/*
 * Licensed 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
 *
 *  https://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.
 *
 * Other licenses:
 * -----------------------------------------------------------------------------
 * Commercial licenses for this work are available. These replace the above
 * Apache-2.0 license and offer limited warranties, support, maintenance, and
 * commercial database integrations.
 *
 * For more information, please visit: https://www.jooq.org/legal/licensing
 *
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 */
package org.jooq.impl;

import static org.jooq.conf.StatementType.STATIC_STATEMENT;

import java.sql.CallableStatement;
import java.sql.ResultSet;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.jooq.DSLContext;
import org.jooq.Explain;
import org.jooq.Field;
import org.jooq.Query;
import org.jooq.Record;
import org.jooq.Result;
import org.jooq.conf.ParamType;

// ...

/**
 * @author Lukas Eder
 */
final class ExplainQuery {

    static Explain explain(final DSLContext ctx, final Query query) {
        Result<Record> result = null;

        switch (ctx.family()) {





















            case H2:
                result = ctx.fetch("{explain analyze} {0}", query);
                break;

            // [#12381] No bind values supported in HSQLDB
            case HSQLDB:
                result = ctx.configuration()
                            .deriveSettings(s -> s.withStatementType(STATIC_STATEMENT))
                            .dsl()
                            .fetch("{explain plan for} {0}", query);
                break;

            default:
                result = ctx.fetch("{explain} {0}", query);
                break;
        }

        double cost = Double.NaN;
        double rows = Double.NaN;

        switch (ctx.family()) {























            // H2's EXPLAIN ANALYZE output is rather difficult to digest
            case H2:

            // HSQLDB's EXPLAIN PLAN FOR output doesn't contain any useful additional information
            case HSQLDB:
                break;

            case MARIADB:
            case MYSQL: {
                // MySQL doesn't expose any cost (yet).
                rows = result.get(0).get("rows", double.class);
                break;
            }


            case POSTGRES:
            case YUGABYTEDB: {
                Matcher matcher = Pattern
                    .compile(".*\\bcost=\\d+\\.\\d+\\.\\.(\\d+\\.\\d+)\\s+rows=(\\d+).*")
                    .matcher(result.get(0).get(0, String.class));
                cost = Double.parseDouble(matcher.replaceAll("$1"));
                rows = Double.parseDouble(matcher.replaceAll("$2"));

                break;
            }
        }

        return new ExplainImpl(rows, cost, result.format());
    }

    private static final record ExplainImpl(double rows, double cost, String plan) implements Explain {

        @Override
        public String toString() {
            return String.format("Explain [cost=%.2f, rows=%.2f]\n\n", cost, rows) + plan;
        }
    }
}
