content: /*
   * 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.kafka.connect.file;
  
  import org.apache.kafka.common.config.AbstractConfig;
  import org.apache.kafka.common.config.ConfigDef;
  import org.apache.kafka.common.config.ConfigDef.Importance;
  import org.apache.kafka.common.config.ConfigDef.Type;
  import org.apache.kafka.common.utils.AppInfoParser;
  import org.apache.kafka.connect.connector.Task;
  import org.apache.kafka.connect.errors.ConnectException;
  import org.apache.kafka.connect.source.ExactlyOnceSupport;
  import org.apache.kafka.connect.source.SourceConnector;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Map;
  
  import static org.apache.kafka.connect.file.FileStreamSourceTask.FILENAME_FIELD;
  import static org.apache.kafka.connect.file.FileStreamSourceTask.POSITION_FIELD;
  
  /**
   * Very simple source connector that works with stdin or a file.
   */
  public class FileStreamSourceConnector extends SourceConnector {
  
      private static final Logger log = LoggerFactory.getLogger(FileStreamSourceConnector.class);
      public static final String TOPIC_CONFIG = "topic";
      public static final String FILE_CONFIG = "file";
      public static final String TASK_BATCH_SIZE_CONFIG = "batch.size";
  
      public static final int DEFAULT_TASK_BATCH_SIZE = 2000;
  
      static final ConfigDef CONFIG_DEF = new ConfigDef()
          .define(FILE_CONFIG, Type.STRING, null, Importance.HIGH, "Source filename. If not specified, the standard input will be used")
          .define(TOPIC_CONFIG, Type.STRING, ConfigDef.NO_DEFAULT_VALUE, new ConfigDef.NonEmptyString(), Importance.HIGH, "The topic to publish data to")
          .define(TASK_BATCH_SIZE_CONFIG, Type.INT, DEFAULT_TASK_BATCH_SIZE, Importance.LOW,
                  "The maximum number of records the source task can read from the file each time it is polled");
  
      private Map<String, String> props;
  
      @Override
      public String version() {
          return AppInfoParser.getVersion();
      }
  
      @Override
      public void start(Map<String, String> props) {
          this.props = props;
          AbstractConfig config = new AbstractConfig(CONFIG_DEF, props);
          String filename = config.getString(FILE_CONFIG);
          filename = (filename == null || filename.isEmpty()) ? "standard input" : filename;
          log.info("Starting file source connector reading from {}", filename);
      }
  
      @Override
      public Class<? extends Task> taskClass() {
          return FileStreamSourceTask.class;
      }
  
      @Override
      public List<Map<String, String>> taskConfigs(int maxTasks) {
          ArrayList<Map<String, String>> configs = new ArrayList<>();
          // Only one input stream makes sense.
          configs.add(props);
          return configs;
      }
  
      @Override
      public void stop() {
          // Nothing to do since FileStreamSourceConnector has no background monitoring.
      }
  
      @Override
      public ConfigDef config() {
          return CONFIG_DEF;
      }
  
      @Override
      public ExactlyOnceSupport exactlyOnceSupport(Map<String, String> props) {
          AbstractConfig parsedConfig = new AbstractConfig(CONFIG_DEF, props);
          String filename = parsedConfig.getString(FILE_CONFIG);
          // We can provide exactly-once semantics if reading from a "real" file
          // (as long as the file is only appended to over the lifetime of the connector)
          // If we're reading from stdin, we can't provide exactly-once semantics
          // since we don't even track offsets
          return filename != null && !filename.isEmpty()
                  ? ExactlyOnceSupport.SUPPORTED
                  : ExactlyOnceSupport.UNSUPPORTED;
      }
  
      @Override
      public boolean alterOffsets(Map<String, String> connectorConfig, Map<Map<String, ?>, Map<String, ?>> offsets) {
          AbstractConfig config = new AbstractConfig(CONFIG_DEF, connectorConfig);
          String filename = config.getString(FILE_CONFIG);
          if (filename == null || filename.isEmpty()) {
              throw new ConnectException("Offsets cannot be modified if the '" + FILE_CONFIG + "' configuration is unspecified. " +
                      "This is because stdin is used for input and offsets are not tracked.");
          }
  
          // This connector makes use of a single source partition at a time which represents the file that it is configured to read from.
          // However, there could also be source partitions from previous configurations of the connector.
          for (Map.Entry<Map<String, ?>, Map<String, ?>> partitionOffset : offsets.entrySet()) {
              Map<String, ?> offset = partitionOffset.getValue();
              if (offset == null) {
                  // We allow tombstones for anything; if there's garbage in the offsets for the connector, we don't
                  // want to prevent users from being able to clean it up using the REST API
                  continue;
              }
  
              if (!offset.containsKey(POSITION_FIELD)) {
                  throw new ConnectException("Offset objects should either be null or contain the key '" + POSITION_FIELD + "'");
              }
  
              // The 'position' in the offset represents the position in the file's byte stream and should be a non-negative long value
              if (!(offset.get(POSITION_FIELD) instanceof Long)) {
                  throw new ConnectException("The value for the '" + POSITION_FIELD + "' key in the offset is expected to be a Long value");
              }
  
              long offsetPosition = (Long) offset.get(POSITION_FIELD);
              if (offsetPosition < 0) {
                  throw new ConnectException("The value for the '" + POSITION_FIELD + "' key in the offset should be a non-negative value");
              }
  
              Map<String, ?> partition = partitionOffset.getKey();
              if (partition == null) {
                  throw new ConnectException("Partition objects cannot be null");
              }
  
              if (!partition.containsKey(FILENAME_FIELD)) {
                  throw new ConnectException("Partition objects should contain the key '" + FILENAME_FIELD + "'");
              }
          }
  
          // Let the task check whether the actual value for the offset position is valid for the configured file on startup
          return true;
      }
  }
  