zlayer.scala

//> using dep dev.zio::zio:2.1.11
//> using dep dev.zio::zio-config-magnolia:4.0.2
//> using dep com.softwaremill.sttp.client3::zio:3.10.1

import sttp.client3.httpclient.zio.HttpClientZioBackend
import zio.*
import zio.config.derivation.name
import zio.config.magnolia.deriveConfig

type Language = String
type SttpClient = sttp.client3.SttpBackend[Task, Any]

case class WordFilterConfig(
    @name("WORDFILTER_URL") url: String
)
object WordFilterConfig {
  given Config[WordFilterConfig] = deriveConfig[WordFilterConfig]
}

trait WordFilter {
  def maskChat(msg: String, language: Option[Language]): Task[String]
}
object WordFilter {
  val live: ZLayer[SttpClient, Throwable, WordFilter] =
    ZLayer.derive[WordFilterLive]
  val test: ZLayer[Any, Nothing, WordFilter] =
    ZLayer.derive[WordFilterTest]
}

class WordFilterLive(config: WordFilterConfig, sttp: SttpClient)
    extends WordFilter {
  def maskChat(msg: String, language: Option[Language]): Task[String] =
    ???
}
class WordFilterTest extends WordFilter {
  def maskChat(msg: String, language: Option[Language]): Task[String] =
    ZIO.succeed(msg)
}

class ChatService(wordFilter: WordFilter) {
  def chat(message: String): Task[Unit] = ???
}

object ChatService {
  val live: ZLayer[WordFilter, Nothing, ChatService] =
    ZLayer.derive[ChatService]
}

class GrpcServer(chatService: ChatService) {
  def start: Task[Nothing] = ZIO.never
}

object GrpcServer {
  val live: ZLayer[ChatService, Nothing, GrpcServer] =
    ZLayer.derive[GrpcServer]
}

object App extends ZIOAppDefault {
  override val bootstrap =
    // this is to tell ZIO to load config keys from env variables
    Runtime.setConfigProvider(ConfigProvider.envProvider)

  val run =
    ZIO
      .serviceWithZIO[GrpcServer](_.start)
      .provide(
        GrpcServer.live,
        ChatService.live,
        WordFilter.live, // or WordFilter.test
        HttpClientZioBackend.layer()
      )
}