molly.core.query.WatchQuery.scala Maven / Gradle / Ivy

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package molly.core.query

import cats.effect.kernel.Async
import cats.syntax.flatMap.*
import cats.syntax.functor.*
import cats.syntax.traverse.*
import com.mongodb.client.model.changestream.ChangeStreamDocument
import com.mongodb.client.model.changestream.FullDocument
import com.mongodb.reactivestreams.client.ChangeStreamPublisher
import fs2.Stream
import molly.core.MollyCodec
import molly.core.query.WatchQuery.decodeChangeStreamDocument
import molly.core.reactivestreams.fromStreamPublisher
import org.bson.BsonDocument

final case class WatchQuery[F[_], A] private[core] (private[core] val publisher: ChangeStreamPublisher[BsonDocument])(
    using
    Async[F],
    MollyCodec[F, A]
):

  /** [[https://mongodb.github.io/mongo-java-driver/5.2/apidocs/mongodb-driver-reactivestreams/com/mongodb/reactivestreams/client/ChangeStreamPublisher.html#resumeAfter(org.bson.BsonDocument)]]
    */
  def resumeAfter(resumeToken: BsonDocument): WatchQuery[F, A] = WatchQuery(publisher.resumeAfter(resumeToken))

  /** [[https://mongodb.github.io/mongo-java-driver/5.2/apidocs/mongodb-driver-reactivestreams/com/mongodb/reactivestreams/client/ChangeStreamPublisher.html#fullDocument(com.mongodb.client.model.changestream.FullDocument)]]
    */
  def fullDocument(fullDocument: FullDocument): WatchQuery[F, A] = WatchQuery(publisher.fullDocument(fullDocument))

  def list(bufferSize: Int = 16): F[List[ChangeStreamDocument[A]]] = stream(bufferSize).compile.toList

  def stream(bufferSize: Int = 16): Stream[F, ChangeStreamDocument[A]] =
    fromStreamPublisher(publisher.batchSize(bufferSize), bufferSize)
      .evalMap: csd =>
        decodeChangeStreamDocument(csd)

object WatchQuery:
  def decodeChangeStreamDocument[F[_], A](csd: ChangeStreamDocument[BsonDocument])(using
      f: Async[F],
      codec: MollyCodec[F, A]
  ): F[ChangeStreamDocument[A]] =
    for
      fd   <- Option(csd.getFullDocument).traverse(codec.decode)
      fdbc <- Option(csd.getFullDocumentBeforeChange).traverse(codec.decode)
    yield new ChangeStreamDocument(
      csd.getOperationTypeString,
      csd.getResumeToken,
      csd.getNamespaceDocument,
      csd.getDestinationNamespaceDocument,
      fd.getOrElse(null.asInstanceOf[A]), // scalafix:ok
      fdbc.getOrElse(null.asInstanceOf[A]), // scalafix:ok
      csd.getDocumentKey,
      csd.getClusterTime,
      csd.getUpdateDescription,
      csd.getTxnNumber,
      csd.getLsid,
      csd.getWallTime,
      csd.getSplitEvent,
      csd.getExtraElements
    )