/*
 * Licensed to Elasticsearch under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch licenses this file to you under
 * the Apache License, Version 2.0 (the "License"); you may
 * not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.elasticsearch.index.query;

import org.apache.lucene.search.BooleanClause;
import org.apache.lucene.search.Filter;
import org.apache.lucene.search.TermRangeFilter;
import org.elasticsearch.common.inject.Inject;
import org.elasticsearch.common.lucene.search.NotFilter;
import org.elasticsearch.common.lucene.search.Queries;
import org.elasticsearch.common.lucene.search.XBooleanFilter;
import org.elasticsearch.common.xcontent.XContentParser;
import org.elasticsearch.index.cache.filter.support.CacheKeyFilter;
import org.elasticsearch.index.mapper.FieldMappers;
import org.elasticsearch.index.mapper.MapperService;
import org.elasticsearch.index.mapper.internal.FieldNamesFieldMapper;

import java.io.IOException;
import java.util.List;
import java.util.Set;

import static org.elasticsearch.index.query.support.QueryParsers.wrapSmartNameFilter;

/**
 *
 */
public class MissingFilterParser implements FilterParser {

    public static final String NAME = "missing";
    public static final boolean DEFAULT_NULL_VALUE = false;
    public static final boolean DEFAULT_EXISTENCE_VALUE = true;

    @Inject
    public MissingFilterParser() {
    }

    @Override
    public String[] names() {
        return new String[]{NAME};
    }

    @Override
    public Filter parse(QueryParseContext parseContext) throws IOException, QueryParsingException {
        XContentParser parser = parseContext.parser();

        String fieldPattern = null;
        String filterName = null;
        boolean nullValue = DEFAULT_NULL_VALUE;
        boolean existence = DEFAULT_EXISTENCE_VALUE;

        XContentParser.Token token;
        String currentFieldName = null;
        while ((token = parser.nextToken()) != XContentParser.Token.END_OBJECT) {
            if (token == XContentParser.Token.FIELD_NAME) {
                currentFieldName = parser.currentName();
            } else if (token.isValue()) {
                if ("field".equals(currentFieldName)) {
                    fieldPattern = parser.text();
                } else if ("null_value".equals(currentFieldName)) {
                    nullValue = parser.booleanValue();
                } else if ("existence".equals(currentFieldName)) {
                    existence = parser.booleanValue();
                } else if ("_name".equals(currentFieldName)) {
                    filterName = parser.text();
                } else {
                    throw new QueryParsingException(parseContext.index(), "[missing] filter does not support [" + currentFieldName + "]");
                }
            }
        }

        if (fieldPattern == null) {
            throw new QueryParsingException(parseContext.index(), "missing must be provided with a [field]");
        }

        return newFilter(parseContext, fieldPattern, existence, nullValue, filterName);
    }

    public static Filter newFilter(QueryParseContext parseContext, String fieldPattern, boolean existence, boolean nullValue, String filterName) {
        if (!existence && !nullValue) {
            throw new QueryParsingException(parseContext.index(), "missing must have either existence, or null_value, or both set to true");
        }

        final FieldMappers fieldNamesMappers = parseContext.mapperService().fullName(FieldNamesFieldMapper.NAME);
        final FieldNamesFieldMapper fieldNamesMapper = fieldNamesMappers == null ? null : (FieldNamesFieldMapper)fieldNamesMappers.mapper();
        MapperService.SmartNameObjectMapper smartNameObjectMapper = parseContext.smartObjectMapper(fieldPattern);
        if (smartNameObjectMapper != null && smartNameObjectMapper.hasMapper()) {
            // automatic make the object mapper pattern
            fieldPattern = fieldPattern + ".*";
        }

        List<String> fields = parseContext.simpleMatchToIndexNames(fieldPattern);
        if (fields.isEmpty()) {
            if (existence) {
                // if we ask for existence of fields, and we found none, then we should match on all
                return Queries.MATCH_ALL_FILTER;
            }
            return null;
        }

        Filter existenceFilter = null;
        Filter nullFilter = null;

        MapperService.SmartNameFieldMappers nonNullFieldMappers = null;

        if (existence) {
            XBooleanFilter boolFilter = new XBooleanFilter();
            for (String field : fields) {
                MapperService.SmartNameFieldMappers smartNameFieldMappers = parseContext.smartFieldMappers(field);
                if (smartNameFieldMappers != null) {
                    nonNullFieldMappers = smartNameFieldMappers;
                }
                Filter filter = null;
                if (fieldNamesMapper != null && fieldNamesMapper.enabled()) {
                    final String f;
                    if (smartNameFieldMappers != null && smartNameFieldMappers.hasMapper()) {
                        f = smartNameFieldMappers.mapper().names().indexName();
                    } else {
                        f = field;
                    }
                    filter = fieldNamesMapper.termFilter(f, parseContext);
                }
                // if _field_names are not indexed, we need to go the slow way
                if (filter == null && smartNameFieldMappers != null && smartNameFieldMappers.hasMapper()) {
                    filter = smartNameFieldMappers.mapper().rangeFilter(null, null, true, true, parseContext);
                }
                if (filter == null) {
                    filter = new TermRangeFilter(field, null, null, true, true);
                }
                boolFilter.add(filter, BooleanClause.Occur.SHOULD);
            }

            // we always cache this one, really does not change... (exists)
            // its ok to cache under the fieldName cacheKey, since its per segment and the mapping applies to this data on this segment...
            existenceFilter = parseContext.cacheFilter(boolFilter, new CacheKeyFilter.Key("$exists$" + fieldPattern));
            existenceFilter = new NotFilter(existenceFilter);
            // cache the not filter as well, so it will be faster
            existenceFilter = parseContext.cacheFilter(existenceFilter, new CacheKeyFilter.Key("$missing$" + fieldPattern));
        }

        if (nullValue) {
            for (String field : fields) {
                MapperService.SmartNameFieldMappers smartNameFieldMappers = parseContext.smartFieldMappers(field);
                if (smartNameFieldMappers != null && smartNameFieldMappers.hasMapper()) {
                    nullFilter = smartNameFieldMappers.mapper().nullValueFilter();
                    if (nullFilter != null) {
                        // cache the not filter as well, so it will be faster
                        nullFilter = parseContext.cacheFilter(nullFilter, new CacheKeyFilter.Key("$null$" + fieldPattern));
                    }
                }
            }
        }

        Filter filter;
        if (nullFilter != null) {
            if (existenceFilter != null) {
                XBooleanFilter combined = new XBooleanFilter();
                combined.add(existenceFilter, BooleanClause.Occur.SHOULD);
                combined.add(nullFilter, BooleanClause.Occur.SHOULD);
                // cache the not filter as well, so it will be faster
                filter = parseContext.cacheFilter(combined, null);
            } else {
                filter = nullFilter;
            }
        } else {
            filter = existenceFilter;
        }

        if (filter == null) {
            return null;
        }

        filter = wrapSmartNameFilter(filter, nonNullFieldMappers, parseContext);
        if (filterName != null) {
            parseContext.addNamedFilter(filterName, existenceFilter);
        }
        return filter;
    }
}
