/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF 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.apache.flink.connector.jdbc.internal.executor;

import org.apache.flink.annotation.Internal;
import org.apache.flink.connector.jdbc.core.database.dialect.JdbcDialectConverter;
import org.apache.flink.connector.jdbc.statement.FieldNamedPreparedStatement;
import org.apache.flink.connector.jdbc.statement.StatementFactory;
import org.apache.flink.table.data.RowData;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Arrays;
import java.util.function.Function;

import static org.apache.flink.util.Preconditions.checkNotNull;

/**
 * {@link JdbcBatchStatementExecutor} that provides upsert semantics by updating row if it exists
 * and inserting otherwise. Only used in Table/SQL API.
 */
@Internal
public final class TableInsertOrUpdateStatementExecutor
        implements JdbcBatchStatementExecutor<RowData> {

    private final StatementFactory existStmtFactory;
    private final StatementFactory insertStmtFactory;
    private final StatementFactory updateStmtFactory;

    private final JdbcDialectConverter existSetter;
    private final JdbcDialectConverter insertSetter;
    private final JdbcDialectConverter updateSetter;

    private final Function<RowData, RowData> keyExtractor;

    private transient FieldNamedPreparedStatement existStatement;
    private transient FieldNamedPreparedStatement insertStatement;
    private transient FieldNamedPreparedStatement updateStatement;

    public TableInsertOrUpdateStatementExecutor(
            StatementFactory existStmtFactory,
            StatementFactory insertStmtFactory,
            StatementFactory updateStmtFactory,
            JdbcDialectConverter existSetter,
            JdbcDialectConverter insertSetter,
            JdbcDialectConverter updateSetter,
            Function<RowData, RowData> keyExtractor) {
        this.existStmtFactory = checkNotNull(existStmtFactory);
        this.insertStmtFactory = checkNotNull(insertStmtFactory);
        this.updateStmtFactory = checkNotNull(updateStmtFactory);
        this.existSetter = checkNotNull(existSetter);
        this.insertSetter = checkNotNull(insertSetter);
        this.updateSetter = checkNotNull(updateSetter);
        this.keyExtractor = keyExtractor;
    }

    @Override
    public void prepareStatements(Connection connection) throws SQLException {
        existStatement = existStmtFactory.createStatement(connection);
        insertStatement = insertStmtFactory.createStatement(connection);
        updateStatement = updateStmtFactory.createStatement(connection);
    }

    @Override
    public void addToBatch(RowData record) throws SQLException {
        processOneRowInBatch(keyExtractor.apply(record), record);
    }

    @Override
    public String insertSql() {
        return insertStatement.getQuery();
    }

    private void processOneRowInBatch(RowData pk, RowData row) throws SQLException {
        if (exist(pk)) {
            updateSetter.toExternal(row, updateStatement);
            updateStatement.addBatch();
        } else {
            insertSetter.toExternal(row, insertStatement);
            insertStatement.addBatch();
        }
    }

    private boolean exist(RowData pk) throws SQLException {
        existSetter.toExternal(pk, existStatement);
        try (ResultSet resultSet = existStatement.executeQuery()) {
            return resultSet.next();
        }
    }

    @Override
    public void executeBatch() throws SQLException {
        updateStatement.executeBatch();
        insertStatement.executeBatch();
    }

    @Override
    public void closeStatements() throws SQLException {
        for (FieldNamedPreparedStatement s :
                Arrays.asList(existStatement, insertStatement, updateStatement)) {
            if (s != null) {
                s.close();
            }
        }
    }
}
