package cbt
import java.nio.file._

trait BuildBuild extends BuildBuildWithoutEssentials{
  override def dependencies =
    super.dependencies :+ plugins.essentials
}
trait BuildBuildWithoutEssentials extends BaseBuild{
  assert(
    projectDirectory.getName === "build",
    "You can't extend BuildBuild in: " + projectDirectory + "/build"
  )

  protected final val managedContext = context.copy(
    workingDirectory = managedBuildDirectory,
    parentBuild=Some(this)
  )

  object plugins{
    // TODO: move this out of the OO
    final lazy val scalaTest = DirectoryDependency( context.cbtHome ++ "/plugins/scalatest" )
    final lazy val sbtLayout = DirectoryDependency( context.cbtHome ++ "/plugins/sbt_layout" )
    final lazy val scalaJs   = DirectoryDependency( context.cbtHome ++ "/plugins/scalajs" )
    final lazy val scalariform = DirectoryDependency( context.cbtHome ++ "/plugins/scalariform" )
    final lazy val scalafmt = DirectoryDependency( context.cbtHome ++ "/plugins/scalafmt" )
    final lazy val wartremover = DirectoryDependency( context.cbtHome ++ "/plugins/wartremover" )
    final lazy val uberJar = DirectoryDependency( context.cbtHome ++ "/plugins/uber-jar" )
    final lazy val sonatypeRelease = DirectoryDependency( context.cbtHome ++ "/plugins/sonatype-release" )
    final lazy val essentials = DirectoryDependency( context.cbtHome ++ "/plugins/essentials" )
  }

  override def dependencies =
    super.dependencies :+ context.cbtDependency
  def managedBuildDirectory: java.io.File = lib.realpath( projectDirectory.parent )
  def managedBuild = taskCache[BuildBuildWithoutEssentials]("managedBuild").memoize{
    val managedBuildFile = projectDirectory++"/build.scala"
    logger.composition("Loading build at " ++ managedBuildDirectory.toString)
    val build = (
      if( !managedBuildFile.exists ){
        throw new Exception(
          "No file build.scala (lower case) found in " ++ projectDirectory.getPath
        )
      } else {
        val contents = new String(Files.readAllBytes(managedBuildFile.toPath))
        val cbtUrl = ("cbt:"++GitDependency.GitUrl.regex++"#[a-z0-9A-Z]+").r
        cbtUrl
          .findFirstIn(contents)
          .flatMap{
            url =>
            val Array(base,hash) = url.drop(4).split("#")
            if(context.cbtHome.string.contains(hash))
              None
            else Some{
              // Note: cbt can't use an old version of itself for building,
              // otherwise we'd have to recursively build all versions since
              // the beginning. Instead CBT always needs to build the pure Java
              // Launcher in the checkout with itself and then run it via reflection.
              val dep = new GitDependency(base, hash, Some("nailgun_launcher"))
              val ctx = managedContext.copy( cbtHome = dep.checkout )
              dep.classLoader
                .loadClass( "cbt.NailgunLauncher" )
                .getMethod( "getBuild", classOf[AnyRef] )
                .invoke( null, ctx )
            }
          }.getOrElse{
            try{
              classLoader
                .loadClass(lib.buildClassName)
                .getConstructors.head
                .newInstance(managedContext)
              } catch {
                case e: ClassNotFoundException if e.getMessage == lib.buildClassName =>
                  throw new Exception("You need to define a class Build in build.scala in: "+projectDirectory)
              }
          }
      }
    )
    try{
      build.asInstanceOf[BuildInterface]
    } catch {
      case e: ClassCastException if e.getMessage.contains("Build cannot be cast to cbt.BuildInterface") =>
        throw new Exception("Your Build class needs to extend BaseBuild in: "+projectDirectory, e)
    }
  }
  override def triggerLoopFiles = super.triggerLoopFiles ++ managedBuild.triggerLoopFiles
  override def finalBuild: BuildInterface = if( projectDirectory == context.cwd ) this else managedBuild.finalBuild
}