http server random hello world using a sealed trait data structure / published by https://github.com/dacr/code-examples-manager #e9f0b49b-8116-417e-a68a-fc5dd73121df/659b14a3ed7b0c4b097c396ec8969d6eb4583e88

tapir-zio-hello-sealed-traits.sc

// summary : http server random hello world using a sealed trait data structure
// keywords : scala, zio, tapir, http, zhttp, @testable, @exclusive
// publish : gist
// authors : David Crosson
// license : Apache License Version 2.0 (https://www.apache.org/licenses/LICENSE-2.0.txt)
// id : e9f0b49b-8116-417e-a68a-fc5dd73121df
// created-on : 2024-01-24T08:42:05+01:00
// managed-by : https://github.com/dacr/code-examples-manager
// run-with : scala-cli $file
// test-with : curl -L http://127.0.0.1:8080/hello

// ---------------------
//> using scala "3.4.2"
//> using dep "com.softwaremill.sttp.tapir::tapir-zio:1.9.6"
//> using dep "com.softwaremill.sttp.tapir::tapir-json-zio:1.9.6"
//> using dep "com.softwaremill.sttp.tapir::tapir-zio-http-server:1.9.6"
//> using dep "com.softwaremill.sttp.tapir::tapir-swagger-ui-bundle:1.9.6"
// ---------------------

import zio.*
import zio.http.Server
import zio.json.{JsonCodec, jsonDiscriminator}
import sttp.tapir.json.zio.*
import sttp.tapir.ztapir.*
import sttp.tapir.server.ziohttp.ZioHttpInterpreter
import sttp.apispec.openapi.Info
import sttp.tapir.Schema
import sttp.tapir.generic.Configuration
import sttp.tapir.swagger.bundle.SwaggerInterpreter
import sttp.tapir.generic.auto.*

/*
curl -L http://127.0.0.1:8080/docs
 */

@jsonDiscriminator("@kind")
sealed trait Feedback derives JsonCodec
case class Message(text: String) extends Feedback derives JsonCodec

@jsonDiscriminator("@kind")
sealed trait Greetings derives JsonCodec
case class Simple(message: Feedback)            extends Greetings derives JsonCodec
case class Polite(tile: Int, message: Feedback) extends Greetings derives JsonCodec

object WebApp extends ZIOAppDefault {
  implicit val tapirConfig: Configuration =
    Configuration.default
      .withDiscriminator("@kind")
  // .withSnakeCaseMemberNames
  // .withKebabCaseDiscriminatorValues

  // ----------------------------------------------------
  // see https://github.com/softwaremill/tapir/issues/3476
  // see https://stackoverflow.com/questions/77739438/generate-right-schema-and-documentation-with-tapir-and-sealed-traits
  given Schema[Message] = Schema.derived[Message].title(classOf[Message].getSimpleName)
  given Schema[Simple]  = Schema.derived[Simple].title(classOf[Simple].getSimpleName)
  given Schema[Polite]  = Schema.derived[Polite].title(classOf[Polite].getSimpleName)
  // ----------------------------------------------------

  val helloEndPoint =
    endpoint
      .description("say hello")
      .get
      .in("hello")
      .out(jsonBody[Feedback])

  val helloRoute = helloEndPoint.zServerLogic[Any](_ => ZIO.succeed(Message("Hello")))

  // --------------------------------------------------
  val greetingEndPoint =
    endpoint
      .description("Return random greeting")
      .get
      .in("greeting")
      .out(jsonBody[Greetings])

  val greetings = List[Greetings](
    Simple(Message("Hi")),
    Simple(Message("Hello")),
    Polite(30, Message("Nice to meed you"))
  )

  val greetingRoute = greetingEndPoint.zServerLogic[Any](_ => Random.shuffle(greetings).map(_.head))

  // --------------------------------------------------

  val docEndpoints =
    SwaggerInterpreter()
      .fromServerEndpoints(
        List(helloRoute, greetingRoute),
        Info(title = "Greeting API", version = "1.0", description = Some("Everything required to be polite"))
      )

  // --------------------------------------------------

  val routes = ZioHttpInterpreter().toHttp(List(helloRoute, greetingRoute) ++ docEndpoints)

  // --------------------------------------------------

  override def run =
    Server
      .serve(routes)
      .provide(Server.default)
}

WebApp.main(Array.empty)