FinchWithDoobie.scala

import cats.effect._
import cats.implicits._
import com.twitter.finagle.{Http, ListeningServer}
import doobie._
import doobie.hikari._
import io.catbird.util._
import io.catbird.util.effect._

object App extends IOApp {
  val transactor: Resource[IO, HikariTransactor[IO]] = {
    val postgresUser = sys.env("POSTGRES_USER")
    val postgresPassword = sys.env("POSTGRES_PASSWORD")
    val postgresDatabase = sys.env("POSTGRES_DB")
    val postgresHost = sys.env("POSTGRES_HOST")

    for {
      ce <- ExecutionContexts.fixedThreadPool[IO](8) // connect EC
      te <- ExecutionContexts.cachedThreadPool[IO] // transaction EC
      xa <- HikariTransactor.newHikariTransactor[IO](
        "org.postgresql.Driver",
        s"jdbc:postgresql://$postgresHost/$postgresDatabase",
        postgresUser,
        postgresPassword,
        ce,
        te
      )
    } yield xa
  }

  def server(transactor: Transactor[IO]): Resource[IO, ListeningServer] = {
    val dataAccess = new DataAccess(transactor)
    val routes = new Routes(dataAccess)
    val startServer = IO(Http.server.serve(":8080", routes.service))

    Resource.make(startServer)(server => rerunnableToIO(Rerunnable.fromFuture(server.close())))
  }

  override def run(args: List[String]): IO[ExitCode] = {
    val serverBootstrap = for {
      xa <- transactor
      s <- server(xa)
    } yield s

    serverBootstrap.use(_ => IO.never).as(ExitCode.Success)
  }
}