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/*
 * 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
 *
 *     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 com.facebook.presto.jdbc;

import java.sql.Statement;
import java.util.Map;
import java.util.Optional;

public interface QueryInterceptor
{
    /**
     * Called once per {@link PrestoConnection} at instantiation.
     *
     * @param properties the session properties supplied in the URI
     */
    default void init(Map properties)
    {
    }

    /**
     * Called once to release any resources when {@link PrestoConnection} is closing.
     */
    default void destroy()
    {
    }

    /**
     * Called before the query has been sent to the server. This method is only called on
     * top-level queries i.e. a query executed by a {@link QueryInterceptor} is not intercepted.
     *
     * This method can optionally return a {@link PrestoResultSet}. If a PrestoResultSet is returned from
     * from preProcess then the intercepted query is not executed and that PrestoResultSet is
     * returned instead. If there are multiple  QueryInterceptors, preProcess will be called
     * on each and the last PrestoResultSet is returned.
     *
     * @param sql the SQL string of the query.
     * @param interceptedStatement the Statement being executed.
     * @return optional PrestoResultSet to be returned
     */
    default Optional preProcess(String sql, Statement interceptedStatement)
    {
        return Optional.empty();
    }

    /**
     * Called after the query has been sent to the server. This method is only called on
     * top-level queries i.e. a query executed by a {@link QueryInterceptor} is not intercepted.
     *
     * This method can optionally return a {@link PrestoResultSet}. If a PrestoResultSet is returned
     * from postProcess then that PrestoResultSet  is returned instead. If there are multiple
     *  QueryInterceptors, postProcess will be called on each and the last PrestoResultSet is returned.
     *
     * @param sql the SQL string of the query.
     * @param interceptedStatement the {@link Statement} being executed.
     * @param interceptedResultSet the intercepted PrestoResultSet
     * @return optional PrestoResultSet to be returned instead of the original PrestoResultSet
     */
    default Optional postProcess(String sql, Statement interceptedStatement, PrestoResultSet interceptedResultSet)
    {
        return Optional.empty();
    }
}