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/*
 * 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.index.Term;
import org.apache.lucene.search.MultiTermQuery;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.WildcardQuery;
import org.elasticsearch.common.ParseField;
import org.elasticsearch.common.ParsingException;
import org.elasticsearch.common.Strings;
import org.elasticsearch.common.io.stream.StreamInput;
import org.elasticsearch.common.io.stream.StreamOutput;
import org.elasticsearch.common.lucene.BytesRefs;
import org.elasticsearch.common.xcontent.XContentBuilder;
import org.elasticsearch.common.xcontent.XContentParser;
import org.elasticsearch.index.mapper.MappedFieldType;
import org.elasticsearch.index.query.support.QueryParsers;

import java.io.IOException;
import java.util.Objects;
import java.util.Optional;

/**
 * Implements the wildcard search query. Supported wildcards are *, which
 * matches any character sequence (including the empty one), and ?,
 * which matches any single character. Note this query can be slow, as it
 * needs to iterate over many terms. In order to prevent extremely slow WildcardQueries,
 * a Wildcard term should not start with one of the wildcards * or
 * ?.
 */
public class WildcardQueryBuilder extends AbstractQueryBuilder implements MultiTermQueryBuilder {
    public static final String NAME = "wildcard";

    private static final ParseField WILDCARD_FIELD = new ParseField("wildcard");
    private static final ParseField VALUE_FIELD = new ParseField("value");
    private static final ParseField REWRITE_FIELD = new ParseField("rewrite");

    private final String fieldName;

    private final String value;

    private String rewrite;

    /**
     * Implements the wildcard search query. Supported wildcards are *, which
     * matches any character sequence (including the empty one), and ?,
     * which matches any single character. Note this query can be slow, as it
     * needs to iterate over many terms. In order to prevent extremely slow WildcardQueries,
     * a Wildcard term should not start with one of the wildcards * or
     * ?.
     *
     * @param fieldName The field name
     * @param value The wildcard query string
     */
    public WildcardQueryBuilder(String fieldName, String value) {
        if (Strings.isEmpty(fieldName)) {
            throw new IllegalArgumentException("field name is null or empty");
        }
        if (value == null) {
            throw new IllegalArgumentException("value cannot be null.");
        }
        this.fieldName = fieldName;
        this.value = value;
    }

    /**
     * Read from a stream.
     */
    public WildcardQueryBuilder(StreamInput in) throws IOException {
        super(in);
        fieldName = in.readString();
        value = in.readString();
        rewrite = in.readOptionalString();
    }

    @Override
    protected void doWriteTo(StreamOutput out) throws IOException {
        out.writeString(fieldName);
        out.writeString(value);
        out.writeOptionalString(rewrite);
    }

    public String fieldName() {
        return fieldName;
    }

    public String value() {
        return value;
    }

    public WildcardQueryBuilder rewrite(String rewrite) {
        this.rewrite = rewrite;
        return this;
    }

    public String rewrite() {
        return this.rewrite;
    }

    @Override
    public String getWriteableName() {
        return NAME;
    }

    @Override
    protected void doXContent(XContentBuilder builder, Params params) throws IOException {
        builder.startObject(NAME);
        builder.startObject(fieldName);
        builder.field(WILDCARD_FIELD.getPreferredName(), value);
        if (rewrite != null) {
            builder.field(REWRITE_FIELD.getPreferredName(), rewrite);
        }
        printBoostAndQueryName(builder);
        builder.endObject();
        builder.endObject();
    }

    public static Optional fromXContent(QueryParseContext parseContext) throws IOException {
        XContentParser parser = parseContext.parser();

        XContentParser.Token token = parser.nextToken();
        if (token != XContentParser.Token.FIELD_NAME) {
            throw new ParsingException(parser.getTokenLocation(), "[wildcard] query malformed, no field");
        }
        String fieldName = parser.currentName();
        String rewrite = null;

        String value = null;
        float boost = AbstractQueryBuilder.DEFAULT_BOOST;
        String queryName = null;
        token = parser.nextToken();
        if (token == XContentParser.Token.START_OBJECT) {
            String currentFieldName = null;
            while ((token = parser.nextToken()) != XContentParser.Token.END_OBJECT) {
                if (token == XContentParser.Token.FIELD_NAME) {
                    currentFieldName = parser.currentName();
                } else {
                    if (parseContext.getParseFieldMatcher().match(currentFieldName, WILDCARD_FIELD)) {
                        value = parser.text();
                    } else if (parseContext.getParseFieldMatcher().match(currentFieldName, VALUE_FIELD)) {
                        value = parser.text();
                    } else if (parseContext.getParseFieldMatcher().match(currentFieldName, AbstractQueryBuilder.BOOST_FIELD)) {
                        boost = parser.floatValue();
                    } else if (parseContext.getParseFieldMatcher().match(currentFieldName, REWRITE_FIELD)) {
                        rewrite = parser.textOrNull();
                    } else if (parseContext.getParseFieldMatcher().match(currentFieldName, AbstractQueryBuilder.NAME_FIELD)) {
                        queryName = parser.text();
                    } else {
                        throw new ParsingException(parser.getTokenLocation(),
                                "[wildcard] query does not support [" + currentFieldName + "]");
                    }
                }
            }
            parser.nextToken();
        } else {
            value = parser.text();
            parser.nextToken();
        }

        if (value == null) {
            throw new ParsingException(parser.getTokenLocation(), "No value specified for wildcard query");
        }
        return Optional.of(new WildcardQueryBuilder(fieldName, value)
                .rewrite(rewrite)
                .boost(boost)
                .queryName(queryName));
    }

    @Override
    protected Query doToQuery(QueryShardContext context) throws IOException {
        MappedFieldType fieldType = context.fieldMapper(fieldName);
        Term term;
        if (fieldType == null) {
            term = new Term(fieldName, BytesRefs.toBytesRef(value));
        } else {
            Query termQuery = fieldType.termQuery(value, context);
            term = MappedFieldType.extractTerm(termQuery);
        }

        WildcardQuery query = new WildcardQuery(term);
        MultiTermQuery.RewriteMethod rewriteMethod = QueryParsers.parseRewriteMethod(context.getParseFieldMatcher(), rewrite, null);
        QueryParsers.setRewriteMethod(query, rewriteMethod);
        return query;
    }

    @Override
    protected int doHashCode() {
        return Objects.hash(fieldName, value, rewrite);
    }

    @Override
    protected boolean doEquals(WildcardQueryBuilder other) {
        return Objects.equals(fieldName, other.fieldName) &&
                Objects.equals(value, other.value) &&
                Objects.equals(rewrite, other.rewrite);
    }
}




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