/*
 * 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.api.java.tuple.Tuple2;
import org.apache.flink.table.data.RowData;
import org.apache.flink.types.RowKind;

import java.sql.Connection;
import java.sql.SQLException;
import java.util.HashMap;
import java.util.Map;
import java.util.function.Function;

/**
 * Currently, this statement executor is only used for table/sql to buffer insert/update/delete
 * events, and reduce them in buffer before submit to external database.
 */
public final class TableBufferReducedStatementExecutor
        implements JdbcBatchStatementExecutor<RowData> {

    private final JdbcBatchStatementExecutor<RowData> upsertExecutor;
    private final JdbcBatchStatementExecutor<RowData> deleteExecutor;
    private final Function<RowData, RowData> keyExtractor;
    // the mapping is [KEY, <+/-, VALUE>]
    private final Map<RowData, Tuple2<Boolean, RowData>> reduceBuffer = new HashMap<>();

    public TableBufferReducedStatementExecutor(
            JdbcBatchStatementExecutor<RowData> upsertExecutor,
            JdbcBatchStatementExecutor<RowData> deleteExecutor,
            Function<RowData, RowData> keyExtractor) {
        this.upsertExecutor = upsertExecutor;
        this.deleteExecutor = deleteExecutor;
        this.keyExtractor = keyExtractor;
    }

    @Override
    public void prepareStatements(Connection connection) throws SQLException {
        upsertExecutor.prepareStatements(connection);
        deleteExecutor.prepareStatements(connection);
    }

    @Override
    public void addToBatch(RowData record) throws SQLException {
        RowData key = keyExtractor.apply(record);
        boolean flag = changeFlag(record.getRowKind());
        reduceBuffer.put(key, Tuple2.of(flag, record));
    }

    /**
     * Returns true if the row kind is INSERT or UPDATE_AFTER, returns false if the row kind is
     * DELETE or UPDATE_BEFORE.
     */
    private boolean changeFlag(RowKind rowKind) {
        switch (rowKind) {
            case INSERT:
            case UPDATE_AFTER:
                return true;
            case DELETE:
            case UPDATE_BEFORE:
                return false;
            default:
                throw new UnsupportedOperationException(
                        String.format(
                                "Unknown row kind, the supported row kinds is: INSERT, UPDATE_BEFORE, UPDATE_AFTER,"
                                        + " DELETE, but get: %s.",
                                rowKind));
        }
    }

    @Override
    public void executeBatch() throws SQLException {
        if (!reduceBuffer.isEmpty()) {
            for (Map.Entry<RowData, Tuple2<Boolean, RowData>> entry : reduceBuffer.entrySet()) {
                if (entry.getValue().f0) {
                    upsertExecutor.addToBatch(entry.getValue().f1);
                } else {
                    // delete by key
                    deleteExecutor.addToBatch(entry.getKey());
                }
            }
            upsertExecutor.executeBatch();
            deleteExecutor.executeBatch();
            reduceBuffer.clear();
        }
    }

    @Override
    public void closeStatements() throws SQLException {
        upsertExecutor.closeStatements();
        deleteExecutor.closeStatements();
    }
}
