/*
 * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
 * or more contributor license agreements. Licensed under the Elastic License
 * 2.0 and the Server Side Public License, v 1; you may not use this file except
 * in compliance with, at your election, the Elastic License 2.0 or the Server
 * Side Public License, v 1.
 */

package org.elasticsearch.index.query;

import org.apache.lucene.queries.spans.FieldMaskingSpanQuery;
import org.apache.lucene.queries.spans.SpanQuery;
import org.apache.lucene.search.Query;
import org.elasticsearch.TransportVersion;
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.index.mapper.MappedFieldType;
import org.elasticsearch.xcontent.ParseField;
import org.elasticsearch.xcontent.XContentBuilder;
import org.elasticsearch.xcontent.XContentParser;

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

import static org.elasticsearch.index.query.SpanQueryBuilder.SpanQueryBuilderUtil.checkNoBoost;

public class FieldMaskingSpanQueryBuilder extends AbstractQueryBuilder<FieldMaskingSpanQueryBuilder> implements SpanQueryBuilder {
    public static final ParseField NAME = new ParseField("span_field_masking", "field_masking_span");

    private static final ParseField FIELD_FIELD = new ParseField("field");
    private static final ParseField QUERY_FIELD = new ParseField("query");

    private final SpanQueryBuilder queryBuilder;

    private final String fieldName;

    /**
     * Constructs a new {@link FieldMaskingSpanQueryBuilder} given an inner {@link SpanQueryBuilder} for
     * a given field
     * @param queryBuilder inner {@link SpanQueryBuilder}
     * @param fieldName the field name
     */
    public FieldMaskingSpanQueryBuilder(SpanQueryBuilder queryBuilder, String fieldName) {
        if (Strings.isEmpty(fieldName)) {
            throw new IllegalArgumentException("field name is null or empty");
        }
        if (queryBuilder == null) {
            throw new IllegalArgumentException("inner clause [query] cannot be null.");
        }
        this.queryBuilder = queryBuilder;
        this.fieldName = fieldName;
    }

    /**
     * Read from a stream.
     */
    public FieldMaskingSpanQueryBuilder(StreamInput in) throws IOException {
        super(in);
        queryBuilder = (SpanQueryBuilder) in.readNamedWriteable(QueryBuilder.class);
        fieldName = in.readString();
    }

    @Override
    protected void doWriteTo(StreamOutput out) throws IOException {
        out.writeNamedWriteable(queryBuilder);
        out.writeString(fieldName);
    }

    /**
     * @return the field name for this query
     */
    public String fieldName() {
        return this.fieldName;
    }

    /**
     * @return the inner {@link QueryBuilder}
     */
    public SpanQueryBuilder innerQuery() {
        return this.queryBuilder;
    }

    @Override
    protected void doXContent(XContentBuilder builder, Params params) throws IOException {
        builder.startObject(NAME.getPreferredName());
        builder.field(QUERY_FIELD.getPreferredName());
        queryBuilder.toXContent(builder, params);
        builder.field(FIELD_FIELD.getPreferredName(), fieldName);
        boostAndQueryNameToXContent(builder);
        builder.endObject();
    }

    public static FieldMaskingSpanQueryBuilder fromXContent(XContentParser parser) throws IOException {
        float boost = AbstractQueryBuilder.DEFAULT_BOOST;

        SpanQueryBuilder inner = null;
        String field = null;
        String queryName = null;

        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_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
                    QueryBuilder query = parseInnerQueryBuilder(parser);
                    if (query instanceof SpanQueryBuilder == false) {
                        throw new ParsingException(
                            parser.getTokenLocation(),
                            "[" + NAME.getPreferredName() + "] query must be of type span query"
                        );
                    }
                    inner = (SpanQueryBuilder) query;
                    checkNoBoost(NAME.getPreferredName(), currentFieldName, parser, inner);
                } else {
                    throw new ParsingException(
                        parser.getTokenLocation(),
                        "[" + NAME.getPreferredName() + "] query does not support [" + currentFieldName + "]"
                    );
                }
            } else {
                if (AbstractQueryBuilder.BOOST_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
                    boost = parser.floatValue();
                } else if (FIELD_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
                    field = parser.text();
                } else if (AbstractQueryBuilder.NAME_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
                    queryName = parser.text();
                } else {
                    throw new ParsingException(
                        parser.getTokenLocation(),
                        "[" + NAME.getPreferredName() + "] query does not support [" + currentFieldName + "]"
                    );
                }
            }
        }
        if (inner == null) {
            throw new ParsingException(parser.getTokenLocation(), NAME.getPreferredName() + " must have [query] span query clause");
        }
        if (field == null) {
            throw new ParsingException(parser.getTokenLocation(), NAME.getPreferredName() + " must have [field] set for it");
        }
        FieldMaskingSpanQueryBuilder queryBuilder = new FieldMaskingSpanQueryBuilder(inner, field);
        queryBuilder.boost(boost);
        queryBuilder.queryName(queryName);
        return queryBuilder;
    }

    @Override
    protected Query doToQuery(SearchExecutionContext context) throws IOException {
        String fieldInQuery = fieldName;
        MappedFieldType fieldType = context.getFieldType(fieldName);
        if (fieldType != null) {
            fieldInQuery = fieldType.name();
        }
        Query innerQuery = queryBuilder.toQuery(context);
        assert innerQuery instanceof SpanQuery;
        return new FieldMaskingSpanQuery((SpanQuery) innerQuery, fieldInQuery);
    }

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

    @Override
    protected boolean doEquals(FieldMaskingSpanQueryBuilder other) {
        return Objects.equals(queryBuilder, other.queryBuilder) && Objects.equals(fieldName, other.fieldName);
    }

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

    @Override
    public TransportVersion getMinimalSupportedVersion() {
        return TransportVersion.ZERO;
    }
}
