import sbt._
import Keys._
import com.github.jodersky.build.NativeKeys._

object Jni {
  val jdkHome = settingKey[File]("Home of JDK.")
  val javahHeaderDirectory = settingKey[File]("Directory where generated javah header files are placed.")
  val javahClasses = settingKey[Seq[String]]("Fully qualified names of classes containing native declarations.")
  val javah = taskKey[Seq[File]]("Generate JNI headers.")

  val defaultSettings: Seq[Setting[_]] = Seq(
    jdkHome := file(sys.env("JAVA_HOME")),
    javahHeaderDirectory := (sourceManaged in Native).value / "javah",
    javah := {
    
      val cp = (classDirectory in Compile).value
      for (clazz <- javahClasses.value) {
        val parts = Seq(
          "javah",
          "-d", javahHeaderDirectory.value,
          "-classpath", cp,
          clazz)
        val cmd = parts.mkString(" ")
        val ev = Process(cmd) ! streams.value.log
        if (ev != 0) throw new RuntimeException("Error occured running javah.")
      }
      IO.listFiles(javahHeaderDirectory.value)
     },
     sourceGenerators in Native <+= javah map {headers =>
       headers
     },
     includeDirectories in Native += javahHeaderDirectory.value,
     javah <<= (javah dependsOn (compile in Compile)),
     includeDirectories in Native += jdkHome.value / "include"
  )
}