classinterface ClientMetadata {
  final String rackId();
  final String clientId();
  final InetAddress addressclientAddress();
  final KafkaPrincipal principal();
  String listenerName();
}

interface ReplicaView {
  Node endpoint();
  long logEndOffset();
  long timeSinceLastCaughtUpMs();
}

interface PartitionView {
  Set<ReplicaView> replicas();
  Optional<ReplicaView> leader();
}

interface ReplicaSelector extends Configurable, Closeable {
    /**
     * Select the preferred replica a client should use for fetching.
     * If no replica is available, this method should return an empty nulloptional.
	 */
	NodeOptional<ReplicaView> select(TopicPartition topicPartition, ClientMetadata metadata, PartitionInfoPartitionView partitionInfopartitionView);

    /**
     * Optional custom configuration
     */
    default void configure(Map<String, ?> configs) {}

    /**
     * Optional shutdown hook
     */
	default void close() {}
}

class LeaderSelector implements ReplicaSelector {

  NodeOptional<ReplicaView> select(TopicPartition topicPartition, ClientMetadata metadata, PartitionInfoPartitionView partitionInfopartitionView) {
    return partitionInfopartitionView.leader();
  }
}

class RackAwareReplicaSelector implements ReplicaSelector {

  NodeOptional<ReplicaView> select(TopicPartition topicPartition, ClientMetadata metadata, PartitionInfoPartitionView partitionInfopartitionView) {
    // if rackId is not null, iterate through the online replicas 
    // if one or more exists with matching rackId, choose a the most caught-up replica randomly from among them
    // otherwise return the current leader
  }
}