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/*
 * Copyright 2018-2024 OVO Energy Limited
 *
 * SPDX-License-Identifier: Apache-2.0
 */

package fs2.kafka

import scala.annotation.nowarn

import cats.effect.*
import cats.syntax.all.*
import fs2.*
import fs2.kafka.internal.*
import fs2.kafka.internal.converters.collection.*
import fs2.kafka.producer.MkProducer

import org.apache.kafka.common.Metric
import org.apache.kafka.common.MetricName
import org.apache.kafka.common.PartitionInfo

/**
  * [[KafkaProducerConnection]] represents a connection to a Kafka broker that can be used to create
  * [[KafkaProducer]] instances. All [[KafkaProducer]] instances created from an given
  * [[KafkaProducerConnection]] share a single underlying connection.
  */
sealed abstract class KafkaProducerConnection[F[_]] {

  def produce[K: KeySerializer[F, *], V: ValueSerializer[F, *]](
    records: ProducerRecords[K, V]
  ): F[F[ProducerResult[K, V]]]

  def metrics: F[Map[MetricName, Metric]]

  /**
    * Creates a new [[KafkaProducer]] using the provided serializers.
    *
    * {{{
    * KafkaProducerConnection.stream[F].using(settings).map(_.withSerializers(keySerializer, valueSerializer))
    * }}}
    */
  def withSerializers[K, V](
    keySerializer: KeySerializer[F, K],
    valueSerializer: ValueSerializer[F, V]
  ): KafkaProducer.PartitionsFor[F, K, V]

  /**
    * Creates a new [[KafkaProducer]] in the `F` context, using serializers from the specified
    * [[ProducerSettings]].
    *
    * {{{
    * KafkaProducerConnection.stream[F].using(settings).evalMap(_.withSerializersFrom(settings))
    * }}}
    */
  def withSerializersFrom[K, V](
    settings: ProducerSettings[F, K, V]
  ): Resource[F, KafkaProducer.PartitionsFor[F, K, V]]

  def partitionsFor(
    topic: String
  ): F[List[PartitionInfo]]

}

object KafkaProducerConnection {

  /**
    * Creates a new [[KafkaProducerConnection]] in the `Stream` context, using the specified
    * [[ProducerSettings]].
    *
    * {{{
    * KafkaProducerConnection.stream[F](settings)
    * }}}
    */
  def stream[F[_]](
    settings: ProducerSettings[F, ?, ?]
  )(implicit
    F: Async[F],
    mk: MkProducer[F]
  ): Stream[F, KafkaProducerConnection[F]] = streamIn(settings)(F, F, mk)

  /**
    * Like [[stream]], but allows use of different effect types for the allocating `Stream` and the
    * allocated `KafkaProducerConnection`.
    */
  def streamIn[F[_], G[_]](
    settings: ProducerSettings[G, ?, ?]
  )(implicit
    F: Async[F],
    G: Async[G],
    mk: MkProducer[F]
  ): Stream[F, KafkaProducerConnection[G]] = Stream.resource(resourceIn(settings)(F, G, mk))

  /**
    * Creates a new [[KafkaProducerConnection]] in the `Resource` context, using the specified
    * [[ProducerSettings]].
    *
    * {{{
    * KafkaProducerConnection.resource[F](settings)
    * }}}
    */
  def resource[F[_]](
    settings: ProducerSettings[F, ?, ?]
  )(implicit
    F: Async[F],
    mk: MkProducer[F]
  ): Resource[F, KafkaProducerConnection[F]] =
    resourceIn(settings)(F, F, mk)

  /**
    * Like [[resource]], but allows use of different effect types for the allocating `Resource` and
    * the allocated `KafkaProducerConnection`.
    */
  def resourceIn[F[_], G[_]](
    settings: ProducerSettings[G, ?, ?]
  )(implicit
    F: Async[F],
    G: Async[G],
    mk: MkProducer[F]
  ): Resource[F, KafkaProducerConnection[G]] =
    WithProducer(mk, settings).map { withProducer =>
      new KafkaProducerConnection[G] {

        override def produce[K, V](
          records: ProducerRecords[K, V]
        )(implicit
          keySerializer: KeySerializer[G, K],
          valueSerializer: ValueSerializer[G, V]
        ): G[G[ProducerResult[K, V]]] =
          KafkaProducer.produce[G, K, V](
            withProducer,
            keySerializer,
            valueSerializer,
            records,
            settings.failFastProduce
          )

        override def metrics: G[Map[MetricName, Metric]] =
          withProducer.blocking(_.metrics().asScala.toMap)

        override def withSerializers[K, V](
          keySerializer: KeySerializer[G, K],
          valueSerializer: ValueSerializer[G, V]
        ): KafkaProducer.PartitionsFor[G, K, V] =
          KafkaProducer.from(this, keySerializer, valueSerializer)

        override def withSerializersFrom[K, V](
          settings: ProducerSettings[G, K, V]
        ): Resource[G, KafkaProducer.PartitionsFor[G, K, V]] =
          (settings.keySerializer, settings.valueSerializer).mapN(withSerializers)

        override def partitionsFor(topic: String): G[List[PartitionInfo]] =
          withProducer.blocking(_.partitionsFor(topic).asScala.toList)

      }
    }

  /*
   * Prevents the default `MkProducer` instance from being implicitly available
   * to code defined in this object, ensuring factory methods require an instance
   * to be provided at the call site.
   */
  @nowarn("msg=never used")
  implicit private def mkAmbig1[F[_]]: MkProducer[F] =
    throw new AssertionError("should not be used")

  @nowarn("msg=never used")
  implicit private def mkAmbig2[F[_]]: MkProducer[F] =
    throw new AssertionError("should not be used")

}