record2js.scala

//> using dep "com.github.tarao::record4s::0.9.1"
//> using dep "org.getshaka::native-converter::0.9.0"

import scala.compiletime.{constValue, erasedValue, summonInline}
import scala.scalajs.js
import scala.util.NotGiven

import com.github.tarao.record4s.{%, ArrayRecord, RecordLike}
import org.getshaka.nativeconverter.{NativeConverter, ParseState}

object ToNative {
  private type ImplicitlyJsAny = String | Boolean | Byte | Short | Int | Float | Double | Null | js.Any

  private inline def fieldsToNative[Types, Labels](
    record: Map[String, Any],
    res: js.Dynamic = js.Object().asInstanceOf[js.Dynamic]
  ): js.Any = {
    inline (erasedValue[Types], erasedValue[Labels]) match {
      case _: (EmptyTuple, EmptyTuple) =>
        res

      case _: (tpe *: types, label *: labels) =>
        val labelStr = constValue[label & String]
        val nativeElem =
          inline erasedValue[tpe] match {
            case _: ImplicitlyJsAny =>
              record(labelStr).asInstanceOf[js.Any]
            case _ =>
              val nc = summonInline[NativeConverter[tpe]]
              val elem = record(labelStr).asInstanceOf[tpe]
              nc.toNative(elem)
          }
        res.updateDynamic(labelStr)(nativeElem)

        fieldsToNative[types, labels](record, res)
    }
  }

  inline given recordToNative[R <: %](using
    r: RecordLike[R],
    nonTuple: NotGiven[R <:< Tuple],
  ): NativeConverter[R] = {
    type Types = r.ElemTypes
    type Labels = r.ElemLabels

    new NativeConverter[R] {
      extension (record: R) {
        def toNative: js.Any = fieldsToNative[Types, Labels](r.iterableOf(record).toMap)
      }

      def fromNative(ps: ParseState): R = ???
    }
  }
}

inline given arrayRecordToNative[R]: NativeConverter[ArrayRecord[R]] =
  NativeConverter.derived

@main def main(): Unit = {
  import ToNative.recordToNative

  locally {
    val r = %(name = "tarao", age = 3, email = %(local = "tarao", domain = "example.com"))
    val obj = r.toNative
    println(js.JSON.stringify(obj))
    // {"name":"tarao","age":3,"email":{"local":"tarao","domain":"example.com"}}
  }

  locally {
    val r = ArrayRecord(name = "tarao", age = 3, email = ArrayRecord(local = "tarao", domain = "example.com"))
    val obj = r.toNative
    println(js.JSON.stringify(obj))
    // {"name":"tarao","age":3,"email":{"local":"tarao","domain":"example.com"}}
  }
}