dealised.scala

import scala.collection.mutable
import scala.collection.mutable.ListBuffer
import scala.reflect.macros.whitebox.Context
import scala.language.experimental.macros

trait Dealised[A] {
  def value: A
}

object Dealised {
  implicit def materialize[A]: Dealised[A] = macro DealisedMacro.macroIml[A]
}

object DealisedMacro {

  def macroIml[T: c.WeakTypeTag](c: Context): c.Expr[Dealised[T]] = {
    import c.universe._

    val searchType = c.weakTypeOf[T]

    def dealiased(t: c.Type): String = {
      val x = t.dealias
      val args = x.typeArgs
      if (args.nonEmpty) {
        val fixed = args.map(dealiased)
        x.typeSymbol.name + fixed.mkString("[", ",", "]")
      } else {
        x.typeSymbol.name.decodedName.toString
      }
    }

    val value = c.inferImplicitValue(searchType)
    if (value.isEmpty) {
      val t = dealiased(searchType)
      val msg = s"could not find implicit value parameter for $t"
      c.info(c.enclosingPosition, msg, true)
      c.abort(c.enclosingPosition, msg)
    } else {
      c.Expr[Dealised[T]](
        q"""
           new Dealised[$searchType] {
              override def value: $searchType = $value
           }
         """
      )
    }
  }
}