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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.PrefixQuery;
import org.apache.lucene.search.Query;
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;

/**
 * A Query that matches documents containing terms with a specified prefix.
 */
public class PrefixQueryBuilder extends AbstractQueryBuilder implements MultiTermQueryBuilder {
    public static final String NAME = "prefix";

    private static final ParseField PREFIX_FIELD = new ParseField("value", "prefix");
    private static final ParseField REWRITE_FIELD = new ParseField("rewrite");

    private final String fieldName;

    private final String value;

    private String rewrite;

    /**
     * A Query that matches documents containing terms with a specified prefix.
     *
     * @param fieldName The name of the field
     * @param value The prefix query
     */
    public PrefixQueryBuilder(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 PrefixQueryBuilder(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 this.fieldName;
    }

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

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

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

    @Override
    public void doXContent(XContentBuilder builder, Params params) throws IOException {
        builder.startObject(NAME);
        builder.startObject(fieldName);
        builder.field(PREFIX_FIELD.getPreferredName(), this.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();

        String fieldName = null;
        String value = null;
        String rewrite = null;

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

        return Optional.of(new PrefixQueryBuilder(fieldName, value)
                .rewrite(rewrite)
                .boost(boost)
                .queryName(queryName));
    }

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

    @Override
    protected Query doToQuery(QueryShardContext context) throws IOException {
        MultiTermQuery.RewriteMethod method = QueryParsers.parseRewriteMethod(rewrite, null);

        Query query = null;
        MappedFieldType fieldType = context.fieldMapper(fieldName);
        if (fieldType != null) {
            query = fieldType.prefixQuery(value, method, context);
        }
        if (query == null) {
            PrefixQuery prefixQuery = new PrefixQuery(new Term(fieldName, BytesRefs.toBytesRef(value)));
            if (method != null) {
                prefixQuery.setRewriteMethod(method);
            }
            query = prefixQuery;
        }

        return query;
    }

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

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