/*
 * This library is part of OpenCms -
 * the Open Source Content Management System
 *
 * Copyright (c) Alkacon Software GmbH & Co. KG (http://www.alkacon.com)
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * For further information about Alkacon Software, please see the
 * company website: http://www.alkacon.com
 *
 * For further information about OpenCms, please see the
 * project website: http://www.opencms.org
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package org.opencms.jsp.search.config.parser;

import org.opencms.file.CmsObject;
import org.opencms.jsp.search.config.CmsSearchConfigurationCommon;
import org.opencms.jsp.search.config.CmsSearchConfigurationDidYouMean;
import org.opencms.jsp.search.config.CmsSearchConfigurationFacetField;
import org.opencms.jsp.search.config.CmsSearchConfigurationFacetQuery;
import org.opencms.jsp.search.config.CmsSearchConfigurationFacetQuery.CmsFacetQueryItem;
import org.opencms.jsp.search.config.CmsSearchConfigurationFacetRange;
import org.opencms.jsp.search.config.CmsSearchConfigurationHighlighting;
import org.opencms.jsp.search.config.CmsSearchConfigurationPagination;
import org.opencms.jsp.search.config.CmsSearchConfigurationSortOption;
import org.opencms.jsp.search.config.CmsSearchConfigurationSorting;
import org.opencms.jsp.search.config.I_CmsSearchConfigurationCommon;
import org.opencms.jsp.search.config.I_CmsSearchConfigurationDidYouMean;
import org.opencms.jsp.search.config.I_CmsSearchConfigurationFacet;
import org.opencms.jsp.search.config.I_CmsSearchConfigurationFacetField;
import org.opencms.jsp.search.config.I_CmsSearchConfigurationFacetQuery;
import org.opencms.jsp.search.config.I_CmsSearchConfigurationFacetQuery.I_CmsFacetQueryItem;
import org.opencms.jsp.search.config.I_CmsSearchConfigurationFacetRange;
import org.opencms.jsp.search.config.I_CmsSearchConfigurationGeoFilter;
import org.opencms.jsp.search.config.I_CmsSearchConfigurationHighlighting;
import org.opencms.jsp.search.config.I_CmsSearchConfigurationPagination;
import org.opencms.jsp.search.config.I_CmsSearchConfigurationSortOption;
import org.opencms.jsp.search.config.I_CmsSearchConfigurationSorting;
import org.opencms.main.CmsLog;
import org.opencms.main.OpenCms;
import org.opencms.search.solr.CmsSolrIndex;
import org.opencms.xml.content.CmsXmlContent;
import org.opencms.xml.content.CmsXmlContentValueSequence;
import org.opencms.xml.types.I_CmsXmlContentValue;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Objects;

import org.apache.commons.logging.Log;

/** Search configuration parser reading XML. */
public class CmsXMLSearchConfigurationParser implements I_CmsSearchConfigurationParser {

    /** Logger for the class. */
    protected static final Log LOG = CmsLog.getLog(CmsXMLSearchConfigurationParser.class);

    /** The element names of the xml content. */
    /** Elements for common options. */
    /** XML element name. */
    private static final String XML_ELEMENT_QUERYPARAM = "QueryParam";
    /** XML element name. */
    private static final String XML_ELEMENT_LAST_QUERYPARAM = "LastQueryParam";
    /** XML element name. */
    private static final String XML_ELEMENT_MAX_RETURNED_RESULTS = "MaxReturnedResults";
    /** XML element name. */
    private static final String XML_ELEMENT_ESCAPE_QUERY_CHARACTERS = "EscapeQueryCharacters";
    /** XML element name. */
    private static final String XML_ELEMENT_RELOADED_PARAM = "ReloadedParam";
    /** XML element name. */
    private static final String XML_ELEMENT_SEARCH_FOR_EMPTY_QUERY = "SearchForEmptyQuery";
    /** XML element name. */
    private static final String XML_ELEMENT_IGNORE_QUERY = "IgnoreQuery";
    /** XML element name. */
    private static final String XML_ELEMENT_IGNORE_RELEASE_DATE = "IgnoreReleaseDate";
    /** XML element name. */
    private static final String XML_ELEMENT_IGNORE_EXPIRATION_DATE = "IgnoreExpirationDate";
    /** XML element name. */
    private static final String XML_ELEMENT_QUERY_MODIFIER = "QueryModifier";
    /** XML element name. */
    private static final String XML_ELEMENT_PAGEPARAM = "PageParam";
    /** XML element name. */
    private static final String XML_ELEMENT_INDEX = "Index";
    /** XML element name. */
    private static final String XML_ELEMENT_CORE = "Core";
    /** XML element name. */
    private static final String XML_ELEMENT_EXTRASOLRPARAMS = "ExtraSolrParams";
    /** XML element name. */
    private static final String XML_ELEMENT_ADDITIONAL_PARAMETERS = "AdditionalRequestParams";
    /** XML element name. */
    private static final String XML_ELEMENT_ADDITIONAL_PARAMETERS_PARAM = "Param";
    /** XML element name. */
    private static final String XML_ELEMENT_ADDITIONAL_PARAMETERS_SOLRQUERY = "SolrQuery";
    /** XML element name. */
    private static final String XML_ELEMENT_PAGESIZE = "PageSize";
    /** XML element name. */
    private static final String XML_ELEMENT_PAGENAVLENGTH = "PageNavLength";

    /** XML element names for facet configuration. */
    /** XML element name for the root element of a field facet configuration. */
    private static final String XML_ELEMENT_FIELD_FACETS = "FieldFacet";
    /** XML element name for the root element of the query facet configuration. */
    private static final String XML_ELEMENT_QUERY_FACET = "QueryFacet";
    /** XML element names for facet options. */
    /** XML element name. */
    private static final String XML_ELEMENT_FACET_LIMIT = "Limit";
    /** XML element name. */
    private static final String XML_ELEMENT_FACET_MINCOUNT = "MinCount";
    /** XML element name. */
    private static final String XML_ELEMENT_FACET_LABEL = "Label";
    /** XML element name. */
    private static final String XML_ELEMENT_FACET_FIELD = "Field";
    /** XML element name. */
    private static final String XML_ELEMENT_FACET_NAME = "Name";
    /** XML element name. */
    private static final String XML_ELEMENT_FACET_PREFIX = "Prefix";
    /** XML element name. */
    private static final String XML_ELEMENT_FACET_ORDER = "Order";
    /** XML element name. */
    private static final String XML_ELEMENT_FACET_FILTERQUERYMODIFIER = "FilterQueryModifier";
    /** XML element name. */
    private static final String XML_ELEMENT_FACET_ISANDFACET = "IsAndFacet";
    /** XML element name. */
    private static final String XML_ELEMENT_FACET_PRESELECTION = "PreSelection";
    /** XML element name. */
    private static final String XML_ELEMENT_FACET_IGNOREALLFACETFILTERS = "IgnoreAllFacetFilters";
    /** XML element name. */
    private static final String XML_ELEMENT_FACET_EXCLUDETAG = "ExcludeTag";
    /** XML element name. */
    private static final String XML_ELEMENT_QUERY_FACET_QUERY = "QueryItem";
    /** XML element name. */
    private static final String XML_ELEMENT_QUERY_FACET_QUERY_QUERY = "Query";
    /** XML element name. */
    private static final String XML_ELEMENT_QUERY_FACET_QUERY_LABEL = "Label";

    /** XML element names for sort options. */
    /** XML element name. */
    private static final String XML_ELEMENT_SORTPARAM = "SortParam";
    /** XML element name for the root element for sort options. */
    private static final String XML_ELEMENT_DEFAULTSORTOPTION = "DefaultSortOption";
    /** XML element name for the root element for sort options. */
    private static final String XML_ELEMENT_SORTOPTIONS = "SortOption";
    /** XML element names for a single search option. */
    private static final String XML_ELEMENT_SORTOPTION_LABEL = "Label";
    /** XML element name. */
    private static final String XML_ELEMENT_SORTOPTION_PARAMVALUE = "ParamValue";
    /** XML element name. */
    private static final String XML_ELEMENT_SORTOPTION_SOLRVALUE = "SolrValue";
    /** XML element name for the root element for the highlighting configuration. */
    private static final String XML_ELEMENT_HIGHLIGHTER = "Highlighting";
    /** XML elements for the highlighting configuration. */
    /** XML element name. */
    private static final String XML_ELEMENT_HIGHLIGHTER_FIELD = "Field";
    /** XML element name. */
    private static final String XML_ELEMENT_HIGHLIGHTER_SNIPPETS = "Snippets";
    /** XML element name. */
    private static final String XML_ELEMENT_HIGHLIGHTER_FRAGSIZE = "FragSize";
    /** XML element name. */
    private static final String XML_ELEMENT_HIGHLIGHTER_ALTERNATE_FIELD = "AlternateField";
    /** XML element name. */
    private static final String XML_ELEMENT_HIGHLIGHTER_MAX_LENGTH_ALTERNATE_FIELD = "MaxAlternateFieldLength";
    /** XML element name. */
    private static final String XML_ELEMENT_HIGHLIGHTER_SIMPLE_PRE = "SimplePre";
    /** XML element name. */
    private static final String XML_ELEMENT_HIGHLIGHTER_SIMPLE_POST = "SimplePost";
    /** XML element name. */
    private static final String XML_ELEMENT_HIGHLIGHTER_FORMATTER = "Formatter";
    /** XML element name. */
    private static final String XML_ELEMENT_HIGHLIGHTER_FRAGMENTER = "Fragmenter";
    /** XML element name. */
    private static final String XML_ELEMENT_HIGHLIGHTER_FASTVECTORHIGHLIGHTING = "UseFastVectorHighlighting";

    /** XML element names for "Did you mean ...?". */
    /** XML element name. */
    private static final String XML_ELEMENT_DIDYOUMEAN = "DidYouMean";
    /** XML elements for the "Did you mean ...?" configuration. */
    /** XML element name. */
    private static final String XML_ELEMENT_DIDYOUMEAN_QUERYPARAM = "QueryParam";
    /** XML element name. */
    private static final String XML_ELEMENT_DIDYOUMEAN_COLLATE = "Collate";
    /** XML element name. */
    private static final String XML_ELEMENT_DIDYOUMEAN_COUNT = "Count";
    /** XML element name. */
    private static final String XML_ELEMENT_RANGE_FACETS = "RangeFacet";
    /** XML element name. */
    private static final String XML_ELEMENT_RANGE_FACET_RANGE = "Range";
    /** XML element name. */
    private static final String XML_ELEMENT_RANGE_FACET_START = "Start";
    /** XML element name. */
    private static final String XML_ELEMENT_RANGE_FACET_END = "End";
    /** XML element name. */
    private static final String XML_ELEMENT_RANGE_FACET_GAP = "Gap";
    /** XML element name. */
    private static final String XML_ELEMENT_RANGE_FACET_OTHER = "Other";
    /** XML element name. */
    private static final String XML_ELEMENT_RANGE_FACET_HARDEND = "HardEnd";
    /** XML element name. */
    private static final String XML_ELEMENT_RANGE_FACET_METHOD = "Method";

    /** Default value. */
    private static final String DEFAULT_QUERY_PARAM = "q";
    /** Default value. */
    private static final String DEFAULT_LAST_QUERY_PARAM = "lq";
    /** Default value. */
    private static final String DEFAULT_RELOADED_PARAM = "reloaded";

    /** The XML content that contains the configuration. */
    CmsXmlContent m_xml;
    /** The locale in which the configuration should be read. */
    Locale m_locale;

    /** Constructor taking the XML content that should be read and the locale in which it should be read.
     * @param xml The XML content that should be read for the configuration.
     * @param locale The locale in which the content should be read.
     */
    public CmsXMLSearchConfigurationParser(final CmsXmlContent xml, final Locale locale) {

        m_xml = xml;
        m_locale = locale;
    }

    /**
     * @see org.opencms.jsp.search.config.parser.I_CmsSearchConfigurationParser#parseCommon(CmsObject)
     */
    @Override
    public I_CmsSearchConfigurationCommon parseCommon(CmsObject cms) {

        String indexName = getIndex(cms);

        return new CmsSearchConfigurationCommon(
            getQueryParam(),
            getLastQueryParam(),
            parseOptionalBooleanValue(XML_ELEMENT_ESCAPE_QUERY_CHARACTERS),
            getFirstCallParam(),
            getSearchForEmtpyQuery(),
            getIgnoreQuery(),
            getQueryModifier(),
            indexName,
            getCore(),
            getExtraSolrParams(),
            getAdditionalRequestParameters(),
            getIgnoreReleaseDate(),
            getIgnoreExpirationDate(),
            getMaxReturnedResults(indexName));
    }

    /**
     * @see org.opencms.jsp.search.config.parser.I_CmsSearchConfigurationParser#parseDidYouMean()
     */
    public I_CmsSearchConfigurationDidYouMean parseDidYouMean() {

        final I_CmsXmlContentValue didYouMean = m_xml.getValue(XML_ELEMENT_DIDYOUMEAN, m_locale);
        if (didYouMean == null) {
            return null;
        } else {
            final String pathPrefix = didYouMean.getPath() + "/";
            String param = parseOptionalStringValue(pathPrefix + XML_ELEMENT_DIDYOUMEAN_QUERYPARAM);
            if (null == param) {
                param = getQueryParam();
            }
            Boolean collate = parseOptionalBooleanValue(pathPrefix + XML_ELEMENT_DIDYOUMEAN_COLLATE);
            Integer count = parseOptionalIntValue(pathPrefix + XML_ELEMENT_DIDYOUMEAN_COUNT);
            return new CmsSearchConfigurationDidYouMean(param, collate, count);
        }
    }

    /**
     * @see org.opencms.jsp.search.config.parser.I_CmsSearchConfigurationParser#parseFieldFacets()
     */
    @Override
    public Map<String, I_CmsSearchConfigurationFacetField> parseFieldFacets() {

        final Map<String, I_CmsSearchConfigurationFacetField> facetConfigs = new LinkedHashMap<String, I_CmsSearchConfigurationFacetField>();
        final CmsXmlContentValueSequence fieldFacets = m_xml.getValueSequence(XML_ELEMENT_FIELD_FACETS, m_locale);
        if (fieldFacets != null) {
            for (int i = 0; i < fieldFacets.getElementCount(); i++) {

                final I_CmsSearchConfigurationFacetField config = parseFieldFacet(
                    fieldFacets.getValue(i).getPath() + "/");
                if (config != null) {
                    facetConfigs.put(config.getName(), config);
                }
            }
        }
        return facetConfigs;
    }

    /**
     * @see org.opencms.jsp.search.config.parser.I_CmsSearchConfigurationParser#parseGeoFilter()
     */
    @Override
    public I_CmsSearchConfigurationGeoFilter parseGeoFilter() {

        return null;
    }

    /**
     * @see org.opencms.jsp.search.config.parser.I_CmsSearchConfigurationParser#parseHighlighter()
     */
    @Override
    public I_CmsSearchConfigurationHighlighting parseHighlighter() {

        final I_CmsXmlContentValue highlighter = m_xml.getValue(XML_ELEMENT_HIGHLIGHTER, m_locale);
        if (highlighter == null) {
            return null;
        } else {
            try {
                final String pathPrefix = highlighter.getPath() + "/";
                final String field = parseMandatoryStringValue(pathPrefix + XML_ELEMENT_HIGHLIGHTER_FIELD);
                final Integer snippets = parseOptionalIntValue(pathPrefix + XML_ELEMENT_HIGHLIGHTER_SNIPPETS);
                final Integer fragsize = parseOptionalIntValue(pathPrefix + XML_ELEMENT_HIGHLIGHTER_FRAGSIZE);
                final String alternateField = parseOptionalStringValue(
                    pathPrefix + XML_ELEMENT_HIGHLIGHTER_ALTERNATE_FIELD);
                final Integer maxAlternateFieldLength = parseOptionalIntValue(
                    pathPrefix + XML_ELEMENT_HIGHLIGHTER_MAX_LENGTH_ALTERNATE_FIELD);
                final String pre = parseOptionalStringValue(pathPrefix + XML_ELEMENT_HIGHLIGHTER_SIMPLE_PRE);
                final String post = parseOptionalStringValue(pathPrefix + XML_ELEMENT_HIGHLIGHTER_SIMPLE_POST);
                final String formatter = parseOptionalStringValue(pathPrefix + XML_ELEMENT_HIGHLIGHTER_FORMATTER);
                final String fragmenter = parseOptionalStringValue(pathPrefix + XML_ELEMENT_HIGHLIGHTER_FRAGMENTER);
                final Boolean useFastVectorHighlighting = parseOptionalBooleanValue(
                    pathPrefix + XML_ELEMENT_HIGHLIGHTER_FASTVECTORHIGHLIGHTING);
                return new CmsSearchConfigurationHighlighting(
                    field,
                    snippets,
                    fragsize,
                    alternateField,
                    maxAlternateFieldLength,
                    pre,
                    post,
                    formatter,
                    fragmenter,
                    useFastVectorHighlighting);
            } catch (final Exception e) {
                LOG.error(Messages.get().getBundle().key(Messages.ERR_MANDATORY_HIGHLIGHTING_FIELD_MISSING_0), e);
                return null;
            }
        }
    }

    /**
     * @see org.opencms.jsp.search.config.parser.I_CmsSearchConfigurationParser#parsePagination()
     */
    @Override
    public I_CmsSearchConfigurationPagination parsePagination() {

        return CmsSearchConfigurationPagination.create(getPageParam(), getPageSizes(), getPageNavLength());
    }

    /**
     * @see org.opencms.jsp.search.config.parser.I_CmsSearchConfigurationParser#parseQueryFacet()
     */
    @Override
    public I_CmsSearchConfigurationFacetQuery parseQueryFacet() {

        final String pathPrefix = XML_ELEMENT_QUERY_FACET + "/";
        try {
            final List<I_CmsFacetQueryItem> queries = parseFacetQueryItems(pathPrefix + XML_ELEMENT_QUERY_FACET_QUERY);
            final String label = parseOptionalStringValue(pathPrefix + XML_ELEMENT_FACET_LABEL);
            final Boolean isAndFacet = parseOptionalBooleanValue(pathPrefix + XML_ELEMENT_FACET_ISANDFACET);
            final List<String> preselection = parseOptionalStringValues(pathPrefix + XML_ELEMENT_FACET_PRESELECTION);
            final List<String> excludeTags = parseOptionalStringValues(pathPrefix + XML_ELEMENT_FACET_EXCLUDETAG);
            final Boolean ignoreAllFacetFilters = parseOptionalBooleanValue(
                pathPrefix + XML_ELEMENT_FACET_IGNOREALLFACETFILTERS);
            return new CmsSearchConfigurationFacetQuery(
                queries,
                label,
                isAndFacet,
                preselection,
                ignoreAllFacetFilters,
                excludeTags);
        } catch (final Exception e) {
            LOG.error(
                Messages.get().getBundle().key(
                    Messages.ERR_QUERY_FACET_MANDATORY_KEY_MISSING_1,
                    XML_ELEMENT_QUERY_FACET_QUERY),
                e);
            return null;
        }
    }

    /**
     * @see org.opencms.jsp.search.config.parser.I_CmsSearchConfigurationParser#parseRangeFacets()
     */
    public Map<String, I_CmsSearchConfigurationFacetRange> parseRangeFacets() {

        final Map<String, I_CmsSearchConfigurationFacetRange> facetConfigs = new LinkedHashMap<String, I_CmsSearchConfigurationFacetRange>();
        final CmsXmlContentValueSequence rangeFacets = m_xml.getValueSequence(XML_ELEMENT_RANGE_FACETS, m_locale);
        if (rangeFacets != null) {
            for (int i = 0; i < rangeFacets.getElementCount(); i++) {

                final I_CmsSearchConfigurationFacetRange config = parseRangeFacet(
                    rangeFacets.getValue(i).getPath() + "/");
                if (config != null) {
                    facetConfigs.put(config.getName(), config);
                }
            }
        }
        return facetConfigs;
    }

    /**
     * @see org.opencms.jsp.search.config.parser.I_CmsSearchConfigurationParser#parseSorting()
     */
    @Override
    public I_CmsSearchConfigurationSorting parseSorting() {

        List<I_CmsSearchConfigurationSortOption> options = getSortOptions();
        String defaultOptionParamValue = parseOptionalStringValue(XML_ELEMENT_DEFAULTSORTOPTION);
        I_CmsSearchConfigurationSortOption defaultSortOption = null;
        if (null != defaultOptionParamValue) {
            Iterator<I_CmsSearchConfigurationSortOption> optIterator = options.iterator();
            while ((null == defaultSortOption) && optIterator.hasNext()) {
                I_CmsSearchConfigurationSortOption opt = optIterator.next();
                if (Objects.equals(opt.getParamValue(), defaultOptionParamValue)) {
                    defaultSortOption = opt;
                }
            }
        }
        if ((null == defaultSortOption) && !options.isEmpty()) {
            defaultSortOption = options.get(0);
        }
        return CmsSearchConfigurationSorting.create(getSortParam(), options, defaultSortOption);
    }

    /** Returns the number of maximally returned results, or <code>null</code> if the indexes default should be used.
     * @param indexName the name of the index to search in.
     * @return The number of maximally returned results, or <code>null</code> if the indexes default should be used.
     */
    protected int getMaxReturnedResults(String indexName) {

        Integer maxReturnedResults = parseOptionalIntValue(XML_ELEMENT_MAX_RETURNED_RESULTS);
        if (null != maxReturnedResults) {
            return maxReturnedResults.intValue();
        }
        try {
            CmsSolrIndex idx = OpenCms.getSearchManager().getIndexSolr(indexName);
            if (null != idx) {
                return idx.getMaxProcessedResults();
            }
        } catch (Throwable t) {
            // This is ok, it's allowed to have an external other index here.
            LOG.debug(
                "Parsing JSON search configuration for none-CmsSolrIndex "
                    + indexName
                    + ". Setting max processed results to unlimited.");
        }
        return CmsSolrIndex.MAX_RESULTS_UNLIMITED;
    }

    /** Helper to read a mandatory String value list.
     * @param path The XML path of the element to read.
     * @return The String list stored in the XML, or <code>null</code> if the value could not be read.
     * @throws Exception thrown if the list of String values can not be read.
     */
    protected List<I_CmsFacetQueryItem> parseFacetQueryItems(final String path) throws Exception {

        final List<I_CmsXmlContentValue> values = m_xml.getValues(path, m_locale);
        if (values == null) {
            return null;
        } else {
            List<I_CmsFacetQueryItem> parsedItems = new ArrayList<I_CmsFacetQueryItem>(values.size());
            for (I_CmsXmlContentValue value : values) {
                I_CmsFacetQueryItem item = parseFacetQueryItem(value.getPath() + "/");
                if (null != item) {
                    parsedItems.add(item);
                } else {
                    // TODO: log
                }
            }
            return parsedItems;
        }
    }

    /** Reads the configuration of a field facet.
     * @param pathPrefix The XML Path that leads to the field facet configuration, or <code>null</code> if the XML was not correctly structured.
     * @return The read configuration, or <code>null</code> if the XML was not correctly structured.
     */
    protected I_CmsSearchConfigurationFacetField parseFieldFacet(final String pathPrefix) {

        try {
            final String field = parseMandatoryStringValue(pathPrefix + XML_ELEMENT_FACET_FIELD);
            final String name = parseOptionalStringValue(pathPrefix + XML_ELEMENT_FACET_NAME);
            final String label = parseOptionalStringValue(pathPrefix + XML_ELEMENT_FACET_LABEL);
            final Integer minCount = parseOptionalIntValue(pathPrefix + XML_ELEMENT_FACET_MINCOUNT);
            final Integer limit = parseOptionalIntValue(pathPrefix + XML_ELEMENT_FACET_LIMIT);
            final String prefix = parseOptionalStringValue(pathPrefix + XML_ELEMENT_FACET_PREFIX);
            final String sorder = parseOptionalStringValue(pathPrefix + XML_ELEMENT_FACET_ORDER);
            I_CmsSearchConfigurationFacet.SortOrder order;
            try {
                order = I_CmsSearchConfigurationFacet.SortOrder.valueOf(sorder);
            } catch (@SuppressWarnings("unused") final Exception e) {
                order = null;
            }
            final String filterQueryModifier = parseOptionalStringValue(
                pathPrefix + XML_ELEMENT_FACET_FILTERQUERYMODIFIER);
            final Boolean isAndFacet = parseOptionalBooleanValue(pathPrefix + XML_ELEMENT_FACET_ISANDFACET);
            final List<String> preselection = parseOptionalStringValues(pathPrefix + XML_ELEMENT_FACET_PRESELECTION);
            final Boolean ignoreAllFacetFilters = parseOptionalBooleanValue(
                pathPrefix + XML_ELEMENT_FACET_IGNOREALLFACETFILTERS);
            final List<String> excludeTags = parseOptionalStringValues(pathPrefix + XML_ELEMENT_FACET_EXCLUDETAG);
            return new CmsSearchConfigurationFacetField(
                field,
                name,
                minCount,
                limit,
                prefix,
                label,
                order,
                filterQueryModifier,
                isAndFacet,
                preselection,
                ignoreAllFacetFilters,
                excludeTags);
        } catch (final Exception e) {
            LOG.error(
                Messages.get().getBundle().key(
                    Messages.ERR_FIELD_FACET_MANDATORY_KEY_MISSING_1,
                    XML_ELEMENT_FACET_FIELD),
                e);
            return null;
        }
    }

    /** Helper to read an optional Boolean value.
     * @param path The XML path of the element to read.
     * @return The Boolean value stored in the XML, or <code>null</code> if the value could not be read.
     */
    protected Boolean parseOptionalBooleanValue(final String path) {

        final I_CmsXmlContentValue value = m_xml.getValue(path, m_locale);
        if (value == null) {
            return null;
        } else {
            final String stringValue = value.getStringValue(null);
            try {
                final Boolean boolValue = Boolean.valueOf(stringValue);
                return boolValue;
            } catch (final NumberFormatException e) {
                LOG.info(Messages.get().getBundle().key(Messages.LOG_OPTIONAL_BOOLEAN_MISSING_1, path), e);
                return null;
            }
        }
    }

    /** Helper to read an optional Integer value.
     * @param path The XML path of the element to read.
     * @return The Integer value stored in the XML, or <code>null</code> if the value could not be read.
     */
    protected Integer parseOptionalIntValue(final String path) {

        final I_CmsXmlContentValue value = m_xml.getValue(path, m_locale);
        if (value == null) {
            return null;
        } else {
            final String stringValue = value.getStringValue(null);
            try {
                final Integer intValue = Integer.valueOf(stringValue);
                return intValue;
            } catch (final NumberFormatException e) {
                LOG.info(Messages.get().getBundle().key(Messages.LOG_OPTIONAL_INTEGER_MISSING_1, path), e);
                return null;
            }
        }
    }

    /** Helper to read an optional String value.
     * @param path The XML path of the element to read.
     * @return The String value stored in the XML, or <code>null</code> if the value could not be read.
     */
    protected String parseOptionalStringValue(final String path) {

        final I_CmsXmlContentValue value = m_xml.getValue(path, m_locale);
        if (value == null) {
            return null;
        } else {
            return value.getStringValue(null);
        }
    }

    /** Helper to read an optional String value list.
     * @param path The XML path of the element to read.
     * @return The String list stored in the XML, or <code>null</code> if the value could not be read.
     */
    protected List<String> parseOptionalStringValues(final String path) {

        final List<I_CmsXmlContentValue> values = m_xml.getValues(path, m_locale);
        if (values == null) {
            return null;
        } else {
            List<String> stringValues = new ArrayList<String>(values.size());
            for (I_CmsXmlContentValue value : values) {
                stringValues.add(value.getStringValue(null));
            }
            return stringValues;
        }
    }

    /** Reads the configuration of a range facet.
     * @param pathPrefix The XML Path that leads to the range facet configuration, or <code>null</code> if the XML was not correctly structured.
     * @return The read configuration, or <code>null</code> if the XML was not correctly structured.
     */
    protected I_CmsSearchConfigurationFacetRange parseRangeFacet(String pathPrefix) {

        try {
            final String range = parseMandatoryStringValue(pathPrefix + XML_ELEMENT_RANGE_FACET_RANGE);
            final String name = parseOptionalStringValue(pathPrefix + XML_ELEMENT_FACET_NAME);
            final String label = parseOptionalStringValue(pathPrefix + XML_ELEMENT_FACET_LABEL);
            final Integer minCount = parseOptionalIntValue(pathPrefix + XML_ELEMENT_FACET_MINCOUNT);
            final String start = parseMandatoryStringValue(pathPrefix + XML_ELEMENT_RANGE_FACET_START);
            final String end = parseMandatoryStringValue(pathPrefix + XML_ELEMENT_RANGE_FACET_END);
            final String gap = parseMandatoryStringValue(pathPrefix + XML_ELEMENT_RANGE_FACET_GAP);
            final String sother = parseOptionalStringValue(pathPrefix + XML_ELEMENT_RANGE_FACET_OTHER);
            List<I_CmsSearchConfigurationFacetRange.Other> other = null;
            if (sother != null) {
                final List<String> sothers = Arrays.asList(sother.split(","));
                other = new ArrayList<I_CmsSearchConfigurationFacetRange.Other>(sothers.size());
                for (String so : sothers) {
                    try {
                        I_CmsSearchConfigurationFacetRange.Other o = I_CmsSearchConfigurationFacetRange.Other.valueOf(
                            so);
                        other.add(o);
                    } catch (final Exception e) {
                        LOG.error(Messages.get().getBundle().key(Messages.ERR_INVALID_OTHER_OPTION_1, so), e);
                    }
                }
            }
            final Boolean hardEnd = parseOptionalBooleanValue(pathPrefix + XML_ELEMENT_RANGE_FACET_HARDEND);
            final String methodStr = parseOptionalStringValue(pathPrefix + XML_ELEMENT_RANGE_FACET_METHOD);
            I_CmsSearchConfigurationFacetRange.Method method = null;
            if (null != methodStr) {
                try {
                    method = I_CmsSearchConfigurationFacetRange.Method.valueOf(methodStr);
                } catch (Exception e) {
                    LOG.error(Messages.get().getBundle().key(Messages.ERR_INVALID_RANGE_METHOD_OPTION_1, methodStr), e);
                }
            }
            final Boolean isAndFacet = parseOptionalBooleanValue(pathPrefix + XML_ELEMENT_FACET_ISANDFACET);
            final List<String> preselection = parseOptionalStringValues(pathPrefix + XML_ELEMENT_FACET_PRESELECTION);
            final Boolean ignoreAllFacetFilters = parseOptionalBooleanValue(
                pathPrefix + XML_ELEMENT_FACET_IGNOREALLFACETFILTERS);
            final List<String> excludeTags = parseOptionalStringValues(pathPrefix + XML_ELEMENT_FACET_EXCLUDETAG);
            return new CmsSearchConfigurationFacetRange(
                range,
                start,
                end,
                gap,
                other,
                hardEnd,
                method,
                name,
                minCount,
                label,
                isAndFacet,
                preselection,
                ignoreAllFacetFilters,
                excludeTags);
        } catch (final Exception e) {
            LOG.error(
                Messages.get().getBundle().key(
                    Messages.ERR_RANGE_FACET_MANDATORY_KEY_MISSING_1,
                    XML_ELEMENT_RANGE_FACET_RANGE
                        + ", "
                        + XML_ELEMENT_RANGE_FACET_START
                        + ", "
                        + XML_ELEMENT_RANGE_FACET_END
                        + ", "
                        + XML_ELEMENT_RANGE_FACET_GAP),
                e);
            return null;
        }

    }

    /** Returns a map with additional request parameters, mapping the parameter names to Solr query parts.
     * @return A map with additional request parameters, mapping the parameter names to Solr query parts.
     */
    private Map<String, String> getAdditionalRequestParameters() {

        List<I_CmsXmlContentValue> parametersToParse = m_xml.getValues(XML_ELEMENT_ADDITIONAL_PARAMETERS, m_locale);
        Map<String, String> result = new HashMap<String, String>(parametersToParse.size());
        for (I_CmsXmlContentValue additionalParam : parametersToParse) {
            String param = m_xml.getValue(
                additionalParam.getPath() + "/" + XML_ELEMENT_ADDITIONAL_PARAMETERS_PARAM,
                m_locale).getStringValue(null);
            String solrQuery = m_xml.hasValue(
                additionalParam.getPath() + "/" + XML_ELEMENT_ADDITIONAL_PARAMETERS_SOLRQUERY,
                m_locale)
                ? m_xml.getValue(
                    additionalParam.getPath() + "/" + XML_ELEMENT_ADDITIONAL_PARAMETERS_SOLRQUERY,
                    m_locale).getStringValue(null)
                : null;
            result.put(param, solrQuery);
        }
        return result;
    }

    /** Returns the configured Solr core, or <code>null</code> if the core is not specified.
     * @return The configured Solr core, or <code>null</code> if the core is not specified.
     */
    private String getCore() {

        try {
            return parseMandatoryStringValue(XML_ELEMENT_CORE);
        } catch (final Exception e) {
            LOG.info(Messages.get().getBundle().key(Messages.LOG_NO_CORE_SPECIFIED_0), e);
            return null;
        }
    }

    /** Returns the extra Solr parameters specified in the configuration, or the empty string if no extra parameters are configured.
     * @return The extra Solr parameters specified in the configuration, or the empty string if no extra parameters are configured.
     */
    private String getExtraSolrParams() {

        return parseOptionalStringValue(XML_ELEMENT_EXTRASOLRPARAMS);
    }

    /** Returns the configured request parameter for the last query, or the default parameter if the core is not specified.
     * @return The configured request parameter for the last query, or the default parameter if the core is not specified.
     */
    private String getFirstCallParam() {

        final String param = parseOptionalStringValue(XML_ELEMENT_RELOADED_PARAM);
        if (param == null) {
            return DEFAULT_RELOADED_PARAM;
        } else {
            return param;
        }
    }

    /** Returns a flag indicating if also expired resources should be found.
     * @return A flag indicating if also expired resources should be found.
     */
    private Boolean getIgnoreExpirationDate() {

        return parseOptionalBooleanValue(XML_ELEMENT_IGNORE_EXPIRATION_DATE);
    }

    /** Returns a flag, indicating if the query and lastquery parameters should be ignored. E.g., if only the additional parameters should be used for the search.
     * @return A flag, indicating if the query and lastquery parameters should be ignored.
     */
    private Boolean getIgnoreQuery() {

        return parseOptionalBooleanValue(XML_ELEMENT_IGNORE_QUERY);
    }

    /** Returns a flag indicating if also unreleased resources should be found.
     * @return A flag indicating if also unreleased resources should be found.
     */
    private Boolean getIgnoreReleaseDate() {

        return parseOptionalBooleanValue(XML_ELEMENT_IGNORE_RELEASE_DATE);
    }

    /** Returns the configured Solr index, or <code>null</code> if the core is not specified.
     * @param cms the current context.
     * @return The configured Solr index, or <code>null</code> if the core is not specified.
     */
    private String getIndex(CmsObject cms) {

        String indexName = parseOptionalStringValue(XML_ELEMENT_INDEX);
        if (null != indexName) {
            indexName = indexName.trim();
        }
        return null != indexName
        ? indexName
        : (cms.getRequestContext().getCurrentProject().isOnlineProject()
        ? CmsSolrIndex.DEFAULT_INDEX_NAME_ONLINE
        : CmsSolrIndex.DEFAULT_INDEX_NAME_OFFLINE);
    }

    /** Returns the configured request parameter for the last query, or the default parameter if the core is not specified.
     * @return The configured request parameter for the last query, or the default parameter if the core is not specified.
     */
    private String getLastQueryParam() {

        final String param = parseOptionalStringValue(XML_ELEMENT_LAST_QUERYPARAM);
        if (param == null) {
            return DEFAULT_LAST_QUERY_PARAM;
        } else {
            return param;
        }
    }

    /** Returns the configured length of the "Google"-like page navigation, or the default length if it is not configured.
     * @return The configured length of the "Google"-like page navigation, or the default length if it is not configured.
     */
    private Integer getPageNavLength() {

        return parseOptionalIntValue(XML_ELEMENT_PAGENAVLENGTH);
    }

    /** Returns the configured request parameter for the current page, or the default parameter if the core is not specified.
     * @return The configured request parameter for the current page, or the default parameter if the core is not specified.
     */
    private String getPageParam() {

        return parseOptionalStringValue(XML_ELEMENT_PAGEPARAM);
    }

    /** Returns the configured page size, or the default page size if it is not configured.
     * @return The configured page size, or the default page size if it is not configured.
     */
    private List<Integer> getPageSizes() {

        final String pageSizes = parseOptionalStringValue(XML_ELEMENT_PAGESIZE);
        if (pageSizes != null) {
            String[] pageSizesArray = pageSizes.split("-");
            if (pageSizesArray.length > 0) {
                try {
                    List<Integer> result = new ArrayList<>(pageSizesArray.length);
                    for (int i = 0; i < pageSizesArray.length; i++) {
                        result.add(Integer.valueOf(pageSizesArray[i]));
                    }
                    return result;
                } catch (NumberFormatException e) {
                    LOG.warn(Messages.get().getBundle().key(Messages.LOG_PARSING_PAGE_SIZES_FAILED_1, pageSizes), e);
                }
            }
        }
        return null;
    }

    /** Returns the optional query modifier.
     * @return the optional query modifier.
     */
    private String getQueryModifier() {

        return parseOptionalStringValue(XML_ELEMENT_QUERY_MODIFIER);
    }

    /** Returns the configured request parameter for the current query string, or the default parameter if the core is not specified.
     * @return The configured request parameter for the current query string, or the default parameter if the core is not specified.
     */
    private String getQueryParam() {

        final String param = parseOptionalStringValue(XML_ELEMENT_QUERYPARAM);
        if (param == null) {
            return DEFAULT_QUERY_PARAM;
        } else {
            return param;
        }
    }

    /** Returns a flag, indicating if search should be performed using a wildcard if the empty query is given.
     * @return A flag, indicating if search should be performed using a wildcard if the empty query is given.
     */
    private Boolean getSearchForEmtpyQuery() {

        return parseOptionalBooleanValue(XML_ELEMENT_SEARCH_FOR_EMPTY_QUERY);
    }

    /** Returns the configured sort options, or the empty list if no such options are configured.
     * @return The configured sort options, or the empty list if no such options are configured.
     */
    private List<I_CmsSearchConfigurationSortOption> getSortOptions() {

        final List<I_CmsSearchConfigurationSortOption> options = new ArrayList<I_CmsSearchConfigurationSortOption>();
        final CmsXmlContentValueSequence sortOptions = m_xml.getValueSequence(XML_ELEMENT_SORTOPTIONS, m_locale);
        if (sortOptions == null) {
            return null;
        } else {
            for (int i = 0; i < sortOptions.getElementCount(); i++) {
                final I_CmsSearchConfigurationSortOption option = parseSortOption(
                    sortOptions.getValue(i).getPath() + "/");
                if (option != null) {
                    options.add(option);
                }
            }
            return options;
        }
    }

    /** Returns the configured request parameter for the current sort option, or the default parameter if the core is not specified.
     * @return The configured request parameter for the current sort option, or the default parameter if the core is not specified.
     */
    private String getSortParam() {

        return parseOptionalStringValue(XML_ELEMENT_SORTPARAM);
    }

    /** Parses a single query facet item with query and label.
     * @param prefix path to the query facet item (with trailing '/').
     * @return the query facet item.
     */
    private I_CmsFacetQueryItem parseFacetQueryItem(final String prefix) {

        I_CmsXmlContentValue query = m_xml.getValue(prefix + XML_ELEMENT_QUERY_FACET_QUERY_QUERY, m_locale);
        if (null != query) {
            String queryString = query.getStringValue(null);
            I_CmsXmlContentValue label = m_xml.getValue(prefix + XML_ELEMENT_QUERY_FACET_QUERY_LABEL, m_locale);
            String labelString = null != label ? label.getStringValue(null) : null;
            return new CmsFacetQueryItem(queryString, labelString);
        } else {
            return null;
        }
    }

    /** Helper to read a mandatory String value.
     * @param path The XML path of the element to read.
     * @return The String value stored in the XML.
     * @throws Exception thrown if the value could not be read.
     */
    private String parseMandatoryStringValue(final String path) throws Exception {

        final String value = parseOptionalStringValue(path);
        if (value == null) {
            throw new Exception();
        }
        return value;
    }

    /** Returns the configuration of a single sort option, or <code>null</code> if the XML cannot be read.
     * @param pathPrefix The XML path to the root node of the sort option's configuration.
     * @return The configuration of a single sort option, or <code>null</code> if the XML cannot be read.
     */
    private I_CmsSearchConfigurationSortOption parseSortOption(final String pathPrefix) {

        try {
            final String solrValue = parseMandatoryStringValue(pathPrefix + XML_ELEMENT_SORTOPTION_SOLRVALUE);
            String paramValue = parseOptionalStringValue(pathPrefix + XML_ELEMENT_SORTOPTION_PARAMVALUE);
            paramValue = (paramValue == null) ? solrValue : paramValue;
            String label = parseOptionalStringValue(pathPrefix + XML_ELEMENT_SORTOPTION_LABEL);
            label = (label == null) ? paramValue : label;
            return new CmsSearchConfigurationSortOption(label, paramValue, solrValue);
        } catch (final Exception e) {
            LOG.error(
                Messages.get().getBundle().key(
                    Messages.ERR_SORT_OPTION_NOT_PARSABLE_1,
                    XML_ELEMENT_SORTOPTION_SOLRVALUE),
                e);
            return null;
        }
    }
}