Trello json-to-csv converter with muster

TrelloJsonToCsvApp.scala

package com.bfritz.trello.trellojsontocsv

import muster.{Consumer,MappingException}
import muster.ast.{AstNode,NullNode,ObjectNode,TextNode}
import muster.codec.jackson.JacksonCodec

import java.io.{File,FileWriter}
import au.com.bytecode.opencsv.CSVWriter

object TrelloJsonToCsvApp extends App { 
  val csvHeaders = List("List", "Card", "Labels", "Link", "Description", "Card Created")

  implicit object ActionConsumer extends Consumer[Option[Action]] {
    def consume(node: AstNode[_]): Option[Action] = node match {
      case obj: ObjectNode => 
        val typeConsumer = implicitly[Consumer[String]]

        for {
          data <- obj.readObjectFieldOpt("data")
          card <- data.readObjectFieldOpt("card")
          id <- card.readStringFieldOpt("id")
        } yield {
          Action(
            typeConsumer.consume(obj.readStringField("type")),
            obj.readStringField("date").value,
            id.value
          )
        }
      case n => throw new MappingException(s"Can't convert a ${n.getClass} to a Action")
    }
  } 
  
  val b = JacksonCodec.as[Board](new File("trello.json"))
  
  val listsByName = b.lists.map(_.name).zip(b.lists).toMap
  val listsById = b.lists.map(_.id).zip(b.lists).toMap
  val cardsByList = b.cards.groupBy(c => listsById(c.idList))
  val cardCreatedActions = b.actions.flatten.filter(_.atype == "createCard")
  val createdDateByCard = cardCreatedActions.map{ a => (a.cardId, a.date) }.toMap
  // println(createdDateByCard)
  
  val writer = new CSVWriter(new FileWriter("trello.csv"))
  writer.writeNext(csvHeaders)
  
  for (c <- cardsByList(listsByName("Doing")).sortBy(_.pos)) writeRow(c)
  for (c <- cardsByList(listsByName("To Do")).sortBy(_.pos)) writeRow(c)
  for (c <- cardsByList(listsByName("Done")).sortBy(_.pos)) writeRow(c)
  for (c <- cardsByList(listsByName("Postponed")).sortBy(_.pos)) writeRow(c)
  
  def writeRow(card: Card) {
      writer.writeNext(Array[String](
        listsById(card.idList).name,
        card.name,
        card.labels.map(_.name).mkString(", "),
        card.shortUrl,
        card.desc,
        createdDateByCard.getOrElse(card.id, "")
      ))
  }
  
  writer.close
  
  case class Card(id: String, idList: String, name: String, desc: String, labels: List[Label], shortUrl: String, pos: Float)
  case class CardList(id: String, name: String)
  case class Label(name: String, color: String)
  case class Action(atype: String, date: String, cardId: String)
  case class Board(id: String, name: String, lists: List[CardList], cards: List[Card], actions: List[Option[Action]])
}