zquery2.scala

package caliban

import caliban.GraphQL._
import zio.ZIO
import zio.console.putStrLn
import zio.zquery._

object Test2 extends zio.App {

  case class User(firstName: UQuery[String], lastName: UQuery[String], age: UQuery[Int])
  case class Query(getUser: String => User)

  case class GetUser[+A](userId: String, field: String) extends Request[Nothing, A]
  val UserDataSource: DataSource[Any, GetUser[Any]] =
    DataSource.fromFunctionBatched[GetUser[Any], Any]("User") { requests =>
      // build SQL query with only the fields in requests
      requests.map { req =>
        req.field match {
          case "first_name" => s"firstName of ${req.userId}"
          case "last_name"  => s"lastName of ${req.userId}"
          case "age"        => 35
        }
      }
    }

  def firstName(id: String): UQuery[String] = ZQuery.fromRequest(GetUser(id, "first_name"))(UserDataSource)
  def lastName(id: String): UQuery[String]  = ZQuery.fromRequest(GetUser(id, "last_name"))(UserDataSource)
  def age(id: String): UQuery[Int]          = ZQuery.fromRequest(GetUser(id, "age"))(UserDataSource)

  val resolver = RootResolver(Query(id => User(firstName(id), lastName(id), age(id))))
  val api      = graphQL(resolver)

  override def run(args: List[String]): ZIO[zio.ZEnv, Nothing, Int] =
    for {
      interpreter <- api.interpreter.orDie
      query       = "{getUser(value:\"userA\"){firstName lastName age}}"
      res         <- interpreter.execute(query)
      _           <- putStrLn(res.data.toString)
    } yield 0
}