LabelledValidatorShapeless.scala

import jto.validation.{Rule, VA}
import shapeless.Witness
import shapeless.labelled.{FieldType, field}
import shapeless._

import scala.language.implicitConversions


trait Validator {
  def rules: Rule[String, String]

  def validate(value: String): VA[String] = rules.validate(value)
}

object EmailValidator extends Validator {
  val rules: Rule[String, String] = Rules.email |+| Rules.notEmpty
}

object FirstnameValidator extends Validator {
  override def rules: Rule[String, String] = Rules.minLength(3)
}

def validField(in: FieldType[T, String])(implicit witness: Witness.Aux[T]) = {
  getFieldName(in) match {
    case v: Validator => v.validate(in)
  }
}



implicit def email(value: String) = field[EmailValidator.type](value)

implicit def firstname(value: String) = field[FirstnameValidator.type](value)

//implicit def cgu(value : String) = field[BooleanValidator.type](value)
//implicit def boolean(value : String)  = field[BooleanValidator.type ](value)

def getFieldName[K, V](value: FieldType[K, V])(implicit witness: Witness.Aux[K]): K = witness.value
def getFieldValue[K, V](value: FieldType[K, V]): V = value

object validate extends Poly1 {
  implicit def genericString[K <: Validator](implicit witness: Witness.Aux[K]) = at((x: FieldType[K, String]) => {

    getFieldName(x).validate(getFieldValue(x))
  })
}


validate(email("[email protected]"))
validate(email("invalid"))
validate(firstname("Da"))
validate(firstname("Damien"))
//validate(cgu("true"))
//validate(boolean("true"))