code: /*
   * Copyright (c) 2022 Airbyte, Inc., all rights reserved.
   */
  
  package io.airbyte.integrations.source.clickhouse;
  
  import com.fasterxml.jackson.databind.JsonNode;
  import com.google.common.collect.ImmutableMap;
  import io.airbyte.commons.json.Jsons;
  import io.airbyte.db.factory.DatabaseDriver;
  import io.airbyte.db.jdbc.JdbcDatabase;
  import io.airbyte.db.jdbc.JdbcUtils;
  import io.airbyte.db.jdbc.streaming.NoOpStreamingQueryConfig;
  import io.airbyte.integrations.base.IntegrationRunner;
  import io.airbyte.integrations.base.Source;
  import io.airbyte.integrations.base.ssh.SshWrappedSource;
  import io.airbyte.integrations.source.jdbc.AbstractJdbcSource;
  import io.airbyte.integrations.source.relationaldb.TableInfo;
  import io.airbyte.protocol.models.CommonField;
  import java.sql.JDBCType;
  import java.sql.PreparedStatement;
  import java.sql.SQLException;
  import java.util.List;
  import java.util.Map;
  import java.util.Set;
  import java.util.stream.Collectors;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  public class ClickHouseSource extends AbstractJdbcSource<JDBCType> implements Source {
  
    /**
     * The default implementation relies on {@link java.sql.DatabaseMetaData#getPrimaryKeys} method to
     * get it but the ClickHouse JDBC driver returns an empty result set from the method
     * {@link ru.yandex.clickhouse.ClickHouseDatabaseMetadata#getPrimaryKeys}. That's why we have to
     * query the system table mentioned here
     * https://clickhouse.tech/docs/en/operations/system-tables/columns/ to fetch the primary keys.
     */
  
    public static final String SSL_MODE = "sslmode=none";
    public static final String HTTPS_PROTOCOL = "https";
    public static final String HTTP_PROTOCOL = "http";
  
    @Override
    protected Map<String, List<String>> discoverPrimaryKeys(final JdbcDatabase database,
                                                            final List<TableInfo<CommonField<JDBCType>>> tableInfos) {
      return tableInfos.stream()
          .collect(Collectors.toMap(
              tableInfo -> sourceOperations.getFullyQualifiedTableName(tableInfo.getNameSpace(), tableInfo.getName()),
              tableInfo -> {
                try {
                  return database.queryStrings(connection -> {
                    final String sql = "SELECT name FROM system.columns WHERE database = ? AND table = ? AND is_in_primary_key = 1";
                    final PreparedStatement preparedStatement = connection.prepareStatement(sql);
                    preparedStatement.setString(1, tableInfo.getNameSpace());
                    preparedStatement.setString(2, tableInfo.getName());
                    return preparedStatement.executeQuery();
                  }, resultSet -> resultSet.getString("name"));
                } catch (final SQLException e) {
                  throw new RuntimeException(e);
                }
              }));
    }
  
    private static final Logger LOGGER = LoggerFactory.getLogger(ClickHouseSource.class);
    public static final String DRIVER_CLASS = DatabaseDriver.CLICKHOUSE.getDriverClassName();
  
    public static Source getWrappedSource() {
      return new SshWrappedSource(new ClickHouseSource(), JdbcUtils.HOST_LIST_KEY, JdbcUtils.PORT_LIST_KEY);
    }
  
    /**
     * The reason we use NoOpStreamingQueryConfig(not setting auto commit to false and not setting fetch
     * size to 1000) for ClickHouse is cause method
     * {@link ru.yandex.clickhouse.ClickHouseConnectionImpl#setAutoCommit} is empty and method
     * {@link ru.yandex.clickhouse.ClickHouseStatementImpl#setFetchSize} is empty
     */
    public ClickHouseSource() {
      super(DRIVER_CLASS, NoOpStreamingQueryConfig::new, JdbcUtils.getDefaultSourceOperations());
    }
  
    @Override
    public JsonNode toDatabaseConfig(final JsonNode config) {
      boolean isSsl = !config.has("ssl") || config.get("ssl").asBoolean();
      final StringBuilder jdbcUrl = new StringBuilder(String.format("jdbc:clickhouse:%s://%s:%s/%s",
          isSsl ? HTTPS_PROTOCOL : HTTP_PROTOCOL,
          config.get(JdbcUtils.HOST_KEY).asText(),
          config.get(JdbcUtils.PORT_KEY).asText(),
          config.get(JdbcUtils.DATABASE_KEY).asText()));
  
      // assume ssl if not explicitly mentioned.
      if (isSsl) {
        jdbcUrl.append("?").append(SSL_MODE);
      }
  
      final ImmutableMap.Builder<Object, Object> configBuilder = ImmutableMap.builder()
          .put(JdbcUtils.USERNAME_KEY, config.get(JdbcUtils.USERNAME_KEY).asText())
          .put(JdbcUtils.JDBC_URL_KEY, jdbcUrl.toString());
  
      if (config.has(JdbcUtils.PASSWORD_KEY)) {
        configBuilder.put(JdbcUtils.PASSWORD_KEY, config.get(JdbcUtils.PASSWORD_KEY).asText());
      }
  
      return Jsons.jsonNode(configBuilder.build());
    }
  
    @Override
    public Set<String> getExcludedInternalNameSpaces() {
      return Set.of("system", "information_schema", "INFORMATION_SCHEMA");
    }
  
    public static void main(final String[] args) throws Exception {
      final Source source = ClickHouseSource.getWrappedSource();
      LOGGER.info("starting source: {}", ClickHouseSource.class);
      new IntegrationRunner(source).run(args);
      LOGGER.info("completed source: {}", ClickHouseSource.class);
    }
  
  }
  