package cbt
import java.nio.file._
import java.net._
import java.io._
import scala.collection.immutable.Seq
import scala.xml._
import paths._

private final class Tree( val root: Dependency, computeChildren: => Seq[Tree] ){
  lazy val children = computeChildren
  def linearize: Seq[Dependency] = root +: children.flatMap(_.linearize)
  def show(indent: Int = 0): Stream[Char] = {
    ("  " * indent ++ root.show ++ "\n").toStream #::: children.map(_.show(indent+1)).foldLeft(Stream.empty[Char])(_ #::: _)
  }
}

trait ArtifactInfo extends Dependency{
  def artifactId: String
  def groupId: String
  def version: String

  protected def str = s"$groupId:$artifactId:$version"
  override def show = super.show ++ s"($str)"
}
abstract class Dependency{
  implicit def logger: Logger
  protected def lib = new Stage1Lib(logger)

  def updated: Boolean
  //def cacheClassLoader: Boolean = false
  def exportedClasspath: ClassPath
  def exportedJars: Seq[File]
  def jars: Seq[File] = exportedJars ++ dependencyJars

  def canBeCached = false
  def cacheDependencyClassLoader = true

  private object cacheClassLoaderBasicBuild extends Cache[URLClassLoader]
  def classLoader: URLClassLoader = cacheClassLoaderBasicBuild{
    val transitiveClassPath = transitiveDependencies.map{
      case d if d.canBeCached => Left(d)
      case d => Right(d)
    }
    val buildClassPath = ClassPath.flatten(
      transitiveClassPath.flatMap(
        _.right.toOption.map(_.exportedClasspath)
      )
    )
    val cachedClassPath = ClassPath.flatten(
      transitiveClassPath.flatMap(
        _.left.toOption
      ).par.map(_.exportedClasspath).seq.sortBy(_.string)
    )

    if(cacheDependencyClassLoader){    
      new URLClassLoader(
        exportedClasspath ++ buildClassPath,
        ClassLoaderCache.get( cachedClassPath )
      )
    } else {
      new URLClassLoader(
        exportedClasspath ++ buildClassPath ++ cachedClassPath, ClassLoader.getSystemClassLoader
      )
    }
  }
  def classpath           : ClassPath = exportedClasspath ++ dependencyClasspath
  def dependencyJars      : Seq[File] = transitiveDependencies.flatMap(_.jars)
  def dependencyClasspath : ClassPath = ClassPath.flatten( transitiveDependencies.map(_.exportedClasspath) )
  def dependencies: Seq[Dependency]

  private def resolveRecursive(parents: List[Dependency] = List()): Tree = {
    // diff removes circular dependencies
    new Tree(this, (dependencies diff parents).map(_.resolveRecursive(this :: parents)))
  }

  def transitiveDependencies: Seq[Dependency] = {
    val deps = dependencies.flatMap(_.resolveRecursive().linearize)
    val hasInfo = deps.collect{ case d:ArtifactInfo => d }
    val noInfo  = deps.filter{
      case _:ArtifactInfo => false
      case _ => true
    }
    noInfo ++ MavenDependency.removeOutdated( hasInfo )
  }

  def show: String = this.getClass.getSimpleName
  // ========== debug ==========
  def dependencyTree: String = dependencyTreeRecursion()
  private def dependencyTreeRecursion(indent: Int = 0): String = (
    ( " " * indent )
    ++ (if(updated) lib.red(show) else show)
    ++ dependencies.map(
      _.dependencyTreeRecursion(indent + 1)
    ).map( "\n" ++ _.toString ).mkString("")
  )
}

// TODO: all this hard codes the scala version, needs more flexibility
class ScalaCompilerDependency(version: String)(implicit logger: Logger) extends MavenDependency("org.scala-lang","scala-compiler",version)
class ScalaLibraryDependency (version: String)(implicit logger: Logger) extends MavenDependency("org.scala-lang","scala-library",version)
class ScalaReflectDependency (version: String)(implicit logger: Logger) extends MavenDependency("org.scala-lang","scala-reflect",version)

case class ScalaDependencies(version: String)(implicit val logger: Logger) extends Dependency{ sd =>
  final val updated = false
  override def canBeCached = true
  def exportedClasspath = ClassPath(Seq())
  def exportedJars = Seq[File]()  
  def dependencies = Seq(
    new ScalaCompilerDependency(version)(logger),
    new ScalaLibraryDependency(version)(logger),
    new ScalaReflectDependency(version)(logger)
  )
}

case class BinaryDependency( path: File, dependencies: Seq[Dependency] )(implicit val logger: Logger) extends Dependency{
  def updated = false
  def exportedClasspath = ClassPath(Seq(path))
  def exportedJars = Seq[File](path)
}

case class Stage1Dependency()(implicit val logger: Logger) extends Dependency{
  def exportedClasspath = ClassPath( Seq(nailgunTarget, stage1Target) )
  def exportedJars = Seq[File]()  
  def dependencies = ScalaDependencies(constants.scalaVersion).dependencies
  def updated = false // FIXME: think this through, might allow simplifications and/or optimizations
}
case class CbtDependency()(implicit val logger: Logger) extends Dependency{
  def exportedClasspath = ClassPath( Seq( stage2Target ) )
  def exportedJars = Seq[File]()  
  override def dependencies = Seq(
    Stage1Dependency()(logger),
    MavenDependency("net.incongru.watchservice","barbary-watchservice","1.0")(logger),
    MavenDependency("com.lihaoyi","ammonite-repl_2.11.7","0.5.5")(logger),
    MavenDependency("org.scala-lang.modules","scala-xml_2.11","1.0.5")(logger)
  )
  def updated = false // FIXME: think this through, might allow simplifications and/or optimizations
}

sealed trait ClassifierBase
final case class Classifier(name: String) extends ClassifierBase
case object javadoc extends ClassifierBase
case object sources extends ClassifierBase

case class MavenDependency( groupId: String, artifactId: String, version: String, sources: Boolean = false )(implicit val logger: Logger)
  extends ArtifactInfo{

  def updated = false
  override def canBeCached = true

  private val groupPath = groupId.split("\\.").mkString("/")
  def basePath = s"/$groupPath/$artifactId/$version/$artifactId-$version"++(if(sources) "-sources" else "")
  
  private def resolverUrl:URL = new URL(
    if(version.endsWith("-SNAPSHOT")) "https://oss.sonatype.org/content/repositories/snapshots" else "https://repo1.maven.org/maven2"
  )
  private def baseUrl: URL = resolverUrl ++ basePath
  private def baseFile: File = mavenCache ++ basePath
  private def pomFile: File = baseFile ++ ".pom"
  private def jarFile: File = baseFile ++ ".jar"
  //private def coursierJarFile = userHome++"/.coursier/cache/v1/https/repo1.maven.org/maven2"++basePath++".jar"
  private def pomUrl: URL = baseUrl ++ ".pom"
  private def jarUrl: URL = baseUrl ++ ".jar"    

  def exportedJars = Seq( jar )
  def exportedClasspath = ClassPath( exportedJars )

  import scala.collection.JavaConversions._
  
  def jarSha1 = {
    val file = jarFile ++ ".sha1"
    scala.util.Try{
      lib.download( jarUrl ++ ".sha1"  , file, None )
      // split(" ") here so checksum file contents in this format work: df7f15de037a1ee4d57d2ed779739089f560338c  jna-3.2.2.pom
      Files.readAllLines(Paths.get(file.string)).mkString("\n").split(" ").head.trim
    }.toOption // FIXME: .toOption is a temporary solution to ignore if libs don't have one (not sure that's even possible)
  }

  def pomSha1 = {
    val file = pomFile++".sha1"
    scala.util.Try{ 
      lib.download( pomUrl++".sha1" , file, None )
      // split(" ") here so checksum file contents in this format work: df7f15de037a1ee4d57d2ed779739089f560338c  jna-3.2.2.pom
      Files.readAllLines(Paths.get(file.string)).mkString("\n").split(" ").head.trim
    }.toOption // FIXME: .toOption is a temporary solution to ignore if libs don't have one (not sure that's even possible)
  }

  def jar = {
    lib.download( jarUrl, jarFile, jarSha1 )
    jarFile
  }
  def pomXml = XML.loadFile(pom.toString)

  def pom = {
    lib.download( pomUrl, pomFile, pomSha1 )
    pomFile
  }

  // ========== pom traversal ==========

  lazy val pomParents: Seq[MavenDependency] = {
    (pomXml \ "parent").collect{
      case parent =>
        MavenDependency(
          (parent \ "groupId").text,
          (parent \ "artifactId").text,
          (parent \ "version").text
        )(logger)
    }
  }
  def dependencies: Seq[MavenDependency] = {
    if(sources) Seq()
    else (pomXml \ "dependencies" \ "dependency").collect{
      case xml if (xml \ "scope").text == "" && (xml \ "optional").text != "true" =>
        MavenDependency(
          lookup(xml,_ \ "groupId").get,
          lookup(xml,_ \ "artifactId").get,
          lookup(xml,_ \ "version").get,
          (xml \ "classifier").text == "sources"
        )(logger)
    }.toVector
  }
  def lookup( xml: Node, accessor: Node => NodeSeq ): Option[String] = {
    //println("lookup in "++pomUrl)
    val Substitution = "\\$\\{([a-z0-9\\.]++)\\}".r
    accessor(xml).headOption.flatMap{v =>
      //println("found: "++v.text)
      v.text match {
        case Substitution(path) =>
          //println("lookup "++path ++ ": "++(pomXml\path).text)
          lookup(pomXml, _ \ "properties" \ path)
        case value => Option(value)
      }
    }.orElse(
      pomParents.map(p => p.lookup(p.pomXml, accessor)).flatten.headOption
    )
  }
}
object MavenDependency{
  def semanticVersionLessThan(left: String, right: String) = {
    // FIXME: this ignores ends when different size
    val zipped = left.split("\\.|\\-").map(toInt) zip right.split("\\.|\\-").map(toInt)
    val res = zipped.map {
      case (Left(i),Left(j)) => i compare j
      case (Right(i),Right(j)) => i compare j
      case (Left(i),Right(j)) => i.toString compare j
      case (Right(i),Left(j)) => i compare j.toString
    }
    res.find(_ != 0).map(_ < 0).getOrElse(false)
  }
  def toInt(str: String): Either[Int,String] = try {
    Left(str.toInt)
  } catch {
    case e: NumberFormatException => Right(str)
  }
  /* this obviously should be overridable somehow */
  def removeOutdated(
    deps: Seq[ArtifactInfo],
    versionLessThan: (String, String) => Boolean = semanticVersionLessThan
  )(implicit logger: Logger): Seq[ArtifactInfo] = {
    val latest = deps
      .groupBy( d => (d.groupId, d.artifactId) )
      .mapValues(
        _.sortBy( _.version )( Ordering.fromLessThan(versionLessThan) )
         .last
      )
    deps.flatMap{
      d => 
        val l = latest.get((d.groupId,d.artifactId))
        if(d != l) logger.resolver("outdated: "++d.show)
        l
    }.distinct
  }
}