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

package fs2.kafka

import cats.{Applicative, Bitraverse, Eq, Eval, Foldable, Show, Traverse}
import cats.syntax.bifoldable.*
import cats.syntax.bitraverse.*
import cats.syntax.eq.*
import cats.syntax.foldable.*
import cats.syntax.functor.*
import cats.syntax.show.*
import cats.syntax.traverse.*
import fs2.kafka.internal.syntax.*
import fs2.Chunk

/**
  * [[CommittableProducerRecords]] represents zero or more [[ProducerRecord]]s and a
  * [[CommittableOffset]], used by [[TransactionalKafkaProducer]] to produce the records and commit
  * the offset atomically.


  *
  * [[CommittableProducerRecords]]s can be created using one of the following options:

  *   - `CommittableProducerRecords#apply` to produce zero or more records within the same
  *     transaction as the offset is committed.

  *   - `CommittableProducerRecords#one` to produce exactly one record within the same transaction
  *     as the offset is committed.
  */
sealed abstract class CommittableProducerRecords[F[_], +K, +V] {

  /**
    * The records to produce. Can be empty to simply commit the offset.
    */
  def records: Chunk[ProducerRecord[K, V]]

  /**
    * The offset to commit.
    */
  def offset: CommittableOffset[F]

}

object CommittableProducerRecords {

  final private[this] class CommittableProducerRecordsImpl[F[_], +K, +V](
    override val records: Chunk[ProducerRecord[K, V]],
    override val offset: CommittableOffset[F]
  ) extends CommittableProducerRecords[F, K, V] {

    override def toString: String =
      if (records.isEmpty) s"CommittableProducerRecords(, $offset)"
      else records.mkString("CommittableProducerRecords(", ", ", s", $offset)")

  }

  /**
    * Creates a new [[CommittableProducerRecords]] for producing zero or more [[ProducerRecord]]s
    * and committing an offset atomically within a transaction.
    *
    * @see
    *   [[chunk]] if your `records` are already contained in an [[fs2.Chunk]]
    */
  def apply[F[_], G[+_], K, V](
    records: G[ProducerRecord[K, V]],
    offset: CommittableOffset[F]
  )(implicit G: Foldable[G]): CommittableProducerRecords[F, K, V] =
    chunk(Chunk.from(Foldable[G].toIterable(records)), offset)

  /**
    * Creates a new [[CommittableProducerRecords]] for producing exactly one [[ProducerRecord]] and
    * committing an offset atomically within a transaction.
    */
  def one[F[_], K, V](
    record: ProducerRecord[K, V],
    offset: CommittableOffset[F]
  ): CommittableProducerRecords[F, K, V] =
    chunk(Chunk.singleton(record), offset)

  /**
    * Creates a new [[CommittableProducerRecords]] for producing zero or more [[ProducerRecord]]s
    * and committing an offset atomically within a transaction.
    */
  def chunk[F[_], K, V](
    records: Chunk[ProducerRecord[K, V]],
    offset: CommittableOffset[F]
  ): CommittableProducerRecords[F, K, V] =
    new CommittableProducerRecordsImpl(records, offset)

  implicit def committableProducerRecordsShow[F[_], K: Show, V: Show]
    : Show[CommittableProducerRecords[F, K, V]] =
    Show.show { committable =>
      if (committable.records.isEmpty)
        show"CommittableProducerRecords(, ${committable.offset})"
      else
        committable
          .records
          .mkStringShow(
            "CommittableProducerRecords(",
            ", ",
            s", ${committable.offset})"
          )
    }

  implicit def committableProducerRecordsEq[F[_], K: Eq, V: Eq]
    : Eq[CommittableProducerRecords[F, K, V]] =
    Eq.instance { case (l, r) =>
      l.records === r.records && l.offset === r.offset
    }

  implicit def committableProducerRecordsBitraverse[F[_]]
    : Bitraverse[CommittableProducerRecords[F, *, *]] =
    new Bitraverse[CommittableProducerRecords[F, *, *]] {

      override def bitraverse[G[_], A, B, C, D](
        fab: CommittableProducerRecords[F, A, B]
      )(f: A => G[C], g: B => G[D])(implicit
        G: Applicative[G]
      ): G[CommittableProducerRecords[F, C, D]] =
        fab
          .records
          .traverse { record =>
            record.bitraverse(f, g)
          }
          .map { (cd: Chunk[ProducerRecord[C, D]]) =>
            CommittableProducerRecords(cd, fab.offset)
          }

      override def bifoldLeft[A, B, C](
        fab: CommittableProducerRecords[F, A, B],
        c: C
      )(f: (C, A) => C, g: (C, B) => C): C =
        fab
          .records
          .foldLeft(c) { case (acc, record) =>
            record.bifoldLeft(acc)(f, g)
          }

      override def bifoldRight[A, B, C](
        fab: CommittableProducerRecords[F, A, B],
        c: Eval[C]
      )(f: (A, Eval[C]) => Eval[C], g: (B, Eval[C]) => Eval[C]): Eval[C] =
        fab
          .records
          .foldRight(c) { case (record, acc) =>
            record.bifoldRight(acc)(f, g)
          }

    }

  implicit def committableProducerRecordsTraverse[F[_], K]
    : Traverse[CommittableProducerRecords[F, K, *]] =
    new Traverse[CommittableProducerRecords[F, K, *]] {

      override def traverse[G[_], A, B](
        fa: CommittableProducerRecords[F, K, A]
      )(f: A => G[B])(implicit G: Applicative[G]): G[CommittableProducerRecords[F, K, B]] =
        fa.records
          .traverse { record =>
            record.traverse(f)
          }
          .map { (b: Chunk[ProducerRecord[K, B]]) =>
            CommittableProducerRecords(b, fa.offset)
          }

      override def foldLeft[A, B](fa: CommittableProducerRecords[F, K, A], b: B)(
        f: (B, A) => B
      ): B =
        fa.records
          .foldLeft(b) { case (acc, record) =>
            record.foldLeft(acc)(f)
          }

      override def foldRight[A, B](
        fa: CommittableProducerRecords[F, K, A],
        lb: Eval[B]
      )(f: (A, Eval[B]) => Eval[B]): Eval[B] =
        fa.records
          .foldRight(lb) { case (record, acc) =>
            record.foldRight(acc)(f)
          }

    }

}