/*
 *  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.Date;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
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.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.repository.RequestAttributeWorkspaceSelector;
import org.ametys.cms.search.SearchResults;
import org.ametys.cms.search.Sort;
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;
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.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.metadata.RichText;
import org.ametys.runtime.i18n.I18nizableText;
import org.ametys.runtime.parameter.ParameterHelper;
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
{
    /** 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 sax parser */
    protected SAXParser _parser;
    /** The searcher factory */
    protected SearcherFactory _searcherFactory;
    
    @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);
        _parser = (SAXParser) manager.lookup(SAXParser.ROLE);
        _uriResolverEP = (URIResolverExtensionPoint) smanager.lookup(URIResolverExtensionPoint.ROLE);
        _metadataManager = (MetadataManager) smanager.lookup(MetadataManager.ROLE);
        _searcherFactory = (SearcherFactory) smanager.lookup(SearcherFactory.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(Page.class.getName());
        if (page != null)
        {
            currentSiteName = page.getSiteName();
            lang = page.getSitemapName();
        }
        else
        {
            currentSiteName = parameters.getParameter("siteName", null);
            lang = parameters.getParameter("lang", null);
        }

        ZoneItem zoneItem = (ZoneItem) request.getAttribute(ZoneItem.class.getName());
        if (zoneItem == null)
        {
            String zoneItemId = request.getParameter("zone-item-id");
            zoneItem = _resolver.resolveById(zoneItemId);
        }

        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.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;
            if (submit && isInputValid())
            {
                searchResults = search(request, siteNames, lang, pageIndex, start, maxResults);
            }
            else
            {
                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();
    }

    /**
     * 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);
            XMLUtils.createElement(contentHandler, sort == null || sort.getField() == null ? "sort-by-score" : "sort-by-" + sort.getField());
            
            Searcher searcher = _searcherFactory.create()
                    .withQuery(queryObject)
                    .withFilterQueries(filterQueries)
                    .addFilterQuery(documentTypesQuery)
                    .withLimits(0, Integer.MAX_VALUE)
                    .withSort(getPrimarySortFields(request))
                    .addSort(sort)
                    .setCheckRights(true);
            
            _additionalSearchProcessing(searcher);
            
            results = searcher.searchWithFacets();
            
            if (saxResults)
            {
                // SAX results
                AttributesImpl atts = new AttributesImpl();
                atts.addCDATAAttribute("total", String.valueOf(results.getResults().getSize()));
                XMLUtils.startElement(contentHandler, "hits", atts);
                saxHits(results, start, maxResults);
                XMLUtils.endElement(contentHandler, "hits");
        
                // SAX pagination
                saxPagination(results.getResults().getSize(), start, maxResults);
            }
        }
        finally
        {
            // Restore context
            RequestAttributeWorkspaceSelector.setForcedWorkspace(request, currentWsp);
        }
        
        return results;
    }
    
    /**
     * 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
    {
        Map<String, Criterion> criteria = getCriteria(request, siteName, lang);

        XMLUtils.startElement(contentHandler, "form");

        XMLUtils.startElement(contentHandler, "fields");
        saxFormFields(request, searchResults, siteName, lang);
        saxCriteria(criteria, request, searchResults, siteName, lang, true);
        XMLUtils.endElement(contentHandler, "fields");

        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, searchResults, start, offset);

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

    /**
     * SAX the form search criteria
     * @param request The request
     * @param searchResults The search results
     * @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, SearchResults<AmetysObject> searchResults, String siteName, String lang) throws SAXException;

    /**
     * SAX criteria.
     * @param criteria the criteria list.
     * @param request the request
     * @param searchResults The search results
     * @param siteName the name of the site
     * @param lang the language
     * @param withHitCount true to sax the hit count as well
     * @throws SAXException If an error occurred while saxing the criteria
     */
    protected void saxCriteria(Map<String, Criterion> criteria, Request request, SearchResults<AmetysObject> searchResults, String siteName, String lang, boolean withHitCount) throws SAXException
    {
        try
        {
            for (String criterionName : criteria.keySet())
            {
                Criterion criterion = criteria.get(criterionName);

                saxCriterion(criterion, searchResults, siteName, lang);
            }
        }
        catch (IOException e)
        {
            getLogger().error("Error generating the criteria.", e);
            throw new SAXException("Error generating the criteria.", e);
        }
    }

    /**
     * SAX a single criterion.
     * @param criterion the criterion.
     * @param searchResults The search results
     * @param siteName the site name.
     * @param lang the language.
     * @throws SAXException If a sax error occurred
     * @throws IOException If another error occurred
     */
    protected void saxCriterion(Criterion criterion, SearchResults<AmetysObject> searchResults, String siteName, String lang) throws SAXException, IOException
    {
        AttributesImpl criterionAttrs = new AttributesImpl();
        
        // TODO Facet count.
//        if (criteriaValuesBitSet != null)
//        {
//            int criterionCount = criteriaValuesBitSet.cardinality();
//            criterionAttrs.addCDATAAttribute("count", Integer.toString(criterionCount));
//        }
        
        XMLUtils.startElement(contentHandler, criterion.getXmlGroupName(), criterionAttrs);
        
        for (String value : criterion.getValues().keySet())
        {
            I18nizableText label = criterion.getValues().get(value);
            
            // TODO Replace with facets
//            int count = getCount(criteriaValuesBitSet, criterion, value, siteName, lang);
            int count = 0;
            
            AttributesImpl valueAttrs = new AttributesImpl();
            valueAttrs.addCDATAAttribute("value", value);
            valueAttrs.addCDATAAttribute("count", Integer.toString(count));
            
            XMLUtils.startElement(contentHandler, criterion.getXmlElementName(), valueAttrs);
            label.toSAX(contentHandler);
            XMLUtils.endElement(contentHandler, criterion.getXmlElementName());
        }

        XMLUtils.endElement(contentHandler, criterion.getXmlGroupName());
    }

    /**
     * SAX the form search criteria values
     * @param request The request
     * @param searchResults The search results
     * @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, SearchResults<AmetysObject> searchResults, 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;

    /**
     * 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();

    /**
     * Get the criteria with their value list.
     * @param request the request.
     * @param siteName the site name.
     * @param lang the language
     * @return the criteria list.
     */
    protected abstract Map<String, Criterion> getCriteria(Request request, String siteName, String lang);

    /**
     * Get the criteria user values.
     * @param criteria the criteria list.
     * @param request the request object.
     * @return the criteria user values.
     */
    protected Map<String, String> getCriteriaValues(Map<String, Criterion> criteria, Request request)
    {
        Map<String, String> values = new HashMap<>();

        for (String name : criteria.keySet())
        {
            Criterion criterion = criteria.get(name);
            String value = request.getParameter(criterion.getFieldName());

            if (StringUtils.isNotEmpty(value))
            {
                values.put(criterion.getLuceneTermName(), value);
            }
        }

        return values;
    }
    
    /**
     * 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");
                    }
                }
            }
        }
    }
    
    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", ParameterHelper.valueToString(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", ParameterHelper.valueToString(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(), "."));
        
        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", ParameterHelper.valueToString(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(ZoneItem.class.getName());
        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(ZoneItem.class.getName());
        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
     * @throws SAXException if an exception occurs while saxing
     */
    protected void saxContent(String contentId, String metadataSetName) 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());
                Map<String, Object> richTextValues = _contentHelper.getMetadataValues(content, richTextMetadataPaths);
                for (String key : richTextValues.keySet())
                {
                    @SuppressWarnings("unchecked")
                    List<RichText> richTextValueArray = (List<RichText>) richTextValues.get(key);
                    for (RichText richTextValue : richTextValueArray)
                    {
                        try (InputStream is = richTextValue.getInputStream())
                        {
                            RichTextHandler txtHandler = new RichTextHandler(200);
                            _parser.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 '" + key + "' of content '" + contentId + "'", e);
                        }
                    }
                }
                
                AttributesImpl attrs = new AttributesImpl();
                attrs.addCDATAAttribute("id", content.getId());
                attrs.addCDATAAttribute("name", content.getName());
                attrs.addCDATAAttribute("language", content.getLanguage());
                XMLUtils.startElement(contentHandler, "content", attrs);
                
                _metadataManager.saxMetadata(contentHandler, content, metadataSet);

                XMLUtils.endElement(contentHandler, "content");
            }
        }
        catch (AmetysRepositoryException | IOException e)
        {
            getLogger().error("Cannot sax information about the content " + contentId, e);
        }
    }

    /**
     * Criterion class.
     */
    protected class Criterion
    {
        /** Form field name. */
        protected String _fieldName;

        /** Lucene field name. */
        protected String _luceneTermName;

        /** XML element name. */
        protected String _xmlElementName;

        /** XML group name. */
        protected String _xmlGroupName;

        /** Value list. */
        protected Map<String, I18nizableText> _values;

        /**
         * Build a new form field.
         */
        public Criterion()
        {
            this("", "", new HashMap<String, I18nizableText>());
        }

        /**
         * Build a new form field.
         * @param fieldName the field's name
         * @param xmlGroupName the name of the xml group
         * @param values the values' list
         */
        public Criterion(String fieldName, String xmlGroupName, Map<String, I18nizableText> values)
        {
            this(fieldName, fieldName, xmlGroupName, values);
        }

        /**
         * Build a new form field.
         * @param fieldName the field's name
         * @param luceneTermName the name of the lucene term 
         * @param xmlGroupName the name of the xml group
         * @param values the values' list
         */
        public Criterion(String fieldName, String luceneTermName, String xmlGroupName, Map<String, I18nizableText> values)
        {
            this(fieldName, luceneTermName, fieldName, xmlGroupName, values);
        }

        /**
         * Build a new form field.
         * @param fieldName the name of the field
         * @param luceneTermName the name of the lucene term
         * @param xmlElementName the name of the xml element
         * @param xmlGroupName the name of the xml group
         * @param values the values' list
         */
        public Criterion(String fieldName, String luceneTermName, String xmlElementName, String xmlGroupName, Map<String, I18nizableText> values)
        {
            this._fieldName = fieldName;
            this._luceneTermName = luceneTermName;
            this._xmlElementName = xmlElementName;
            this._xmlGroupName = xmlGroupName;
            this._values = values;
        }

        /**
         * Get the fieldName.
         * @return the fieldName
         */
        public String getFieldName()
        {
            return _fieldName;
        }

        /**
         * Set the fieldName.
         * @param fieldName the fieldName to set
         */
        public void setFieldName(String fieldName)
        {
            this._fieldName = fieldName;
        }

        /**
         * Get the luceneTermName.
         * @return the luceneTermName
         */
        public String getLuceneTermName()
        {
            return _luceneTermName;
        }

        /**
         * Set the luceneTermName.
         * @param luceneTermName the luceneTermName to set
         */
        public void setLuceneTermName(String luceneTermName)
        {
            this._luceneTermName = luceneTermName;
        }

        /**
         * Get the xmlElementName.
         * @return the xmlElementName
         */
        public String getXmlElementName()
        {
            return _xmlElementName;
        }

        /**
         * Set the xmlElementName.
         * @param xmlElementName the xmlElementName to set
         */
        public void setXmlElementName(String xmlElementName)
        {
            this._xmlElementName = xmlElementName;
        }

        /**
         * Get the xmlGroupName.
         * @return the xmlGroupName
         */
        public String getXmlGroupName()
        {
            return _xmlGroupName;
        }

        /**
         * Set the xmlGroupName.
         * @param xmlGroupName the xmlGroupName to set
         */
        public void setXmlGroupName(String xmlGroupName)
        {
            this._xmlGroupName = xmlGroupName;
        }

        /**
         * Get the values.
         * @return the values
         */
        public Map<String, I18nizableText> getValues()
        {
            return _values;
        }

        /**
         * Set the values.
         * @param values the values to set
         */
        public void setValues(Map<String, I18nizableText> values)
        {
            this._values = values;
        }
    }
}