/*
 * Licensed to ElasticSearch and Shay Banon 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.ConstantScoreQuery;
import org.apache.lucene.search.Filter;
import org.apache.lucene.search.Query;
import org.elasticsearch.common.Strings;
import org.elasticsearch.common.inject.Inject;
import org.elasticsearch.common.lucene.search.XBooleanFilter;
import org.elasticsearch.common.lucene.search.XFilteredQuery;
import org.elasticsearch.common.xcontent.XContentParser;
import org.elasticsearch.index.mapper.DocumentMapper;
import org.elasticsearch.index.mapper.internal.ParentFieldMapper;
import org.elasticsearch.index.search.child.HasParentFilter;
import org.elasticsearch.index.search.child.ParentQuery;
import org.elasticsearch.search.internal.SearchContext;

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

public class HasParentQueryParser implements QueryParser {

    public static final String NAME = "has_parent";

    @Inject
    public HasParentQueryParser() {
    }

    @Override
    public String[] names() {
        return new String[]{NAME, Strings.toCamelCase(NAME)};
    }

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

        Query innerQuery = null;
        boolean queryFound = false;
        float boost = 1.0f;
        String parentType = null;
        String scope = null;
        boolean score = false;
        String executionType = "uid";

        String currentFieldName = null;
        XContentParser.Token token;
        while ((token = parser.nextToken()) != XContentParser.Token.END_OBJECT) {
            if (token == XContentParser.Token.FIELD_NAME) {
                currentFieldName = parser.currentName();
            } else if (token == XContentParser.Token.START_OBJECT) {
                if ("query".equals(currentFieldName)) {
                    // TODO handle `query` element before `type` element...
                    String[] origTypes = QueryParseContext.setTypesWithPrevious(parentType == null ? null : new String[]{parentType});
                    try {
                        innerQuery = parseContext.parseInnerQuery();
                        queryFound = true;
                    } finally {
                        QueryParseContext.setTypes(origTypes);
                    }
                } else {
                    throw new QueryParsingException(parseContext.index(), "[has_parent] query does not support [" + currentFieldName + "]");
                }
            } else if (token.isValue()) {
                if ("type".equals(currentFieldName) || "parent_type".equals(currentFieldName) || "parentType".equals(currentFieldName)) {
                    parentType = parser.text();
                } else if ("_scope".equals(currentFieldName)) {
                    scope = parser.text();
                } else if ("execution_type".equals(currentFieldName) || "executionType".equals(currentFieldName)) {
                    executionType = parser.text();
                } else if ("score_type".equals(currentFieldName) || "scoreType".equals(currentFieldName)) {
                    String scoreTypeValue = parser.text();
                    if ("score".equals(scoreTypeValue)) {
                        score = true;
                    } else if ("none".equals(scoreTypeValue)) {
                        score = false;
                    }
                } else if ("boost".equals(currentFieldName)) {
                    boost = parser.floatValue();
                } else {
                    throw new QueryParsingException(parseContext.index(), "[has_parent] query does not support [" + currentFieldName + "]");
                }
            }
        }
        if (!queryFound) {
            throw new QueryParsingException(parseContext.index(), "[parent] query requires 'query' field");
        }
        if (innerQuery == null) {
            return null;
        }

        if (parentType == null) {
            throw new QueryParsingException(parseContext.index(), "[parent] query requires 'parent_type' field");
        }

        DocumentMapper parentDocMapper = parseContext.mapperService().documentMapper(parentType);
        if (parentDocMapper == null) {
            throw new QueryParsingException(parseContext.index(), "[parent] query configured 'parent_type' [" + parentType + "] is not a valid type");
        }

        List<String> childTypes = new ArrayList<String>(2);
        for (DocumentMapper documentMapper : parseContext.mapperService()) {
            ParentFieldMapper parentFieldMapper = documentMapper.parentFieldMapper();
            if (parentFieldMapper == null) {
                continue;
            }

            if (parentDocMapper.type().equals(parentFieldMapper.type())) {
                childTypes.add(documentMapper.type());
            }
        }

        Filter childFilter;
        if (childTypes.size() == 1) {
            DocumentMapper documentMapper = parseContext.mapperService().documentMapper(childTypes.get(0));
            childFilter = parseContext.cacheFilter(documentMapper.typeFilter(), null);
        } else {
            XBooleanFilter childrenFilter = new XBooleanFilter();
            for (String childType : childTypes) {
                DocumentMapper documentMapper = parseContext.mapperService().documentMapper(childType);
                Filter filter = parseContext.cacheFilter(documentMapper.typeFilter(), null);
                childrenFilter.add(filter, BooleanClause.Occur.SHOULD);
            }
            childFilter = childrenFilter;
        }

        innerQuery.setBoost(boost);
        // wrap the query with type query
        innerQuery = new XFilteredQuery(innerQuery, parseContext.cacheFilter(parentDocMapper.typeFilter(), null));
        SearchContext searchContext = SearchContext.current();
        Query query;
        if (score) {
            ParentQuery parentQuery = new ParentQuery(searchContext, innerQuery, parentType, childTypes, childFilter, scope);
            searchContext.addScopePhase(parentQuery);
            query = parentQuery;
        } else {
            HasParentFilter hasParentFilter = HasParentFilter.create(executionType, innerQuery, scope, parentType, searchContext);
            searchContext.addScopePhase(hasParentFilter);
            query = new ConstantScoreQuery(hasParentFilter);
        }
        query.setBoost(boost);
        return query;
    }

}