/*
 *  Copyright 2015 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.frontoffice;

import java.io.IOException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Date;
import java.util.Enumeration;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Objects;
import java.util.Set;
import java.util.regex.Pattern;
import java.util.stream.Collectors;

import org.apache.avalon.framework.context.Context;
import org.apache.avalon.framework.context.ContextException;
import org.apache.avalon.framework.context.Contextualizable;
import org.apache.avalon.framework.service.ServiceException;
import org.apache.avalon.framework.service.ServiceManager;
import org.apache.cocoon.ProcessingException;
import org.apache.cocoon.environment.ObjectModelHelper;
import org.apache.cocoon.environment.Request;
import org.apache.cocoon.generation.ServiceableGenerator;
import org.apache.cocoon.xml.AttributesImpl;
import org.apache.cocoon.xml.XMLUtils;
import org.apache.commons.lang.StringUtils;
import org.apache.excalibur.xml.sax.SAXParser;
import org.apache.solr.client.solrj.util.ClientUtils;
import org.apache.tika.Tika;
import org.slf4j.Logger;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

import org.ametys.cms.content.ContentHelper;
import org.ametys.cms.content.RichTextHandler;
import org.ametys.cms.contenttype.ContentType;
import org.ametys.cms.contenttype.ContentTypeExtensionPoint;
import org.ametys.cms.contenttype.ContentTypesHelper;
import org.ametys.cms.contenttype.MetadataDefinition;
import org.ametys.cms.contenttype.MetadataManager;
import org.ametys.cms.contenttype.MetadataSet;
import org.ametys.cms.contenttype.MetadataType;
import org.ametys.cms.repository.Content;
import org.ametys.cms.search.SearchField;
import org.ametys.cms.search.SearchResults;
import org.ametys.cms.search.Sort;
import org.ametys.cms.search.content.ContentSearchHelper;
import org.ametys.cms.search.query.DocumentTypeQuery;
import org.ametys.cms.search.query.OrQuery;
import org.ametys.cms.search.query.Query;
import org.ametys.cms.search.solr.SearcherFactory.Searcher;
import org.ametys.cms.tag.TagProviderExtensionPoint;
import org.ametys.cms.transformation.URIResolverExtensionPoint;
import org.ametys.core.util.DateUtils;
import org.ametys.core.util.LambdaUtils;
import org.ametys.plugins.explorer.dublincore.DublinCoreMetadataProvider;
import org.ametys.plugins.explorer.resources.Resource;
import org.ametys.plugins.explorer.resources.metadata.TikaProvider;
import org.ametys.plugins.repository.AmetysObject;
import org.ametys.plugins.repository.AmetysObjectResolver;
import org.ametys.plugins.repository.AmetysRepositoryException;
import org.ametys.plugins.repository.UnknownAmetysObjectException;
import org.ametys.plugins.repository.metadata.RichText;
import org.ametys.plugins.repository.provider.RequestAttributeWorkspaceSelector;
import org.ametys.runtime.i18n.I18nizableText;
import org.ametys.web.WebConstants;
import org.ametys.web.frontoffice.FrontOfficeSearcherFactory.QueryFacet;
import org.ametys.web.indexing.solr.SolrWebFieldNames;
import org.ametys.web.repository.page.Page;
import org.ametys.web.repository.page.Page.PageType;
import org.ametys.web.repository.page.Zone;
import org.ametys.web.repository.page.ZoneItem;
import org.ametys.web.repository.page.ZoneItem.ZoneType;
import org.ametys.web.repository.site.Site;
import org.ametys.web.repository.site.SiteManager;

/**
 * Abstract class for solr search
 */
public abstract class AbstractSearchGenerator extends ServiceableGenerator implements Contextualizable, SolrWebFieldNames
{
    /** The name of the facet.query testing the pageResources */
    public static final String DOCUMENT_TYPE_IS_PAGE_RESOURCE_FACET_NAME = "isPageResource";
    
    /** Textfield pattern */
    protected static final Pattern _TEXTFIELD_PATTERN = Pattern.compile("^[^?*].*$");
    
    /** The {@link ContentType} manager */
    protected ContentTypeExtensionPoint _cTypeExtPt;
    /** The sites manager */
    protected SiteManager _siteManager;
    /** The cocoon context */
    protected org.apache.cocoon.environment.Context _context;
    /** The tag extension point */
    protected TagProviderExtensionPoint _tagExtPt;
    /** The Ametys resolver */
    protected AmetysObjectResolver _resolver;
    /** DublinCore provider */
    protected DublinCoreMetadataProvider _dcProvider;
    /** The helper to handler content types */
    protected ContentTypesHelper _contentTypesHelper;
    /** The helper to handler contents */
    protected ContentHelper _contentHelper;
    /** The uri resolver extension point */
    protected URIResolverExtensionPoint _uriResolverEP;
    /** Metadata manager. */
    protected MetadataManager _metadataManager;
    /** The searcher factory */
    protected FrontOfficeSearcherFactory _searcherFactory;
    /** The content searcher */
    protected ContentSearchHelper _searchHelper;
    
    @Override
    public void service(ServiceManager smanager) throws ServiceException
    {
        super.service(smanager);
        _cTypeExtPt = (ContentTypeExtensionPoint) smanager.lookup(ContentTypeExtensionPoint.ROLE);
        _siteManager = (SiteManager) smanager.lookup(SiteManager.ROLE);
        _tagExtPt = (TagProviderExtensionPoint) smanager.lookup(TagProviderExtensionPoint.ROLE);
        _resolver = (AmetysObjectResolver) smanager.lookup(AmetysObjectResolver.ROLE);
        _dcProvider = (DublinCoreMetadataProvider) smanager.lookup(DublinCoreMetadataProvider.ROLE);
        _contentTypesHelper = (ContentTypesHelper) smanager.lookup(ContentTypesHelper.ROLE);
        _contentHelper = (ContentHelper) smanager.lookup(ContentHelper.ROLE);
        _uriResolverEP = (URIResolverExtensionPoint) smanager.lookup(URIResolverExtensionPoint.ROLE);
        _metadataManager = (MetadataManager) smanager.lookup(MetadataManager.ROLE);
        _searcherFactory = (FrontOfficeSearcherFactory) smanager.lookup(FrontOfficeSearcherFactory.ROLE);
        _searchHelper = (ContentSearchHelper) manager.lookup(ContentSearchHelper.ROLE);
    }

    @Override
    public void contextualize(Context context) throws ContextException
    {
        _context = (org.apache.cocoon.environment.Context) context.get(org.apache.cocoon.Constants.CONTEXT_ENVIRONMENT_CONTEXT);
    }

    @Override
    public void generate() throws IOException, SAXException, ProcessingException
    {
        Request request = ObjectModelHelper.getRequest(objectModel);
        
        String currentSiteName = null;
        String lang = null;
        Page page = (Page) request.getAttribute(WebConstants.REQUEST_ATTR_PAGE);
        if (page != null)
        {
            currentSiteName = page.getSiteName();
            lang = page.getSitemapName();
        }
        else
        {
            currentSiteName = parameters.getParameter("siteName", request.getParameter("siteName"));
            lang = parameters.getParameter("lang", request.getParameter("lang"));
        }

        int pageIndex = getPageIndex(request);
        // TODO Rename to maxResults
        int maxResults = parameters.getParameterAsInteger("offset", 10);
        int start = (pageIndex - 1) * maxResults;

        String[] sites = request.getParameterValues("sites");
        List<String> siteNames = new ArrayList<>();
        if (sites != null && sites.length > 0 && !(sites.length == 1 && sites[0].equals("")))
        {
            for (String site : sites)
            {
                siteNames.add(site);
            }
        }
        else
        {
            siteNames.add(currentSiteName);
        }
        
        contentHandler.startDocument();

        AttributesImpl attrs = new AttributesImpl();
        attrs.addCDATAAttribute("site", currentSiteName);
        attrs.addCDATAAttribute("lang", lang);

        XMLUtils.startElement(contentHandler, "search", attrs);

        saxServiceIdentifiers();
        saxAdditionalInfos();

        // The search url
        XMLUtils.createElement(contentHandler, "url", page != null ? lang + "/" + page.getPathInSitemap() + ".html" : lang + "/_plugins/" + currentSiteName + "/" + lang + "/service/search-pages.html");

        // Display the form and results on same page?
        String searchMode = getSearchMode();
        XMLUtils.createElement(contentHandler, "search-mode", searchMode);

        try
        {
            SearchResults<AmetysObject> searchResults = null;
            boolean submit = request.getParameter("submit-form") != null;
            boolean criteriaOnly = "criteria-only".equals(getSearchMode());
            if (submit && isInputValid() && !criteriaOnly)
            {
                searchResults = search(request, siteNames, lang, pageIndex, start, maxResults);
            }
            else if (!getFacets(request).isEmpty())
            {
                searchResults = search(request, siteNames, lang, pageIndex, start, maxResults, false);
            }
            
            saxFormParameters(request, searchResults, start, maxResults, currentSiteName, lang);
        }
        catch (IllegalArgumentException e)
        {
            getLogger().error("The search field is invalid", e);
            XMLUtils.createElement(contentHandler, "illegal-textfield");
            saxPagination(0, start, maxResults);
        }
        catch (Exception e)
        {
            getLogger().error("Unable to search", e);
            saxPagination(0, start, maxResults);
        }
        
        XMLUtils.endElement(contentHandler, "search");
        contentHandler.endDocument();
    }

    /**
     * Get the zone item
     * @param request The request
     * @return the zone item
     */
    protected ZoneItem getZoneItem(Request request)
    {
        ZoneItem zoneItem = (ZoneItem) request.getAttribute(WebConstants.REQUEST_ATTR_ZONEITEM);
        if (zoneItem != null)
        {
            return zoneItem;
        }
        
        String zoneItemId = parameters.getParameter("zoneItemId", request.getParameter("zone-item-id"));
        if (StringUtils.isNotEmpty(zoneItemId))
        {
            try
            {
                return _resolver.resolveById(zoneItemId);
            }
            catch (UnknownAmetysObjectException e)
            {
                return null;
            }
        }
        
        return null;
    }
    
    /**
     * Search
     * @param request the request
     * @param siteNames The name of the sites to search in 
     * @param language The language code to search
     * @param pageIndex the page index
     * @param start The offset for search results
     * @param maxResults The maximum number of results
     * @return The search results
     * @throws Exception If an error occurred during search
     */
    protected SearchResults<AmetysObject> search(Request request, Collection<String> siteNames, String language, int pageIndex, int start, int maxResults) throws Exception
    {
        return search(request, siteNames, language, pageIndex, start, maxResults, true);
    }
    
    /**
     * Search
     * @param request the request
     * @param siteNames The name of the sites to search in 
     * @param language The language code to search
     * @param pageIndex the page index
     * @param start The offset for search results
     * @param maxResults The maximum number of results
     * @param saxResults false to not sax results
     * @return The search results
     * @throws Exception If an error occurred during search
     */
    protected SearchResults<AmetysObject> search(Request request, Collection<String> siteNames, String language, int pageIndex, int start, int maxResults, boolean saxResults) throws Exception
    {
        // Retrieve current workspace
        String currentWsp = RequestAttributeWorkspaceSelector.getForcedWorkspace(request);
        
        SearchResults<AmetysObject> results = null;
        
        try
        {
            // Query
            Query queryObject = getQuery(request, siteNames, language);
            
            // Filter queries
            Collection<Query> filterQueries = getFilterQueries(request, siteNames, language);
            // Document types query
            Collection<String> documentTypes = getDocumentTypes(request);
            Query documentTypesQuery = getDocumentTypesQuery(documentTypes);
            
            // Get first sort field
            Sort sort = getSortField(request);
            saxSort(sort);
            
            Searcher searcher = _searcherFactory.create()
                    .withQuery(queryObject)
                    .withFilterQueries(filterQueries)
                    .addFilterQuery(documentTypesQuery)
                    .withLimits(0, Integer.MAX_VALUE)
                    .withSort(getPrimarySortFields(request))
                    .addSort(sort)
                    .setCheckRights(true);
            
            _additionalSearchProcessing(searcher);
            
            // Facets 
            Collection<SearchField> facets = getFacets(request).values().stream().map(f -> f.getSearchField()).collect(Collectors.toList());
            if (!facets.isEmpty())
            {
                searcher.withFacets(facets)
                        .withFacetValues(getFacetValues(request, siteNames, language));
            }
            
            try
            {
                results = searcher.searchWithFacets();
            }
            catch (Exception e)
            {
                getLogger().error("An error occured with Solr query", e);
            }
            
            if (saxResults)
            {
                // SAX results
                AttributesImpl atts = new AttributesImpl();
                long total = results != null ? results.getResults().getSize() : 0;
                atts.addCDATAAttribute("total", String.valueOf(total));
                XMLUtils.startElement(contentHandler, "hits", atts);
                if (results != null)
                {
                    saxHits(results, start, maxResults);
                }
                XMLUtils.endElement(contentHandler, "hits");
        
                // SAX pagination
                saxPagination(total, start, maxResults);
            }
        }
        finally
        {
            // Restore context
            RequestAttributeWorkspaceSelector.setForcedWorkspace(request, currentWsp);
        }
        
        return results;
    }
    
    /**
     * SAX sort
     * @param sort the current sort
     * @throws SAXException SAXException If an error occurs while SAXing
     */
    protected void saxSort(Sort sort) throws SAXException
    {
        XMLUtils.createElement(contentHandler, sort == null || sort.getField() == null ? "sort-by-score" : "sort-by-" + sort.getField());
    }
    
    /**
     * Allow to perform other searcher configuration
     * @param searcher The searcher that will be used for the search operation
     */
    protected void _additionalSearchProcessing(Searcher searcher)
    {
        // Nothing by default
    }
    
    /**
     * Build the search query to have results matching at least one of the given document types
     * @param documentTypes The document types
     * @return The document type query
     */
    protected Query getDocumentTypesQuery(Collection<String> documentTypes)
    {
        List<Query> queries = documentTypes.stream()
                .map(t -> "\"" + ClientUtils.escapeQueryChars(t) + "\"")
                .map(DocumentTypeQuery::new)
                .collect(Collectors.toList());
        return new OrQuery(queries);
    }
    
    /**
     * Get the document types.
     * @param request The request.
     * @return the document types to search.
     */
    protected abstract Collection<String> getDocumentTypes(Request request);
    
    /**
     * Get the sort field
     * @param request The request
     * @return The sort field or null to sort by score
     */
    protected abstract Sort getSortField(Request request);
    
    /**
     * Get the primary sort fields
     * @param request The request
     * @return the list additional sort fields or empty list.
    */
    protected abstract List<Sort> getPrimarySortFields(Request request);
    
    /**
     * SAX the search parameters from the request parameters
     * @param request The request
     * @param searchResults The search results
     * @param start The start index
     * @param offset The number of results
     * @param siteName The current site name
     * @param lang The current language
     * @throws SAXException If an error occurs while SAXing
     */
    protected void saxFormParameters (Request request, SearchResults<AmetysObject> searchResults, int start, int offset, String siteName, String lang) throws SAXException
    {
        XMLUtils.startElement(contentHandler, "form");

        XMLUtils.startElement(contentHandler, "fields");
        saxFormFields(request, siteName, lang);
        XMLUtils.endElement(contentHandler, "fields");

        saxFacets(request, searchResults, siteName, lang);
        
        boolean submit = request.getParameter("submit-form") != null;
        if (submit)
        {
            if (isInputValid())
            {
                XMLUtils.startElement(contentHandler, "values");

                XMLUtils.createElement(contentHandler, "start", String.valueOf(start));
                XMLUtils.createElement(contentHandler, "offset", String.valueOf(offset));

                saxFormValues(request, start, offset);

                XMLUtils.endElement(contentHandler, "values");
            }
        }
        XMLUtils.endElement(contentHandler, "form");
    }

    /**
     * SAX the form search criteria
     * @param request The request
     * @param siteName The current site name
     * @param lang The current language
     * @throws SAXException if an error occurs while SAXing
     */
    protected abstract void saxFormFields(Request request, String siteName, String lang) throws SAXException;

    /**
     * SAX the facets results
     * @param request The request
     * @param searchResults The search result
     * @param siteName The site name
     * @param lang The language
     * @throws SAXException if an error occurred while saxing
     */
    protected void saxFacets(Request request, SearchResults<AmetysObject> searchResults, String siteName, String lang) throws SAXException
    {
        XMLUtils.startElement(contentHandler, "facets");
        
        Map<String, Map<String, Integer>> facetResults = searchResults != null ? searchResults.getFacetResults() : Collections.EMPTY_MAP;
        if (!facetResults.isEmpty())
        {
            Map<String, FacetField> facets = getFacets(request);
            
            for (String fieldName : facets.keySet())
            {
                if (facetResults.containsKey(SolrWebFieldNames.FACETABLE_CONTENT_FIELD_PREFIX + fieldName))
                {
                    Map<String, Integer> values = facetResults.get(SolrWebFieldNames.FACETABLE_CONTENT_FIELD_PREFIX + fieldName);
                    
                    AttributesImpl attr = new AttributesImpl();
                    attr.addCDATAAttribute("name", fieldName);
                    attr.addCDATAAttribute("total", String.valueOf(values.values().stream().mapToInt(Integer::intValue).sum()));
                    XMLUtils.startElement(contentHandler, "facet", attr);
                    
                    facets.get(fieldName).getLabel().toSAX(contentHandler, "label");
                    
                    Set<Entry<String, Integer>> entrySet = values.entrySet();
                    for (Entry<String, Integer> entry : entrySet)
                    {
                        AttributesImpl valueAttrs = new AttributesImpl();
                        valueAttrs.addCDATAAttribute("value", entry.getKey());
                        valueAttrs.addCDATAAttribute("count", Integer.toString(entry.getValue()));
                        
                        XMLUtils.startElement(contentHandler, "item", valueAttrs);
                        facets.get(fieldName).getFacetLabel(entry.getKey(), new Locale(lang)).toSAX(contentHandler);
                        XMLUtils.endElement(contentHandler, "item");
                    }
                    
                    XMLUtils.endElement(contentHandler, "facet");
                }
                
            }
        }
        
        XMLUtils.endElement(contentHandler, "facets");
    }

    /**
     * SAX the form search criteria values
     * @param request The request
     * @param start The start index
     * @param offset The number of results
     * @throws SAXException if an error occurs while SAXing
     */
    protected abstract void saxFormValues (Request request, int start, int offset) throws SAXException;

    /**
     * Get the query from request parameters
     * @param request The request
     * @param siteNames The site names.
     * @param language The language
     * @return The query object.
     * @throws IllegalArgumentException If the search field is invalid.
     */
    protected abstract Query getQuery(Request request, Collection<String> siteNames, String language) throws IllegalArgumentException;
    
    /**
     * Get the filter queries from the request parameters.
     * @param request The request.
     * @param siteNames The site names.
     * @param language The language.
     * @return A collection of filter queries.
     * @throws IllegalArgumentException If a search field is invalid.
     */
    protected abstract Collection<Query> getFilterQueries(Request request, Collection<String> siteNames, String language) throws IllegalArgumentException;
    
    /**
     * Template methods to disable/enable the processing of the facets during the search.
     * @return <code>true</code> to enable facets
     */
    protected boolean useFacets()
    {
        return parameters.getParameterAsBoolean("facets", false);
    }
    
    /**
     * Get the facets from request parameters
     * @param request The request
     * @return The facet fields
     * @throws IllegalArgumentException If the search field is invalid.
     */
    protected abstract Map<String, FacetField> getFacets(Request request) throws IllegalArgumentException;
    
    /**
     * Get the facet.queries
     * @param request The request
     * @return The facet.queries
     * @throws IllegalArgumentException If the search field is invalid.
     */
    protected abstract Set<QueryFacet> getQueryFacets(Request request);

    /**
     * Get the facet values
     * @param request The request
     * @param siteNames The site names
     * @param language The language
     * @return The facet values
     */
    protected abstract Map<String, List<String>> getFacetValues(Request request, Collection<String> siteNames, String language);
    
    /**
     * Get the facet.query values
     * @param request The request
     * @return The facet.query values
     */
    protected abstract Collection<String> getQueryFacetValues(Request request);
    
    /**
     * SAX the result hits
     * @param results The search results.
     * @param start The start index
     * @param maxResults The number of results to generate.
     * @throws SAXException If an error occurs while SAXing
     * @throws IOException If there is a low-level IO error
     */
    protected abstract void saxHits(SearchResults<AmetysObject> results, int start, int maxResults) throws SAXException, IOException;

    /**
     * Get the searchable fields
     * @return The fields
     */
    protected abstract Collection<String> getFields();

    /**
     * SAX a hit of type page.
     * @param score The score of the page
     * @param maxScore The maximum score of the search results
     * @param page The page
     * @throws SAXException If an error occurs while SAXing
     */
    protected void saxPageHit(float score, float maxScore, Page page) throws SAXException
    {
        int percent = Math.min(Math.round(score * 100f / maxScore), 100);
        
        XMLUtils.startElement(contentHandler, "hit");
        XMLUtils.createElement(contentHandler, "score", Float.toString(score));
        XMLUtils.createElement(contentHandler, "percent", Integer.toString(percent));
        XMLUtils.createElement(contentHandler, "title", page.getTitle());
        
        _saxPageContents(page);
        
        XMLUtils.createElement(contentHandler, "type", "page");
        XMLUtils.createElement(contentHandler, "uri", page.getSitemap().getName() + "/" + page.getPathInSitemap());
        
        _saxLastModifiedDate(page);
        _saxLastValidationDate(page);
        
        String siteName = page.getSiteName();
        if (siteName != null)
        {
            Site site = _siteManager.getSite(siteName);
            XMLUtils.createElement(contentHandler, "siteName", siteName);
            XMLUtils.createElement(contentHandler, "siteTitle", site.getTitle());
            String url = site.getUrl();
            if (url != null)
            {
                XMLUtils.createElement(contentHandler, "siteUrl", url);
            }
        }
        
        saxAdditionalInfosOnPageHit(page);
        
        XMLUtils.endElement(contentHandler, "hit");
    }
    
    private void _saxPageContents(Page page) throws SAXException
    {
        if (page.getType() == PageType.CONTAINER)
        {
            for (Zone zone : page.getZones())
            {
                for (ZoneItem zoneItem : zone.getZoneItems())
                {
                    if (zoneItem.getType() == ZoneType.CONTENT)
                    {
                        // Content
                        Content content = zoneItem.getContent();
                        saxContent(content.getId(), "index", new Locale(page.getSitemapName()));
                    }
                }
            }
        }
    }
    
    private void _saxLastModifiedDate(Page page) throws SAXException
    {
        Date lastModified = null;

        if (page.getType() == PageType.CONTAINER)
        {
            for (Zone zone : page.getZones())
            {
                for (ZoneItem zoneItem : zone.getZoneItems())
                {
                    switch (zoneItem.getType())
                    {
                        case SERVICE:
                            // A service has no last modification date
                            break;
                        case CONTENT:
                            Date contentLastModified = zoneItem.getContent().getLastModified();

                            if (contentLastModified != null && (lastModified == null || contentLastModified.after(lastModified)))
                            {
                                // Keep the latest modification date
                                lastModified = contentLastModified;
                            }
                            break;
                        default:
                            break;
                    }
                }
            }
        }
        if (lastModified != null)
        {
            XMLUtils.createElement(contentHandler, "lastModified", DateUtils.dateToString(lastModified));
        }
    }
    
    private void _saxLastValidationDate(Page page) throws SAXException
    {
        Date lastValidated = null;
        
        if (page.getType() == PageType.CONTAINER)
        {
            for (Zone zone : page.getZones())
            {
                for (ZoneItem zoneItem : zone.getZoneItems())
                {
                    switch (zoneItem.getType())
                    {
                        case SERVICE:
                            // A service has no last validation date
                            break;
                        case CONTENT:
                            Date contentLastValidation = zoneItem.getContent().getLastValidationDate();
                            
                            if (contentLastValidation != null && (lastValidated == null || contentLastValidation.after(lastValidated)))
                            {
                                // Keep the latest validation date
                                lastValidated = contentLastValidation;
                            }
                            break;
                        default:
                            break;
                    }
                }
            }
        }
        if (lastValidated != null)
        {
            XMLUtils.createElement(contentHandler, "lastValidation", DateUtils.dateToString(lastValidated));
        }
    }
    
    /**
     * SAX additional information on page hit
     * @param page the page
     * @throws SAXException if something goes wrong when saxing the information
     */
    protected void saxAdditionalInfosOnPageHit(Page page) throws SAXException
    {
        // Nothing to do here.
    }
    
    /**
     * SAX a hit of type "resource".
     * @param score The score of the page
     * @param maxScore The maximum score of the search results
     * @param resource The resource
     * @throws SAXException If an error occurs while SAXing
     */
    protected void saxResourceHit(float score, float maxScore, Resource resource) throws SAXException
    {
        int percent = Math.min(Math.round(score * 100f / maxScore), 100);
        
        String filename = resource.getName();
        
        XMLUtils.startElement(contentHandler, "hit");
        XMLUtils.createElement(contentHandler, "score", Float.toString(score));
        XMLUtils.createElement(contentHandler, "percent", Integer.toString(percent));
        XMLUtils.createElement(contentHandler, "filename", filename);
        XMLUtils.createElement(contentHandler, "title", StringUtils.substringBeforeLast(resource.getName(), "."));
        XMLUtils.createElement(contentHandler, "id", resource.getId());
        
        String dcDescription = resource.getDCDescription();
        String excerpt = _getResourceExcerpt(resource);
        if (StringUtils.isNotBlank(dcDescription))
        {
            XMLUtils.createElement(contentHandler, "excerpt", dcDescription);
        }
        else if (StringUtils.isNotBlank(excerpt))
        {
            XMLUtils.createElement(contentHandler, "excerpt", excerpt + "...");
        }
        
        XMLUtils.createElement(contentHandler, "type", "resource");
        
        Page page = _getResourcePage(resource);
        if (page != null)
        {
            String pageUri = page.getSitemapName() + "/" + page.getPathInSitemap();
            String encodedPath = _encodePath(_encodePath(resource.getResourcePath().substring(1)));
            XMLUtils.createElement(contentHandler, "uri", pageUri + "/_attachments/" + encodedPath + "?download=true");
        }
        XMLUtils.createElement(contentHandler, "mime-types", resource.getMimeType());
        _saxSize(resource.getLength());
        _saxIcon(filename);
        
        Date lastModified = resource.getLastModified();
        if (lastModified != null)
        {
            XMLUtils.createElement(contentHandler, "lastModified", DateUtils.dateToString(lastModified));
        }
        if (page != null)
        {
            Site site = page.getSite();
            XMLUtils.createElement(contentHandler, "siteName", site.getName());
            XMLUtils.createElement(contentHandler, "siteTitle", site.getTitle());
            XMLUtils.createElement(contentHandler, "siteUrl", site.getUrl());
        }
        
        XMLUtils.endElement(contentHandler, "hit");
    }
    
    private String _getResourceExcerpt(Resource resource)
    {
        try (InputStream is = resource.getInputStream())
        {
            TikaProvider tikaProvider = (TikaProvider) manager.lookup(TikaProvider.ROLE);
            Tika tika = tikaProvider.getTika();
            String value = tika.parseToString(is);
            if (StringUtils.isNotBlank(value))
            {
                int summaryEndIndex = value.lastIndexOf(' ', 200);
                if (summaryEndIndex == -1)
                {
                    summaryEndIndex = value.length();
                }
                return value.substring(0, summaryEndIndex) + (summaryEndIndex != value.length() ? "…" : "");
            }
        }
        catch (Exception e)
        {
            getLogger().error("Unable to index resource at " + resource.getPath(), e);
        }
        return null;
    }
    
    private Page _getResourcePage(Resource resource)
    {
        if (resource != null)
        {
            AmetysObject parent = resource.getParent();
            while (parent != null)
            {
                if (parent instanceof Page)
                {
                    // We have gone up to the page
                    return (Page) parent;
                }
                parent = parent.getParent();
            }
        }
        
        return null;
    }
    
    private String _encodePath(String path)
    {
        StringBuilder sb = new StringBuilder();
        
        String[] parts = StringUtils.split(path, '/');
        for (int i = 0; i < parts.length; i++)
        {
            if (i > 0 || path.charAt(0) == '/')
            {
                sb.append("/");
            }
            try
            {
                sb.append(URLEncoder.encode(parts[i], "UTF-8"));
            }
            catch (UnsupportedEncodingException e)
            {
                throw new IllegalStateException("Cannot encode path", e);
            }
        }
        return sb.toString();
    }
    
    /**
     * SAX elements for pagination
     * @param totalHits The total number of result
     * @param start The start index of search
     * @param offset The max number of results per page
     * @throws SAXException SAXException If an error occurs while SAXing
     */
    protected void saxPagination(long totalHits, int start, int offset) throws SAXException
    {
        int nbPages = (int) Math.ceil((double) totalHits / (double) offset);
        
        AttributesImpl atts = new AttributesImpl();
        atts.addCDATAAttribute("total", String.valueOf(nbPages)); // Number of pages
        atts.addCDATAAttribute("start", String.valueOf(start)); // Index of the first hit
        atts.addCDATAAttribute("end", start + offset > totalHits ? String.valueOf(totalHits) : String.valueOf(start + offset)); // Index of the last hit
        
        XMLUtils.startElement(contentHandler, "pagination", atts);
        
        for (int i = 0; i < nbPages; i++)
        {
            AttributesImpl attr = new AttributesImpl();
            attr.addAttribute("", "index", "index", "CDATA", String.valueOf(i + 1));
            attr.addAttribute("", "start", "start", "CDATA", String.valueOf(i * offset));
            XMLUtils.createElement(contentHandler, "page", attr);
        }
        
        XMLUtils.endElement(contentHandler, "pagination");
    }
    
    /**
     * Get the page index
     * @param request The request
     * @return The page index
     */
    protected int getPageIndex(Request request)
    {
        Enumeration paramNames = request.getParameterNames();
        while (paramNames.hasMoreElements())
        {
            String param = (String) paramNames.nextElement();
            if (param.startsWith("page-"))
            {
                return Integer.parseInt(param.substring("page-".length()));
            }
        }
        return 1;
    }
    
    private void _saxIcon(String filename) throws SAXException
    {
        int index = filename.lastIndexOf('.');
        String extension = filename.substring(index + 1);

        XMLUtils.createElement(contentHandler, "icon", "plugins/explorer/icon-medium/" + extension + ".png");
    }
    
    private void _saxSize(long size) throws SAXException
    {
        XMLUtils.startElement(contentHandler, "size");
        if (size < 1024)
        {
            // Bytes
            List<String> params = new ArrayList<>();
            params.add(String.valueOf(size));
            I18nizableText i18nSize = new I18nizableText("plugin.web", "ATTACHMENTS_FILE_SIZE_BYTES", params);
            i18nSize.toSAX(contentHandler);
        }
        else if (size < 1024 * 1024)
        {
            // Kb
            int sizeInKb = Math.round(size * 10 / 1024 / 10);
            List<String> params = new ArrayList<>();
            params.add(String.valueOf(sizeInKb));
            I18nizableText i18nSize = new I18nizableText("plugin.web", "ATTACHMENTS_FILE_SIZE_KB", params);
            i18nSize.toSAX(contentHandler);

        }
        else
        {
            // Mb
            int sizeInMb = Math.round(size * 10 / (1024 * 1024) / 10);
            List<String> params = new ArrayList<>();
            params.add(String.valueOf(sizeInMb));
            I18nizableText i18nSize = new I18nizableText("plugin.web", "ATTACHMENTS_FILE_SIZE_MB", params);
            i18nSize.toSAX(contentHandler);
        }
        XMLUtils.endElement(contentHandler, "size");
    }
    
    /**
     * Generate the service identifiers: service group ID, ZoneItem ID, ...
     * @throws SAXException if an error occurs SAXing data.
     * @throws IOException if an error occurs SAXing data.
     * @throws ProcessingException if a processing error occurs.
     */
    protected void saxServiceIdentifiers() throws SAXException, IOException, ProcessingException
    {
        Request request = ObjectModelHelper.getRequest(objectModel);
        ZoneItem zoneItem = (ZoneItem) request.getAttribute(WebConstants.REQUEST_ATTR_ZONEITEM);
        String serviceGroupId = parameters.getParameter("service-group-id", "");
        
        // The service group ID.
        if (StringUtils.isNotEmpty(serviceGroupId))
        {
            XMLUtils.createElement(contentHandler, "group-id", serviceGroupId);
        }
        
        // Generate the ZoneItem ID if it exists.
        if (zoneItem != null)
        {
            AttributesImpl atts = new AttributesImpl();
            atts.addCDATAAttribute("id", zoneItem.getId());
            XMLUtils.createElement(contentHandler, "zone-item", atts);
        }
    }
    
    /**
     * Generate any additional information.
     * @throws SAXException if an error occurs SAXing data.
     * @throws IOException if an error occurs SAXing data.
     * @throws ProcessingException if a processing error occurs.
     */
    protected void saxAdditionalInfos() throws SAXException, IOException, ProcessingException
    {
        // Nothing to do here.
    }
    
    /**
     * Get the search mode.
     * @return the search mode as a string.
     */
    protected String getSearchMode()
    {
        return parameters.getParameter("search-mode", "criteria-and-results");
    }
    
    /**
     * Check if the input is valid.
     * @return true if the input is valid, false otherwise.
     */
    protected boolean isInputValid()
    {
        boolean valid = true;
        
        Request request = ObjectModelHelper.getRequest(objectModel);
        ZoneItem zoneItem = (ZoneItem) request.getAttribute(WebConstants.REQUEST_ATTR_ZONEITEM);
        String serviceGroupId = parameters.getParameter("service-group-id", "");
        String requestParamGroupId = StringUtils.defaultString(request.getParameter("submit-form"));
        String requestParamZoneItemId = StringUtils.defaultString(request.getParameter("zone-item-id"));
        
        // If the generator is not used as part of a service (zoneItem is null), consider the input valid.
        if (zoneItem != null)
        {
            // If the generator is used as part of a service and both "group ID"
            // and "zone item ID" are missing from the input, consider the input valid.
            if (StringUtils.isNotEmpty(requestParamGroupId) || StringUtils.isNotEmpty(requestParamZoneItemId))
            {
                if (StringUtils.isEmpty(serviceGroupId))
                {
                    // No specified group ID: check the provided ZoneItem ID.
                    valid = requestParamZoneItemId.equals(zoneItem.getId());
                }
                else
                {
                    // Check the group ID against the one sent by the form.
                    valid = requestParamGroupId.equals(serviceGroupId);
                }
            }
        }
        return valid;
    }
    
    /**
     * SAX the metadata set of a content if exists
     * @param contentId the id of the content 
     * @param metadataSetName The name of metadata set to sax
     * @param defaultLocale The locale to use to sax localized values such as multilingual content or multilingual string. Only use if initial content's language is not null.
     * @throws SAXException if an exception occurs while saxing
     */
    protected void saxContent(String contentId, String metadataSetName, Locale defaultLocale) throws SAXException
    {   
        try
        {
            Content content = _resolver.resolveById(contentId);
            String[] contentTypes = content.getTypes();
            
            // content-name
            XMLUtils.createElement(contentHandler, "content-name", content.getName());
            
            // content-types
            XMLUtils.startElement(contentHandler, "content-types");
            Arrays.asList(contentTypes).forEach(LambdaUtils.wrapConsumer(cType -> XMLUtils.createElement(contentHandler, "content-type", cType)));
            XMLUtils.endElement(contentHandler, "content-types");
            
            MetadataSet metadataSet = _contentTypesHelper.getMetadataSetForView(metadataSetName, contentTypes, content.getMixinTypes());
            if (metadataSet != null)
            {
                Map<String, MetadataDefinition> metadataDefinitions = _contentTypesHelper.getMetadataDefinitions(metadataSet, content);
                Set<String> richTextMetadataPaths = metadataDefinitions.entrySet().parallelStream()
                                                                                  .filter(Objects::nonNull)
                                                                                  .filter(e -> e.getValue() != null && e.getValue().getType() == MetadataType.RICH_TEXT)
                                                                                  .map(Map.Entry::getKey)
                                                                                  .collect(Collectors.toSet());
                for (String metadataPath : richTextMetadataPaths)
                {
                    Object value = _contentHelper.getMetadataValue(content, metadataPath, defaultLocale, false, false);
                    if (value != null && value instanceof RichText)
                    {
                        saxRichTextExcerpt(metadataPath, contentId, (RichText) value);
                    }
                    else if (value instanceof Collection<?>)
                    {
                        for (Object v : (Collection<?>) value)
                        {
                            if (v instanceof RichText)
                            {
                                saxRichTextExcerpt(metadataPath, contentId, (RichText) v);
                            }
                        }
                    }
                }
               
                AttributesImpl attrs = new AttributesImpl();
                attrs.addCDATAAttribute("id", content.getId());
                attrs.addCDATAAttribute("name", content.getName());
                if (content.getLanguage() != null)
                {
                    attrs.addCDATAAttribute("language", content.getLanguage());
                }
                XMLUtils.startElement(contentHandler, "content", attrs);
                
                _metadataManager.saxMetadata(contentHandler, content, metadataSet, defaultLocale);

                XMLUtils.endElement(contentHandler, "content");
            }
        }
        catch (AmetysRepositoryException | IOException e)
        {
            getLogger().error("Cannot sax information about the content " + contentId, e);
        }
    }
    
    /**
     * SAX excerpt for rich text
     * @param metadataPath The path of metadata
     * @param contentId The content id
     * @param richText The rich text
     */
    protected void saxRichTextExcerpt(String metadataPath, String contentId, RichText richText)
    {
        SAXParser saxParser = null;
        try (InputStream is = richText.getInputStream())
        {
            RichTextHandler txtHandler = new RichTextHandler(200);
            saxParser = (SAXParser) manager.lookup(SAXParser.ROLE);
            saxParser.parse(new InputSource(is), txtHandler);
            String textValue = txtHandler.getValue();
            if (textValue != null)
            {
                XMLUtils.createElement(contentHandler, "excerpt", textValue);
            }
        }
        catch (Exception e)
        {
            getLogger().error("Cannot convert a richtextvalue at path '" + metadataPath + "' of content '" + contentId + "'", e);
        }
        finally
        {
            manager.release(saxParser);
        }
    }

    /**
     * Interface representing a facet field
     *
     */
    protected interface FacetField
    {
        /**
         * Get the search field for this facet 
         * @return the search field
         */
        public SearchField getSearchField();
        
        /**
         * Get the label of the facet
         * @return the label
         */
        public I18nizableText getLabel();
        
        /**
         * Get the label for a facet value
         * @param value the value
         * @param currentLocale the current locale
         * @return the label for this value
         */
        public I18nizableText getFacetLabel(String value, Locale currentLocale);
    }
    
    /**
     * Facet field for content types
     *
     */
    protected class ContentTypeFacetField implements FacetField
    {
        private SearchField _field;
        
        /**
         * Constructor
         * @param field The search field
         */
        public ContentTypeFacetField(SearchField field)
        {
            _field = field;
        }
        
        @Override
        public SearchField getSearchField()
        {
            return _field;
        }
        
        @Override
        public I18nizableText getLabel()
        {
            return new I18nizableText("plugin.web", "PLUGINS_WEB_SERVICE_FRONT_SEARCH_CONTENT_TYPE_FACET_LABEL");
        }
        
        @Override
        public I18nizableText getFacetLabel(String value, Locale currentLocale)
        {
            ContentType cType = _cTypeExtPt.getExtension(value);
            if (cType != null)
            {
                return cType.getLabel();
            }
            
            return new I18nizableText(value);
        }
    }
    
    /**
     * Facet field for a metadata
     *
     */
    protected class MetadataFacetField implements FacetField
    {
        private SearchField _field;
        private MetadataDefinition _metadataDefinition;
        private Logger _logger;
        
        /**
         * Constructor
         * @param field The search field
         * @param definition The metadata definition
         * @param logger The logger
         */
        public MetadataFacetField(SearchField field, MetadataDefinition definition, Logger logger)
        {
            _field = field;
            _metadataDefinition = definition;
            _logger = logger;
        }
        
        @Override
        public SearchField getSearchField()
        {
            return _field;
        }
        
        @Override
        public I18nizableText getLabel()
        {
            return _metadataDefinition.getLabel();
        }
        
        @Override
        public I18nizableText getFacetLabel(String value, Locale currentLocale)
        {
            try
            {
                if (_metadataDefinition != null && _metadataDefinition.getEnumerator() != null)
                {
                    return _metadataDefinition.getEnumerator().getEntry(value);
                }
                else if (_metadataDefinition != null && _metadataDefinition.getType().equals(MetadataType.CONTENT))
                {
                    Content content = _resolver.resolveById(value);
                    return new I18nizableText(content.getTitle(currentLocale));
                }
            }
            catch (Exception e)
            {
                _logger.error("Failed to get label of facet value '" + value + "'. Raw value itself will be used.", e);
            }
            
            return new I18nizableText(value);
        }
    }
}