version.scala

package com.gtan.turing

import akka.shapeless.HNil
import org.parboiled2._

import scala.util.Try

/**
 * Created by zhang on 2015/7/14.
 */
case class Version(first:Int,second:Int,third:Int,rc:Option[Int]){
  override def toString = {
    first+"."+second+"."+third + rc.map("-RC"+_).getOrElse("")
  }
}
object Version{
  def apply(str:String): Try[Version] =
    new VersionParser(str).InputLine.run()

  def notZeroOr(x:Int)(f: =>Int)=
    if (x != 0) {
      x
    } else f

  implicit val VersionOrdering = new Ordering[Version] {
    override def compare(x: Version, y: Version): Int = {
      notZeroOr(x.first-y.first) {
        notZeroOr(x.second - y.second) {
          notZeroOr(x.third - y.third) {
            (x.rc,y.rc) match {
              case (Some(a),None) => 1
              case (Some(a),Some(b)) => a-b
              case (None,Some(b)) => -1
              case (None,None) => 0
            }
          }
        }
      }
    }
  }
}

class VersionParser(val input:ParserInput) extends Parser {
  def Number = rule { capture(Digits) ~> (_.toInt)}
  def Digits = rule { oneOrMore(CharPredicate.Digit) }

  def RC = rule { optional("-RC" ~ Number)}

  def Expression:Rule1[Version] = rule {
    (Number ~ '.' ~ Number ~ '.' ~ Number ~ RC) ~>
      ((a:Int,b:Int,c:Int,rc:Option[Int])=>Version(a,b,c,rc))
  }

  def InputLine = rule {Expression ~ EOI}
}

object VersionApp extends App{
  def latest(versionStrs:List[String]) = {
    versionStrs.flatMap(Version(_).toOption).max.toString
  }

  assert(latest(List("0.13.7", "0.9.10", "0.9.11-RC1")) == "0.13.7")
  assert(latest(List("0.13.6", "0.13.7-RC1", "0.13.7-RC2")) == "0.13.7-RC2")
}