package cbt
import java.io._
import java.net._
import org.eclipse.jgit.api._
import org.eclipse.jgit.transport.UsernamePasswordCredentialsProvider
import org.eclipse.jgit.lib.Ref

object GitDependency{
  val GitUrl = "(git:|https:|file:/)//([^/]+)/(.+)".r
}
case class GitDependency(
  url: String, ref: String, subDirectory: Option[String] = None // example: git://github.com/cvogt/cbt.git#<some-hash>
)(implicit val logger: Logger, classLoaderCache: ClassLoaderCache, context: Context ) extends DependencyImplementation{
  import GitDependency._
  override def lib = new Lib(logger)

  // TODO: add support for authentication via ssh and/or https
  // See http://www.codeaffine.com/2014/12/09/jgit-authentication/
  private val GitUrl( _, domain, path ) = url  
  case class GitCredentials(
    username: String,
    password: String
  )

  private object checkoutCache extends Cache[File]
  def checkout: File = checkoutCache{
    def authenticate(creds: Option[GitCredentials], git: CloneCommand): CloneCommand = creds match {
      case Some(credentials) => git.setCredentialsProvider(new UsernamePasswordCredentialsProvider(credentials.username, credentials.password))
      case None => git
    }
    val checkoutDirectory = context.cache ++ s"/git/$domain/$path/$ref"
    if(checkoutDirectory.exists){
      logger.git(s"Found existing checkout of $url#$ref in $checkoutDirectory")
    } else {
      logger.git(s"Cloning $url into $checkoutDirectory")
      val credentials = {
        try {
          val credentials = scala.io.Source.fromFile(context.projectDirectory + "/git.login").mkString.split("\n")
          Some(GitCredentials(credentials(0), credentials(1)))
        } catch {
          case e: FileNotFoundException => None
        }
      }
      val git = authenticate(credentials, Git.cloneRepository().setURI(url))
          .setDirectory(checkoutDirectory)
          .call()

      logger.git(s"Checking out ref $ref")
      git.checkout()
          .setName(ref)
          .call()
    }
    checkoutDirectory
  }
  private object dependencyCache extends Cache[DependencyImplementation]
  def dependency = dependencyCache{
    DirectoryDependency(
      context.copy(
        projectDirectory = checkout ++ subDirectory.map("/" ++ _).getOrElse("")
      )
    )
  }

  def dependencies = Seq(dependency)

  def exportedClasspath = ClassPath()
  private[cbt] def targetClasspath = exportedClasspath
  def needsUpdate: Boolean = false
}