.MapElement;
import org.ametys.core.util.dom.MapElement.MapNode;
import org.ametys.core.util.dom.StringElement;
import org.ametys.plugins.explorer.resources.Resource;
import org.ametys.plugins.explorer.resources.ResourceCollection;
import org.ametys.plugins.explorer.resources.dom.ResourceCollectionElement;
import org.ametys.plugins.explorer.resources.dom.ResourceElement;
import org.ametys.plugins.repository.AmetysObject;
import org.ametys.plugins.repository.AmetysObjectIterable;
import org.ametys.plugins.repository.AmetysObjectResolver;
import org.ametys.plugins.repository.UnknownAmetysObjectException;
import org.ametys.plugins.repository.metadata.CompositeMetadata;
import org.ametys.plugins.repository.metadata.CompositeMetadata.MetadataType;
import org.ametys.plugins.repository.metadata.UnknownMetadataException;
import org.ametys.plugins.repository.query.expression.Expression.Operator;
import org.ametys.runtime.parameter.ParameterHelper;
import org.ametys.web.URIPrefixHandler;
import org.ametys.web.WebConstants;
import org.ametys.web.renderingcontext.RenderingContext;
import org.ametys.web.renderingcontext.RenderingContextHandler;
import org.ametys.web.repository.content.WebContent;
import org.ametys.web.repository.dom.PageElement;
import org.ametys.web.repository.dom.SitemapElement;
import org.ametys.web.repository.page.Page;
import org.ametys.web.repository.page.PageQueryHelper;
import org.ametys.web.repository.page.Zone;
import org.ametys.web.repository.page.ZoneItem;
import org.ametys.web.repository.site.Site;
import org.ametys.web.repository.site.SiteManager;
import org.ametys.web.repository.sitemap.Sitemap;
import org.ametys.web.service.ServiceExtensionPoint;
import org.ametys.web.service.ServiceParameter;
import org.ametys.web.service.ServiceParameterOrRepeater;
import org.ametys.web.service.ServiceParameterRepeater;
import org.ametys.web.site.SiteConfigurationExtensionPoint;
import org.ametys.web.tags.TagExpression;

/**
 * Helper component to be used from XSL stylesheets.
 */
public class AmetysXSLTHelper extends org.ametys.cms.transformation.xslt.AmetysXSLTHelper
{
    private static SiteManager _siteManager;
    private static RenderingContextHandler _renderingContextHandler;
    private static SiteConfigurationExtensionPoint _siteConf;
    private static RightManager _rightManager;
    private static URIPrefixHandler _prefixHandler;
    private static SourceResolver _sourceResolver;
    private static ServiceExtensionPoint _serviceEP;
    
    @Override
    public void service(ServiceManager manager) throws ServiceException
    {
        _siteManager = (SiteManager) manager.lookup(SiteManager.ROLE);
        _renderingContextHandler = (RenderingContextHandler) manager.lookup(RenderingContextHandler.ROLE);
        _siteConf = (SiteConfigurationExtensionPoint) manager.lookup(SiteConfigurationExtensionPoint.ROLE);
        _rightManager = (RightManager) manager.lookup(RightManager.ROLE);
        _ametysObjectResolver = (AmetysObjectResolver) manager.lookup(AmetysObjectResolver.ROLE);
        _i18nUtils = (I18nUtils) manager.lookup(I18nUtils.ROLE);
        _prefixHandler = (URIPrefixHandler) manager.lookup(URIPrefixHandler.ROLE);
        _sourceResolver = (SourceResolver) manager.lookup(SourceResolver.ROLE);
        _serviceEP = (ServiceExtensionPoint) manager.lookup(ServiceExtensionPoint.ROLE);
    }
    
    /**
     * Returns the current URI prefix, depending on the rendering context.
     * @return the current URI prefix.
     */
    public static String uriPrefix()
    {
        return _prefixHandler.getUriPrefix();
    }
    
    /**
     * Returns the URI prefix corresponding to the current site, depending on the rendering context.
     * @return the URI prefix corresponding to the current site.
     */
    public static String siteUriPrefix()
    {
        Request request = ContextHelper.getRequest(_context);
        String siteName = (String) request.getAttribute("site");
        return _prefixHandler.getUriPrefix(siteName);
    }
    
    /**
     * Returns the absolute URI prefix, depending on the rendering context.
     * @return the absolute URI prefix.
     */
    public static String absoluteUriPrefix()
    {
        return _prefixHandler.getAbsoluteUriPrefix();
    }
    
    /**
     * Returns the absolute URI prefix corresponding to the current site, depending on the rendering context.
     * @return the absolute URI prefix corresponding to the current site.
     */
    public static String absoluteSiteUriPrefix()
    {
        Request request = ContextHelper.getRequest(_context);
        String siteName = (String) request.getAttribute("site");
        return _prefixHandler.getAbsoluteUriPrefix(siteName);
    }
    
    /**
     * Returns the absolute URI prefix corresponding to the given site, depending on the rendering context.
     * @param siteName The site name. Can be null to get the current site.
     * @return the absolute URI prefix corresponding to the current site.
     */
    public static String absoluteSiteUriPrefix(String siteName)
    {
        if (StringUtils.isEmpty(siteName))
        {
            return absoluteSiteUriPrefix();
        }
        return _prefixHandler.getAbsoluteUriPrefix(siteName);
    }
    
    /**
     * Returns the current skin name.
     * @return the current skin name.
     */
    public static String skin()
    {
        Request request = ContextHelper.getRequest(_context);
        return (String) request.getAttribute("skin");
    }
    
    /**
     * Returns the current template name.
     * @return the current template name.
     */
    public static String template()
    {
        Request request = ContextHelper.getRequest(_context);
        return (String) request.getAttribute("template");
    }
    
    /**
     * Returns the current sitemap name.
     * @return the current sitemap name.
     */
    public static String lang()
    {
        Request request = ContextHelper.getRequest(_context);
        return (String) request.getAttribute("sitemapLanguage");
    }
    
    /**
     * Returns the current sitemap name.
     * @param pageId The page identifier to get sitemap on
     * @return the current sitemap name.
     */
    public static String lang(String pageId)
    {
        try
        {
            Page page = _getPage(pageId);
            return page.getSitemapName();
        }
        catch (UnknownAmetysObjectException e)
        {
            _logger.error("Can not get sitemap lang on page '" + pageId + "'", e);
            return "";
        }
    }
    
    /**
     * Computes the URI for the given resource in the current site's skin.<br>
     * If the URI is requested by the front-office, it will be absolutized.
     * @param path the resource path.
     * @return the URI for the given resource.
     */
    public static String skinURL(String path)
    {
        Request request = ContextHelper.getRequest(_context);
        String siteName = (String) request.getAttribute("site");
        Site site = _siteManager.getSite(siteName);
        String skin = (String) request.getAttribute("skin");
        
        String resourcePath = "/skins/" + skin + "/resources/" + path;
        
        return _getResourceURL(request, site, resourcePath);
    }
    
    /**
     * Computes the URI for the given image with a given heigth and width in the current site's skin.<br>
     * If the URI is requested by the front-office, it will be absolutized.
     * @param path the resource path
     * @param height the height for the resource to get
     * @param width the width for the resource to get
     * @return the URI of the given resource
     */
    public static String skinImageURL(String path, int height, int width)
    {
        String skinPath = skinURL(path);
        return StringUtils.substringBeforeLast(skinPath, ".") + "_" + height + "x" + width + "." + StringUtils.substringAfterLast(skinPath, "."); 
    }
    
    /**
     * Computes the base 64 representation of the image at the specified path. <br>
     * @param path the path of the image
     * @return the base 64-encoded image
     * @throws IOException if an error occurs while trying to get the file
     */
    public static String skinImageBase64 (String path) throws IOException
    {
        FileSource source = (FileSource) _sourceResolver.resolveURI("skin://resources/" + path);
        return _getResourceBase64(source); 
    }
    
    /**
     * Computes the URI for the given image with a given heigth and width in the current site's skin.<br>
     * If the URI is requested by the front-office, it will be absolutized.
     * @param path the resource path
     * @param maxHeight the maximum height for the resource to get
     * @param maxWidth the maximum width for the resource to get
     * @return the URI of the given resource
     */
    public static String skinBoundedImageURL(String path, int maxHeight, int maxWidth)
    {
        String skinPath = skinURL(path);
        return StringUtils.substringBeforeLast(skinPath, ".") + "_max" + maxHeight + "x" + maxWidth + "." + StringUtils.substringAfterLast(skinPath, "."); 
    }
    
    /**
     * Computes the URI for the given resource in the current template.<br>
     * If the URI is requested by the front-office, it will be absolutized.
     * @param path the resource path.
     * @return the URI for the given resource.
     */
    public static String templateURL(String path)
    {
        Request request = ContextHelper.getRequest(_context);
        String siteName = (String) request.getAttribute("site");
        Site site = _siteManager.getSite(siteName);
        String skin = (String) request.getAttribute("skin");
        String template = (String) request.getAttribute("template");
        
        String resourcePath = "/skins/" + skin + "/templates/" + template + "/resources/" + path;
        
        return _getResourceURL(request, site, resourcePath);
    }
    
    /**
     * Computes the URI for the given resource in the given plugin.<br>
     * If the URI is requested by the front-office, it will be absolutized.
     * @param plugin the plugin name.
     * @param path the resource path.
     * @return the URI for the given resource.
     */
    public static String pluginResourceURL(String plugin, String path)
    {
        Request request = ContextHelper.getRequest(_context);
        String siteName = (String) request.getAttribute("site");
        Site site = _siteManager.getSite(siteName);
        
        String resourcePath = "/plugins/" + plugin + "/resources/" + path;
        
        return _getResourceURL(request, site, resourcePath);
    }
    
    /**
     * Computes the base 64 representation of the image at the specified path in the given plugin.<br>
     * @param plugin the plugin's name.
     * @param path the resource path.
     * @return the base 64 encoding for the given resource.
     * @throws IOException if an error occurs when trying to get the file
     * @throws MalformedURLException if the url is invalid
     */
    public static String pluginImageBase64(String plugin, String path) throws MalformedURLException, IOException
    {
        FileSource source = (FileSource) _sourceResolver.resolveURI("plugin:" + plugin + "://resources/" + path);
        return _getResourceBase64(source); 
    }

    
    private static String _getResourceURL(Request request, Site site, String resourcePath)
    {
        String prefix;
        switch (_renderingContextHandler.getRenderingContext())
        {
            case FRONT:
                String[] aliases = site.getUrlAliases();
                int position = Math.abs(resourcePath.hashCode()) % aliases.length;
                
                boolean absolute = request.getAttribute("forceAbsoluteUrl") != null ? (Boolean) request.getAttribute("forceAbsoluteUrl") : false;
                prefix = position == 0 && !absolute ? siteUriPrefix() : aliases[position];  
                return prefix + resourcePath;
                
            default:
                prefix = StringUtils.trimToEmpty((String) request.getAttribute(WebConstants.PATH_PREFIX));
                return request.getContextPath() + prefix + resourcePath;
        }
    }
    
    /**
     * Get the base 64 encoding for the given source
     * @param source the source 
     * @return the base 64 encoding of the source
     */
    private static String _getResourceBase64(FileSource source)
    {
        if (source.exists())
        {
            
            try (InputStream dataIs = source.getInputStream())
            {
                return ImageResolverHelper.resolveImageAsBase64(dataIs, source.getMimeType(), 0, 0, 0, 0);
            }
            catch (Exception e)
            {
                throw new IllegalStateException(e);
            }
        }

        return "";
    }
    
    /**
     * Returns the current {@link RenderingContext}.
     * @return the current {@link RenderingContext}.
     */
    public static String renderingContext()
    {
        return _renderingContextHandler.getRenderingContext().toString();
    }
    
    /**
     * Return the name of the zone beeing handled
     * @param defaultValue If no page is handled currently, this value is returned (can be null, empty...)
     * @return the name or the default value (so can be null or empty)
     */
    public static String zone(String defaultValue)
    {
        Request request = ContextHelper.getRequest(_context);
        
        return StringUtils.defaultIfEmpty((String) request.getAttribute(Zone.class.getName()), defaultValue);
    }

    /**
     * Return the value of a site parameter as a String.
     * @param parameter the parameter ID.
     * @return the parameter value as a String.
     */
    public static String siteParameter(String parameter)
    {
        Request request = ContextHelper.getRequest(_context);
        
        String siteName = (String) request.getAttribute("site");
        if (StringUtils.isBlank(siteName))
        {
            // In BO xsl
            siteName = (String) request.getAttribute("siteName");
        }
        
        return siteParameter(siteName, parameter);
    }
    
    /**
     * Return the value of a site parameter as a String.
     * @param siteName the site name
     * @param parameter the parameter ID.
     * @return the parameter value as a String.
     */
    public static String siteParameter(String siteName, String parameter)
    {
        try
        {
            return _siteConf.getUntypedValue(siteName, parameter);
        }
        catch (Exception e)
        {
            String message = "Error retrieving the value of the site parameter " + parameter;
            _logger.error(message, e);
            throw new RuntimeException(message, e);
        }
    }
    
    /**
     * Get the service parameters as a {@link Node}.
     * @return the service parameters as a {@link Node}.
     */
    public static Node serviceParameters()
    {
        Request request = ContextHelper.getRequest(_context);
        ZoneItem zoneItem = (ZoneItem) request.getAttribute(ZoneItem.class.getName());
        CompositeMetadata parameters = zoneItem.getServiceParameters();
        
        String serviceId = zoneItem.getServiceId();
        
        Map<String, MapNode> paramValues = new HashMap<>();
        
        for (String paramName : parameters.getMetadataNames())
        {
            ServiceParameterOrRepeater paramDef = _serviceEP.getExtension(serviceId).getParameters().get(paramName);
            if (paramDef != null && parameters.hasMetadata(paramName))
            {
                paramValues.putAll(_getParameterValue(paramName, parameters, paramDef, ""));
            }
        }
        
        return new MapElement("serviceParameters", paramValues);
    }
    
    /**
     * Returns the value of the given parameter for the current service, or the empty string if the parameter does not exist.
     * @param parameter the parameter name.
     * @return the value of the given parameter for the current service.
     */
    public static Node serviceParameter(String parameter)
    {
        return serviceParameter(parameter, "");
    }
    
    /**
     * Returns the value of the given parameter for the current service, or the provided default value if the parameter does not exist.
     * @param parameter the parameter name or path.
     * @param defaultValue the default value. Note that default value is ignored if the parameter is a composite parameter.
     * @return the value of the given parameter for the current service.
     */
    public static Node serviceParameter(String parameter, String defaultValue)
    {
        Request request = ContextHelper.getRequest(_context);
        ZoneItem zoneItem = (ZoneItem) request.getAttribute(ZoneItem.class.getName());
        CompositeMetadata parameters = zoneItem.getServiceParameters();
        
        String serviceId = zoneItem.getServiceId();
        ServiceParameterOrRepeater paramDef = _serviceEP.getExtension(serviceId).getParameters().get(parameter);
        
        if (paramDef == null)
        {
            // The parameter is unknown
            if (StringUtils.isEmpty(defaultValue))
            {
                return null;
            }
            else
            {
                return new StringElement(parameter, Collections.EMPTY_MAP, defaultValue);
            }
        }
        
        Map<String, MapNode> value = _getParameterValue(parameter, parameters, paramDef, defaultValue);
        
        if (!value.containsKey(parameter))
        {
            return null;
        }
        else if (paramDef instanceof ServiceParameterRepeater || (paramDef instanceof ServiceParameter && ((ServiceParameter) paramDef).isMultiple()))
        {
            MapNode node = value.get(parameter);
            @SuppressWarnings("unchecked")
            Map<String, ? extends Object> values = (Map<String, ? extends Object>) node.getValue();
            return new MapElement(parameter, node.getAttributes(), values);
        }
        else 
        {
            return new StringElement(parameter, value.get(parameter).getAttributes(), (String) value.get(parameter).getValue());
        }
    }
    
    private static String _convertTagName(String name)
    {
        char c = name.charAt(0);
        if (c >= '0' && c <= '9')
        {
            String hex = Integer.toHexString(c);
            return "_x" + StringUtils.leftPad(hex, 4, '0') + "_" + name.substring(1);
        }
        else
        {
            return name;
        }
    }
    
    private static Map<String, MapNode> _getParameterValue(String paramName, CompositeMetadata parentMetadata, ServiceParameterOrRepeater paramDef, String defaultValue)
    {
        Map<String, MapNode> paramValues = new HashMap<>();
        
        if (paramDef instanceof ServiceParameterRepeater)
        {
            if (!parentMetadata.hasMetadata(paramName))
            {
                return paramValues;
            }
                    
            Map<String, String> attributes = new HashMap<>();
            attributes.put("name", paramName);
            attributes.put("type", MetadataType.COMPOSITE.name().toLowerCase());
            
            Map<String, Object> children = new HashMap<>();
            
            CompositeMetadata compositeMetadata = parentMetadata.getCompositeMetadata(paramName); 
            String[] entryNames = compositeMetadata.getMetadataNames();
            for (String entryName : entryNames)
            {
                Map<String, Object> entryValue = new HashMap<>();
                
                for (String childParamName : ((ServiceParameterRepeater) paramDef).getChildrenParameters().keySet())
                {
                    ServiceParameter childParamDef = ((ServiceParameterRepeater) paramDef).getChildrenParameters().get(childParamName);
                    // Default value is ignored if parameter is a composite metadata
                    Map<String, MapNode> childParamValues = _getParameterValue(childParamName, compositeMetadata.getCompositeMetadata(entryName), childParamDef, "");
                    entryValue.putAll(childParamValues);
                }
                
                Map<String, String> entryAttributes = new HashMap<>();
                entryAttributes.put("name", entryName);
                entryAttributes.put("type", MetadataType.COMPOSITE.name().toLowerCase());
                
                MapNode entryNode = new MapNode(entryValue, entryAttributes);
                children.put(_convertTagName(entryName), entryNode);
            }
            
            MapNode node = new MapNode(children, attributes);
            paramValues.put(paramName, node);
        }
        else 
        {
            if (!parentMetadata.hasMetadata(paramName) && StringUtils.isEmpty(defaultValue))
            {
                return paramValues;
            }
            
            Map<String, String> attributes = new HashMap<>();
            attributes.put("name", paramName);
            attributes.put("type", ParameterHelper.typeToString(((ServiceParameter) paramDef).getType()));
            
            if (((ServiceParameter) paramDef).isMultiple())
            {
                Map<String, Object> values = new HashMap<>();
                values.put("value", Arrays.asList(parentMetadata.getStringArray(paramName, new String[] {defaultValue})));
                
                MapNode node = new MapNode(values, attributes);
                paramValues.put(paramName, node);
            }
            else
            {
                String value = parentMetadata.getString(paramName, defaultValue);
                if (StringUtils.isEmpty(value))
                {
                    value = defaultValue;
                }
                MapNode node = new MapNode(value, attributes);
                paramValues.put(paramName, node);
            }
        }
        
        return paramValues;
    }
    
    /**
     * Returns the current site
     * @return the current site
     */
    public static String site()
    {
        Request request = ContextHelper.getRequest(_context);
        return (String) request.getAttribute("site");
    }
    
    /**
     * Returns the current site
     * @param pageId The identifier ot the page
     * @return the current site
     */
    public static String site(String pageId)
    {
        try
        {
            Page page = _getPage(pageId);
            return page.getSiteName();
        }
        catch (UnknownAmetysObjectException e)
        {
            _logger.error("Can not get site on page '" + pageId + "'", e);
            return "";
        }
    }

    /**
     * Return the current sitemap as a {@link Node}.
     * Invisible pages will not be displayed
     * @return the current sitemap.
     */
    public static Node sitemap()
    {
        return sitemap(false);
    }
    
    /**
     * Return the current sitemap as a {@link Node}.
     * @param includeInvisiblePages Should return child invisible pages
     * @return the current sitemap.
     */
    public static Node sitemap(boolean includeInvisiblePages)
    {
        Request request = ContextHelper.getRequest(_context);
        Sitemap sitemap = (Sitemap) request.getAttribute(Sitemap.class.getName());
        
        if (sitemap == null)
        {
            // Try to get sitemap from content
            Content content = (Content) request.getAttribute(Content.class.getName());
            if (content instanceof WebContent)
            {
                sitemap = ((WebContent) content).getSite().getSitemap(content.getLanguage());
            }
        }
        
        if (sitemap == null)
        {
            return new EmptyElement("sitemap");
        }
        
        Page page = (Page) request.getAttribute(Page.class.getName());
        
        return new SitemapElement(sitemap, page != null ? page.getPathInSitemap() : null, _rightManager, _renderingContextHandler, _currentUserProvider.getUser(), includeInvisiblePages);
    }

    /**
     * Return the subsitemap of the given page as a {@link Node}.
     * Invisible child pages will not be returned;
     * @param pageId The root page
     * @return The page as node.
     */
    public static Node sitemap(String pageId)
    {
        return sitemap(pageId, false);
    }
        
    /**
     * Return the subsitemap of the given page as a {@link Node}.
     * @param pageId The root page
     * @param includeInvisiblePages Should return child invisible pages
     * @return The page as node.
     */
    public static Node sitemap(String pageId, boolean includeInvisiblePages)
    {
        Page rootPage = null;
        try
        {
            rootPage = _ametysObjectResolver.resolveById(pageId);
        }
        catch (UnknownAmetysObjectException e)
        {
            return new EmptyElement("page");
        }
        
        Request request = ContextHelper.getRequest(_context);
        Page page = (Page) request.getAttribute(Page.class.getName());

        return new PageElement(rootPage, _rightManager, _renderingContextHandler, page != null ? page.getPathInSitemap() : null,  _currentUserProvider.getUser(), includeInvisiblePages);
    }
    
    /**
     * Computes the breadcrumb of the current page.
     * @return a NodeList containing all ancestor pages, rooted at the sitemap.
     */
    public static NodeList breadcrumb()
    {
        Request request = ContextHelper.getRequest(_context);
        Page page = (Page) request.getAttribute(Page.class.getName());
  
        List<Element> result = new ArrayList<>();

        AmetysObject parent = page.getParent();
        while (parent instanceof Page)
        {
            Element node = new StringElement("page", (Map<String, String>) null, parent.getId());
            result.add(node);
            parent = parent.getParent();
        }
        
        Collections.reverse(result);
        return new AmetysNodeList(result);
    }

    /**
     * Returns a DOM {@link Element} representing files and folder of the resources explorer, 
     * under the {@link ResourceCollection} corresponding to the given id.
     * @param collectionId the id of the root {@link ResourceCollection}.
     * @return an Element containing files and folders.
     */
    public static Node resourcesById(String collectionId)
    {
        ResourceCollection collection = _ametysObjectResolver.resolveById(collectionId);
        return new ResourceCollectionElement(collection);
    }
    
    /**
     * Returns a DOM {@link Element} representing files and folder of the resources explorer, 
     * under the {@link ResourceCollection} corresponding to the given path. <br>
     * This path is intended to be relative to the current site's resource explorer.
     * @param path the path of the root {@link ResourceCollection}, relative to the current site's resource explorer.
     * @return an Element containing files and folders or null if the specified resource does not exist.
     */
    public static Node resourcesByPath(String path)
    {
        Request request = ContextHelper.getRequest(_context);
        String siteName = (String) request.getAttribute("site");
        Site site = _siteManager.getSite(siteName);
        
        try
        {
            ResourceCollection collection = site.getRootResources().getChild(path);
            return new ResourceCollectionElement(collection);
        }
        catch (UnknownAmetysObjectException ex)
        {
            return null;
        }
    }

    /**
     * Returns a DOM {@link Element} representing a single file of the resources explorer. <br>
     * This path is intended to be relative to the current site's resource explorer.
     * @param path the path of the {@link Resource}, relative to the current site's resource explorer.
     * @return an Element containing a file or null if the specified resource does not exist.
     */
    public static Node resourceByPath(String path)
    {
        Request request = ContextHelper.getRequest(_context);
        String siteName = (String) request.getAttribute("site");
        Site site = _siteManager.getSite(siteName);

        try
        {
            Resource resource = site.getRootResources().getChild(path);
            return new ResourceElement(resource, null);
        }
        catch (UnknownAmetysObjectException ex)
        {
            return null;
        }
    }

    /**
     * Returns a DOM {@link Element} representing files and folder of a skin directory. <br>
     * This path is intended to be relative to the current skin's 'resources' directory.
     * @param path the path of the root {@link ResourceCollection}, relative to the current skin's 'resources' directory. Can be a file path to test its existance.
     * @return an Element containing files and folders. node name is 'collection' or 'resource' with an attribute 'name'. Return null if the path does not exits.
     * @throws IOException if an error occured while listing files.
     */
    public static Node skinResources(String path) throws IOException
    {
        FileSource source = (FileSource) _sourceResolver.resolveURI("skin://resources/" + path);
        if (source.exists())
        {
            return new FileElement(source.getFile());
        }
        else
        {
            return null;
        }
    }
    
    //*************************
    // Page methods
    //*************************
    
    private static String _getMetadata(CompositeMetadata cm, String metadataName)
    {
        int i = metadataName.indexOf("/");
        if (i == -1)
        {
            return cm.getString(metadataName);
        }
        else
        {
            return _getMetadata(cm.getCompositeMetadata(metadataName.substring(0, i)), metadataName.substring(i + 1));
        }
    }
    
    private static Page _getPage(String sitename, String lang, String path)
    {
        Site site = _siteManager.getSite(sitename);
        Sitemap sitemap = site.getSitemap(lang);
        return sitemap.getChild(path);
    }
    
    private static Page _getPage(String id)
    {
        return _ametysObjectResolver.resolveById(id);
    }
    
    /**
     * Get the site name of a page.
     * @param pageId The page id.
     * @return The name or empty if the page does not exist.
     */
    public static String pageSiteName(String pageId)
    {
        try
        {
            Page page = _getPage(pageId);
            return page.getSiteName();
        }
        catch (UnknownAmetysObjectException e)
        {
            _logger.error("Can not get site name on page with id '" + pageId + "'", e);
            return "";
        }
    }
    
    /**
     * Get the title of a page.
     * @param sitename the site name.
     * @param lang the sitemap name.
     * @param path the page path.
     * @return The name or empty if the meta or the page does not exist.
     */
    public static String pageTitle(String sitename, String lang, String path)
    {
        try
        {
            Page page = _getPage(sitename, lang, path);
            return page.getTitle();
        }
        catch (UnknownAmetysObjectException e)
        {
            _logger.error("Can not get title on page '" + sitename + "/" + lang + "/" + path + "'", e);
            return "";
        }
    }
    
    /**
     * Get the title of a page.
     * @param pageId The page id.
     * @return The name or empty if the meta or the page does not exist.
     */
    public static String pageTitle(String pageId)
    {
        try
        {
            Page page = _getPage(pageId);
            return page.getTitle();
        }
        catch (UnknownAmetysObjectException e)
        {
            _logger.error("Can not get title on page with id '" + pageId + "'", e);
            return "";
        }
    }

    /**
     * Get the long title of a page
     * @param sitename the site name
     * @param lang the page's language
     * @param path the page's path
     * @return The name or empty if the meta or the page does not exist
     */
    public static String pageLongTitle(String sitename, String lang, String path)
    {
        try
        {
            Page page = _getPage(sitename, lang, path);
            return page.getLongTitle();
        }
        catch (UnknownAmetysObjectException e)
        {
            _logger.error("Can not get long title on page '" + sitename + "/" + lang + "/" + path + "'", e);
            return "";
        }
    }
    /**
     * Get the long title of a page
     * @param pageId The page id
     * @return The name or empty if the meta or the page does not exist
     */
    public static String pageLongTitle(String pageId)
    {
        try
        {
            Page page = _getPage(pageId);
            return page.getLongTitle();
        }
        catch (UnknownAmetysObjectException e)
        {
            _logger.error("Can not get long title on page with id '" + pageId + "'", e);
            return "";
        }
    }

    /**
     * Get the meta of a page
     * @param sitename the site name
     * @param lang the page's language
     * @param path the page's path
     * @param metadataName The meta name (/ for composite)
     * @return The name or empty if the meta or the page does not exist
     */
    public static String pageMetadata(String sitename, String lang, String path, String metadataName)
    {
        try
        {
            Page page = _getPage(sitename, lang, path);
            try
            {
                return _getMetadata(page.getMetadataHolder(), metadataName);
            }
            catch (UnknownMetadataException e)
            {
                _logger.error("Can not get meta '" + metadataName + "' on page with id '" + page.getId() + "'", e);
                return "";
            }
        }
        catch (UnknownAmetysObjectException e)
        {
            _logger.error("Can not get meta '" + metadataName + "' on page '" + sitename + "/" + lang + "/" + path + "'", e);
            return "";
        }
    }
    
    /**
     * Get the meta of a page
     * @param pageId The page id
     * @param metadataName The meta name (/ for composite)
     * @return The name or empty if the meta or the page does not exist
     */
    public static String pageMetadata(String pageId, String metadataName)
    {
        try
        {
            Page page = _getPage(pageId);
            try
            {
                return _getMetadata(page.getMetadataHolder(), metadataName);
            }
            catch (UnknownMetadataException e)
            {
                _logger.error("Can not get meta '" + metadataName + "' on page with id '" + page.getId() + "'", e);
                return "";
            }
        }
        catch (UnknownAmetysObjectException e)
        {
            _logger.error("Can not get meta '" + metadataName + "' on page with id '" + pageId + "'", e);
            return "";
        }
    }

    /**
     * Returns true if the given page is visible into navigation elements
     * @param pageId the page id.
     * @return true if the page is visible
     */
    public static boolean pageIsVisible (String pageId)
    {
        try
        {
            Page page = _getPage(pageId);
            return page.isVisible();
        }
        catch (UnknownAmetysObjectException e)
        {
            _logger.error("Can not get visibility status on page with id '" + pageId + "'", e);
            return false;
        }
    }
    
    /**
     * Returns true if the given page is visible into navigation elements
     * @param sitename the site name
     * @param lang the page's language
     * @param path the page's path
     * @return true if the page is visible
     */
    public static boolean pageIsVisible (String sitename, String lang, String path)
    {
        try
        {
            Page page = _getPage(sitename, lang, path);
            return page.isVisible();
        }
        catch (UnknownAmetysObjectException e)
        {
            _logger.error("Can not get visibility status on page with id '" + sitename + "/" + lang + "/" + path + "'", e);
            return false;
        }
    }
    
    /**
     * Returns true if the given page has restricted access.
     * @param pageId the page id.
     * @return true if the page exists and has restricted access.
     */
    public static boolean pageHasRestrictedAccess(String pageId)
    {
        try
        {
            Page page = _getPage(pageId);
            return !_rightManager.hasAnonymousReadAccess(page);
        }
        catch (UnknownAmetysObjectException e)
        {
            _logger.error("Can not get page access info on page with id '" + pageId + "'", e);
            return false;
        }
    }

    /**
     * Returns true if the current user has the specified right on the current page
     * @param rightId Right Id
     * @return true if the current user has the specified right on the current page
     */
    public static boolean hasRightOnPage(String rightId)
    {
        Request request = ContextHelper.getRequest(_context);
        Page page = (Page) request.getAttribute(Page.class.getName());
        return _hasRightOnPage(rightId, page);
    }

    /**
     * Returns true if the current user has the specified right on the specified page
     * @param rightId Right Id
     * @param pageId Page Id
     * @return true if the current user has the specified right on the specified page
     */
    public static boolean hasRightOnPage(String rightId, String pageId)
    {
        Page page = _getPage(pageId);
        return _hasRightOnPage(rightId, page);
    }

    /**
     * Returns true if the current user has the specified right on the specified page
     * @param rightId Right Id
     * @param page Page
     * @return true if the current user has the specified right on the specified page
     */
    private static boolean _hasRightOnPage(String rightId, Page page)
    {
        RightResult rightResult = _rightManager.currentUserHasRight(rightId, page);
        return rightResult == RightResult.RIGHT_ALLOW;
    }

    /**
     * Returns true if the given page has restricted access.
     * @param sitename the site name
     * @param lang the page's language
     * @param path the page's path
     * @return true if the page exists and has restricted access.
     */
    public static boolean pageHasRestrictedAccess(String sitename, String lang, String path)
    {
        try
        {
            Page page = _getPage(sitename, lang, path);
            return !_rightManager.hasAnonymousReadAccess(page);
        }
        catch (UnknownAmetysObjectException e)
        {
            _logger.error("Can not get page access info on page with id '" + sitename + "/" + lang + "/" + path + "'", e);
            return false;
        }
    }
    
    /**
     * Returns the path of the current page, relative to the sitemap's root.
     * @return the path of the current Page, or empty if there's no current page.
     */
    public static String pagePath()
    {
        Request request = ContextHelper.getRequest(_context);
        Page page = (Page) request.getAttribute(Page.class.getName());
        
        return page == null ? "" : page.getPathInSitemap();
    }
    
    /**
     * Returns the path in sitemap of a page
     * @param pageId The id of page
     * @return the path of the Page, or empty if not exists
     */
    public static String pagePath(String pageId)
    {
        try
        {
            Page page = _getPage(pageId);
            return page.getPathInSitemap();
        }
        catch (UnknownAmetysObjectException e)
        {
            _logger.error("Can not get title on page with id '" + pageId + "'", e);
            return "";
        }
    }
    
    /**
     * Returns the id of the current page.
     * @return the id of the current Page, or empty if there's no current page.
     */
    public static String pageId()
    {
        Request request = ContextHelper.getRequest(_context);
        Page page = (Page) request.getAttribute(Page.class.getName());
        
        return page == null ? "" : page.getId();
    }
    
    /**
     * Returns the id of the current zone item id.
     * @return the id of the current zone item id, or empty if there's no current zone item.
     */
    public static String zoneItemId()
    {
        Request request = ContextHelper.getRequest(_context);
        ZoneItem zoneItem = (ZoneItem) request.getAttribute(ZoneItem.class.getName());
        
        return zoneItem == null ? "" : StringUtils.defaultString(zoneItem.getId());
    }
    
    /**
     * Determines if the current zone item or (if there is no current zone item) the current page is cacheable
     * This method is only valid for a page.
     * @return true if the current zone item or page is cacheable.
     */
    public static boolean isCacheable()
    {
        Request request = ContextHelper.getRequest(_context);
        if (request.getAttribute("IsZoneItemCacheable") != null)
        {
            return (Boolean) request.getAttribute("IsZoneItemCacheable");
        }
        
        // The method was called from the skin, out of a zone item
        Response response = ContextHelper.getResponse(_context);
        if (response.containsHeader("X-Ametys-Cacheable"))
        {
            return true;
        }
        return false;
    }
    
    /**
     * Determines if we are in an edition mode
     * @return true if we are in edition mode
     */
    public static boolean isEditionMode()
    {
        RenderingContext renderingContext = _renderingContextHandler.getRenderingContext();
        Request request = ContextHelper.getRequest(_context);
        if (renderingContext == RenderingContext.FRONT && request.getParameter("_edition") != null && "true".equals(request.getParameter("_edition")))
        {
            return true;
        }
        return false;
    }

    /**
     * Returns the id of pages referencing the content and for which the Front-office user can access
     * @param contentId The content's id
     * @return The pages' id
     */
    public static NodeList accessibleReferencedPages (String contentId)
    {
        RenderingContext renderingContext = _renderingContextHandler.getRenderingContext();
        boolean inBackOffice = renderingContext == RenderingContext.BACK || renderingContext == RenderingContext.PREVIEW;
        
        List<StringElement> pages = new ArrayList<>(); 
        
        Content content = _ametysObjectResolver.resolveById(contentId);
        if (content instanceof WebContent)
        {
            Collection<ZoneItem> zoneItems = ((WebContent) content).getReferencingZoneItems();
            
            for (ZoneItem zoneItem : zoneItems)
            {
                String metadataSetName = zoneItem.getMetadataSetName();
                Page page = zoneItem.getZone().getPage();
                
                if (inBackOffice || _rightManager.hasReadAccess(_currentUserProvider.getUser(), page))
                {
                    Map<String, String> attrs = new HashMap<>();
                    attrs.put("id", page.getId());
                    attrs.put("metadataSetName", metadataSetName);
                    pages.add(new StringElement("page", attrs));
                }
            }
        }
        
        return new AmetysNodeList(pages);
    }
    
    /**
     * Returns the id of pages referencing the content
     * @param contentId The content's id
     * @return The pages' id
     */
    public static NodeList referencedPages (String contentId)
    {
        List<StringElement> pages = new ArrayList<>(); 
        
        Content content = _ametysObjectResolver.resolveById(contentId);
        if (content instanceof WebContent)
        {
            Collection<ZoneItem> zoneItems = ((WebContent) content).getReferencingZoneItems();
            
            for (ZoneItem zoneItem : zoneItems)
            {
                String metadataSetName = zoneItem.getMetadataSetName();
                Page page = zoneItem.getZone().getPage();
                
                Map<String, String> attrs = new HashMap<>();
                attrs.put("id", page.getId());
                attrs.put("metadataSetName", metadataSetName);
                pages.add(new StringElement("page", attrs));
            }
        }
        
        return new AmetysNodeList(pages);
    }
    
    /**
     * Returns the ids of the pages
     * @param sitename The site id
     * @param lang The language code
     * @param tag The tag id
     * @return Array of pages ids
     */
    public static NodeList findPagesIdsByTag(String sitename, String lang, String tag)
    {
        String xpath = PageQueryHelper.getPageXPathQuery(sitename, lang, null, new TagExpression(Operator.EQ, tag), null);
        AmetysObjectIterable<Page> pages = _ametysObjectResolver.query(xpath);
        Iterator<Page> it = pages.iterator();

        List<StringElement> list = new ArrayList<>(); 
        while (it.hasNext())
        {
            list.add(new StringElement("page", "id", it.next().getId()));
        }
        return new AmetysNodeList(list);
    }
    
    /**
     * Returns the ids of the pages
     * @param tag The tag id
     * @return Array of pages ids
     */
    public static NodeList findPagesIdsByTag(String tag)
    {
        Request request = ContextHelper.getRequest(_context);
        String siteName = (String) request.getAttribute("site");
        
        String lang = (String) request.getAttribute("sitemapLanguage");
        if (lang == null)
        {
            // Try to get current language from content
            Content content = (Content) request.getAttribute(Content.class.getName());
            if (content != null)
            {
                lang = content.getLanguage();
            }
        }
        
        return findPagesIdsByTag(siteName, lang, tag);
    }
}