http server keeping a state at server side / published by https://github.com/dacr/code-examples-manager #50add5a2-2132-4255-a56d-375d1ed6656b/498fd887cc292705fcfc66eea32078cd7f74cb0b

tapir-zio-hello-states.sc

// summary : http server keeping a state at server side
// keywords : scala, zio, tapir, http, zhttp, stateful, state, @testable, @exclusive
// publish : gist
// authors : David Crosson
// license : Apache NON-AI License Version 2.0 (https://raw.githubusercontent.com/non-ai-licenses/non-ai-licenses/main/NON-AI-APACHE2)
// id : 50add5a2-2132-4255-a56d-375d1ed6656b
// created-on : 2022-03-20T07:26:31+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/david

// ---------------------
//> using scala "3.3.1"
//> using dep "com.softwaremill.sttp.tapir::tapir-zio:1.9.4"
//> using dep "com.softwaremill.sttp.tapir::tapir-zio-http-server:1.9.4"
//> using lib "com.softwaremill.sttp.tapir::tapir-swagger-ui-bundle:1.9.4"
// ---------------------

/*
other examples :
- https://github.com/softwaremill/tapir/blob/master/examples/src/main/scala/sttp/tapir/examples/ZioExampleZioHttpServer.scala
 */

import sttp.tapir.ztapir.*
import sttp.tapir.server.ziohttp.ZioHttpInterpreter
import sttp.apispec.openapi.Info
import sttp.tapir.swagger.bundle.SwaggerInterpreter
import zio.*, zio.http.Server

/*
curl -L http://127.0.0.1:8080/docs
curl http://127.0.0.1:8080/hello/david
curl http://127.0.0.1:8080/hello/joe
 */

object WebApp extends ZIOAppDefault {

  case class AppState(counters: Map[String, Int] = Map.empty) {
    def manage(id: String): AppState =
      copy(counters = counters + (id -> (1 + counters.getOrElse(id, 0))))
  }

  // --------------------------------------------------
  def helloLogic(name: String) =
    for {
      ref   <- ZIO.service[Ref[AppState]]
      state <- ref.updateAndGet(state => state.manage(name))
      count  = state.counters.getOrElse(name, 0)
    } yield s"Hello $name $count"

  val helloEndPoint =
    endpoint
      .description("Returns stateful greeting")
      .get
      .in("hello" )
      .in(path("name").example("joe"))
      .out(stringBody)

  val helloRoute = helloEndPoint.zServerLogic(helloLogic)

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

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

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

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

  // --------------------------------------------------
  val appStateLayer = ZLayer(Ref.make(AppState()))

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

WebApp.main(Array.empty)