import com.twitter.util.Eval

object InterpolationDemo {

  case class Indicator(basetime: String, key: String, value: Double)

  case class ExprImplicit(basetime: String, data: Map[String, Double])

  implicit class IndicatorExpressionHelper(val sc: StringContext) extends AnyVal {
    def indicator(args: Any*)(implicit default: ExprImplicit): Indicator = {
      val strings = sc.parts.iterator
      val expressions = args.iterator
      var basetime: Option[String] = None
      var key: String = null
      var value: Double = -1

      val env = default.data.map{ case (k, v) => s"val $k = $v" }.mkString("\n")

      while (strings.hasNext && expressions.hasNext) {
        val k = strings.next.trim.stripPrefix(",").stripSuffix(":").trim
        val v = expressions.next
        k match {
          case "basetime" =>
            basetime = Some(v.toString)
          case "key" =>
            key = v.toString
          case "value" =>
            val eval = new Eval
            val expr = s"""$env
                          |${v.toString}
                          |""".stripMargin
            try {
              value = eval[Double](expr)
            } catch {
              case e: com.twitter.util.Eval.CompilerException =>
                println(s"key[$key] expr[${expr.split("\n").mkString("; ")}] exception[${e.getMessage}]")
            }

          case _ =>
            println(v)
        }
      }

      if (strings.nonEmpty && strings.next.nonEmpty) {
        println("error: " + strings.next)
      }

      if (expressions.nonEmpty) {
        println("error: " + expressions.next)
      }

      if (basetime.isDefined) {
        Indicator(basetime.get, key, value)
      } else {
        Indicator(default.basetime, key, value)
      }
    }
  }

  def main(args: Array[String]): Unit = {
    val basetime = "2019042805"

    implicit val expr = ExprImplicit(basetime, Map("a" -> 50, "b" -> 2300, "c" -> 230))


    println((indicator"basetime: $basetime, key: ${"ratio_1"}  , value: ${"a/b"}"))
    println((indicator"basetime: ${"2019043009"}, key: ${"ratio_2"}  , value: ${"c/b"}"))
    println((indicator"key: ${"ratio_1"}  , value: ${"a/b"}"))
    println((indicator"key: ${"ratio_1"}  , value: ${"d/b"}"))
  }
}