package com.lightbend.scala.akkastream.queryablestate.inmemory

import akka.actor.ActorSystem
import akka.http.scaladsl.Http
import akka.http.scaladsl.server.Directives.{complete, get, path}
import akka.http.scaladsl.server.Route
import akka.stream.ActorMaterializer

import scala.concurrent.ExecutionContextExecutor
// import akka.util.timeout  // See usage below.
import com.lightbend.scala.akkastream.modelserver.stage.ModelStateStore
import com.lightbend.scala.modelServer.model.ModelToServeStats
import de.heikoseeberger.akkahttpjackson.JacksonSupport

/**
 * Implements Queryable State for the Akka Streams-based model scoring application.
 * Uses Akka HTTP to implement this capability, with state held in memory.
 * Note that a production implementation might need better scalability, if it's used
 * heavily and also we ignore security considerations here!
 */
object RestServiceInMemory {

  // Serve model status: http://localhost:5500/state
  def startRest(service: ModelStateStore)(implicit system: ActorSystem, materializer: ActorMaterializer): Unit = {

    implicit val executionContext: ExecutionContextExecutor = system.dispatcher
    // Use with HTTP methods that accept an implicit timeout argument
    // implicit val timeout = Timeout(10.seconds)
    val host = "127.0.0.1"
    val port = 5500
    val routes = QueriesAkkaHttpResource.storeRoutes(service)

    Http().bindAndHandle(routes, host, port) map
      { binding => println(s"Starting models observer on port ${binding.localAddress}") } recover {
      case ex =>
        println(s"Models observer could not bind to $host:$port - ${ex.getMessage}")
    }
  }
}

object QueriesAkkaHttpResource extends JacksonSupport {

  def storeRoutes(service: ModelStateStore): Route =
    get {
      path("state") {
        val info: ModelToServeStats = service.getCurrentServingInfo
        complete(info)
      }
    }
}