package cbt
import java.nio.file._
import java.nio.charset.StandardCharsets
import java.net._
import java.io._
import scala.xml._

trait DependencyImplementation extends Dependency{
  implicit protected def logger: Logger
  protected def lib = new Stage1Lib(logger)
  implicit protected def transientCache: java.util.Map[AnyRef,AnyRef]
  implicit protected def classLoaderCache: ClassLoaderCache

  /** key used by taskCache to identify different objects that represent the same logical module */
  protected def moduleKey: String
  /**
   caches given value in context keyed with given key and projectDirectory
   the context is fresh on every complete run of cbt
   */
  protected lazy val taskCache = new PerClassCache(transientCache, moduleKey)

  private[cbt] def targetClasspath: ClassPath
  def exportedClasspathArray: Array[File] = exportedClasspath.files.toArray
  def exportedClasspath: ClassPath
  def dependenciesArray: Array[Dependency] = dependencies.to

  @deprecated("this method was replaced by lastModifiedCompat","")
  def needsUpdateCompat = true
  @deprecated("this method was replaced by dependenciesArray","")
  def dependencyClasspathArray = dependencyClasspath.files.toArray

  /*
  //private type BuildCache = KeyLockedLazyCache[Dependency, Future[ClassPath]]
  def exportClasspathConcurrently: ClassPath = {
    // FIXME: this should separate a blocking and a non-blocking EC
    import scala.concurrent.ExecutionContext.Implicits.global
    Await.result(
      exportClasspathConcurrently(
        transitiveDependencies
          .collect{ case d: ArtifactInfo => d }
          .groupBy( d => (d.groupId,d.artifactId) )
          .mapValues( _.head )
        //, new BuildCache
      ), // FIXME
      Duration.Inf
    )
  }

  def concurrencyEnabled = false

  /**
  The implementation of this method is untested and likely buggy
  at this stage.
  */
  def exportClasspathConcurrently(
    latest: Map[(String, String),Dependency with ArtifactInfo]//, cache: BuildCache
  )( implicit ec: ExecutionContext ): Future[AnyRef] = {
    Future.sequence( // trigger compilation / download of all dependencies first
      this.dependencies.map{
        d =>
          // find out latest version of the required dependency
          val l = d match {
            case m: BoundMavenDependency => latest( (m.groupId,m.artifactId) )
            case _ => d
          }
          // // trigger compilation if not already triggered
          // cache.get( l, l.exportClasspathConcurrently( latest, cache ) )
          l.exportClasspathConcurrently( latest ) // FIXME
      }
    ).map(
      // merge dependency classpaths into one
      ClassPath.flatten(_)
    ).map(
      _ =>
      // now that all dependencies are done, compile the code of this
      exportedClasspath
    )
  }
  */

  def runMain( className: String, args: Seq[String] ): ExitCode =
    lib.getMain( classLoader.loadClass( className ) )( args )

  def runMain( args: Seq[String] ): ExitCode =
    runMain( mainClassOrFail.getName, args )

  def mainClassOrFail = mainClass.getOrElse(
    throw new RuntimeException( "No main class found in " + this )
  )

  def mainClass = lib.pickOne(
    "Which one do you want to run?",
    classes.filter( lib.findMain(_).nonEmpty )
  )( _.name.stripSuffix( "$" ) )

  def classes = exportedClasspath.files.flatMap(
    lib.topLevelClasses( _, classLoader, false )
  )

  def flatClassLoader: Boolean = false

  override def classLoader: ClassLoader = taskCache[DependencyImplementation]( "classLoader" ).memoize{
    if( flatClassLoader ){
      new java.net.URLClassLoader(classpath.strings.map(f => new URL("file://" ++ f)).toArray)
    } else {
      /*
      if( concurrencyEnabled ){
        // trigger concurrent building / downloading dependencies
        exportClasspathConcurrently
      }
      */
      lib.classLoaderRecursion(
        this,
        (this +: transitiveDependencies).collect{
          case d: ArtifactInfo => d 
        }.groupBy(
          d => (d.groupId,d.artifactId)
        ).mapValues(_.head)
      )
    }
  }

  // FIXME: these probably need to update outdated as well
  def classpath: ClassPath = exportedClasspath ++ dependencyClasspath
  def verifyClasspath: Unit = classpath.verify(lib)
  def dependencyClasspath: ClassPath = taskCache[DependencyImplementation]( "dependencyClasspath" ).memoize{
    ClassPath(
      transitiveDependencies
      .flatMap(_.exportedClasspath.files)
      .distinct // <- currently needed here to handle diamond dependencies on builds (duplicate in classpath)
    )
  }
  def dependencies: Seq[Dependency]

  /** return dependencies in order of linearized dependence. this is a bit tricky. */
  def transitiveDependencies: Seq[Dependency] =
    taskCache[DependencyImplementation]( "transitiveDependencies" ).memoize{
      lib.transitiveDependencies(this)
    }

  override def show: String = this.getClass.getSimpleName
  // ========== debug ==========
  def dependencyTree: String = lib.dependencyTreeRecursion(this)
}

// TODO: all this hard codes the scala version, needs more flexibility
class ScalaCompilerDependency(cbtLastModified: Long, mavenCache: File, version: String)(implicit logger: Logger, transientCache: java.util.Map[AnyRef,AnyRef], classLoaderCache: ClassLoaderCache) extends BoundMavenDependency(cbtLastModified, mavenCache, MavenDependency("org.scala-lang","scala-compiler",version, Classifier.none), Seq(mavenCentral))
class ScalaLibraryDependency (cbtLastModified: Long, mavenCache: File, version: String)(implicit logger: Logger, transientCache: java.util.Map[AnyRef,AnyRef], classLoaderCache: ClassLoaderCache) extends BoundMavenDependency(cbtLastModified, mavenCache, MavenDependency("org.scala-lang","scala-library",version, Classifier.none), Seq(mavenCentral))
class ScalaReflectDependency (cbtLastModified: Long, mavenCache: File, version: String)(implicit logger: Logger, transientCache: java.util.Map[AnyRef,AnyRef], classLoaderCache: ClassLoaderCache) extends BoundMavenDependency(cbtLastModified, mavenCache, MavenDependency("org.scala-lang","scala-reflect",version, Classifier.none), Seq(mavenCentral))

class ScalaDependencies(cbtLastModified: Long, mavenCache: File, version: String)(implicit logger: Logger, transientCache: java.util.Map[AnyRef,AnyRef], classLoaderCache: ClassLoaderCache) extends Dependencies(
  Seq(
    new ScalaCompilerDependency(cbtLastModified, mavenCache, version),
    new ScalaLibraryDependency(cbtLastModified, mavenCache, version),
    new ScalaReflectDependency(cbtLastModified, mavenCache, version)
  )
)

case class BinaryDependency( paths: Seq[File], dependencies: Seq[Dependency] )(implicit val logger: Logger, val transientCache: java.util.Map[AnyRef,AnyRef], val classLoaderCache: ClassLoaderCache) extends DependencyImplementation{
  assert(paths.nonEmpty)
  paths.foreach(p => assert(p.exists))
  def exportedClasspath = ClassPath(paths)
  override def lastModified = paths.map(_.lastModifiedRecursive).max // FIXME: cache this
  def targetClasspath = exportedClasspath
  override lazy val moduleKey = this.getClass.getName + "(" + paths.mkString(", ") + ")" // PERFORMANCE HOTSPOT
}

/** Allows to easily assemble a bunch of dependencies */
case class Dependencies( dependencies: Seq[Dependency] )(implicit val logger: Logger, val transientCache: java.util.Map[AnyRef,AnyRef], val classLoaderCache: ClassLoaderCache) extends DependencyImplementation{
  override def lastModified = dependencies.map(_.lastModified).maxOption.getOrElse(0)
  override lazy val moduleKey = this.getClass.getName + "(" + dependencies.map(_.moduleKey).mkString(", ") + ")" // PERFORMANCE HOTSPOT
  def targetClasspath = ClassPath() 
  def exportedClasspath = ClassPath() 
  override def show: String = this.getClass.getSimpleName + "( " + dependencies.map(_.show).mkString(", ") + " )"
}

case class PostBuildDependency(target: File, _dependencies: Seq[DependencyImplementation])(implicit val logger: Logger, val transientCache: java.util.Map[AnyRef,AnyRef], val classLoaderCache: ClassLoaderCache) extends DependencyImplementation{
  override final lazy val lastModified = (target++".last-success").lastModified
  override lazy val moduleKey = target.string
  override def show = s"PostBuildDependency($target)"
  override def targetClasspath = exportedClasspath
  override def exportedClasspath = ClassPath( Seq(target) )
  override def dependencies = _dependencies
}
case class CbtDependencies(cbtLastModified: Long, mavenCache: File, nailgunTarget: File, stage1Target: File, stage2Target: File, compatibilityTarget: File)(implicit logger: Logger, transientCache: java.util.Map[AnyRef,AnyRef], classLoaderCache: ClassLoaderCache){
  val compatibilityDependency = PostBuildDependency(compatibilityTarget, Nil)
  val stage1Dependency = PostBuildDependency(
    stage1Target,
    Seq(
      PostBuildDependency(nailgunTarget, Nil),
      compatibilityDependency
    ) ++
    MavenResolver(cbtLastModified,mavenCache,mavenCentral).bind(
      MavenDependency("org.scala-lang","scala-library",constants.scalaVersion),
      MavenDependency("org.scala-lang.modules","scala-xml_"+constants.scalaMajorVersion,constants.scalaXmlVersion)
    )
  )
  val stage2Dependency = PostBuildDependency(
    stage2Target,
    stage1Dependency +:
    MavenResolver(cbtLastModified, mavenCache,mavenCentral).bind(
      MavenDependency("org.eclipse.jgit", "org.eclipse.jgit", "4.2.0.201601211800-r"),
      MavenDependency("net.java.dev.jna", "jna-platform", "4.4.0"),
      MavenDependency("org.scala-lang","scala-compiler",constants.scalaVersion)
    )
  )
}

case class Classifier(name: Option[String])
object Classifier{
  object none extends Classifier(None)
  object javadoc extends Classifier(Some("javadoc"))
  object sources extends Classifier(Some("sources"))
}
abstract class DependenciesProxy{

}
case class MavenDependency(
  groupId: String, artifactId: String, version: String, classifier: Classifier = Classifier.none, verifyHash: Boolean = true
){
  private[cbt] def serialize = // PERFORMANCE HOTSPOT
    groupId + ":" + artifactId + ":" + version + ( if(classifier.name.nonEmpty) ":" + classifier.name.get else "" )
  private[cbt] def javafy: Array[String] =
    Array(groupId,artifactId,version) ++ classifier.name
}
object MavenDependency{
  private[cbt] def deserialize = (_:String).split(":") match {
    case col => MavenDependency( col(0), col(1), col(2), Classifier(col.lift(3)) )
  }
  private[cbt] def dejavafy =
    ( cols:Array[Array[String]] ) => cols.map(
      col => MavenDependency( col(0), col(1), col(2), Classifier(col.lift(3)) )
    ).toSeq
}
// FIXME: take MavenResolver instead of mavenCache and repositories separately
case class BoundMavenDependency(
  cbtLastModified: Long, mavenCache: File, mavenDependency: MavenDependency, repositories: Seq[URL],
  replace: MavenDependency => Seq[MavenDependency] => Seq[MavenDependency] = _ => (identity _)
)(
  implicit val logger: Logger, val transientCache: java.util.Map[AnyRef,AnyRef], val classLoaderCache: ClassLoaderCache
) extends ArtifactInfo with DependencyImplementation{
  override lazy val moduleKey = this.getClass.getName + "(" + mavenDependency.serialize + ")" // PERFORMANCE HOTSPOT
  override def hashCode = mavenDependency.hashCode
  override def equals(other: Any) = other match{
    case o: BoundMavenDependency => o.mavenDependency == mavenDependency && o.repositories == repositories
    case _ => false
  }
  val MavenDependency( groupId, artifactId, version, classifier, verifyHash ) = mavenDependency
  assert(
    Option(groupId).collect{
      case BoundMavenDependency.ValidIdentifier(_) =>
    }.nonEmpty,
    s"not a valid groupId: '$groupId'"
  )
  assert(
    Option(artifactId).collect{
      case BoundMavenDependency.ValidIdentifier(_) =>
    }.nonEmpty,
    s"not a valid artifactId: '$artifactId'"
  )
  assert(
    version != "" && version != null && !version.startsWith(" ") && !version.endsWith(" "),
    s"not a valid version: '$version'"
  )
  override def show: String = this.getClass.getSimpleName ++ "(" ++ mavenDependency.serialize ++ ")"

  override final lazy val lastModified: Long = taskCache[BoundMavenDependency]( "lastModified" ).memoize[java.lang.Long]{
    classpath.strings.map(new File(_).lastModified).max
  }

  private lazy val base = {
    val v = BoundMavenDependency.extractVersion(version)
    "/" + groupId.split("\\.").mkString("/") + "/" + artifactId + "/" + v + "/" + artifactId + "-" + v
  }
  protected[cbt] def basePath(useClassifier: Boolean) = // PERFORMANCE HOTSPOT
    base + (if (useClassifier && classifier.name.nonEmpty) "-" + classifier.name.get else "")

  //private def coursierJarFile = userHome++"/.coursier/cache/v1/https/repo1.maven.org/maven2"++basePath++".jar"

  def exportedJars = Seq( jar )
  override def exportedClasspath = ClassPath( exportedJars )
  override def targetClasspath = exportedClasspath
  import scala.collection.JavaConverters._

  private def resolve(suffix: String, hash: Option[String], useClassifier: Boolean): File = {
    logger.resolver(lib.blue("Resolving ")+this)
    val file = mavenCache ++ basePath(useClassifier) ++ "." ++ suffix
    val urls = repositories.map(_ ++ basePath(useClassifier) ++ "." ++ suffix)
    urls.find(
      lib.download(_, file, hash)
    ).getOrElse(
      throw new Exception(s"\nCannot resolve\n$this\nCan't find any of\n"++urls.mkString("\n"))
    )
    file
  }

  private def resolveHash(suffix: String, useClassifier: Boolean) = {
    val path = resolve( suffix ++ ".sha1", None, useClassifier ).toPath
    Option( classLoaderCache.hashMap.get("hash:"+path) ).map(_.asInstanceOf[String]).getOrElse{
      val result = Files.readAllLines(
        path,
        StandardCharsets.UTF_8
      ).asScala.mkString("\n").split(" ").head.trim
      classLoaderCache.hashMap.put("hash:"+path, result)
      result
    }
  }

  def jarSha1: String = taskCache[BoundMavenDependency]("jarSha1").memoize{ resolveHash("jar", true) }
  def pomSha1: String = taskCache[BoundMavenDependency]("pomSha1").memoize{ resolveHash("pom", false) }
  def jar: File = taskCache[BoundMavenDependency]("jar").memoize{ resolve("jar", if(verifyHash) Some(jarSha1) else None, true) }
  def pom: File = taskCache[BoundMavenDependency]("pom").memoize{ resolve("pom", if(verifyHash) Some(pomSha1) else None, false) }

  private def pomXml = {
    logger.resolver( "Loading pom file: " ++ pom.string )
    XML.loadFile(pom.string)
  }
  // ========== pom traversal ==========

  private lazy val transitivePom: Seq[BoundMavenDependency] = {
    (pomXml \ "parent").collect{
      case parent =>
        BoundMavenDependency(
          cbtLastModified: Long,
          mavenCache,
          MavenDependency(
            (parent \ "groupId").text,
            (parent \ "artifactId").text,
            (parent \ "version").text
          ),
          repositories,
          replace
        )(logger, transientCache, classLoaderCache)
    }.flatMap(_.transitivePom) :+ this
  }

  private lazy val properties: Map[String, String] = (
    transitivePom.flatMap{ d =>
      val props = (d.pomXml \ "properties").flatMap(_.child).map{
        tag => tag.label -> tag.text
      }
      logger.pom(s"Found properties in $pom: $props")
      props
    }
  ).toMap

  private lazy val dependencyVersions: Map[String, (String,String)] =
    transitivePom.flatMap(
      p =>
      (p.pomXml \ "dependencyManagement" \ "dependencies" \ "dependency").map{
        xml =>
          val groupId = p.lookup(xml,_ \ "groupId").get
          val artifactId = p.lookup(xml,_ \ "artifactId").get
          val version = p.lookup(xml,_ \ "version").get
          artifactId -> (groupId, version)
      }
    ).toMap

  def dependencies: Seq[BoundMavenDependency] = {
    replace(mavenDependency)(
      if(classifier == Classifier.sources) Seq()
      else {
        lib.cacheOnDisk(
          cbtLastModified, mavenCache ++ basePath(true) ++ ".pom.dependencies", classLoaderCache.hashMap
        )( MavenDependency.deserialize )( _.serialize )( MavenDependency.dejavafy )( _.map(_.javafy).toArray ){
          (pomXml \ "dependencies" \ "dependency").collect{
          case xml if ( (xml \ "scope").text == "" || (xml \ "scope").text == "compile" ) && (xml \ "optional").text != "true" =>
              val artifactId = lookup(xml,_ \ "artifactId").get
              val groupId =
                lookup(xml,_ \ "groupId").getOrElse(
                  dependencyVersions
                    .get(artifactId).map(_._1)
                    .getOrElse(
                      throw new Exception(s"$artifactId not found in \n$dependencyVersions")
                    )
                )
              val version =
                lookup(xml,_ \ "version").getOrElse(
                  dependencyVersions
                    .get(artifactId).map(_._2)
                    .getOrElse(
                      throw new Exception(s"$artifactId not found in \n$dependencyVersions")
                    )
                )
              val classifier = Classifier( Some( (xml \ "classifier").text ).filterNot(_ == "").filterNot(_ == null) )
              MavenDependency( groupId, artifactId, version, classifier )
          }.toVector
        }
      }
    ).map(
      BoundMavenDependency( cbtLastModified, mavenCache, _, repositories, replace )
    ).toVector
  }
  def lookup( xml: Node, accessor: Node => NodeSeq ): Option[String] = {
    // println("lookup in " + xml)
    val Substitution = "\\$\\{([^\\}]+)\\}".r

    def matcherFunc(matcher: scala.util.matching.Regex.Match): String = {
      val path = matcher.group(1)
      val ret = properties.get(path).orElse(
        transitivePom.reverse.flatMap{ d =>
          Some(path.split("\\.").toList).collect{
            case "project" :: path =>
              path.foldLeft(d.pomXml:NodeSeq){ case (xml,tag) => xml \ tag }.text
          }.filter(_ != "")
        }.headOption
      )
        .getOrElse(
          throw new Exception(s"Can't find $path in \n$properties.\n\npomParents: $transitivePom\n\n pomXml:\n$pomXml" )
        )

      Substitution.replaceAllIn(
        ret,
        matcherFunc _
      )
    }

    accessor(xml).headOption.map { v =>
      Substitution.replaceAllIn(
        v.text,
        matcherFunc _
      )
    }
  }
}
object BoundMavenDependency{
  private lazy val versionRangeRegex = "^[\\[\\(]([^,\\]\\)]*)(,([^\\]\\)]*))?[\\]\\)]".r
  def extractVersion( versionOrRange: String ) = {
    versionOrRange match {
      case versionRangeRegex(left,middle,right) if left != null || right != null => {
        Option(left).filterNot(_ == "") getOrElse right
      }
      case version => version
    }
  }

  val ValidIdentifier = "^([A-Za-z0-9_\\-.]+)$".r // according to maven's DefaultModelValidator.java
  def semanticVersionLessThan(left: Array[Either[Int,String]], right: Array[Either[Int,String]]) = {
    // FIXME: this ignores ends when different size
    val zipped = left zip right
    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 updateOutdated(
    deps: Seq[Dependency with ArtifactInfo],
    versionLessThan: (Array[Either[Int,String]], Array[Either[Int,String]]) => Boolean = semanticVersionLessThan
  )(implicit logger: Logger): Seq[Dependency with ArtifactInfo] = {
    val latest = deps
      .groupBy( d => (d.groupId, d.artifactId) )
      .mapValues(
        _.groupBy(_.version) // remove duplicates
         .map( _._2.head )
         .toVector
         .sortBy( _.version.split("\\.|\\-").map(toInt) )( Ordering.fromLessThan(versionLessThan) )
         .last
      )
    deps.map{
      d => 
        val l = latest((d.groupId,d.artifactId))
        if(d != l) logger.resolver("outdated: "++d.show)
        l
    }
  }
}
/*
case class DependencyOr(first: DirectoryDependency, second: JavaDependency) extends ProjectProxy with DirectoryDependencyBase{
  val isFirst = new File(first.projectDirectory).exists
  protected val delegate = if(isFirst) first else second
}
*/