/**
  * Copyright (C) 2009-2018 Lightbend Inc. <https://www.lightbend.com>
  */

package akka

import java.io.File

import sbt._

import scala.annotation.tailrec
import scala.collection.immutable.ListMap

case class JavaVersion(numbers: Vector[Long], vendor: Option[String]) {
  def numberStr: String = numbers.mkString(".")

  def withVendor(vendor: Option[String]) = copy(vendor = vendor)
  def withVendor(vendor: String) = copy(vendor = Option(vendor))
  def withNumbers(numbers: Vector[Long]) = copy(numbers = numbers)

  override def toString: String = {
    vendor.map(_ + "@").getOrElse("") + numberStr
  }
}
object JavaVersion {
  def apply(version: String): JavaVersion = CrossJava.parseJavaVersion(version)
  def apply(numbers: Vector[Long], vendor: String): JavaVersion = new JavaVersion(numbers, Option(vendor))
}


/** Tools for discovering different Java versions,
  * will be in sbt 1.1.7 (https://github.com/sbt/sbt/pull/4139) but until that time replicated here */
object CrossJava {
  object Keys {
    val discoveredJavaHomes = settingKey[Map[String, File]]("Discovered Java home directories")
    val javaHomes = settingKey[Map[String, File]]("The user-defined additional Java home directories")
    val fullJavaHomes = settingKey[Map[String, File]]("Combines discoveredJavaHomes and custom javaHomes.")
  }

  import Keys._

  val crossJavaSettings = Seq(
    discoveredJavaHomes := CrossJava.discoverJavaHomes,
    javaHomes := ListMap.empty,
    fullJavaHomes := CrossJava.expandJavaHomes(discoveredJavaHomes.value ++ javaHomes.value),
  )

  // parses jabaa style version number adopt@1.8
  def parseJavaVersion(version: String): JavaVersion = {
    def splitDot(s: String): Vector[Long] =
      Option(s) match {
        case Some(x) => x.split('.').toVector.filterNot(_ == "").map(_.toLong)
        case _       => Vector()
      }
    def splitAt(s: String): Vector[String] =
      Option(s) match {
        case Some(x) => x.split('@').toVector
        case _       => Vector()
      }
    splitAt(version) match {
      case Vector(vendor, rest) => JavaVersion(splitDot(rest), Option(vendor))
      case Vector(rest)         => JavaVersion(splitDot(rest), None)
      case _                    => sys.error(s"Invalid JavaVersion: $version")
    }
  }

  def discoverJavaHomes: ListMap[String, File] = {
    import JavaDiscoverConfig._
    val configs = Vector(jabba, linux, macOS)
    ListMap(configs flatMap { _.javaHomes }: _*)
  }

  sealed trait JavaDiscoverConf {
    def javaHomes: Vector[(String, File)]
  }

  // Sort version strings, considering 1.8.0 < 1.8.0_45 < 1.8.0_121
  @tailrec
  def versionOrder(left: String, right: String): Boolean = {
    val Pattern = """.*?([0-9]+)(.*)""".r
    left match {
      case Pattern(leftNumber, leftRest) =>
        right match {
          case Pattern(rightNumber, rightRest) =>
            if (Integer.parseInt(leftNumber) < Integer.parseInt(rightNumber)) true
            else if (Integer.parseInt(leftNumber) > Integer.parseInt(rightNumber)) false
            else versionOrder(leftRest, rightRest)
          case _ =>
            false
        }
      case _ =>
        true
    }
  }

  object JavaDiscoverConfig {
    val linux = new JavaDiscoverConf {
      val base: File = file("/usr") / "lib" / "jvm"
      val JavaHomeDir = """java-([0-9]+)-.*""".r

      def javaHomes: Vector[(String, File)] =
        wrapNull(base.list())
          .sortWith(versionOrder)
          .collect {
            case dir@JavaHomeDir(ver) => JavaVersion(ver).toString -> (base / dir)
          }
    }

    val macOS = new JavaDiscoverConf {
      val base: File = file("/Library") / "Java" / "JavaVirtualMachines"
      val JavaHomeDir = """jdk-?(1\.)?([0-9]+).*""".r

      def javaHomes: Vector[(String, File)] =
        wrapNull(base.list())
          .sortWith(versionOrder)
          .collect {
            case dir@JavaHomeDir(m, n) =>
              JavaVersion(nullBlank(m) + n).toString -> (base / dir / "Contents" / "Home")
            }
    }

    // See https://github.com/shyiko/jabba
    val jabba = new JavaDiscoverConf {
      val base: File = Path.userHome / ".jabba" / "jdk"
      val JavaHomeDir = """([\w\-]+)\@(1\.)?([0-9]+).*""".r

      def javaHomes: Vector[(String, File)] =
        wrapNull(base.list())
          .sortWith(versionOrder)
          .collect {
            case dir@JavaHomeDir(vendor, m, n) =>
              val v = JavaVersion(nullBlank(m) + n).withVendor(vendor).toString
              if ((base / dir / "Contents" / "Home").exists) v -> (base / dir / "Contents" / "Home")
              else v -> (base / dir)
          }
    }
  }

    def nullBlank(s: String): String =
      if (s eq null) ""
      else s


  // expand Java versions to 1-20 to 1.x, and vice versa to accept both "1.8" and "8"
  private val oneDot = Map((1L to 20L).toVector flatMap { i =>
    Vector(Vector(i) -> Vector(1L, i), Vector(1L, i) -> Vector(i))
  }: _*)
  def expandJavaHomes(hs: Map[String, File]): Map[String, File] =
    hs flatMap {
      case (k, v) =>
        val jv = JavaVersion(k)
        if (oneDot.contains(jv.numbers))
          Vector(k -> v, jv.withNumbers(oneDot(jv.numbers)).toString -> v)
        else Vector(k -> v)
    }

  def wrapNull(a: Array[String]): Vector[String] =
    if (a eq null) Vector()
    else a.toVector

}