field_name.scala

import scala.deriving.Mirror
import jsonvalue.*

import scala.compiletime.{constValue, erasedValue}

case class Employee ( name: String, age: Int )

trait HelpersLabelledGeneric:

  trait JsonEncoder[A]:
    def encodeField(a: A): JsonValue

  type Row = List[JsonValue]

  trait RowEncoder[A]:
    def encodeRow(a: A): Row

  given JsonEncoder[Int] = JsonInt ( _ ) // when the trait has only one method.

  given JsonEncoder[String] with
    override def encodeField(a: String): JsonValue = JsonString(a)

  given RowEncoder[EmptyTuple] with
    override def encodeRow(a: EmptyTuple): Row = List.empty

  given [H: JsonEncoder, T <: Tuple: RowEncoder]: RowEncoder[ H *: T] with
    override def encodeRow(a: H *: T): Row =
      summon[JsonEncoder[H]].encodeField(a.head) :: summon[RowEncoder[T]].encodeRow(a.tail)

  /** * to get the field name */
  inline def getElemLabels[A <: Tuple]: List[String] =
    inline erasedValue[A] match {
      case _: EmptyTuple => Nil
      case _: (head *: tail) =>
        val headElementLabel = constValue[head].toString
        val tailElementLabels = getElemLabels[tail]
        headElementLabel :: tailElementLabels
    }

  inline def getElemLabelsHelper[A](using m: Mirror.Of[A]) =
    getElemLabels[m.MirroredElemLabels]

  def tupleToCsv[X : RowEncoder](tuple: X): List[JsonValue] =
    summon[RowEncoder[X]].encodeRow(tuple)

end HelpersLabelledGeneric

@main def hello(): Unit =

  case class TestGrid ( look: String, amount: Int)

  val helpersLabelledGeneric = new HelpersLabelledGeneric {}

  val bob = Employee("Bob changos", 42)

  trait Grid1[A]:     
    def loadValues(a: List[A]): Unit =
      import helpersLabelledGeneric.given_RowEncoder_*:      
      import helpersLabelledGeneric.{given_JsonEncoder_String, given_RowEncoder_EmptyTuple, given_JsonEncoder_Int}
      
      //val valores = helpersLabelledGeneric.tupleToCsv ( bob )
      val valores = a.map( b => helpersLabelledGeneric.tupleToCsv ( b ) ) 
      println(valores)

      val fields = helpersLabelledGeneric.getElemLabelsHelper [ A ]
      println ( fields )

  end Grid1