package xyz.driver.server.parsers

import xyz.driver.server.parsers.errors.ParseQueryArgException
import xyz.driver.pdsuicommon.db.{Sorting, SortingOrder}
import fastparse.all._
import fastparse.core.Parsed
import play.api.routing.sird._

import scala.util.Try

object SortingParser {

  private val sortingOrderParser: Parser[SortingOrder] = P("-".!.?).map {
    case Some(_) => SortingOrder.Descending
    case None    => SortingOrder.Ascending
  }

  private def dimensionSortingParser(validDimensions: Seq[String]): Parser[Sorting.Dimension] = {
    P(sortingOrderParser ~ StringIn(validDimensions: _*).!).map {
      case (sortingOrder, field) =>
        val prefixedFields = field.split("\\.", 2)
        prefixedFields.size match {
          case 1 => Sorting.Dimension(None, field, sortingOrder)
          case 2 => Sorting.Dimension(Some(prefixedFields.head), prefixedFields.last, sortingOrder)
        }
    }
  }

  private def sequentialSortingParser(validDimensions: Seq[String]): Parser[Sorting.Sequential] = {
    P(dimensionSortingParser(validDimensions).rep(min = 1, sep = ",") ~ End).map { dimensions =>
      Sorting.Sequential(dimensions)
    }
  }

  def parse(validDimensions: Set[String], queryString: QueryString): Try[Sorting] = Try {
    queryString.getOrElse("sort", Seq.empty) match {
      case Nil => Sorting.Sequential(Seq.empty)

      case rawSorting +: Nil =>
        val parser = sequentialSortingParser(validDimensions.toSeq)
        parser.parse(rawSorting) match {
          case Parsed.Success(x, _) => x
          case e: Parsed.Failure =>
            throw new ParseQueryArgException("sort" -> formatFailure(e))
        }

      case xs => throw new ParseQueryArgException("sort" -> "multiple sections are not allowed")
    }
  }

  private def formatFailure(e: Parsed.Failure): String = {
    ParseError.msg(e.extra.input, e.extra.traced.expected, e.index)
  }

}