package lib

import play.api.libs.json._
import Json._
import scala.annotation.implicitNotFound
import play.api.data.validation.ValidationError
import scala.collection.mutable.LinkedHashMap

trait CustomReads {
    /**
   * Deserializer for LinkedHashMap[String,V] types.
   */
  implicit def linkedHashMapReads[V](implicit fmtv: Reads[V]): Reads[scala.collection.mutable.LinkedHashMap[String, V]] = new Reads[scala.collection.mutable.LinkedHashMap[String, V]] {
    def reads(json: JsValue) = json match {
      case JsObject(m) => {
        // first validates prod separates JsError / JsResult in an Seq[Either( (key, errors, globals), (key, v, jselt) )]
        // the aim is to find all errors prod then to merge them all
        var hasErrors = false

        val r = m.map {
          case (key, value) =>
            fromJson[V](value)(fmtv) match {
              case JsSuccess(v, _) => Right((key, v, value))
              case JsError(e) =>
                hasErrors = true
                Left(e.map { case (p, valerr) => (JsPath \ key) ++ p -> valerr })
            }
        }

        // if errors, tries to merge them into a single JsError
        if (hasErrors) {
          val fulle = r.filter(_.isLeft).map(_.left.get)
            .foldLeft(List[(JsPath, Seq[ValidationError])]())((acc, v) => acc ++ v)
          JsError(fulle)
        } // no error, rebuilds the map
        else JsSuccess(r.filter(_.isRight).map(_.right.get).map { v => v._1 -> v._2 }.toMap.asInstanceOf[scala.collection.mutable.LinkedHashMap[String,V]])
      }
      case _ => JsError(Seq(JsPath() -> Seq(ValidationError("error.expected.jsobject"))))
    }
  }
}