zquery.scala

package caliban

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

object Test extends zio.App {

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

  sealed trait GetUser[+A]                extends Request[Nothing, A]
  case class GetFirstName(userId: String) extends GetUser[String]
  case class GetLastName(userId: String)  extends GetUser[String]
  case class GetAge(userId: String)       extends GetUser[Int]
  val UserDataSource: DataSource[Any, GetUser[Any]] =
    DataSource.fromFunctionBatched[GetUser[Any], Any]("User") { requests =>
      // build SQL query with only the fields in requests
      requests.map {
        case GetFirstName(userId) => s"firstName of $userId"
        case GetLastName(userId)  => s"lastName of $userId"
        case GetAge(_)            => 35
      }
    }

  def firstName(id: String): UQuery[String] = ZQuery.fromRequest(GetFirstName(id))(UserDataSource)
  def lastName(id: String): UQuery[String]  = ZQuery.fromRequest(GetLastName(id))(UserDataSource)
  def age(id: String): UQuery[Int]          = ZQuery.fromRequest(GetAge(id))(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
}