AoC day 23

package day23

import io.Source
import collection.mutable

object day23 extends App {

  val registry = mutable.Map[Char, Int]('a' -> 0, 'b' -> 0, 'c' -> 0, 'd' -> 0)
  val instructions = mutable.ListBuffer[Instruction]()

  abstract class Instruction {
    def exec(args: AnyVal*): Int
  }

  case class Jump(a: String, b: String) extends Instruction {
    val _a: AnyVal = if (a.forall(_.isLetter)) a.head else a.toInt
    val _b: AnyVal = if (b.forall(_.isLetter)) b.head else b.toInt
    def this(cmd: Array[String]) = {
      this(cmd.head.mkString, cmd.last.mkString)
    }
    def this(cmd: String) = {
      this(cmd split ' ' drop 1)
    }
    override def toString = "jnz " + _a + " " + _b
    override def exec(args: AnyVal*) = _a match {
      case i: Int => if (i > 0) _b match {
        case j: Int => j
        case j: Char => registry(j)
      } else 1
      case c: Char => if (registry(c) > 0) _b match {
        case j: Int => j
        case j: Char => registry(j)
      } else 1
    }
  }

  case class Copy(a: String, b: Char) extends Instruction {
    val _a: AnyVal = if (a.forall(_.isLetter)) a.head else a.toInt
    def this(cmd: String) = {
      this((cmd split ' ' slice (1, 2)).mkString, cmd.split(' ').last.head)
    }
    override def toString = "cpy " + _a + " " + b
    override def exec(args: AnyVal*) = _a match {
      case i: Int =>
        if (registry.keySet.contains(b)) registry(b) = i
        1
      case c: Char =>
        if (registry.keySet.contains(b) && registry.keySet.contains(c)) registry(b) = registry(c)
        1
    }
  }

  case class Inc(a: Char) extends Instruction {
    def this(cmd: String) {
      this(cmd.last)
    }
    override def toString = "inc " + a
    override def exec(args: AnyVal*) = {
      registry(a) += 1
      1
    }
  }

  case class Dec(a: Char) extends Instruction {
    def this(cmd: String) {
      this(cmd.last)
    }
    override def toString = "dec " + a
    override def exec(args: AnyVal*) = {
      registry(a) -= 1
      1
    }
  }

  case class Multi(a: Char, b: Char, c: Char) extends Instruction {
    def this(cmd: Array[String]) {
      this(cmd.head.head, cmd.slice(1,2).head.head, cmd.last.head)
    }
    def this(cmd: String) {
      this(cmd split ' ' drop 1)
    }
    override def toString = "mlt " + a + " " + b + " " + c
    override def exec(args: AnyVal*) = {
      registry(c) = registry(a) * registry(b)
      1
    }
  }

  class Nop extends Instruction {
    override def exec(args: AnyVal*) = 1
  }

  case class Toggle(a: Char) extends Instruction {
    def this(cmd: String) {
      this(cmd.last)
    }
    def toggleInstruction(x: Instruction): Instruction = x match {
      case i: Inc => Dec(i.a)
      case i: Dec => Inc(i.a)
      case i: Toggle => Inc(i.a)
      case i: Jump => Copy(i.a, i.b.head)
      case i: Copy => Jump(i.a, i.b.toString)
    }
    override def toString = "tgl " + a
    override def exec(args: AnyVal*) = args(0) match {
      case cp: Int =>
        val i = cp + registry(a)
        if (0 <= i && i < instructions.length) {
          instructions(i) = toggleInstruction(instructions(i))
        }
        1
    }
  }

  def parse(xs: String): Instruction = xs match {
    case s if s.startsWith("jnz") => new Jump(s)
    case s if s.startsWith("cpy") => new Copy(s)
    case s if s.startsWith("inc") => new Inc(s)
    case s if s.startsWith("dec") => new Dec(s)
    case s if s.startsWith("tgl") => new Toggle(s)
    case s if s.startsWith("mlt") => new Multi(s)
    case s if s.startsWith("nop") => new Nop
  }

  def exec(): Any = {
    var p = 0
    while (p < instructions.length) {
      p += instructions(p).exec(p)
    }
  }

  def input = Source.fromFile("day23.txt").getLines.toList
  instructions ++= input.map(parse)
  // part 1
  registry('a') = 7
  exec
  println(registry('a'))

  // part 2
  def input2 = Source.fromFile("day23b.txt").getLines.toList
  registry.keys.foreach(k => if (k == 'a') registry(k) = 12 else registry(k) = 0)
  instructions.clear
  instructions ++= input2.map(parse)
  exec
  println(registry('a'))

}