// DQCategory.scala
case class DQCategory (
  id            : Option[BSONObjectID],
  title         : String,
  sentences     : List[DailyQuotesSentence]
)

object DQCategory {

  implicit object DQCategoryBSONReader extends BSONDocumentReader[DQCategory] {
    def read (doc: BSONDocument): DQCategory = {
      DQCategory (
        doc.getAs[BSONObjectID]("id"),
        doc.getAs[String]("title").get,
        doc.getAs[List[DailyQuotesSentence]]("sentences").toList.flatten
      )
    }
  }

}

// DQSentence.scala
case class DQSentence(
  id            : Option[BSONObjectID],
  link          : String,
  xpath         : String,
  content       : String,
  categories    : List[DQCategory]
)

object DQSentence {

  implicit object DQSentenceBSONReader extends BSONDocumentReader[DQSentence] {
    def read (doc: BSONDocument): DQSentence = {
      DQSentence (
        doc.getAs[BSONObjectID]("id"),
        doc.getAs[String]("link").get,
        doc.getAs[String]("xpath").get,
        doc.getAs[String]("content").get,
        doc.getAs[List[DQCategory]]("categories").toList.flatten
      )
    }
  }

  implicit object DQSentenceBSONWriter extends BSONDocumentWriter[DQSentence] {
    def write(sentence: DQSentence): BSONDocument = {
      BSONDocument (
        "id"              -> sentence.id.getOrElse(BSONObjectID.generate),
        "link"            -> sentence.link,
        "xpath"           -> sentence.xpath,
        "content"         -> sentence.content,
        "categories"      -> sentence.categories
      )
    }
  }


}