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/*
 * 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; you may not use this file except in compliance with the Elastic License
 * 2.0.
 */

package org.elasticsearch.xpack.esql.optimizer.rules;

import org.elasticsearch.xpack.esql.core.expression.Expression;
import org.elasticsearch.xpack.esql.core.expression.Literal;
import org.elasticsearch.xpack.esql.core.expression.predicate.nulls.IsNotNull;
import org.elasticsearch.xpack.esql.core.expression.predicate.regex.RegexMatch;
import org.elasticsearch.xpack.esql.core.expression.predicate.regex.StringPattern;
import org.elasticsearch.xpack.esql.core.type.DataType;
import org.elasticsearch.xpack.esql.expression.predicate.operator.comparison.Equals;

public final class ReplaceRegexMatch extends org.elasticsearch.xpack.esql.core.optimizer.OptimizerRules.OptimizerExpressionRule<
    RegexMatch> {

    public ReplaceRegexMatch() {
        super(org.elasticsearch.xpack.esql.core.optimizer.OptimizerRules.TransformDirection.DOWN);
    }

    @Override
    public Expression rule(RegexMatch regexMatch) {
        Expression e = regexMatch;
        StringPattern pattern = regexMatch.pattern();
        if (pattern.matchesAll()) {
            e = new IsNotNull(e.source(), regexMatch.field());
        } else {
            String match = pattern.exactMatch();
            if (match != null) {
                Literal literal = new Literal(regexMatch.source(), match, DataType.KEYWORD);
                e = regexToEquals(regexMatch, literal);
            }
        }
        return e;
    }

    protected Expression regexToEquals(RegexMatch regexMatch, Literal literal) {
        return new Equals(regexMatch.source(), regexMatch.field(), literal);
    }
}