package aoc

object AoC2017 extends Year {

  override def days = Map(
    "1" -> Day1,
    "2" -> Day2,
    "3" -> Day3,
    "25" -> Day25
  )

  object Day1 extends Day {

    override def part1(input: String): String = {
      val reg = """(\d)(?=\1)""".r
      val matches = reg.findAllIn(input).toList
      val csum = matches.map(_.toInt).sum
      if(input.head == input.last) {
        (csum + input.head.toString.toInt).toString
      } else {
        csum.toString
      }
    }

    override def part2(input: String): String = {
      val (left, right) = input.splitAt(input.length / 2)
      val zipped = left.zip(right)
      val doubled = zipped.filter { case (l, r) => l == r}.map { case (c, _) => c.toString }
      (doubled.map(_.toInt).sum * 2).toString
    }

  }

  object Day2 extends Day {

    override def part1(input: String): String = {
      val lines = input.lines.toList
      val rows = lines.map(_.split("""\s+""").map(_.toInt))
      val minMax = rows.map(r => (r.min, r.max))
      val differences = minMax.map { case (min, max) => max - min }
      differences.sum.toString
    }

    override def part2(input: String): String = {
      val lines = input.lines.toList
      val rows = lines.map(_.split("""\s+""").map(_.toInt))
      rows.flatMap { r =>
        val q = r.zipWithIndex.flatMap { case (e, i) =>
          r.drop(i + 1).map(f => {
            val (min, max) = (Math.min(e, f), Math.max(e, f))
            if(max % min == 0) {
              Some(max / min)
            } else {
              None
            }
          })
        }
        q.filter(_.isDefined).map(_.get)
      }.sum.toString
    }

  }

  object Day3 extends Day {

    override def part1(input: String): String = {
      case class Cell(num: Int, stepSize: Int, stepFrac: Int, stepped: Int, dist: (Int, Int))
      val inum = input.toInt
      (inum match {
        case 1  => 0
        case _ =>
          val layer = (Math.sqrt(inum).ceil / 2).floor.toInt
          val square = ((layer + 1) * 2) - 1
          val diff = (square * square) - inum
          val wave = Math.abs(layer - (diff % (layer * 2)))
          layer + wave
      }).toString
    }

    override def part2(input: String): String = {
      "Not Currently Implemented" // TODO Implement this
    }

  }

  object Day25 extends Day {

    import fastparse._, MultiLineWhitespace._

    case class State(name: String)
    case class InState(state: State, whenZero: Branch, whenOne: Branch)
    case class Branch(write: Int, move: Direction, stateChange: State)
    sealed trait Direction {
      def change: Int
    }
    case object MoveLeft extends Direction {
      override def change: Int = -1
    }
    case object MoveRight extends Direction {
      override def change: Int = 1
    }
    case class Program(beginIn: State, diagnosticCount: Int, states: Map[State, InState], index: Int = 0, tape: Map[Int, Int] = Map()) {

      def step: Program = {
        val ndc = diagnosticCount - 1
        val cs = states(beginIn)
        val cc = tape.getOrElse(index, 0)
        val br = cc match {
          case 0 => cs.whenZero
          case 1 => cs.whenOne
        }
        val wr = br.write
        val mv = br.move
        val ns = br.stateChange
        val nm = tape + (index -> wr)
        Program(ns, ndc, states, index + mv.change, nm)
      }

    }

    def stateParser[_: P]: P[State] = P( "state" ~ CharIn("A-Z").rep.! ).map(State)
    def writeParser[_: P]: P[Int] = P( "- Write the value" ~ ("0" | "1").! ~ "." ).map(_.toInt)
    def directionParser[_: P]: P[Direction] = P( "- Move one slot to the" ~ ("left" | "right").! ~ "." ).map {
      case "left" => MoveLeft
      case "right" => MoveRight
    }
    def stateChangeParser[_: P]: P[State] = P("- Continue with" ~ stateParser ~ ".")
    def branchParser[_: P]: P[Branch] = P( writeParser ~ directionParser ~ stateChangeParser ).map {
      case (write, dir, state) => Branch(write, dir, state)
    }
    def inStateParser[_: P]: P[InState] = P(
      "In" ~ stateParser ~ ":" ~ "If the current value is 0:" ~ branchParser ~ "If the current value is 1:" ~ branchParser
    ).map {
      case (state, v0, v1) => InState(state, v0, v1)
    }
    def programParser[_: P]: P[Program] = P(
      "Begin in" ~ stateParser ~ "." ~
      "Perform a diagnostic checksum after" ~ CharIn("0-9").rep(1).!.map(_.toInt) ~ "steps." ~
      inStateParser.rep.map(f => {
        val z = f.map(_.state).zip(f)
        z.toMap
      })
    ).map {
      case (begin, steps, states) => Program(begin, steps, states)
    }

    override def part1(input: String): String = {
      val Parsed.Success(program, _) = parse(input, programParser(_))
      def finalState(p: Program): Program = {
        val np = p.step
        print(s"\rInstructions Left: ${np.diagnosticCount}${" " * program.diagnosticCount.toString.length}")
        np.diagnosticCount match {
          case 0 => np
          case _ => finalState(np)
        }
      }
      println()
      finalState(program).tape.values.count(_ == 1).toString
    }

    override def part2(input: String): String = {
      "You Win!"
    }

  }

}