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RESTHeart MongoDB - MongoDB plugin
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/*-
 * ========================LICENSE_START=================================
 * restheart-mongodb
 * %%
 * Copyright (C) 2014 - 2024 SoftInstigate
 * %%
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see .
 * =========================LICENSE_END==================================
 */
package org.restheart.mongodb.handlers.aggregation;

import java.util.regex.Matcher;

import org.bson.BsonDocument;
import org.bson.BsonValue;
import org.restheart.exchange.InvalidMetadataException;
import org.restheart.exchange.QueryVariableNotBoundException;
import org.restheart.mongodb.utils.VarsInterpolator;
import static org.restheart.mongodb.utils.VarsInterpolator.VAR_OPERATOR;
import org.restheart.utils.BsonUtils;

/**
 * represents a map reduce.
 *
 * @author Andrea Di Cesare {@literal }
 */
public class MapReduce extends AbstractAggregationOperation {

    /**
     *
     */
    public static final String MAP_ELEMENT_NAME = "map";

    /**
     *
     */
    public static final String REDUCE_ELEMENT_NAME = "reduce";

    /**
     *
     */
    public static final String QUERY_ELEMENT_NAME = "query";
    private final String map;
    private final String reduce;
    private final BsonValue query;

    /**
     * @param properties the json properties object. It must include the
     * following properties:
     * 
     * type
     * uri
     * map
     * reduce
     * 
     * Optionally it can include the following property:
     * 
     * query
     * 
     * Note that the dollar prefixed operators in the query
     * must be underscore escaped, e.g. "_$exits"
     * 
     * Example:      
     * aggregations: [
     * {
     *   "type":"mapReduce",
     *   "uri":"test",
     *   "map":"function() { emit(this.name, this.age) }",
     *   "reduce":"function(key, values) { return Array.avg(values) }",
     *   "query": {"name":{"_$exists":true}}
     * }]
     * 
     * @throws org.restheart.exchange.InvalidMetadataException
     */
    public MapReduce(BsonDocument properties)
            throws InvalidMetadataException {
        super(properties);

        BsonValue _map = properties.get(MAP_ELEMENT_NAME);
        BsonValue _reduce = properties.get(REDUCE_ELEMENT_NAME);
        BsonValue _query = properties.get(QUERY_ELEMENT_NAME);

        if (_map == null || !_map.isString()) {
            throw new InvalidMetadataException("invalid query with uri "
                    + getUri() + "; the "
                    + MAP_ELEMENT_NAME
                    + " property is not valid: " + _map);
        }

        if (_reduce == null || !_map.isString()) {
            throw new InvalidMetadataException("invalid query with uri "
                    + getUri()
                    + "; the " + REDUCE_ELEMENT_NAME
                    + " property is not valid: " + _reduce);
        }

        if (_query == null || !_query.isDocument()) {
            throw new InvalidMetadataException("invalid query with uri "
                    + getUri()
                    + "; the " + QUERY_ELEMENT_NAME
                    + " property is not valid: " + _query);
        }

        this.map = _map.asString().getValue();
        this.reduce = _reduce.asString().getValue();
        this.query = _query;
    }

    /**
     * @return the map
     */
    public String getMap() {
        return map;
    }

    /**
     * @return the reduce
     */
    public String getReduce() {
        return reduce;
    }

    /**
     * @return the query
     */
    public BsonValue getQuery() {
        return query;
    }

    /**
     * @param aVars RequestContext.getAggregationVars()
     * @return the query with unescaped operators and bound variables
     * @throws org.restheart.exchange.InvalidMetadataException
     * @throws org.restheart.exchange.QueryVariableNotBoundException
     */
    public BsonDocument getResolvedQuery(BsonDocument aVars)
            throws InvalidMetadataException, QueryVariableNotBoundException {
        return VarsInterpolator.interpolate(VAR_OPERATOR.$var, BsonUtils.unescapeKeys(query), aVars).asDocument();
    }

    /**
     * @param aVars RequestContext.getAggregationVars()
     * @return the map function with bound aggregation variables
     */
    public String getResolvedMap(BsonDocument aVars) {
        if (aVars == null || aVars.isEmpty()) {
            return map;
        } else {
            String escapedAVars = "\""
                    + aVars.toString().replaceAll("\"", "\\\\\\\\\"")
                    + "\"";

            String ret = map == null ? null
                    : map.replaceAll(
                            Matcher.quoteReplacement("$") + "vars",
                            escapedAVars);

            return ret;
        }
    }

    /**
     * @param aVars RequestContext.getAggregationVars()
     * @return the reduce function with bound aggregation variables
     */
    public String getResolvedReduce(BsonDocument aVars) {
        if (aVars == null || aVars.isEmpty()) {
            return reduce;
        } else {
            String escapedAVars = "\""
                    + aVars.toString().replaceAll("\"", "\\\\\\\\\"")
                    + "\"";

            String ret = reduce == null ? null
                    : reduce.replaceAll(
                            Matcher.quoteReplacement("$") + "vars",
                            escapedAVars
                    );

            return ret;
        }
    }
}